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Patrick McCullough: Good morning, everybody. This is Patrick McCullough. I am

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Patrick McCullough: I have pre-recorded this for the meeting. Sorry I could not be with you today.

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Patrick McCullough: I'm recording this on Friday, November 10th.

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Patrick McCullough: And this presentation is going to cover weed control topics in turfgrass management.

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Patrick McCullough: We're going to review the basics and also get some recent updates on some current trends

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Patrick McCullough: and some new products that are coming out in the turfgrass industry for pre- and post-emergent weed control.

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Patrick McCullough: Just to start off, going over some of the basics here.

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Patrick McCullough: Books for weed identification are very important for turfgrass managers to have.

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Patrick McCullough: We recommend two specific books for turfgrass managers to have to help identify weeds in their turf.

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Patrick McCullough: One is the Color Atlas of Turfgrass Weeds.

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Patrick McCullough: This is a hardback book published by the Golf Course Superintendents Association of America.

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Patrick McCullough: The other is Weeds of Southern Turfgrass.

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Patrick McCullough: This is a UGA publication that you can get to the Athens bookstore.

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Patrick McCullough: Both of these books are available online.

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Patrick McCullough: You can buy them through the Amazon site, eBay, and various other online sites.

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Patrick McCullough: vendors. But weed identification is very critical. We need to first identify the weed species

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Patrick McCullough: before we can select appropriate control options. And having a good book to reference can help

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Patrick McCullough: you key out a weed species as you see new species emerging in your turf.

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Patrick McCullough: Weed identification books are typically broken down into two main categories.

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Patrick McCullough: The first is grassy weeds versus broadleaf weeds.

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Patrick McCullough: Weeds are typically classified as either grasses or broadleaf weeds, monocots or dicots.

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Patrick McCullough: There's also a third category that we often find in weed identification books,

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Patrick McCullough: sort of a miscellaneous weed species section, and this is grass-like weeds.

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Patrick McCullough: This includes everything from sedges, wild garlic, wild onion, plants like Star of Bethlehem.

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Patrick McCullough: These plants typically don't fall under the category of grasses or broadleaf weeds,

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Patrick McCullough: but they are in that third category of grass-like weeds.

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Patrick McCullough: Some of the key characteristics that can help you identify weed species, starting with seed heads.

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Patrick McCullough: This is usually the first characteristic that I look for on a weed sample when we are trying to identify the species.

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Patrick McCullough: Most grassy plants have a very distinct seed head that is indicative of a certain species.

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Patrick McCullough: You can see here on this slide where we've got various seed heads on the top left there.

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Patrick McCullough: That is dallisgrass where it's a group of alternating spikes on the

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Patrick McCullough: seed head structure. The bottom left you can see crowfootgrass where the spikes

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Patrick McCullough: join together at the main point at the end of the seed head stem there. So these

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Patrick McCullough: are all very good characteristics that can help you quickly identify a weed species.

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Patrick McCullough: Typically in turfgrass we don't always have seed heads present, especially during the growing season when we're constantly mowing off shoot growth and the seed head formation.

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Patrick McCullough: But this is typically the best characteristic to quickly key out a weed species.

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Patrick McCullough: species that you may have in your turf. Here's a good example looking at two Paspalum

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Patrick McCullough: species here. You can see they have a very similar seed head spike

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Patrick McCullough: there between bahiagrass and dallisgrass.

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Patrick McCullough: These are two warm season perennial weedy species that have very different selective

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Patrick McCullough: control options.

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Patrick McCullough: We can get very good control of bahiagrass using herbicides like metsulfuron and various

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Patrick McCullough: warm season species. Whereas dallisgrass, we need to have very specific application programs and certain turfgrass species.

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Patrick McCullough: So getting the identification of those species keyed out can be critical. You can see

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Patrick McCullough: bahiagrass has a B-shaped seed head where the spikes join at the

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Patrick McCullough: base of the seed head versus dallisgrass that again has the alternating spike. So if

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Patrick McCullough: you don't have that seed head structure present, it may be difficult to key out those two weed

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Patrick McCullough: species in your turf. So a good example there where seed heads can help you identify the species

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Patrick McCullough: of the weed.

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Patrick McCullough: Here's a look at the Poa annua seed head. We're going to start seeing a lot more this

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Patrick McCullough: here in the winter and the springtime. The panicle inflorescence where it's got multiple

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Patrick McCullough: branches and this is also a great characteristic to determine Poa annua versus some of the other

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Patrick McCullough: grassy weeds we may have present in turf.

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Patrick McCullough: Grassy weeds also have a very distinct structure on the base of the leaf blade called ligules.

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Patrick McCullough: This is a structure that is found at the base of the leaf where it joins the stem.

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Patrick McCullough: Grassy weeds have typically a very distinct ligule that can help you determine the species if you do not have a seed head present.

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Patrick McCullough: Ligules can be tall, fleshy, white structures. They can be smooth there on the margins.

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Patrick McCullough: Some weeds like barnyardgrass on the top right of this slide do not have a distinct ligule where that structure is absent.

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Patrick McCullough: from the plant. So if you do not see a ligule, very good chance it could be barnyardgrass

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Patrick McCullough: in the summertime versus crabgrass that has a very similar appearance but has a fleshy

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Patrick McCullough: ligule often with a fringe of hairs there at the base of the leaf. So ligules are distinct

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Patrick McCullough: structures on grassy plants only, broadleaf weeds and sedges. We are not looking for ligules at the base of the

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Patrick McCullough: but good characteristic to help identify grassy weed species.

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Patrick McCullough: Broadleaf weeds often have distinct flowers. They can have colorful showy flowers like you see there on the top left with weeds like oxalis.

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Patrick McCullough: Other weeds like henbit, purple dead nettle, can have very small flowers but can be very

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Patrick McCullough: colorful, pink to purplish in color as the plant matures.

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Patrick McCullough: We can also use flowers to determine one species from another based on the color of the

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Patrick McCullough: petals on the flower. A good example here are the two day flowers where the species on the left has two blue petals and one white petal versus spreading day flower on the right that's got three blue petals. So good examples there where flowers can help you determine the species on broadleaf weed and the colors and the size of the flower also can be a good characteristic to help you identify a

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Patrick McCullough: broadleaf weed in your turfgrass. Broadleaf weeds, we can also take a look at how the

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Patrick McCullough: leaves are arranged on the stems. Some broadleaf weeds can have sort of the alternate arrangement

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Patrick McCullough: of leaves there on the stem. Some can also have the opposite arrangement where the leaves

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Patrick McCullough: sort of join together at the base of the stem of the plant.

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Patrick McCullough: So something else to consider as you are trying to key out weeds species.

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Patrick McCullough: This is how are the leaves arranged on the stem of the plant.

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Patrick McCullough: Some weeds have dense hairs all over the leaves and the stems like you see there on

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Patrick McCullough: the left with sticky chickweed.

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Patrick McCullough: And then some plants have a few hairs or are smooth like you see with common chickweed on

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Patrick McCullough: the right.

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Patrick McCullough: Common chickweed typically has soft hairs on the margin of the leaf.

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Patrick McCullough: versus sticky chickweed, which is generally covered with hairs on the leaves and stems.

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Patrick McCullough: Another good example where you can take a look at the hairs on the plant to help key out a grassy weed would be crabgrass.

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Patrick McCullough: We have various crabgrass species that are found in turfgrass in Georgia.

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Patrick McCullough: Smooth crabgrass gets its name because it is hairless.

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Patrick McCullough: Large crabgrass is covered with hairs all over the stems and all over the leaves.

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Patrick McCullough: And then southern crabgrass typically has hairy stems, hairy stolons, and has smooth leaves.

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Patrick McCullough: So another good example where the hairs on the plant can help you identify the species of the weed.

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Patrick McCullough: And then of course leaf markings, other characteristics to key out broadleaf weeds.

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Patrick McCullough: White clover on the left with the white markings on the base of the leaf

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Patrick McCullough: versus spotted burr clover on the right that has the purplish dot there in the center of the leaf.

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Patrick McCullough: This is important because we're looking at two different clover species.

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Patrick McCullough: One is a cool season perennial white clover versus the winter annual spotted burr clover.

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Patrick McCullough: Looking at characteristics, identifying the plant can help you determine when those weeds will emerge,

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Patrick McCullough: how they're going to grow, and how we can plan weed control programs around their lifecycle.

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Patrick McCullough: Right now we're seeing many winter annual weeds begin to germinate. We're already seeing species like henbits, weeds like annual bluegrass, bittercress, and hop clovers.

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Patrick McCullough: These are true winter annual weeds that are germinating in the fall. They are starting to grow actively in landscapes and in turfgrass.

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Patrick McCullough: These plants go to seed in the springtime and then they will complete their life cycle and then die out in the summertime.

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Patrick McCullough: And this is a good example of the annual life cycle that these weeds will grow for one year and then go to seed and then die out.

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Patrick McCullough: The advantage of this life cycle is that it is predictable.

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Patrick McCullough: We know when annual bluegrass begins to germinate in turfgrasses.

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Patrick McCullough: We know when crabgrass begins to germinate in the late winter and springtime.

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Patrick McCullough: And therefore, we can plan management programs around when these weeds begin to emerge in turfgrass.

