 Okay everybody, let's get started with our second talk tonight and Crabgrass is one of the most common grassy weeds in our lawns and here to teach us how to control this weed is Esther McGuinness. Esther is an Extension Horticulturist and Director of the NDSU Extension Master Gardener Program and her graduate students conduct research in the areas of native plant evaluation, pollinator conservation, and plants for rain garden environments. As the administrator of the Extension Master Gardener Program, impactful initiatives of hers include planting pollinator habitat and fighting food insecurity and then community beautification as well as plant diagnosis. So Esther welcome to the forums. Thank you very much. Welcome. All right well thank you for inviting me to speak and believe it or not we're almost to the point where we would be putting down our crabgrass preventers. I mean this is so strange to me because last year I still remember we were having blizzards and in fact I missed a couple of my speaking engagements because there was no travel advice last year at this time. So we're in for a very different spring than last year but I also need to give credit where credit is due Tom. So Yolanda Schmidt helped with this she actually wrote this PowerPoint. So Yolanda was my was my grad student and in fact she got her master's in extension education so I was her advisor and we worked together on a package program regarding crabgrass management so I can't take all the credit here. So what's the problem with crabgrass? Well the problem is that this is the most common annual weedy grass that we have. Let me just hide this there we go. So crabgrass is the most common annual weedy grass that we have. It's a warm season grass. One of the big problems though is it produces a ton of seed and that seed will form a seed bank in your soil. So once you have it you will have it for years because it will continue to germinate each year. And then we have not one but two species of crabgrass. We have smooth and large crabgrass and then what makes them undesirable in our lawns is that they really don't have aesthetic qualities. So they're actually quite ugly. They have a coarse texture. When you look at crabgrass it's got a leaf blade that is much wider than you would find with respect to our desirable turf grasses like Kentucky bluegrass, our fine fescus, and perennial ryegrass. And then it has a color that makes it stand out. So it's kind of yellowish green in color instead of being that deep green that we want to see in our lawns. It's also very competitive. It grows fast and then it crowds out our desirable turf grasses with this being an annual it will then die come fall and then it'll leave bare spare bare patches in spring. It has some competitive advantages here. So I mentioned that it had this tremendous seed bank in the soil and it germinates when the top two to four inches of the soil starts reaching 55 degrees and then it will continue to germinate throughout summer. It really likes the soil temperatures between 60 and 70 but you're going to find that it just continues to germinate. And then to make matters worse is that this is a warm season grass. Now if you consider our cool season grasses which do not thrive during the heat of summer when you take it and compare it to a warm season grass that warm season grass is going to out compete it. It's going to thrive during times of drought and in the heat. So that makes crabgrass really a formidable weed in our lawns. We're going to talk a little bit here about crabgrass identification. So the seedlings aren't very distinctive. They do look a little bit like tiny corn seedlings but for the average homeowner you're not going to notice the seedlings. You'd have to get onto your hands and knees and be searching in the turf grass to find them. This is a stage in which you're more likely to recognize it. So there's a reason why this is called crabgrass and this is because the the tillers will lie flat on the ground and then it just kind of has that crab-like appearance. Hence the name crabgrass. So other ways to identify it you can look at the seed head. Now most of the time you're not going to see the seed head because the lawnmower may in fact cut off the seed head but sometimes when you allow things to to grow a little bit taller or sometimes you will have the seed head growing sideways into the sidewalk then you'll be able to see this distinctive seed head and it's very finger-like in appearance two to five spikes and then of course the large crabgrass has a larger seed head. To distinguish between the two species we've got smooth crabgrass and large crabgrass. As the name implies smooth crabgrass doesn't have as many hairs on this stem but hopefully you can see the photo of large crabgrass and on that comb you'll notice that it has a bunch of hairs. So that's an easy way to tell them apart but for them for the average home owner it's not that important once you're able to identify that it's a crabgrass it's really the same management strategies whether it's smooth or large. Now the big issue is that a lot of our home owners mistake quackgrass for crabgrass so you need to be able to distinguish the two of them because they're different management strategies and quackgrass is a lot harder to control compared to crabgrass. So there's going to be some terms you need to know so you've got the turf blade