 Hi, everyone. My name is Caitlin Casimer, and I am an extension entomologist with the Alabama Cooperative Extension System. For today's webinar, I will be covering insect control and alfalfa as part of the Animal Science Alfalfa in the South program. So let's get started. To begin, I want to point out one resource we have as part of the Alabama Cooperative Extension System IPM guides. This one is particularly for alfalfa. You can find them on our website. The link is posted at the top of this slide for the sake of time. I'm going to pull some of the most important information here and go over some of the basics of a solid proactive IPM plan, which will cover sampling methods in your alfalfa field, because that's really the key to discovering some of these sporadic pests that you'll encounter, how to identify these pests in your field, thresholds knowing when and if you need to treat. And then in the case of an infestation, you can consult this guide for specific control recommendations. And then feel free to contact me if you have any questions. I'll have all my contact information at the end of this webinar. So diving right in, when you're growing alfalfa, you're going to have a lot of insects that make alfalfa their home. Most of these are going to be either beneficial or incidental. And what I mean by that is the beneficial insects. Think about your natural enemies, your predators, your parasitoids, your pathogens, things that are going to actually provide you with free biological control. So ladybugs, lacewings, spiders, parasitic wasps. So you actually want them in your field. And then the incidentals, they're not actually causing any sort of harm. They're not really providing any benefit, but they're making alfalfa their home. So we're not concerned about them either way. However, pests do occur. Normally, they're in populations too small to cause any yield loss. However, some years and some fields may experience economic yield loss. So it's important that we do scout. And being in the South, this means we have to do it actually most of the year. So this would be from green up through the last cutting from February to November. And being in the South is fantastic. We have a really long growing season. We can grow a whole variety of crops with great weather. So it's a fantastic advantage. But on the insect side, that makes for a really long reproductive season for insects. It's important to remember, insects are cold-blooded. So their reproduction, their movement, their feeding behavior is entirely dependent on the environment, the weather, the temperature. And so if we have, for example, a very short winter without a lot of cold weather, a late hard freeze, that just means insects can get started sooner and they can come out of overwintering and start feeding on our crops. And so that's something you certainly want to keep in mind when you start scouting your crops. And so I mentioned a long growing season. You can see by this alfalfa scouting calendar that goes from January to December at the top of the slide, and then down the left you have major insect pests that you're going to encounter in alfalfa. And this gives an approximate time throughout the year of when you want to keep an eye out for each of these pests. And so starting very early on, you want to be looking out for alfalfa weevils, pea aphids, and true armyworms. And where you see these dashed lines for a very big category of other caterpillars, so corn earworms, fall armyworms, bee armyworms, for example. And then also for grasshoppers, these are really variable depending on the year, temperature, weather. And so it could start a lot earlier. It could go later into the season. It could be dependent if we have a big drought. We may see a big influx of caterpillars. It could be dependent on last year's weather. So keep that in mind. But a lot of these are approximate, but they're not going to shift too much. And so we know we're going to have a good six to eight weeks of Japanese beetles in the middle of the summer. But reference this when you know when to start scouting for each of these pests. So there are various ways to scout for insects and alfalfa. Most of them involve very simple items that you either already have or can easily acquire. And importantly, a lot of our thresholds depend on these sampling methods. Since there's a diversity of insects in alfalfa that really all inhabit different parts of the plant, it's important that you're familiar with each sampling method to ensure that you have a really accurate picture of what's going on in your field. So the first one is the bucket method. And this is simply just grabbing individual stems and beating them inside a bucket about 20 to 30 times to dislodge any insects. And so you can really grab more than one stem at a time, but make sure you count how many stems you're doing so you can calculate your insect pressure. For example, after you look at what's in the bucket and you know how many stems you beat inside the bucket, you can say, I found 10 aphids per 30 stems. And that's going to factor in to whether or not you need to take action for your current pest pressure. The next method is what we call a per unit area. And so the most common one we use is per square foot. And the easiest way to do this is getting some old PVC pipe, which I'm sure a lot of you have, laying around in your garage or your shed or your barn and connecting it into a square that measures one square foot. And then you can take this square out to the field and sample multiple places in the field and see what is inside that square. And that will give you a good representation per square foot and look at the insect pressure in there. And then the last and most common method is using a sweep net. And sweep nets, I'm sure we're all familiar with, these can be purchased very inexpensively at forestry supply stores. We also have them at all of our county extension offices throughout the state. It's a great habit to get into is just to keep one in the back of your truck at all times. And so when you're walking through the field, you take figure eight sweeps through the foliage. I like to take 10 consecutive figure eight sweeps at multiple spots through the field. And you really want to be swinging hard enough so that you're dislodging the insects. So you'll have insects in your net, but you also want to end up seeing plant material in the net. If you're not seeing plant material, then