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Patrick McCullough: And we can apply pre-emergent herbicides to prevent their establishment based on when these weeds begin to germinate

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Patrick McCullough: in the soil. Summer annual weeds include species like goosegrass, crabgrass, foxtail, sandbur.

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Patrick McCullough: Some of the broadleaf weeds that are true summer annuals include species like spotted spurge,

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Patrick McCullough: Doveweed, purslane, these are all weeds that germinate in the springtime.

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Patrick McCullough: They resume active growth throughout the summertime.

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Patrick McCullough: They go to seed in the fall and then they transition out and die out in the wintertime.

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Patrick McCullough: So they complete their lifecycle during the warm season of the year.

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Patrick McCullough: Perennial weeds are much more difficult to control in turfgrass than the annuals because these plants can germinate from seed, but they can also regrow from tap roots and below ground plant parts, stolons, rhizomes, and tubers.

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Patrick McCullough: Simple perennials can primarily be reproduced by a seed. We can partially control these plants by hand pulling and digging them out of the ground.

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Patrick McCullough: Pre-emergent herbicides can be effective, but they are often providing erratic levels of control.

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Patrick McCullough: because these plants can also emerge from below ground vegetative structures.

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Patrick McCullough: So perennials are less predictable on their establishment and their growth.

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Patrick McCullough: They are much more difficult to control than the annual weeds that we have in turfgrass.

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Patrick McCullough: A good example of a simple perennial that is starting to emerge in turf in the fall. Weeds like wild garlic, wild onion, they are emerging from not only seed, but they are also starting to establish from below ground bulbs.

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Patrick McCullough: that stay dormant during the summertime. As temperatures cool down, these plants will

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Patrick McCullough: then begin to reemerge and wild garlic can be a very troublesome weed and dormant turf

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Patrick McCullough: grasses during the wintertime. So typically, pre-emergent herbicides do not control plants

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Patrick McCullough: that are emerging from below ground vegetative structures, such as below ground bulbs like

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Patrick McCullough: we see with wild garlic.

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Patrick McCullough: Complex perennials are the most difficult weeds to control in turfgrass because they are going to survive multiple years. They primarily reproduce and spread through asexual reproduction, which includes

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Patrick McCullough: Stolens, rhizomes, tubers such as with the sedges. These weeds include species such as white clover, Canada thistle, ground ivy, bermudagrass, yellow nutsedge, purple nutsedge. These are all perennial weeds.

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Patrick McCullough: that are going to survive multiple years in our lawns and landscapes.

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Patrick McCullough: Management implications here, we can hand pull and dig some of these plants out of the ground,

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Patrick McCullough: but it's often not a long-term control strategy.

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Patrick McCullough: Because these plants can spread laterally, because they can produce runners, those plants can then create daughter plants and trying to dig those plants out of the ground, we often leave behind some of the stems and stolons that are present in a turf.

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Patrick McCullough: And when they're growing in patches, sometimes the best way to

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Patrick McCullough: control these species, especially in turf, is to come in with non-selective options such as roundup and

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Patrick McCullough: just treating the patch and then treating the area around the patch to ensure that you're getting all the surrounding

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Patrick McCullough: stems and stolons that may have

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Patrick McCullough: been created from that

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Patrick McCullough: main patch of the weed.

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Patrick McCullough: A good example here of a complex perennial is bermudagrass. This of course is a major

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Patrick McCullough: warm season turfgrass species, but if you had Bermuda growing in the middle of centipedegrass,

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Patrick McCullough: zoysiagrass, or fescue, or various other turf species, it can be a long-term invasive

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Patrick McCullough: weed species that can be a long-term invasive weed species.

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Patrick McCullough: and be very competitive with other turf species. And if it's not controlled early,

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Patrick McCullough: bermudagrass is going to spread from lateral stems and it will eventually have significant competition that can lead to

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Patrick McCullough: the need to renovate a lawn because selective control of bermudagrass is very difficult in many warm and cool season turfgrass species.

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Patrick McCullough: So it's important to routinely scout your turf. You know, identify weeds that may warrant

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Patrick McCullough: control, but also note new weed species that may be present. Early detection is very critical,

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Patrick McCullough: especially with perennial weeds. We want to get on top of these species as soon as possible,

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Patrick McCullough: get them removed, hand pull them out, treat herbicides if needed, and prevent their spread

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Patrick McCullough: populations because most of the time if a perennial weed is left uncontrolled it's going to over time

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Patrick McCullough: spread reproduce and create a long-term problem for us so detecting these weeds early on can be

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Patrick McCullough: very critical a good example would be something like purple nutsedge where if you have a few small

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Patrick McCullough: plants it's important to get those

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Patrick McCullough: controlled, get them removed because there will be significant reproduction below ground with tuber chains and that weed will continue to spread and

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Patrick McCullough: be a very severe infestation over time if it's left uncontrolled.

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Patrick McCullough: Also, as you are identifying new weed species present, it's important to evaluate turfgrass cultural practices that may need to be adjusted.

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Patrick McCullough: Oftentimes, when we see weeds that are starting to emerge or new weed species, they are taking advantage of the lack of competition from turfgrass growth.

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Patrick McCullough: And if we can make adjustments in mowing programs, fertility, modifying how much we irrigate,

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Patrick McCullough: this all can enhance turfgrass competition to reduce the overall spread and the population of weeds present in our turfgrass.

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Patrick McCullough: A good example of a cultural practice that will influence the population of a weed species

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Patrick McCullough: in a lawn is mowing height on crabgrass. This is very important in tall fescue where during

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Patrick McCullough: the summertime, tall fescue typically declines due to summer stress and crabgrass becomes

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Patrick McCullough: very competitive. But making a simple adjustment in the height of cut of a tall fescue lawn

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Patrick McCullough: can significantly increase the competition.

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Patrick McCullough: of tall fescue with crabgrass in the summertime. So this is a look at a study that was conducted in

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Patrick McCullough: North Carolina where they looked at four different mowing heights of tall fescue on the percent cover of crabgrass

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Patrick McCullough: in that lawn. And as you can see when they raised the mowing height from one to four inches,

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Patrick McCullough: they cut the crabgrass population down from 95% cover to basically 0%.

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Patrick McCullough: So as they increased the height of tall fescue, it became more competitive.

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Patrick McCullough: It was able to shade out crabgrass and they were able to basically prevent

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Patrick McCullough: the emergence of crabgrass because the fescue was so competitive.

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Patrick McCullough: So mowing height and mowing frequency can be very critical.

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Patrick McCullough: This will affect the competitive growth of turfgrasses

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Patrick McCullough: can help cut down on weed populations and which over time can of course help

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Patrick McCullough: cut down on the need to apply herbicides and various other management inputs. So

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Patrick McCullough: depending on the species that you're managing, there is an appropriate mower

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Patrick McCullough: and height of cut and mowing frequency.

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Patrick McCullough: to prevent scalping. So typically we want to remove no more than one-third of the

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Patrick McCullough: total leaf area with the mowing. And based on the turf species that could be

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Patrick McCullough: every five to seven days.

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Patrick McCullough: five to ten days for grass like centipede that doesn't grow quite as quickly as some

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Patrick McCullough: of the other warm season grasses. So something to consider is just make sure you are mowing

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Patrick McCullough: at the appropriate height and the appropriate frequency during active growth. And this will

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Patrick McCullough: just help promote the recovery of a lawn from a mowing operation and should help with promoting competition with weed species

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Patrick McCullough: in your turf. We populations are influenced by irrigation, how much we water,

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Patrick McCullough: how frequently. Typically weed species thrive in areas that remain wet for

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Patrick McCullough: extended periods of time. A good example there is weeds like dollarweed. This is a

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Patrick McCullough: slide that shows the effects of watering programs either daily, conditionally, or as or when the grass showed severe wilt on the x-axis there on percent dollarweed cover.

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Patrick McCullough: And this was a three-year field study in Florida and you can see there where they watered every single day. They had about five to six

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Patrick McCullough: fold increase in dollarweed cover compared to when they watered as the grass needed it.

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Patrick McCullough: So how much we water will certainly influence the pressure and the growth of weeds like sedges,

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Patrick McCullough: which thrive in wet soils. White clover likes to have wet feet as well, so poorly drained, high irrigation,

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Patrick McCullough: programs will certainly favor and encourage the growth of those types of weeds in our turf.

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Patrick McCullough: For weeds in the wintertime, Poa Annua likes also to have wet soils. It's going to thrive in poorly drained areas.

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Patrick McCullough: making modifications in the frequency of the watering program, improving drainage, and also trying to relieve compaction,

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Patrick McCullough: trying to promote the health of the grass by core airification and minimizing compaction can also help reduce weed populations in your turfgrass as well.

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Patrick McCullough: Here's a picture of a tall fescue lawn that has a significant infestation of broadleaf

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Patrick McCullough: dock. You would think that looking at this picture, there's a major problem with this

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Patrick McCullough: weed species in this area. However, as we pull back from this picture, you can see that

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Patrick McCullough: only that center plot, that center rectangle has broadleaf dock present.

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Patrick McCullough: Whereas all the other rectangles of different tall fescue cultivars are weed-free.