and that's going to be the leafy structure and then on the bottom is the sheath and the sheath can be rolled or folded but I'm going to have you focus on the collar region where the blade and the sheath meet. In that collar region I want you to learn two terms I want you to learn the term ligule and the term oracle. The ligule will be a little piece of tissue that is at the base of the blade and that's on the back side of the collar. Now the oracle will be in the front so hopefully you can see my cursor here the oracles in the front and if you might want to think of it as arms that are hugging the sheath so remember those two terms and that will help you differentiate crabgrass and quackgrass. So showing you the ligule on crabgrass now if you pull back the blade to reveal the collar section you'll see there's a ligule in crabgrass so it's that that tissue like portion there. Now you're not seeing the front of the collar that's being blocked by the blade so this is kind of the view from the back you pull the blade down and then the ligule pops up. Now showing you from the side this is a little smaller picture but you can still see that that membrane there the ligule is very prominent. If we look at the front of it you'll notice we don't have those hugging arms we don't have an oracle so no oracle in crabgrass. Now let's contrast that with quackgrass. Quackgrass does have an oracle on the front of it so that's going to be on the front of the collar. If you were to pull down the blade there would be a little bit of a ligule but it's really tiny it's not prominent like it is on crabgrass but I want to show you a better picture of that oracle so you've got the oracle there on the front side of it and that's a dead giveaway that you've got quackgrass rather than crabgrass. You could also compare the root systems so quackgrass spreads by rhizomes and it's really the bane of those of us that have lawns you know you'd like to pull it out but you can't you've got this underground stem called the rhizome and the rhizome initiates new tillers you know that's the leafy structure coming out the top and then of course you've got the root system on the bottom but when you see these white smooth rhizomes you know you've got quackgrass. In contrast crabgrass has a fibrous root system it doesn't spread by rhizomes it doesn't have stolons it just has roots that are branched all coming from the main point. All right to recap that and then I've got a few new points in here crabgrass remember is an annual so it germinates in spring grows through summer and then dies with the hard frost now we've got quackgrass. Quackgrass is a perennial unfortunately it doesn't die we all wish it would die but it doesn't. Crabgrass is a warm season grass thriving in the summer months quackgrass is a cool season grass you know so you'll see that quackgrass will be one of the first to really green up and become a parent in your lawn this spring and then going back to the oracles and the ligule no oracles in crabgrass but prominent oracles on quackgrass and then really just really large membranous ligule on the crabgrass and then if we look at the habit that tells us a lot too remember the the crabgrass is spread out like a crab and our quackgrass is going to go vertical so you're going to see the leaf blade growing upwards and then of course we discussed the difference in the root system. So let's talk management and frankly I could probably talk for the next 30 minutes on how to manage and how to promote a health dense and vigorous lawn and that does go a long ways so we got to look at our cultural practices because if you have a dense lawn that does help prevent some weed germination and you know it helps crowd out some of the weeds so you got to make sure that you you know are using the right form of turfgrass so we've got you know NDSU extension definitely has recommendations on turfgrass so if you if you're struggling with what you have we might be able to recommend something to replace it you know then think about mowing so mowing is so very important and most people are mowing too short so you want to mow higher if you can raise that mower deck up to three three and a half inches and in some cases four inches you're going to find that your lawn is a lot more dense and then when it's hauler it will in fact shade out some of the weeds and we know that some of the weeds require light to germinate so if we can shade them out that's helpful you know proper watering is good so if you want to maintain and have your lawn active through the summer about an inch of water a week and then fertilization fertilization also helps thicken up the lawn best time to fertilize is around the Labor Day weekend really the summer holidays so Memorial Day and then Labor Day if you're irrigating but despite all all the things that you are doing to increase the density of your lawn you're still you're still might have to resort to herbicides because remember we've got that seed bank of crabgrass and it just wants to germinate and it will it will be a problem so then we can look at a couple different classes of herbicides so we can use a pre-emergence herbicide or a post-emergence herbicide now the pre-emergence herbicide you would apply it before the seeds germinate and you water it in and essentially forms a barrier on the soil surface so the seed starts germinating but it's killed when that