you're not swinging hard enough. Because you really want to make sure that you dislodge any insects that are feeding on the plant or inside the plant stem or plant material. And then one sweep net is one full figure eight. And then you can calculate the average number of caterpillars or plant bugs per sweep. And that can be used for thresholds. Like I mentioned, there's a lot of insects that are going to make alfalfa their home. Many are going to be beneficial and are good to have, but many actually do cause economic yield loss. And so occasionally we do see outbreaks or pests that can cause damage by feeding on the leaves, the stems, the crowns or flowers. And then many are listed here. They come from a variety of groups, including beetles, caterpillars, true bugs, grasshoppers, leafhoppers, et cetera. I'm not going to go over all of these for the sake of time, but I'm going to spend some time going over the main ones, how to identify them, what we use for thresholds here in the south and some management techniques you can use to help control them. So starting with the alfalfa weevil, this is probably the first one you're going to need to start scouting for early in the season. The adults are beetles and weevils have a very characteristic long snout that comes off their face and is over their chewing mouth parts. They are light to dark brown and they can defoliate the alfalfa and cause yield loss, but it's really the larvae or the immature weevils that we're concerned about. You can see the larvae are pictured here. They're a light green with a white stripe down their body and they have a black head. The smaller larvae chew holes in the leaf terminals and on the leaf buds and as they get bigger, a larger larvae can actually skeletonize and really cause a lot of damage to the leaf tissue. And then when you're looking at the alfalfa from afar, it'll take on this frosted appearance and can look almost white from a distance. So the first cutting is at the greatest risk from alfalfa weevil. In especially bad years, this risk can run into the second cutting from both the larvae and adults and this is in extreme situations when we have really high populations. And then like I mentioned in the south, you really want to begin sampling for this pest in February, March. If we've had a really mild winter, you may need to start sampling even earlier. A sweet net is your best bet to start looking for the larvae and then the thresholds will vary based on how far along or how tall your crop is. If you're close to harvest within a week and a half, 10 days or so, it's best to harvest early. If not, go ahead and apply a chemical application. What we use for thresholds is 50% of stems have injury in addition to insects still being present. And so the injury may still be there without the insects present. So we need both of those for a chemical application to be warranted. So the next pest is this big group called caterpillars. And I'm not going to go into detail in all of these for the sake of time, but the ones we see the most consistently and early are the true army worms. You can see them pictured here in a sweet net and they come in a variety of colors, but you're always going to see multiple longitudinal stripes down the sides of their body. And they also have a modeled color appearance on their head capsule. We also do see occasional other caterpillars causing damage, beet army worms, yellow sharp army worms, fall army worms. And those are going to vary each season. As we know, a lot of those pests will migrate up on weather patterns. And so those are going to vary each season depending on the weather, the temperature, the climate, etc. It's important to note that the caterpillars as they're developing, the small worms aren't eating much those first 10 days of their life. They're really causing the most damage the last couple days as they're getting ready to move down to the soil and pupate and turn into an adult moth. And so the key to control is to find them before they cause all that damage in those last couple days. Because, one, they're causing all that damage in those last couple days, and those bigger caterpillars are really hard, if not impossible to kill with the chemistries we have available. A lot of them just don't work against the big caterpillars. And so the best way to sample is to use your sweet net to get a pulse of what's going on in the field. And then if you start to pick up caterpillars in your sweet net, grab your square foot measuring tool and use that and to see within a square foot, have you reached the approximate two to three caterpillars per square foot. And similar to alfalfa weevils, if you're close to harvest, you can go ahead and harvest early. If not, then a chemical application may be necessary. The next pest to look out for, especially in this region, is the three-cornered alfalfa hopper. This is a very distinct-looking pest. It's a wedge-shaped green insect with clear wings. As adults, the imagers are a more tannish white color or green, and they have a row of spines along their back. They are true bugs, so both the adults and the imagers have piercing, sucking mouth parts. And they use those to suck juices out and they feed at the base of the plants and they commonly feed repeatedly from the same spot of the plant. And so they'll cause that spot on the plant at the base to be weakened. And so the plant will eventually fall over and, additionally, the females will lay eggs into the stems of the plant. And so that will also contribute to the reduced integrity of the plant. You may not be able to see these if you're out scouting in the field. They're very flighty. And so what you're going to look for is the plant lodging, so the plants that have fallen over, or a purple discoloration above the feeding site. If you do end up with this damage, what we recommend is about 10% of the stems in the field are destroyed. And for this to happen, it takes approximately three hoppers per plant to cause that much damage. So I do want to just spend a minute mentioning grasshoppers. They are an occasional pest, but outbreaks, when they do happen, they can cause a lot of damage. We've already started seeing high numbers this spring in 2020. And so that's why I wanted to mention them. Grasshoppers will overwinter as eggs. And then in March and April, as the spring rains come and the soil temperatures increase, the eggs will hatch into nymphs or imatures, and then they'll