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Patrick McCullough: And this is a picture of a tall fescue NTEP trial where that specific seedlot that they seeded

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Patrick McCullough: had seedlot contamination with broadleaf docks. So they brought that

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Patrick McCullough: seed in when they planted that particular plot. And this is just a great example of

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Patrick McCullough: the importance of planting high-quality certified seed so that we're not

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Patrick McCullough: bringing in new weed species when we plant. And this is a look at

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Patrick McCullough: a fescue lawn there where they bought basically the low quality seed and this can be an issue with a lot of the cheap seed that is sold in the big box retailers

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Patrick McCullough: that may have noxious weeds present or unwanted species such as ryegrass or carpet grass present

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Patrick McCullough: in the seed bag. So just taking a look at the percent seed, what's in the bag that

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Patrick McCullough: you're purchasing, and just make sure that you are making a good investment

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Patrick McCullough: when you are planting turfgrasses, not only from seed but sod as well. Looking at

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Patrick McCullough: the sod before you purchase it, making sure that there's no weeds present can

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Patrick McCullough: certainly be important so you're not bringing in weeds when you're planting a

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Patrick McCullough: a new field or

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Patrick McCullough: new lawn. Pre-emergent herbicides are some of the most important tools that we have to prevent the establishment of weed species and turfgrass.

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Patrick McCullough: Pre-emergent herbicides are applied prior to weed seed germination. So we need to get these herbicides out in high enough concentration before we see the emergence of

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Patrick McCullough: winter and summer annual weeds.

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Patrick McCullough: Pre-emergent herbicides are applied to the soil. They are tightly bound to the upper half inch or so of the soil profile and they are not readily mobile in the soil. So they are bound and they typically stay put

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Patrick McCullough: once they finally bind to the soil.

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Patrick McCullough: Pre-emergent herbicides are concentrated

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Patrick McCullough: in the upper layer of the soil profile,

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Patrick McCullough: which is important because that is where

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Patrick McCullough: the weed seed bank is in the soil.

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Patrick McCullough: Weeds are going to germinate and the young roots

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Patrick McCullough: and shoots will absorb that pre-emergent herbicide

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Patrick McCullough: out of the soil.

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Patrick McCullough: It will then absorb that product

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Patrick McCullough: through the soil water solution.

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Patrick McCullough: And most pre-emergent herbicides are going to tie up cell division.

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Patrick McCullough: So weed seedlings that germinate first,

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Patrick McCullough: taking the herbicide will fail to establish a healthy root system and they will die out.

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Patrick McCullough: Pre-emergent herbicides do not prevent weed seed germination.

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Patrick McCullough: So the weeds must first germinate. They must take in the herbicide through the roots and shoots. And that is how we control weeds prior to establishment with the use of a pre-emergent herbicide in a lawn and landscape.

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Patrick McCullough: Pre-emergent herbicides typically do not inhibit the root growth of well-established

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Patrick McCullough: turfgrasses.

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Patrick McCullough: Usually turfgrasses that are mature have a deep and healthy root system that penetrate

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Patrick McCullough: below the layer or where the presence of that pre-emergent herbicide is in the soil.

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Patrick McCullough: A lawn that has a three to four inch root depth on it typically will not be affected

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Patrick McCullough: by pre-emergent herbicides concentrated in the upper half inch of the soil profile.

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Patrick McCullough: Where we run into trouble with pre-emergent herbicides and turfgrass rooting is when we

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Patrick McCullough: have winter kill, when we have thinned out grass, when we have disease, and that grass

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Patrick McCullough: is trying to re-root into treated areas.

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Patrick McCullough: when it's spreading a lateral stem or a stolon,

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Patrick McCullough: and it's trying to tack down a new root on that lateral stem,

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Patrick McCullough: that's where we see the greatest potential

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Patrick McCullough: to inhibit turfgrass rooting is when

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Patrick McCullough: it's trying to produce a new root on a lateral stem.

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Patrick McCullough: when it's trying to peg down in a bare ground situation. But generally speaking, well-established lawns, there's limited to no risk on the health of the root system using pre-emergent herbicides at appropriate label use rates.

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Patrick McCullough: We have a wide variety of pre-emergent herbicides that are available to turfgrass managers.

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Patrick McCullough: They're sold under a wide variety of trade names and they can also be found in various

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Patrick McCullough: formulations, either sprayable or spreadable formulations.

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Patrick McCullough: Some of these can be impregnated on a fertilizer with a weed and feed type of application.

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Patrick McCullough: So some of these herbicides like Prodiamine and Pendimethalin, these are widely used for

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Patrick McCullough: pre-emergent crabgrass control in the late wintertime and in the spring.

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Patrick McCullough: We can also use these herbicides in late summer and fall to prevent the establishment of annual

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Patrick McCullough: grassy weeds.

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Patrick McCullough: So we can control annual bluegrass with a timely application of those herbicides as well in the fall.

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Patrick McCullough: However, pre-emergent herbicides generally do not provide acceptable levels of post-emergent weed control.

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Patrick McCullough: So once the weed has established, these products generally are not effective for controlling established weeds.

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Patrick McCullough: present in our turf. There are some active ingredients like isoxaben or

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Patrick McCullough: gallery which is very strong on broadleaf weeds specifically but a little

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Patrick McCullough: bit weaker on grassy weeds versus some products like prodiamine which is very

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Patrick McCullough: strong on grassy weeds but can be weak on broadleaf weeds. So these all have

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Patrick McCullough: strengths and weaknesses, depending on the weeds that you're targeting with that application.

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Patrick McCullough: We are using pre-emergent herbicides to control summer and winter annual weeds only.

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Patrick McCullough: Again, these are weeds that establish from seed.

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Patrick McCullough: And pre-emergent herbicides are most effective for controlling weeds that are germinating from seed only.

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Patrick McCullough: We are not targeting perennial weeds with pre-emergent herbicides.

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Patrick McCullough: We are also not targeting weeds that are currently present in our turf,

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Patrick McCullough: generally speaking with most pre-emergent herbicides,

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Patrick McCullough: because they are not effective once the plant has been established and is healthy and actively growing.

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Patrick McCullough: One of the concerns that we have is we have to get pre-emergent herbicides activated.

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Patrick McCullough: We need to irrigate behind these treatments to get them off of the shoots of turfgrass

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Patrick McCullough: and get them activated in the soil so that they will be available for absorption.

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Patrick McCullough: by weed seedlings. So one of the concerns is that if you cannot irrigate and you don't have timely rainfall,

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Patrick McCullough: going out with a sprayable formulation could lead to potential failures because it's not getting into the soil and it's not getting activated as readily as a dry granule formulation.

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Patrick McCullough: We can have herbicide losses with a sprayable formulation where it fails to get to the soil,

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Patrick McCullough: either through photo degradation or breakdown by sunlight,

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Patrick McCullough: volatilization where it's lost through a gas form,

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Patrick McCullough: and then of course clipping collection and traffic.

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Patrick McCullough: If we actually physically remove that herbicide from the area,

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Patrick McCullough: of course it's not going to be in high enough concentration,

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Patrick McCullough: to provide effective weed control when the product gets into the soil.

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Patrick McCullough: Dry granular formulations, spreadable products are much better if you do not have irrigation

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Patrick McCullough: or we're in a drought situation.

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Patrick McCullough: These products can get to the soil much better and they are not moved and there's much less

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Patrick McCullough: potential for losses using a granular product compared to a sprayable product if you cannot

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Patrick McCullough: water behind the treatments.

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Patrick McCullough: Typically, we are looking at pre-emergent herbicide applications in March in most parts of the state of Georgia.

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Patrick McCullough: The application timing is going to depend on soil temperatures.

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Patrick McCullough: So in the springtime, we typically get our pre-emergent herbicide applications out when soil temperatures reach the low 50s.

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Patrick McCullough: in the upper two inches of the soil profile. And this is going to vary based on where you are in the state. So obviously the southern part of Georgia is going to warm up much earlier than the central and northern part of the state. And these dates are just general guidelines for

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Patrick McCullough: when we should be targeting getting those applications out for pre-emergent weed control.

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Patrick McCullough: A very good website to track local soil temperatures, air temperatures, and growing degree days is georgiaweather.net.

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Patrick McCullough: GeorgiaWeather.net has many different weather stations scattered throughout the state,

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Patrick McCullough: and it is a very good resource to get local soil temperatures to help time management inputs

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Patrick McCullough: such as pre-emergent herbicide applications

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Patrick McCullough: in the spring and the fall. So georgiaweather.net

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Patrick McCullough: you can go in type in your location and it will give you the closest weather

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Patrick McCullough: station to your area and a great way to

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Patrick McCullough: track local growing conditions so that you can more effectively time

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Patrick McCullough: pre-emergent herbicides in the spring.

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Patrick McCullough: Pre-emergent herbicides using turfgrass all have different lengths of residual activity.

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Patrick McCullough: Some of these herbicides are going to last longer in the soil at labeled use rates compared

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Patrick McCullough: to products that have a moderate or short activity such as products like Siduron, Tupersan,

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Patrick McCullough: pendimethalin, dithiopyr. These typically are going to last a few months in the soil based on

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Patrick McCullough: labeled use rate. Products like prodiamine, oxadiazon at labeled rates are going to last

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Patrick McCullough: four to six months depending on the conditions, soil temperatures, and factors that are going to influence the

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Patrick McCullough: residual effects of a herbicide and the degradation of the herbicide in the soil.