first root absorbs that pre-emergence herbicide so you won't even see it so it's not a successful germination now if you miss the window of opportunity to put down your pre-emergence herbicide that's when you would resort to a post emergence herbicide you apply that after you've had successful germination we're going to focus on pre-emergence herbicides because it is more economical but it's also more effective in the long term so we want to get people in the habit of putting down their pre-emergence herbicides to prevent crabgrass and other weedy grasses from germinating there are different formulations out there most homeowners put down a granular formulation but our turfgrass professionals do also have liquid formulations application timing is critical so we want to apply this approximately one week before the average soil temperature reaches 55 degrees at a four inch depth so there are different ways of measuring that now hopefully you can see whoops i don't know if you can see that i've got a little bit of a probe here so i've got a digital thermometer here that looks like a meat thermometer so hopefully you can see it's got the probe on it and that works really well so just invest in a cheap one now don't take your spouse's roast thermometer they may not appreciate that but buy yourself a cheap a cheap digital thermometer and then you can use it to measure soil temperature you'll measure it in a few spots and then average that together if you don't want to do that you can certainly look at our North Dakota agricultural weather network and they do show soil temperatures as you look at the different cities and towns that show up on this map you'll see that the first number is the soil temperature of bare soil we don't care about that we want the turf soil temperature so you're looking at the second number and this is from yesterday so you looking at Fargo our our turf soil temperature yesterday was about 47 and and really that's to be expected when we're starting to reach 70 degrees but in the next few days that temperature may drop again because we're having cooler temperatures so we're not quite reaching you know reaching that stage but very shortly if we have a few more days of warm temperatures we're really going to be in that in that frame where we would be putting down the crabgrass free emergence herbicide and in fact there may be some areas of your lawn that are warmer than others areas along your driveway because you know whether it's asphalt or cement it's retaining the heat a little bit areas along your sidewalk and such so it's important to to do this now I mentioned in the previous slide to put it down a week before the soil temperature reaches an average of 55 degrees so that's really as you're starting to reach 50 degrees so as you're consistently starting to reach 50 degrees I would put down the pre-emergence herbicide because as we start to get into that 55 degree range that's when you're going to see the beginning of crabgrass seed germination so if you can get ahead of that that is wonderful our pre-emergence herbicides are influenced by the grass species and cultivars that you have in your lawn and we'll talk a little bit about that we're going to talk about the age of your turf is it is it newly seeded or is it an established lawn and that's going to affect what products you put down and then of course your application rate but no matter what always read the label read it thoroughly you know make sure that the mix of turf grass species that you have in your lawn is listed as a host here and can and can tolerate these pre-emergence herbicides and then look for the weeds the weeds that are listed on there but I'll certainly show you some different active ingredients here that can be very effective for pre-emergence control the most common one has the active ingredient of pendymethylene and you'll be able to read the the herbicide bag and you'll see under active ingredients that pendymethylene is is the chemical that's being used now of course there are lots of brand names I'm not able to list all the brand names that provide pendymethylene as their active ingredient in the crabgrass preventer the second one here is pro-diamine and I would that's not going to be something that is readily accessible to the homeowner that's more likely to be purchased by a commercial turf grass company but I want you to notice that the first two products they're only effective as a pre-emergence herbicide the third active ingredient dithiope here can provide control as a pre-emergence but it also has a little bit of post-emergence control too because they can provide some control for crabgrass seedlings before they tiller and I'm going to define tillering here in a few minutes now dithiope here I'm starting to notice is more commonly available than it used to be but I do like it because it's a little bit more forgiving if you've missed that window you know you could use dithiope here and it would be able to take care of the crabgrass seedlings we're starting to notice more of that in the big box stores and more available to home consumers all right so those were recommendations for established lawns now we're going to look at what you can put on a newly seeded lawn you don't dare put pendymethylene or are the others that were mentioned in the previous in the previous slide because they will in fact prevent your turf grass seed from