crawl to start finding food. The nymphs, those immature grasshoppers, their wings aren't developed yet, so they can't fly. They're not moving long distances, but really just crawling into the field margins. And so it's important that if you start seeing grasshoppers and you need to treat, you can get away with a border spray before they move into the rest of the field. However, if you're experiencing a very big outbreak and they've infested the entire field, it might be best to harvest early if you're close enough to harvest time and then imply and insecticide to protect the regrowth because all these eggs aren't hatching at exactly the same time. Treatment is warranted when both the populations are really, really heavy and causing defoliation, and this usually is about 12 grasshoppers per square yard. And similar to caterpillars, as the grasshoppers get bigger, they get a lot harder to control. And so it's important to scout and see when you have grasshoppers because you don't want them to get to be adults because one, they're harder to control, and two, like I mentioned, they're going to be a lot more mobile and can move to other parts of the field and start causing damage. All right, the last pest I want to mention are blister beetles. These are certainly not as common as the other pests, but they can have really drastic consequences. So I do want to cover them, especially how to identify them here. Blister beetles are very distinct looking beetles. You can see these are all blister beetles here. They have a very narrow neck with a broad head. They are about anywhere from a half an inch to an inch long with long, skinny legs, and their antennae are about one third the length of their body. And this is an important character because that distinguishes them from another group, the longhorn beetles, which you may have seen that actually have antennae that are much longer than their body, about one and a half times the length of their body. So as you can see from this picture here, they come in a variety of colors, but they're going to be gray or black, yellow or orange, and can either be solid colors or have a striped or spotted pattern. We have several different species in the Southeast. About six of these species are associated with alfalfa or hay, and the adults are attracted to flowering plants. And so we usually see them when the plants start flowering. So I mentioned that blister beetles can have really drastic consequences. And it's because they can cause blistering, has the name blister beetles on humans or animals. They can actually squeeze this chemical called cantheridin from their leg joints as a protective measure. It's really a defensive mechanism from potential predators. And we are concerned about blister beetles not because of yield loss, sometimes they'll swarm, sometimes they'll swarm a field and cause some defoliation. But that's really not why we're concerned about them. Really the threat they pose is because of this chemical cantheridin. If they are in hay and they can have this chemical, they are crushed during harvesting, that chemical can cause internal blistering or inflammation in the livestock that feeds on that hay. And it's really important to note that while all blister beetles have cantheridin in their bodies, they all produce this chemical. The content varies among species, it varies among individuals and in locations around this area. So that makes it very difficult to give an accurate number of how many beetles it takes to have toxic or lethal effects on livestock. So we haven't actually definitively defined how many beetles does it take to say kill a horse. We do know though horses are the most susceptible, sheep and cattle are slightly more tolerant. Overall health does play a role. If we're looking at average amount of this chemical in beetles, we can say that it takes anywhere from a couple dozen to a couple hundred beetles that could be potentially lethal to animals. However, there hasn't been understandably a ton of research in this area. However, just a few beetles can cause distress or colic in horses. And we do have some lab studies that show cantheridin can reduce digestibility of forages in other animals. And so while they may not have completely lethal effects, they can have indirect effects that can harm livestock. So what do you do about it? Well, I think the most important thing is proper identification. So knowing what these blister beetles look like in your alfalfa and knowing whether or not you have a problem. If you grow your own alfalfa, that is great. So you can know whether or not you have a problem. If you're getting your hay from someone else, know your suppliers and their management practices. So know that they know how to properly identify blister beetles. They can swarm during harvest. If they're agitated from the harvest machinery, this is this is what's going on. And so be on the lookout. So stop harvesting because that's when you're going to crush them and get them in the hay. Let the beetles disperse and pick it up after they've stopped swarming. If you have big populations and insecticide treatment may be necessary, the beetles that are killed should fall to the ground and not be picked up by the harvest equipment. And so again, after you do this, recheck the field again prior to harvest. We do know that the adult beetles are attracted to flowering plants. And so harvest the alfalfa before bloom or right after it begins. So they don't have a chance to come into the field with the flowers. Another good method is to control weeds, especially flowering weeds, because they don't really distinguish between alfalfa flowers and weed flowers. And so control that. And then also scout your field before you harvest. And so if you know there are no blister beetles, you're not going to run the risk of crushing them and getting cantheridin in your hay. And finally, I just want to bring your attention back to our IPM guides. I didn't have time to go over every single pest or specific chemical recommendations, but they're all listed in our IPM guides here. And so if you end up with any of these pests in your fields, you can revisit this for all the thresholds I covered and specific chemicals that you may need to control your pests. And lastly, if you have any questions, feel free to reach out and hopefully I can help you with any sort of insect questions you may have in alfalfa or any other pasture crops in Alabama. Thanks.