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Tarnished plant bugs, spider mites, bollworms, thrips and stinkbugs are on the top of the list that Mid-South cotton producers must be aware of during the 2013 growing season. Though these insects are common in many regions, management of these pests will vary. Angus Catchot, Mississippi State University Extension Entomologist, gives Mid-South producers recommendations on how to best control these pests in order to help achieve maximum yield potential.
Question: What are some major early season pests in your area and how would you recommend controlling them?
AC: Thrips. We deal with thrips every year. We treat with seed treatments and granular in-furrow insecticides on every acre of cotton, but in recent years we have moved almost exclusively over to seed treatments for thrips protection. In the Mid-South region, normally we may have to make an additional foliar application somewhere in the 20-30% of the cotton acres. The last couple years, thrips have been a lot worse. We’ve actually had to make a couple more applications on 70-80% of the cotton acres. Growers really need to be concentrating on watching for thrips. The trend seems to be that we may have to make additional foliar applications on top of the seed treatments. Thrips damage will hold cotton plants back and delay it. Anything that delays cutout sets us up for late season problems with other pests such as spider mites and plant bugs. Once cotton starts squaring, growers need to be aware of tarnished plant bugs. In our region, it is not uncommon for growers to make seven to ten applications depending on the year for tarnished plant bugs. Because of the high number of sprays we have to make in the Mid-South for thrips and tarnished plant bugs, we also have a tendency to flare spider mites. As a consequence of numerous insecticide sprays for plant bugs and thrips, we will create a spider mite problem for ourselves, and that is an additional spray.
Question: Why do you think the trend for thrips has changed over the last year?
AC: Anything that holds the cotton plant back or slows the growth and keeps in the susceptible window for thrips damage essentially exacerbates the injury we see from thrips. Often times, during cold spells when cotton is not growing off well, we see worse thrips damage. In the last few years because of resistant pigweed and other resistant weeds, most of our growers have adopted residual herbicides, which also have a tendency to hold the cotton plants back in the beginning of the season. This may be a contributing factor. If a cotton plant is healthy and shoots out of the ground, then we get out of the thrips stage sooner, which leads to fewer foliar applications
Question: Do any of these pests cause problems later in the growing season?
AC: Tarnish plant bugs are a season-long problem. Prior to bloom, most damage done by tarnish plant bugs is by adults. Usually by the third week of squaring to right around the first week of bloom they will start laying eggs. Once we get into bloom period, we're fighting both nymph and adults. A lot of times nymphs are down low in the canopy, which makes them tough to control. We also have documented resistance to pyrethroid and organophosphate insecticides. They're just a pest we deal with every year and are also difficult to control even though we know they're there.
Question: What are some other major late season pests in your area and how would you recommend controlling them?
AC: Bollworms and stinkbugs. Even though 98-99% of our cotton is traited cotton varieties, we still have to make treatments for bollworms. Genes [in the varieties] are doing a fantastic job, but it is not enough under intense pressure. Sometimes we'll have to supplement those and make at least one or two additional bollworm applications to protect the fruit. Also, stinkbugs are specific to late season. They're not as big of a problem here as they are in the Southeast because we're making so many plant bug applications we are controlling them coincidentally with these applications. When we get into an occasional “lull65533;? where plant bug pressure has slowed and growers are not treating, we quickly see stinkbugs fill that gap. Stinkbugs are there and ready to move in at any time and we need to not let our guard down just because they are not as common of a pest for us.
Question: When should growers be scouting for these pests and what are some of the warning signs?
AC: We don't have a lot of growers that do their own scouting. We have independent crop consultants on 95% of every acre that is grown. Whether it's cotton, corn, or soybeans, it doesn't matter. We depend heavily on crop consultants throughout the Mid-South. We have people putting footprints in the field usually twice a week in cotton. They know what to look for, they're aware, they're on top of these things. Our consultants continue to go to trainings and follow newsletters and academic meetings to stay on top of the latest information and control recommendations. So I'd say we have a highly educated, independent consultant base that are on top of these things on behalf of the growers.
Question: Besides seed treatment products and foliar sprays, what are some other best management practices?
AC: Although the Mid-South is a high spray environment due to intense pest pressure, we try our best to utilize every control strategy available; not just insecticides. We try to work in some cultural management practices, especially when controlling tarnished bugs. We educate our growers on trying to isolate their cotton from their corn. I'd recommend NOT having corn/cotton interfaces because we'll see a large number of plant bugs in corn/cotton interfaces moving out of corn into cotton. Corn is also a host for these pests, which creates tremendous problems when in close proximity to cotton. Another recommendation is to plant early, although it's not that easy. You can only do so much of that when you have concerns such as the weather and other crops to work around. We know for a fact that if we can get an early cotton crop in and get it to set we will definitely save on plant bug sprays because the crop cuts out prior to the late season buildup of plant bugs. It's the same strategy that was used before B.t. cotton when growers would try to plant an early maturing variety early to avoid late season insecticide resistant tobacco budworms. It works equally as well for tarnished plant bugs.
Over the years, growers have learned how to deal with these pest outbreaks and can still make very good cotton crops despite some of these issues. Following these best management practices will help growers achieve maximum yield potential. Remember, things change quickly. Timeliness and awareness of product performance are critical when treating the Mid-South cotton pest complex. For more information on timely control in cotton, read this article.
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