germinating so remember you know you've got you're trying to control a weedy grass but same time you're trying to seed a new lawn here in that situation it becomes trickier so if you use most of the pre-emergence herbicides that I listed previously it's not going to work in this situation because it would prevent the germination of your Kentucky bluegrass or your fine fescue or whatever grass that you're trying to grow so in that situation if you're trying to seed you would use one of these two products there's Sidgeron and the brand name on that is 2% and that is being phased out I'm not even sure if it's still registered with the EPA I need to look that up but I know it's being phased out and part of the reason is that there's a better product on the market called mesotrile so Sidgeron was pretty weak when it was being used as a pre-emergence in a newly seeded lawn mesotrione is is a little bit better and can provide control for up to four weeks so you would put down the mesotrione right at seeding or just right just prior to seeding you don't want to put it down after the seed germinates because mesotrione will cause those seedlings instead of being green they'll look kind of bleached and will damage them so you would put this down at seeding or right before seeding and then it will provide control from crabgrass and other weed germination for four weeks mesotrione can be applied to a Kentucky bluegrass mix as long as the fine fescue component is less than 20 percent the fine fescus are a little bit more susceptible to mesotrione than Kentucky bluegrass and perennial rye grass all right so let's say you got really busy this spring let's say you're an extension horticulturist that is traveling all around and neglecting her own lawn and misses the window of opportunity to put down a pre-emergence herbicide when she gets home she notices that she's got crabgrass seedlings growing so what can you do in that situation you can use a post emergence herbicide the post emergence herbicides are most effective at the seedling stage so when that newly newly germinated crabgrass is still pretty small we do have some herbicides that can be effective in the tiller stage but i'm going to tell you this is going to be a little bit more work now you're going to need to do multiple applications one application may not do it and then there's a little bit more likelihood that you might injure your desirable turf grasses but i promised that i would define what a tiller is so after the crabgrass seedling grows you'll when you just have one it's a seedling but you'll notice that we've got these side shoots coming out so in this in this photo right here you'll notice i've got three arrows hence we have three tillers that would be at the three tiller stage and that will become important when we talk about the post-emergence herbicides so we're going to cover dethype here again because remember this was the one pre-emergence that has some post-emergence activity so dethype here is effective when applied at the seedling stage um you know through the development of leaves but once it starts sending out tillers it's not going to be effective so the two you would rely upon once you reach the tillering stage is phenoxaprop or quid and chlorac now i have less experience with phenoxaprop i think the farmers tend to use this a little bit more and that can provide control after tillering but the effectiveness decreases as the plant size increases so quinn chlorac we see quite a bit now on the market so you'll see like ortho weed begun was it crabgrass and that could contains quinn chlorac in it and quinn chlorac is quite effective at the seedling stage and up through the first tiller and then there's a little gap when it has two three or four tillers it's not as effective but then once it reaches five six seven tillers it is effective again so i don't quite understand why that is the case but quinn chlorac works you know up into the one tiller stage less effective two three four tiller stage and then five on up and it's it's a little it's quite effective but quinn chlorac is what what you'll most likely find in the big box stores now and and that's really been very helpful so as crabgrass grows post emergence herbicides are less effective so probably when we reach like mid july or so i would say that you know it's really not worth it anymore to be spraying a post emergence herbicide you're gonna have to apply it many times and there's more of a risk of turfgrass injury but as we get into late summer you know early fall it's perfectly acceptable to give up for the year so remember crabgrass is an annual so if if you haven't been keeping up with it the crabgrass will in fact die come winter and then you have next spring you know to get on top of it to apply the pre-emergence herbicides so in conclusion the most effective crabgrass control is achieved when we use a variety of methods so when we use our cultural practices to make sure we've got a healthy dense lawn and then when we use effective chemical weed control strategies my advice would be to make sure you do the pre-emergence herbicide but if you if you in fact miss out on that window then you can resort to the post emergence herbicides but remember any time you're using a pesticide the label is the law so read that label know how much to apply make sure you follow it and use the label rate and it'd be very cautious