Most of the reports we have received this week is that overall, we are in pretty good shape. However. There are some fields that are in need of reprieve. We have some fields in SW Alabama that cannot miss a rain, and other fields in N Alabama that cannot catch a rain. Cotton across much of central Alabama looks to be in good shape. We are hopeful for a good August and September so we can finish the crop out and maximize whatever yield potential we have in the field as of today.
Not much has changed with the bug complex (plant bugs + stink bugs) situation over the past 7 days. Some fields are still requiring attention from plant bugs, but we are at the point with most of our cotton that we need to kill stink bugs when going across the field. We walked some fields today in S Alabama with a 2x threshold of both plant bugs and stink bugs. Many of these fields were missing lots of fruiting sites, but still have time to make a top crop if bugs are managed moving forward.
Our observations and reports have been that most fields sprayed over the past week to 10 days have not required follow up sprays. We typically expect to get about 2 weeks out of a stink bug spray before retreatment is necessary. This is not residual control, just typically about the time it takes another infestation of stink bugs to build to population levels that can cause economic damage (=10% internal damage). This may not be the case if sources of stink bug populations are nearby (corn, peanuts, pecans, etc.) and fields should still be monitored weekly to ensure damage is not building.
We have received reports that spider mites are requiring attention, primarily in the Wiregrass this week. Abamectin is typically the go-to for mites based on economics, but we wouldn’t normally recommend using abamectin as a follow up if retreatment is needed. There are pockets of resistance across the southern Cotton Belt and if abamectin doesn’t provide satisfactory control one week, I would not expect much to change the following week. We talked about alternative options in last week’s Blog (link).
Thus far, the bollworm flight has seemed to be pretty low overall when looking at our trap counts across the state. Historically, the expected peak flight varies with South Alabama ≈July 10, Central AL ≈July 20 and North AL ≈August 1. However, we have received reports of egg lays varying from 1-10% in the TN Valley and high numbers of moths in fields in SE Alabama. In general, we do not recommend making insecticide applications based on eggs in Alabama, as we still rarely find escaped worms in our Bt cottons.
We are beginning to hear about infestations of defoliating caterpillars in peanut fields. Often, we have a complex of species including green cloverworms, soybean loopers, velvetbean caterpillars and some others such as fall armyworms, beet armyworms, bollworms, cutworms, or others. Our threshold is 4-8 worms per foot of row. The low end is advised when peanuts are small or stressed from other factors.
We also have received reports of lesser cornstalk borers (LCB) requiring treatment in the Wiregrass. This pest prefers fields with skippy stands and they thrive in hot, dry conditions. With the loss of chlorpyrifos (Lorsban), we only have a couple of options including chlorantraniliprole (Vantacor 1.2-2.5 oz), or chlorantraniliprole products pre-mixed with the pyrethroids bifenthrin (Elevest 5.6-9.6 oz) or lambda-cyhalothrin (Besiege 10 oz). Another option is the insect growth regulator Diamond (6-12 oz). Keep in mind that the weather conditions that LCB thrive in are the same the spider mites can blow up in as well. If spider mites are a concern, consider using products without the added pyrethroid as this may flare mites.
In response to a farmer request, the Alabama Extension Agronomics Crops Team is conducting a survey to better understand the impacts of deer population on crop production. Please take a few moments to help us collect information to try to use to figure out ways to mitigate deer losses in your row crops.
You can take the anonymous survey here (link).