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Patrick McCullough: But something to have an appreciation for is that there are pre-emergent herbicides that

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Patrick McCullough: you can use that will provide four to six weeks of residual weed control.

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Patrick McCullough: And that may be all you need if you need to come in and seed or sod in a treated area in

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Patrick McCullough: There are some products that will not last quite as long.

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Patrick McCullough: And then there may be cases such as in long care where you want the longest control possible.

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Patrick McCullough: So going with a Prodiamine treatment may be more appropriate there where you're trying

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Patrick McCullough: to extend the length of residual control throughout the growing season.

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Patrick McCullough: Winter annual weeds, we typically target getting pre-emergent herbicides out in September in most areas in the state.

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Patrick McCullough: South Georgia, typically we start looking at pre-emergent herbicide applications around the first week of October.

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Patrick McCullough: This is when soil temperatures start to dip below 70 degrees.

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Patrick McCullough: So as we cool down, winter annual weeds begin germination.

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Patrick McCullough: and we need to get our pre-emergent herbicides out before those weeds start to emerge.

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Patrick McCullough: Weeds like annual bluegrass, henbit, we can see them germinate in mid-September, late September,

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Patrick McCullough: depending on where you are in the state. So this is just a general reference and a guideline to

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Patrick McCullough: get fall pre-emergent herbicides out at various locations in the state.

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Patrick McCullough: One of the ways that we can extend the length of pre-emergent weed control is to apply split applications of a pre-emergent herbicide. So instead of putting out all the product at once, we can make multiple applications at a six to eight week interval.

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Patrick McCullough: A good example here is instead of applying Barricade or Prodiamine to one pound active ingredient per acre, putting that application into half a pound active applied in March and come back around late May or June with another half pound active per acre has shown to extend residual control greater than just putting out all the product at once.

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Patrick McCullough: We are able to get better control of the late season flushes of crabgrass and other annual

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Patrick McCullough: weeds by just splitting that application and going with a split program.

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Patrick McCullough: Helps provide a fresh supply of that herbicide to the soil and can extend the length of control

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Patrick McCullough: compared to just a single treatment of that total application rate all with one shot.

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Patrick McCullough: Pre-emergent herbicides that we can use this time of year for controlling winter annual

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Patrick McCullough: weeds such as Poa annua. There are many different products on the market. Many of the herbicides

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Patrick McCullough: that control crabgrass and goosegrass also can provide pre-emergent control of weeds like annual bluegrass.

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Patrick McCullough: So crabgrass halts preventer, crabgrass preventer herbicide can also be used in the fall to control weeds like annual bluegrass.

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Patrick McCullough: So we have products like prodiamine, pendimethalin.

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Patrick McCullough: One of the most popular herbicides now in lawn care in Georgia and in golf course turf in parks as well is Specticle.

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Patrick McCullough: The active ingredient indaziflam is very good, very active on Poa annua.

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Patrick McCullough: And it also provides a different mode of action to the dinitroanilines that we are using for

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Patrick McCullough: controlling crabgrass and other weeds with that different mode of action.

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Patrick McCullough: Some of the concerns that we have right now especially with annual bluegrass is herbicide

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Patrick McCullough: resistance. We are seeing pictures like this where turf managers are

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Patrick McCullough: telling us that control is just not what it used to be using the same product year after year.

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Patrick McCullough: And typically what we're seeing with weeds like annual bluegrass that have received the same herbicide in an area for multiple years is segregation in the population.

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Patrick McCullough: We are seeing a shift where we are seeing resistant biotypes emerging that are not responding

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Patrick McCullough: to a herbicide that may have been used exclusively for a certain period of time.

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Patrick McCullough: And this resistance issue is increasing with annual bluegrass, goosegrass, and other weeds

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Patrick McCullough: in turfgrass. And something to have an appreciation for is that if you use the same

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Patrick McCullough: products or the same herbicide mode of action year over year, you can cause a shift in the weed population. We're seeing this right now,

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Patrick McCullough: especially with annual bluegrass and turfgrass throughout the state of Georgia where we're seeing resistance issues

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Patrick McCullough: that are increasing in lawns, golf courses, sod farms, and various turfgrass areas.

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Patrick McCullough: Herbicide resistance occurs through selection pressure.

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Patrick McCullough: This graph shows in year one where all the green plants present are controlled by a certain herbicide.

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Patrick McCullough: However, that one plant in orange

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Patrick McCullough: survives that treatment. It is a naturally resistant biotype that does not respond to that specific herbicide.

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Patrick McCullough: That one plant in year one could be one in a thousand, it could be one in a million, but over time with selection pressure,

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Patrick McCullough: using the same herbicide over and over, that one plant will spread, it will go to seed,

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Patrick McCullough: And over time, year two, year three, four, and five, we are shifting that population.

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Patrick McCullough: And we are giving the opportunity of that resistant biotype to spread, reproduce, and

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Patrick McCullough: it is not being controlled by the use of the same product over and over.

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Patrick McCullough: And then by year five, you've got a very serious problem where you are now dealing with a weed

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Patrick McCullough: population that is resistant to that specific herbicide. And this is something that we are

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Patrick McCullough: finding in turfgrass throughout the state. We're seeing more and more weeds with this issue that are not responding to a pre or post-emergent herbicide.

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Patrick McCullough: Typically what is happening here is resistant weeds have an altered target site.

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Patrick McCullough: where the herbicide simply just does not bind the way it normally does to a

359
00:40:23,320 --> 00:40:28,320
Patrick McCullough: susceptible population. So the target site where that herbicide normally binds

360
00:40:28,340 --> 00:40:32,380
Patrick McCullough: on the right of this slide, that herbicide is obviously not going to bind

361
00:40:32,560 --> 00:40:37,280
Patrick McCullough: properly and therefore it is not controlled. And this is the most common

362
00:40:37,440 --> 00:40:43,900
Patrick McCullough: form of herbicide resistance in a weed. It is a naturally occurring

363
00:40:44,299 --> 00:41:01,140
Patrick McCullough: traits in that specific biotype. So we are not causing a change in the plant by using a herbicide, but what we are doing is selecting for biotypes that have that mutation present that prevents that herbicide from binding properly to get effective control.

364
00:41:01,840 --> 00:41:06,400
Patrick McCullough: This is a big problem right now for us in Georgia with Poa annua.

365
00:41:07,440 --> 00:41:10,880
Patrick McCullough: Annual bluegrass is one of the most difficult weeds to control,

366
00:41:11,040 --> 00:41:14,700
Patrick McCullough: probably the most troublesome weed for us in turfgrass,

367
00:41:15,360 --> 00:41:16,460
Patrick McCullough: especially in the wintertime.

368
00:41:16,880 --> 00:41:21,760
Patrick McCullough: We are seeing widespread resistance to dinitroaniline pre-emergent herbicides.

369
00:41:22,820 --> 00:41:27,340
Patrick McCullough: This includes some of the active ingredients like pendimethalin and prodiamine.

370
00:41:28,000 --> 00:41:33,880
Patrick McCullough: Some of the other herbicides that are group three mitotic inhibitors include

371
00:41:34,040 --> 00:41:39,540
Patrick McCullough: products like Dimension. This is widely used for crabgrass but it has a similar

372
00:41:39,760 --> 00:41:44,280
Patrick McCullough: mode of action to the dinitroanilines and what we're seeing in Georgia is that

373
00:41:45,720 --> 00:41:49,060
Patrick McCullough: Poa annua populations that are resistant to pendimethalin and

374
00:41:49,060 --> 00:41:52,200
Patrick McCullough: pro-diamine are also cross-resistant to Dimension.

375
00:41:51,720 --> 00:41:57,900
Patrick McCullough: mentioned as well. So that is a concern because these are very popular pre-emergent herbicides.

376
00:41:58,960 --> 00:42:04,460
Patrick McCullough: Here's a look at Barricade resistant Poa and some of our field research where we went out

377
00:42:04,460 --> 00:42:09,240
Patrick McCullough: with Barricade at the standard timing. This is Prodiamine.

378
00:42:10,119 --> 00:42:16,680
Patrick McCullough: And you can see we're getting very significant failures in control with that pre-emergent

379
00:42:16,839 --> 00:42:20,320
Patrick McCullough: treatment of barricade there where it just looks like we sprayed water.

380
00:42:20,540 --> 00:42:27,300
Patrick McCullough: There's just no response at all. What we are doing is testing plants to confirm resistance

381
00:42:27,720 --> 00:42:33,940
Patrick McCullough: the field. So what we are doing is growing these plants out hydroponically and exposing

382
00:42:34,000 --> 00:42:40,540
Patrick McCullough: them to various concentrations of a pre-emergent herbicide. And what we're typically doing is

383
00:42:40,740 --> 00:42:48,000
Patrick McCullough: coming in and cutting the roots off the plants and then sticking them in the tanks that have

384
00:42:48,740 --> 00:42:49,240
Patrick McCullough: hydroponic

385
00:42:52,480 --> 00:42:58,520
Patrick McCullough: solutions with or without the pre-emergent herbicide present. And if a weed is resistant

386
00:42:58,740 --> 00:43:03,860
Patrick McCullough: to dinitroaniline herbicides like Prodiamine, it will grow a nice healthy root system in

387
00:43:03,860 --> 00:43:10,780
Patrick McCullough: the presence of that herbicide in the hydroponic tank. And this is what we're seeing where weeds

388
00:43:10,780 --> 00:43:15,680
Patrick McCullough: are growing right through pre-emergent herbicides like Prodiamine. We're growing a nice healthy

389
00:43:15,780 --> 00:43:18,000
Patrick McCullough: root system there versus the

390
00:43:18,080 --> 00:43:25,600
Patrick McCullough: susceptible biotypes on the right that are completely controlled by that treatment,

391
00:43:26,960 --> 00:43:33,320
Patrick McCullough: which is showing very susceptible root systems there, growing in the presence of that pre-emergent herbicide.