as you're doing so so do we have a plethora of questions now okay if anybody has any questions please type them in the question and answer box and we do have a few questions right away asked her you did mention about the importance of timing to put a pre-emergence herbicide on does it hurt if you like now the weather's nice is it okay if we put it on a little bit earlier than the perfect time yes yes actually we're starting we're starting to get there one thing I'm noticing here in Fargo is that we have forsythia blooming and in some other states they use forsythia as their indicator plant now we haven't done the tests to confirm that that works in North Dakota but it really seems like we're going to get there very fast now if we were living in Alabama or something like that it would be a different story but our growing season is short enough that you can put it down you can put it down a little bit early and it should be effective through the summer months so you're not going to be having an issue with it if you do apply it a little on the early side yeah it'll just wear out faster and but you'll still give you good control through much of the summer absolutely good how about uh you know as far as recommendations for the does it matter what type of lawn we have like a tall fescue or a Kentucky bluegrass is that affected by this your cracked grass recommendations does that matter what type of lawn you have it does when it comes to the fine fescus I'd have to I'd have to look back up on the tall fescus but the the fine fescus are a little bit more sub subject to damage from um mesotrion and such but there's also a little bit of difference you know when it comes to the post emergence herbicide so that's why it's so important to read the label but if you are applying a pre-emergence herbicide to an established lawn it should not matter it really shouldn't matter how do these herbicides affect pollinators these herbicides do not directly impact pollinators per se however if you're putting down pre-emergence they can indirectly affect them by in fact controlling for some of the from the weedy flowers that's that germinate so you know say for example dandelions and such so when we do control for control for weeds in our lawn there are fewer flowers for the bees so that's certainly that's certainly an impact but it's an indirect impact these particular herbicides do not seem to be affecting bee health other than the fact that it's depriving them of the flowers the nectar and the pollen that they need okay how do these crabgrass herbicides affect broadleaf plants for example nearby shrubs trees okay okay i would stay i would stay away um i would stay away from them per se so we want to make sure that we are not spraying particularly our post emergence so that that's the thing is that okay we do want to keep these away from the trees and whatnot now when it comes to pendymethylene that's that's less of an issue the pre-emergence like that is less of an issue it's the post emergence that we want to stay away from i wouldn't want to be spraying quinclorac anywhere close to a tree i i also wouldn't want to be having mesotrion close to trees either so we've seen some damage from that hey how do we figure out how much herbicide to apply and about a re-entry interval when it's safe to go back on the lawn okay so that's going to differ per product so make sure that you read the label and that you are in fact using the labeled rate you some people will try and go lower but in fact we find that that is counterproductive so i would use the labeled rate and i would use it based on the type of spreader that you have okay i know we're talking about crab grass but you did you did mention quack grass so do you have any quick recommendations on dealing with quack grass yes you can unfortunately we do not have a selective herbicide that will take quack grass out of our desirable turf grass so in that situation we try number one to keep our desirable turf grass as dense as possible if in fact your quack grass infestation has taken over what you would do in that situation if it's really bothering you is that you would take it out with a non-selective herbicide like glyphosate which is in roundup so you would spray out that area but you're going to be killing the desirable turf grass in that area too so once you've killed the quack grass you might have to spray twice i'm going to be honest here you might have to spray twice to totally kill the quack grass you would then recede so unfortunately we don't have an easy answer there are some individuals that will go out and try and hit the quack grass you know using a little paint brush and trying to avoid the the other turf grass but i don't have patience for that i just don't okay are there any let's see any last questions i think you got it all covered here thanks astrid that was great presentation we're ready to attack that crab grass perfect timing okay thanks okay just one thing i just want to make sure with with the herbicides we do want to stay away from the trees so we do want to stay away from the trees so i do want to emphasize that okay so how close can i tree like our lawn has trees on it so like how far what are you what are you mentioning there like well and and that's if you do have trees in your lawn i would stay outside the mulch line for sure okay so i think that would be good okay that's very helpful