392
00:43:34,820 --> 00:43:39,540
Patrick McCullough: Fall is a great time of year also to come out with post-emergent herbicides to

393
00:43:39,740 --> 00:43:44,340
Patrick McCullough: control annual bluegrass. That is when winter annual weeds,

394
00:43:45,080 --> 00:43:51,060
Patrick McCullough: poa, henbit, hop clovers, that's typically when we get the best control.

395
00:43:51,850 --> 00:43:57,900
Patrick McCullough: When these plants are at the seedling stage, they are most susceptible. Certain products like Katana

396
00:43:58,440 --> 00:44:05,000
Patrick McCullough: monuments, some of the sulfonylureas can provide very good post-emergent

397
00:44:05,260 --> 00:44:10,000
Patrick McCullough: control early in the fall and then it has enough residual to get through peak

398
00:44:10,849 --> 00:44:15,579
Patrick McCullough: winter annual weed germination periods. Here's a look at Katana, which is applied

399
00:44:15,839 --> 00:44:19,660
Patrick McCullough: in the fall and this picture was taken in March in

400
00:44:19,720 --> 00:44:24,280
Patrick McCullough: you can just see the pressure of the annual bluegrass that sort of surrounds that plot there.

401
00:44:24,410 --> 00:44:30,400
Patrick McCullough: So this can be a very good treatment to control seedling winter weeds at that fall timing.

402
00:44:31,119 --> 00:44:36,220
Patrick McCullough: Typically getting these treatments out around mid-November, sometime around Thanksgiving or so,

403
00:44:37,380 --> 00:44:44,440
Patrick McCullough: can get very good post-emergent control of the seedling weeds and get you through that peak germination period

404
00:44:45,329 --> 00:44:46,920
Patrick McCullough: that will hold throughout the season.

405
00:44:47,540 --> 00:44:52,480
Patrick McCullough: However, again, we are seeing sulfonylurea resistance like this, where we come in and

406
00:44:52,480 --> 00:44:53,579
Patrick McCullough: we're getting just segregation.

407
00:44:54,079 --> 00:44:58,300
Patrick McCullough: You come in and you get complete control of some plants and other plants are growing right

408
00:44:58,380 --> 00:44:59,260
Patrick McCullough: through those treatments.

409
00:44:59,420 --> 00:45:05,480
Patrick McCullough: And this is a widespread problem now in turfgrass throughout the southeast, specifically with

410
00:45:05,599 --> 00:45:12,220
Patrick McCullough: sulfonylurea herbicides, triazine herbicides, and the dinitroaniline pre-emergent herbicides

411
00:45:12,380 --> 00:45:12,640
Patrick McCullough: as well.

412
00:45:14,460 --> 00:45:21,300
Patrick McCullough: What we're seeing is sort of classic target site resistance with sulfonylurea herbicides

413
00:45:22,020 --> 00:45:23,060
Patrick McCullough: with annual bluegrass.

414
00:45:23,920 --> 00:45:29,440
Patrick McCullough: Here's a look at a resistant biotype that we tested in the greenhouse on the top versus

415
00:45:29,560 --> 00:45:33,940
Patrick McCullough: the local Griffin biotype on the bottom there, susceptible population to monument.

416
00:45:34,580 --> 00:45:37,440
Patrick McCullough: You can see where we started these rate titrations.

417
00:45:38,380 --> 00:45:43,920
Patrick McCullough: with the resistant biotype, the standard labeled use rate is half an ounce of product per acre.

418
00:45:44,420 --> 00:45:50,480
Patrick McCullough: We went up to about a 300x rate and there was simply just no response there from the plant.

419
00:45:50,720 --> 00:45:57,280
Patrick McCullough: So this is a classic target site resistance where no matter how much herbicide you apply to the plant,

420
00:45:57,859 --> 00:46:05,500
Patrick McCullough: because there's an altered mutated target site, it is just not going to bind properly and there's no response from the plant.

421
00:46:05,880 --> 00:46:13,560
Patrick McCullough: So what we did was looked at some resistance management programs for controlling annual bluegrass last fall.

422
00:46:14,350 --> 00:46:20,700
Patrick McCullough: These were done on three different golf courses that had expressed concerns over herbicide resistance issues.

423
00:46:20,700 --> 00:46:27,600
Patrick McCullough: And I think this kind of tells a nice story to show some of the plans and programs that you could...

424
00:46:27,780 --> 00:46:32,500
Patrick McCullough: use in warm season grasses to combat herbicide resistant

425
00:46:32,720 --> 00:46:36,300
Patrick McCullough: Poa this fall and winter in your turf.

426
00:46:38,020 --> 00:46:41,820
Patrick McCullough: At these three golf courses we apply barricade at the standard pre-emergent

427
00:46:41,920 --> 00:46:42,160
Patrick McCullough: timing.

428
00:46:43,180 --> 00:46:49,220
Patrick McCullough: At golf course one and two, we saw that we had resistance problems where we were not getting good control.

429
00:46:49,460 --> 00:46:56,160
Patrick McCullough: At golf course three, we had susceptible Poa, so we had actually very good control at that third golf course.

430
00:46:56,819 --> 00:47:01,020
Patrick McCullough: However, when we switched from barricade to a different mode of action, which is Specticle,

431
00:47:02,020 --> 00:47:06,640
Patrick McCullough: we got basically good to excellent control at all three locations.

432
00:47:07,360 --> 00:47:24,420
Patrick McCullough: So rotating modes of action, rotating chemistries from a dinitroaniline to a different chemistry Specticle was a great tool to get that DNA resistant Poa control at golf course 1 and 2.

433
00:47:25,120 --> 00:47:29,700
Patrick McCullough: We also found simazine resistance at golf course one and three.

434
00:47:30,380 --> 00:47:35,400
Patrick McCullough: However, golf course two did have simazine susceptible Poa annua.

435
00:47:36,560 --> 00:47:41,340
Patrick McCullough: We also tested revolver, which is a sulfonylurea herbicide.

436
00:47:41,560 --> 00:47:45,680
Patrick McCullough: At golf course one and three, we had susceptible Poa to that mode of action.

437
00:47:46,180 --> 00:47:52,640
Patrick McCullough: However, at golf course two, where simazine was working, we had resistance issues there using revolver.

438
00:47:53,240 --> 00:48:06,520
Patrick McCullough: And what we found was that when we came in with a combination of the revolver with Simazine, having those two modes of action gave us complete control of Poa at all the golf courses that we tested.

439
00:48:06,670 --> 00:48:22,880
Patrick McCullough: So, we're going to have to do that.

440
00:48:08,160 --> 00:48:14,020
Patrick McCullough: Really the take home message here is that rotating modes of action can be important,

441
00:48:14,540 --> 00:48:17,620
Patrick McCullough: but for post-emergent Poa control in Georgia,

442
00:48:18,120 --> 00:48:20,860
Patrick McCullough: especially in bermudagrass and zoysiagrass turf,

443
00:48:21,640 --> 00:48:23,400
Patrick McCullough: coming in with two modes of action,

444
00:48:24,140 --> 00:48:32,100
Patrick McCullough: Combining a sulfonylurea herbicide with a triazine herbicide, two different chemistries that offer different modes of action,

445
00:48:32,930 --> 00:48:41,100
Patrick McCullough: can help control biotypes with suspected resistance issues to one of those modes of action.

446
00:48:41,420 --> 00:48:48,500
Patrick McCullough: So the combination, this is a fairly cost-effective way to help combat resistance issues.

447
00:48:49,440 --> 00:48:54,320
Patrick McCullough: and help prevent the spread of biotypes with herbicide resistance as well.

448
00:48:55,740 --> 00:49:03,900
Patrick McCullough: So for controlling Poa annua in centipedegrass, mid-November, early December, timings of Katana,

449
00:49:04,280 --> 00:49:10,780
Patrick McCullough: which is a sulfonylurea herbicide, can work very well with Simazine. We can also use rimsulfuron,

450
00:49:10,780 --> 00:49:15,760
Patrick McCullough: which is TranXit, in non-residential areas with Simazine at a quart per acre.

451
00:49:16,460 --> 00:49:22,720
Patrick McCullough: Having that simazine in there is a nice kicker to using sulfonylureas.

452
00:49:22,880 --> 00:49:31,480
Patrick McCullough: It is about a $5 per acre treatment and can provide a second mode of action in the mix with a sulfonylurea to help combat resistance.

453
00:49:32,000 --> 00:49:37,700
Patrick McCullough: Curb can also be used in non-residential turfgrass at that late November timing.

454
00:49:38,460 --> 00:49:45,280
Patrick McCullough: One and a half pounds active ingredient per acre can also help control Poa annua at that timing,

455
00:49:45,440 --> 00:49:47,200
Patrick McCullough: and it provides a different mode of action.

456
00:49:47,420 --> 00:49:51,079
Patrick McCullough: and then most other post-emergent herbicides used in turfgrass.

457
00:49:51,700 --> 00:49:57,960
Patrick McCullough: And then pre-emergent control, obviously, in September, the first week of October, depending

458
00:49:58,039 --> 00:50:05,020
Patrick McCullough: on where you are in the state, dinitroanilines, rotating as Specticles as possible, and lawns

459
00:50:05,020 --> 00:50:10,660
Patrick McCullough: and landscapes is a very good program to prevent the establishment of Poa in turf.

460
00:50:12,079 --> 00:50:15,880
Patrick McCullough: Here's a look at centipedegrass that was treated with the tank mixtures and you can

461
00:50:16,000 --> 00:50:24,020
Patrick McCullough: see using simazine with Katana, using it with rimsulfuron, it has shown to be safe

462
00:50:24,119 --> 00:50:30,059
Patrick McCullough: at that application time again in late fall. So as the grass is slowing down we can use

463
00:50:30,059 --> 00:50:36,599
Patrick McCullough: those combinations safely as long as the centipede is healthy and is not

464
00:50:37,900 --> 00:50:41,500
Patrick McCullough: growing under pressure from disease or other stresses, those

465
00:50:42,250 --> 00:50:45,080
Patrick McCullough: tank mixture combinations can be very effective for

466
00:50:45,440 --> 00:50:48,520
Patrick McCullough: controlling Poa and can be safe in that species.

467
00:50:51,110 --> 00:50:55,420
Patrick McCullough: For controlling Poa in Bermudagrass and Zoysiagrass, again sulfonylurea

468
00:50:55,560 --> 00:51:01,240
Patrick McCullough: urea herbicides applied with simazine is a great program. We've got a

469
00:51:01,320 --> 00:51:04,760
Patrick McCullough: lot more sulfonylureas that are safe for use in these

470
00:51:04,600 --> 00:51:11,500
Patrick McCullough: two turf species, products like Revolver, Monument, Katana, Tribute Total, those are all

471
00:51:12,700 --> 00:51:18,140
Patrick McCullough: sulfonylurea, ALS inhibiting herbicides, but having that second mode of action in there with

472
00:51:18,220 --> 00:51:23,080
Patrick McCullough: Simazine can make a big difference whether or not you're successful for controlling Poa,

473
00:51:23,740 --> 00:51:37,640
Patrick McCullough: Curb also again non-residential sites one and a half pounds active ingredient per acre and then pre-emergent control if possible in the fall is going to set you up for success for controlling Poa in those lawns.

474
00:51:38,360 --> 00:51:40,980
Patrick McCullough: We're also seeing resistance issues now with

475
00:51:41,960 --> 00:51:50,279
Patrick McCullough: Sedges, this is a look at Cyperus compressus annual sedge, which is a true summer annual, goes to seed.

476
00:51:50,740 --> 00:51:56,880
Patrick McCullough: We are seeing problems with multiple populations found throughout the state of

477
00:51:57,279 --> 00:52:02,420
Patrick McCullough: halosulfuron-resistant sedge, and it's also cross-resistant to other sulfonylureas.

478
00:52:02,599 --> 00:52:07,400
Patrick McCullough: So rotating modes of action there, coming in with sulfentrazone or Dismiss,

479
00:52:07,860 --> 00:52:17,520
Patrick McCullough: Having Basagran as a tank mix partner can also help combat resistance issues with ALS resistance sedges that we're seeing in the state.

480
00:52:18,520 --> 00:52:26,480
Patrick McCullough: There is also other sedge species that have confirmed resistance to post-emergent applications of sulfonylureas.

481
00:52:26,800 --> 00:52:36,859
Patrick McCullough: Products like halosulfuron or SedgeHammer, we have seen resistance with yellow nutsedge and various other sedge species that we can also find in turfgrass.

482
00:52:36,970 --> 00:52:40,740
Patrick McCullough: These have been reported in various cropping systems throughout the southeast.

483
00:52:41,599 --> 00:52:47,520
Patrick McCullough: Ways to combat resistance with sedges, again using Dismiss, which is a different mode of action.

484
00:52:47,859 --> 00:52:53,680
Patrick McCullough: sulfentrazone, 10 to 12 ounces of product per acre in a tank mixture with sulfonylureas.

485
00:52:54,440 --> 00:53:00,640
Patrick McCullough: can help control resistant biotypes and help delay the spread of resistance in sedge populations.

486
00:53:01,460 --> 00:53:03,000
Patrick McCullough: Basagran can also be used.

487
00:53:03,819 --> 00:53:07,859
Patrick McCullough: And we do have some pre-emergent herbicides that will control certain sedge species.

488
00:53:08,900 --> 00:53:11,779
Patrick McCullough: Products like Ronstar in non-residential turf.

489
00:53:12,480 --> 00:53:28,540
Patrick McCullough: Products like Echelon and Dismiss that contain sulfentrazone going out in late springtime with those treatments can provide pre-emergent control of sedges, such as annual sedge, yellow nutsedge, and certain kyllinga species.

490
00:53:28,600 --> 00:53:34,000
Patrick McCullough: species as well. And then we do have other pre-emergent herbicides that are labeled in

491
00:53:34,080 --> 00:53:39,600
Patrick McCullough: warm season turfgrasses like pennant, tower, and Freehand that also have very good activity

492
00:53:39,880 --> 00:53:43,200
Patrick McCullough: for pre-emergent control of said species.

493
00:53:44,300 --> 00:53:49,680
Patrick McCullough: Other herbicide resistant weeds that we have found in turf include goosegrass, which has

494
00:53:50,050 --> 00:53:56,680
Patrick McCullough: we found multiple populations with resistance to pre and post-emergent herbicides that are

495
00:53:56,830 --> 00:54:04,140
Patrick McCullough: popular in turfgrass. Spotted spurt, ryegrass, plantain, southern crabgrass. So this is an

496
00:54:04,190 --> 00:54:08,300
Patrick McCullough: issue that will continue to

497
00:54:10,540 --> 00:54:26,200
Patrick McCullough: be a problem for us in turfgrass. Something that turf managers need to have an appreciation for is how weeds develop resistance to herbicides and what we can do to be proactive in preventing resistance from becoming a long-term problem.

498
00:54:26,780 --> 00:54:34,240
Patrick McCullough: And sometimes we don't have alternative herbicide chemistries that are safe and selected for controlling resistant biotypes.

499
00:54:34,620 --> 00:54:36,860
Patrick McCullough: And that creates great concern for us.

500
00:54:37,400 --> 00:54:41,860
Patrick McCullough: But we are now seeing more and more weed species with resistance issues.

501
00:54:42,000 --> 00:54:47,980
Patrick McCullough: It's just something that you need to have an appreciation for, especially for weeds like

502
00:54:48,040 --> 00:54:51,320
Patrick McCullough: Poa annua, where it is just so difficult to control now.

503
00:54:51,670 --> 00:54:57,580
Patrick McCullough: We need to have multiple programs and rotation of herbicides and the modes of action that

504
00:54:57,580 --> 00:54:59,940
Patrick McCullough: are going out in weed control programs.

505
00:55:01,200 --> 00:55:09,580
Patrick McCullough: All right, new herbicides that are coming out here in 2018. The first one is a new active

506
00:55:09,780 --> 00:55:15,800
Patrick McCullough: ingredient from Dow called halauxifen. This is a synthetic auxin herbicide group 4 broadleaf

507
00:55:16,960 --> 00:55:22,779
Patrick McCullough: product that provides post-emergent control of annual and perennial broadleaf weeds.

508
00:55:23,270 --> 00:55:30,020
Patrick McCullough: It has very fast activity. halauxifen is a fast active ingredient. We typically see the response

509
00:55:30,369 --> 00:55:39,339
Patrick McCullough: in susceptible broadleaf weeds within about five to seven days. Very rapid browning and necrosis of the

510
00:55:41,980 --> 00:55:47,420
Patrick McCullough: of the tissue on the plant. It has favorable characteristics for turfgrass and also sod

511
00:55:47,560 --> 00:55:53,540
Patrick McCullough: production where it has rapid degradation. There's no composting issues so it has a favorable

512
00:55:53,940 --> 00:56:00,000
Patrick McCullough: characteristic for us in lawns and landscapes. The first product that's going to be released

513
00:56:00,160 --> 00:56:07,400
Patrick McCullough: from Dow that contains halauxifen is going to be called RELZAR. This is a combination with

514
00:56:07,460 --> 00:56:10,520
Patrick McCullough: Broadleaf herbicide with a different mode of action,

515
00:56:10,819 --> 00:56:15,720
Patrick McCullough: florasulam, which is found in the product Defender.

516
00:56:16,660 --> 00:56:18,980
Patrick McCullough: This will be released as a WG formulation

517
00:56:19,760 --> 00:56:21,940
Patrick McCullough: in the second quarter of 2018.

518
00:56:22,900 --> 00:56:28,619
Patrick McCullough: It's going to be used in all major warm and cool season turfgrasses for post-emergent broadleaf weed control.

519
00:56:29,160 --> 00:56:40,060
Patrick McCullough: And they're going to keep it simple. It's going to have one labeled use rate, which is 0.72 ounces of product per acre.

520
00:56:40,520 --> 00:56:44,400
Patrick McCullough: That's going to be the standard use rate for all labeled turfgrass species.

521
00:56:44,859 --> 00:56:50,099
Patrick McCullough: And this will be a good tool, I think, for us in Georgia, because it's going to include...

522
00:56:50,420 --> 00:56:56,120
Patrick McCullough: centipede, bermuda, zoysiagrass, fescue. So if you're managing lawns with mixed

523
00:56:56,300 --> 00:57:02,080
Patrick McCullough: species or if you need to make up a tank and spray multiple lawns of various turf

524
00:57:02,300 --> 00:57:05,660
Patrick McCullough: species, this product will have a nice fit for that use.

525
00:57:07,520 --> 00:57:13,119
Patrick McCullough: Again, this product has very rapid activity. This is four weeks after treatments for controlling

526
00:57:13,260 --> 00:57:19,500
Patrick McCullough: common chickweed in the winter time where many broadleaf weed products are slow with cold temperatures

527
00:57:20,220 --> 00:57:27,440
Patrick McCullough: there in the winter. Very rapid knockdown control with RELZAR applied in the winter for controlling

528
00:57:27,900 --> 00:57:32,840
Patrick McCullough: common chickweed. Very active on broadleaf weeds as well in the summertime

529
00:57:33,370 --> 00:57:41,000
Patrick McCullough: weeds like buttonweed, matchweed here in St. Augustinegrass and it should

530
00:57:41,300 --> 00:57:48,820
Patrick McCullough: have a good fit for use in the summertime for controlling weeds like doveweed.

531
00:57:50,300 --> 00:57:54,080
Patrick McCullough: some activity on common lespedeza, but it's not going to be a standalone product.

532
00:57:54,610 --> 00:57:58,020
Patrick McCullough: But there's going to be some weeds like plantain and dandelion, which can provide

533
00:57:58,230 --> 00:58:02,520
Patrick McCullough: very rapid knockdown control with a single treatment.

534
00:58:03,940 --> 00:58:06,960
Patrick McCullough: Game On is another new product from Dow that's going to

535
00:58:07,220 --> 00:58:12,680
Patrick McCullough: contain halauxifen. This is a three-way combination with 2,4-D choline and

536
00:58:12,880 --> 00:58:16,099
Patrick McCullough: fluroxypyr. It will also be released in 2018.

537
00:58:17,140 --> 00:58:20,599
Patrick McCullough: They're going to primarily target game on for using cool season grasses.

538
00:58:21,640 --> 00:58:23,560
Patrick McCullough: Most warm season species like

539
00:58:24,380 --> 00:58:29,320
Patrick McCullough: centipede and St. Augustine are going to have sensitivity issues to 2,4-D.

540
00:58:29,760 --> 00:58:35,060
Patrick McCullough: So it's going to be a cool season grass, tall fescue, Kentucky bluegrass, ryegrass product.

541
00:58:35,830 --> 00:58:42,520
Patrick McCullough: We can use it in bermudagrass and zoysiagrass and this product provides very

542
00:58:42,920 --> 00:58:49,720
Patrick McCullough: rapid knockdown control of perennial broadleaf weeds and I think it's going to be a strong

543
00:58:50,670 --> 00:58:56,880
Patrick McCullough: new combination product for us in turfgrass. Here's a look at dandelion four days after

544
00:58:57,140 --> 00:59:05,859
Patrick McCullough: treatments with game on. Very rapid necrosis discoloration there of the plant and we see

545
00:59:06,860 --> 00:59:10,880
Patrick McCullough: Broadleaf weeds like dandelion and plantain twist up within about seven days.

546
00:59:11,180 --> 00:59:18,320
Patrick McCullough: So very rapid control of susceptible broadleaf weeds to these active ingredients.

547
00:59:19,000 --> 00:59:26,380
Patrick McCullough: There can be some bermudagrass injury from game on, which can last two weeks or so at labeled use rates.

548
00:59:27,180 --> 00:59:37,800
Patrick McCullough: There can be some off-coloring, especially during spring transition, but this treatment will probably have a good fit for mid-summer applications after

549
00:59:38,340 --> 00:59:45,640
Patrick McCullough: the bermudagrass has resumed active growth, it's greened up, and it's healthy, should have good tolerance to those treatments.

550
00:59:46,700 --> 00:59:55,579
Patrick McCullough: RELZAR and Game On have shown very good activity for controlling doveweed, which is a very problematic weed for us in Georgia right now.

551
00:59:56,500 --> 01:00:08,160
Patrick McCullough: You can see here the percent cover with RELZAR on the left and Game On there in the middle, compared to Celsius. Very comparable levels of activity to Celsius.

552
01:00:08,720 --> 01:00:13,920
Patrick McCullough: and therefore controlling doveweed in the summertime.

553
01:00:14,390 --> 01:00:19,560
Patrick McCullough: And you can see what the non-treated is doing on the far right where the population is going to increase over time.

554
01:00:19,839 --> 01:00:24,500
Patrick McCullough: So new tools in the toolbox for controlling problem weeds, especially doveweed,

555
01:00:24,550 --> 01:00:32,480
Patrick McCullough: which I think is going to be one of the most promising uses of these new products coming out from Dow here next year.

556
01:00:33,640 --> 01:00:41,700
Patrick McCullough: The next new product that contains halauxifen that's going to be released in late 2018 is called Switchblade.

557
01:00:42,180 --> 01:00:49,660
Patrick McCullough: This is a three-way combination product similar to Game On, except they replaced the 2,4-D choline with dicamba.

558
01:00:49,839 --> 01:00:57,980
Patrick McCullough: So it's going to contain the new active ingredient, halauxifen, has a rapid knockdown control, dicamba and fluroxypyr.

559
01:00:58,700 --> 01:01:06,819
Patrick McCullough: This will be labeled in most major warm season turfgrasses including centipedegrass and cool season grasses.

560
01:01:08,349 --> 01:01:13,220
Patrick McCullough: It will also have a St. Augustinegrass use on the label as well.

561
01:01:14,010 --> 01:01:21,720
Patrick McCullough: And again, very good three-way combination for controlling many troublesome perennial broadleaf weeds and turfgrass.

562
01:01:22,760 --> 01:01:37,460
Patrick McCullough: The next new active ingredient that's going to be released in 2018 in turfgrass is called pyrimisulfan. This is going to be a combination product with penoxsulam and sold as a trade name Vexis.

563
01:01:37,800 --> 01:01:40,420
Patrick McCullough: This will be released again in 2018.

564
01:01:41,400 --> 01:01:45,560
Patrick McCullough: This product is a combination of two ALS inhibiting herbicides.

565
01:01:45,680 --> 01:01:48,220
Patrick McCullough: So the same mode of action as sulfonylureas.

566
01:01:49,180 --> 01:01:51,180
Patrick McCullough: And it will come out as a granular product.

567
01:01:51,520 --> 01:01:55,140
Patrick McCullough: So it's going to be a spreadable product.

568
01:01:55,660 --> 01:01:58,140
Patrick McCullough: Likely going to have a fertilizer carrier on it.

569
01:01:58,720 --> 01:02:01,460
Patrick McCullough: The potential uses is going to be for warm season grasses.

570
01:02:02,579 --> 01:02:06,059
Patrick McCullough: This combination product, Vexis, will control broadleaf weeds.

571
01:02:06,279 --> 01:02:13,700
Patrick McCullough: It does have good activity on many sedges as well, but it's weak on crabgrass and goosegrass

572
01:02:13,779 --> 01:02:15,920
Patrick McCullough: and some of the grassy weeds that we have in the summertime.

573
01:02:16,339 --> 01:02:21,240
Patrick McCullough: But the advantage of using Vexis is going to be the root uptake.

574
01:02:21,880 --> 01:02:26,480
Patrick McCullough: You don't have to have dew on the plant for it to stick and provide control.

575
01:02:26,590 --> 01:02:31,880
Patrick McCullough: So you can go out on dry turf, spread it, and both of these active ingredients have significant

576
01:02:32,050 --> 01:02:40,300
Patrick McCullough: root uptake and you can still get very good weed control with this product without dew present.

577
01:02:41,400 --> 01:02:47,839
Patrick McCullough: Here's a look at some of our plots where we've researched Vexis over the years with the fertilizer carrier.

578
01:02:48,329 --> 01:02:53,960
Patrick McCullough: We have seen very good control of winter annual broadleaf weeds in our plots.

579
01:02:54,880 --> 01:03:02,140
Patrick McCullough: Weeds like parsley-piert, cudweed, some of those types of weeds that are starting to emerge right now.

580
01:03:02,400 --> 01:03:08,720
Patrick McCullough: Vexis has very good activity on those species. And then of course the fertilizer can give a little greening effect.

581
01:03:10,380 --> 01:03:17,280
Patrick McCullough: following those treatments. We have seen some erratic levels for controlling annual bluegrass.

582
01:03:17,980 --> 01:03:22,620
Patrick McCullough: So I don't think this is going to be a very good Poa herbicide, but the strength is going

583
01:03:22,620 --> 01:03:29,980
Patrick McCullough: to be primarily broadleaf weeds in warm season turfgrasses, especially winter and annual

584
01:03:30,080 --> 01:03:31,520
Patrick McCullough: weeds with those fall treatments.

585
01:03:33,539 --> 01:03:52,240
Patrick McCullough: Here's a look at Prodiamine in those plots where we got very good Poa control, but basically released lawn burweed. We've seen that barricade and Prodiamine when we select for annual grassy weeds, we can actually enhance the establishment of some of the weeds that are not susceptible to that mode of action.

586
01:03:52,820 --> 01:03:58,720
Patrick McCullough: lawn burweed, as you can see in those plots, is not controlled by Barricade applications.

587
01:03:59,160 --> 01:04:05,640
Patrick McCullough: So using a product like Barricade with Vexis or different broadleaf herbicide is going to

588
01:04:05,640 --> 01:04:10,160
Patrick McCullough: be important if you're targeting both grassy and broadleaf weeds in the fall.

589
01:04:11,920 --> 01:04:17,340
Patrick McCullough: One of the advantages with Vexis is that it has very good activity for controlling sedges.

590
01:04:17,600 --> 01:04:21,080
Patrick McCullough: Here's just a look at some of our research in the greenhouse where we looked at

591
01:04:22,690 --> 01:04:27,600
Patrick McCullough: the control of biotypes that are susceptible and resistant

592
01:04:28,180 --> 01:04:29,940
Patrick McCullough: to sulfonylurea herbicides.

593
01:04:30,560 --> 01:04:34,920
Patrick McCullough: And Vexis is there on the right with its experimental code number there.

594
01:04:35,560 --> 01:04:39,780
Patrick McCullough: Very good activity on susceptible biotype to sulfonylureas.

595
01:04:40,020 --> 01:04:44,140
Patrick McCullough: It also has some activity for controlling resistant biotypes there on the right

596
01:04:44,480 --> 01:04:54,380
Patrick McCullough: You can see the activity on the ALS resistance edge, and this product is showing good activity for partial suppression.

597
01:04:54,770 --> 01:05:06,200
Patrick McCullough: I think multiple applications may have a nice fit with other chemistries for controlling the sedge populations with resistance issues to sulfonylurea.

598
01:05:06,460 --> 01:05:13,279
Patrick McCullough: Although this is the same mode of action as the sulfonylurea, Vexis has one of the active

599
01:05:13,520 --> 01:05:18,279
Patrick McCullough: ingredients from a different chemical family and that difference in the binding is giving

600
01:05:18,500 --> 01:05:23,200
Patrick McCullough: partial control of resistant biotypes to sulfonylurea herbicides.

601
01:05:23,250 --> 01:05:29,579
Patrick McCullough: So another tool in the toolbox, I guess, for managing resistant weeds in turfgrass.

602
01:05:31,400 --> 01:05:37,900
Patrick McCullough: The next new product is a trade name called Solero. The active ingredient is a

603
01:05:38,120 --> 01:05:43,700
Patrick McCullough: mesosulfuron. This is a product being sold by Nufarm that was released about a

604
01:05:43,780 --> 01:05:49,080
Patrick McCullough: year or two ago. This was developed by Valent over the years. It's now sold by Nufarm.

605
01:05:49,380 --> 01:06:04,360
Patrick McCullough: It is labeled for all major warm and cool season turfgrasses. It controls annual and perennial sedges, comparable levels of control to monument and certainty for controlling perennial sedges in kyllinga.

606
01:06:04,660 --> 01:06:08,120
Patrick McCullough: It also does have some activity for controlling broadleaf weeds.

607
01:06:08,360 --> 01:06:11,060
Patrick McCullough: So just something to have an appreciation for.

608
01:06:11,180 --> 01:06:12,140
Patrick McCullough: Solero is out there.

609
01:06:12,740 --> 01:06:19,960
Patrick McCullough: It has comparable levels of use or use patterns as SedgeHammer, halosulfuron, for use in

610
01:06:19,960 --> 01:06:21,900
Patrick McCullough: both warm and cool season turfgrasses.

611
01:06:22,460 --> 01:06:26,240
Patrick McCullough: It has very good activity for controlling many different sedge species and turf.

612
01:06:27,220 --> 01:06:33,040
Patrick McCullough: Dismiss NXT is another new product that was released in the turfgrass industry this year.

613
01:06:34,060 --> 01:06:41,060
Patrick McCullough: This was brought to the market by FMC in their line of sulfentrazone products.

614
01:06:42,020 --> 01:06:46,580
Patrick McCullough: This is a combination of sulfentrazone, which is the active ingredient in Dismiss,

615
01:06:47,240 --> 01:06:50,500
Patrick McCullough: with carfentrazone, which is the active ingredient in Quicksilver.

616
01:06:51,140 --> 01:06:56,640
Patrick McCullough: And the benefits of using carfentrazone in the mix with this product is the speed of control.

617
01:06:57,690 --> 01:07:05,900
Patrick McCullough: We are getting much... we are getting rapid control of sedges, kyllinga with Dismiss NXT.

618
01:07:07,119 --> 01:07:10,660
Patrick McCullough: It's labeled for most major warm and cool season turfgrasses.

619
01:07:12,119 --> 01:07:17,880
Patrick McCullough: And we are using Dismiss NXT on the same spectrum of weeds that we use Dismiss for.

620
01:07:18,000 --> 01:07:23,700
Patrick McCullough: So the sedges and kyllinga, certain broadleaf weeds as well, does have some activity on goosegrass.

621
01:07:23,900 --> 01:07:30,200
Patrick McCullough: But Dismiss NXT provides rapid control of kyllinga, seven days after treatments like you see there,

622
01:07:30,640 --> 01:07:35,980
Patrick McCullough: very fast takedown and response of Dismiss NXT.

623
01:07:35,680 --> 01:07:53,299
Patrick McCullough: those types of weeds. However, we are not seeing a significant difference in the levels of control, long-term control, with Dismiss NXT compared to straight Dismiss. So the speed of control with Dismiss NXT, I think, is the

624
01:07:53,740 --> 01:08:01,180
Patrick McCullough: major advantage here, but in terms of it being better than Dismiss, we just do not have data

625
01:08:01,400 --> 01:08:07,780
Patrick McCullough: to support that claim. But still, good product, rapid control, and sometimes getting that response

626
01:08:08,020 --> 01:08:15,300
Patrick McCullough: from the weeds can make your clients happy, can make homeowners happy, and that rapid activity

627
01:08:15,330 --> 01:08:17,980
Patrick McCullough: is certainly nice to see after you make those applications.

628
01:08:19,540 --> 01:08:24,480
Patrick McCullough: And finally, we are testing a new three-way combination product that should be released

629
01:08:24,500 --> 01:08:26,840
Patrick McCullough: next year from a company called Sipcam.

630
01:08:27,920 --> 01:08:35,140
Patrick McCullough: This is a three-way combination product for a simazine, imazaquin, and prodiamine.

631
01:08:38,020 --> 01:08:43,320
Patrick McCullough: product called Coastal. This is going to be simazine and imazaquin, which is going to

632
01:08:43,460 --> 01:08:48,320
Patrick McCullough: have post-emergent activity for controlling broadleaf weeds and sedges. They will also

633
01:08:48,680 --> 01:08:54,840
Patrick McCullough: control Poa annua. So having two chemistries in there for post-emergent Poa control is nice.

634
01:08:54,980 --> 01:09:00,880
Patrick McCullough: It has two different modes of action. And then Prodiamine, which is a barricade for the

635
01:09:01,260 --> 01:09:04,460
Patrick McCullough: residual pre-emergent control of the plant.

636
01:09:04,920 --> 01:09:08,920
Patrick McCullough: weeds in there as well. So it's a pre-emergent plus post-emergent treatment.

637
01:09:09,500 --> 01:09:14,060
Patrick McCullough: We have seen very good control of winter annual weeds like Clover,

638
01:09:15,020 --> 01:09:21,060
Patrick McCullough: Poa annua, and various other winter annual broadleaf weeds in our test plots. As you can

639
01:09:21,120 --> 01:09:26,980
Patrick McCullough: see here from Coastal and with the Prodiamine in the mix with those spring treatments we can get

640
01:09:27,080 --> 01:09:31,560
Patrick McCullough: very good crabgrass control as well throughout the year. So I think we're going to start seeing

641
01:09:31,560 --> 01:09:38,220
Patrick McCullough: a lot more of these combination products that are combining multiple chemistries that provide both

642
01:09:38,500 --> 01:09:44,660
Patrick McCullough: pre and post-emergent weed control, different modes of action as well there to combat resistant weeds

643
01:09:45,000 --> 01:09:50,300
Patrick McCullough: and Coastal is going to be the first of many of these types of combinations that will be

644
01:09:51,540 --> 01:09:53,259
Patrick McCullough: coming out for the turfgrass industry.

645
01:09:53,619 --> 01:09:58,219
Patrick McCullough: So with that, I conclude my presentation.

646
01:09:59,020 --> 01:10:00,119
Patrick McCullough: Thank you for your attendance

647
01:10:00,760 --> 01:10:03,900
Patrick McCullough: and hope to see you guys sometime soon.

648
01:10:04,239 --> 01:10:04,780
Patrick McCullough: Thank you so much.

649
01:10:19,400 --> 01:10:22,200
Patrick McCullough: *music*