Alabama Crops Insect Situation: Thursday July 27, 2023

The plant bug situation has not changed over the past week. There are still some hotspots with high numbers of nymphs, but overall populations are manageable. We have also observed and received reports that adult plant bugs are showing back up in places, presumably moving in from nearby corn fields. When scouting, keep an eye out for borders with corn because that is likely to be where the highest pressure is. We have reached the point of the season where a sweep-net may be needed in addition to a drop cloth as nets are more efficient in picking up adults. Managing these populations of adult plant bugs is important because they will also be depositing eggs that will hatch out in the following 7-10 days. Keep scouting for plant bugs and be prepared to treat when needed.

Spider mites should be in the back of everyone’s mind right now. Spider mites have been reported at treatable levels in NE and SE Alabama this week, and we have observed populations in fields in central Alabama as well. The current long-range forecast doesn’t look favorable for soaking rains, which help beat spider mite populations back. At this point in the season, we recommend using higher rates of abamectin for controls. There are two formulations of abamectin sold (0.15EC and 0.7EC). Higher rates (12oz+ or 3oz) provide more consistent control in bigger cotton with a lot of canopy. Based on the current forecast, I could suggest being proactive on a spider mite infestation, particularly if going across the field anyway. Spider mite infestations are much easier to control before they “get out of hand.”

We have also heard about a few fields in south Alabama with escape worms in Bollgard 2 (BG2) cotton. We do not believe this is widespread, in other words, I wouldn’t start automatically treating all my BG2 fields, but we should be aware. Our threshold is when 5% small larvae (5 worms on 100 plants) or when 6% damage is observed (squares, flowers or bolls). There are several options for control, however they are all most effective when applied to small worms (>0.25”). We know there is some bollworm pyrethroid resistance, however, they may provide adequate control in some cases. The diamides (Besiege, Vantacor, Elevest) provide the best control, but at a price. If a pyrethroid is used, it should be monitored closely after application because the cost of a “miss” could be high.

Where are the stink bugs? That is one of the biggest questions we are getting right now. My answer is, I don’t know, but I hope they stay where ever they are. In general, there just hasn’t been a whole lot of stink bugs or damage observed in fields so far. It could be that we were more proactive in corn this year, or on plant bug management, or it could be related to weather somehow. Whatever the reason, we know the high damage potential stink bugs have and we need to continue scouting and be prepared to intervene when necessary.

Things have been very quiet on the soybean and peanut front. We have talked to a several folks this week and there doesn’t appear to be much action out there. There are some cloverworms in most fields, a few loopers and stink bugs here and there, but overall, not much. This highlights the importance of scouting and only treating when necessary. If there are no damaging levels of pests in the field, then there is no return on an insecticide application.

As always, if we can ever be of any help, or if you would like to provide input on the situation in your area, please don’t hesitate to reach out (Scott Graham: 662-809-3368; Ron Smith: 334-332-9501). For more information on thresholds and insecticide recommendations, visit the Alabama Cotton IPM Guide (IPM-0415). To stay up-to-date on the Alabama cotton insect situation, subscribe to the Alabama Cotton Shorts Newsletter, Alabama Crops Report Newsletter, and the Syngenta Pest Patrol Hotline.

Alabama Cotton Insect Situation: Thursday July 20, 2023

Plant Bug Situation

Overall, we appear to be in good shape after the onslaught of adult plant bugs that infested fields in June. Phone calls have slowed down considerably, and most of the reports are that plant bugs are out there and in some fields at damaging levels, but manageable. I think we have two big factors that have helped us in this regard.

The first was our adult plant bug management. As we have talked about a lot this year, our recommendation in Alabama is to treat a threshold population of adult plant bugs, regardless of square retention. We believe this helps to preserve square loss before it happens and reduces egg lay. The immature populations in fields now are a result of this egg lay in June. Allowing a threshold population of adults to “ride” a week to wait for square loss gives them the chance to lay tens of thousands of eggs per acre over the following 7 days. Killing these adults before they have the chance to feed and lay eggs has helped keep populations manageable.

The second thing that has helped us to this point is the use of Diamond. When timed properly, Diamond provides residual suppression of plant bug nymphs. While not in all cases, reports we have received seem to indicate that following an application of Diamond + a knockdown insecticide, many fields have bought themselves to the stink bug window (≈3^rd week of bloom).

Stink Bug Situation

Speaking of stink bugs, reports of populations and damage in fields are trickling in. Remember our threshold changes by week of bloom. Early bloom (weeks 1-2), threshold is 50-30% boll damage. Peak bloom (weeks 3-6), threshold is 10% boll damage. Late bloom (weeks 7-8), threshold is 30-50% boll damage. Right now, reports are that most of the populations are brown stink bugs. Typically, the green species show up towards the end of July or first of August. In general, pyrethroids aren’t as good on browns as organophosphates (Bidrin, acephate). However, pyrethroids often do a good enough job on browns to keep populations below threshold. Also consider your plant bug situation and resistance levels if needed to make a bug complex spray.

Others

We have received several calls on aphids over the past week. In most fields, populations are heavy in localized areas and are not a concern for treatment. We don’t often recommend treating aphids, but some situations may require an application, such as if cotton is drought stressed and/or late or if populations are making scouting other insects, like plant bugs difficult. We have gotten a report of the fungus killing aphids in the Wiregrass, so we should expect populations to start crashing soon.

We have some pockets of spider mites in fields but overall we have not gotten too many calls lately. Watch the weather and behind applications of broad-spectrum insecticides for mites building.

We observed some bollworm egg lay in fields in central Alabama this week, but we have not heard of any escapes in two or three-gene cotton.

Update on ThryvOn

I also wanted to give a quick update on some of the calls we are getting with ThryvOn. ThryvOn provided excellent control of thrips in every field we visited and based on all the feedback we received during the thrips window. In June, when adults were migrating in, it was hard to see what ThryvOn was doing. In many fields, populations were above threshold and square retention was dropping. Some folks were frustrated with having to treat these fields since it has a “plant bug trait.” However, we are now starting to realize some of the benefits. We have gotten calls across the state reporting that non-ThryvOn fields with similar planting dates and pre-bloom insecticide regimes are being treated for immature plant bugs, while they cannot find many nymphs or dirty bloom in the ThryvOn. This is what we hoped to get from this technology in Alabama, “saving” a spray in July and pushing us to the stink bug window.

Final Thoughts

We are off to a good start, but still have a long way to go. Keep scouting and monitoring fields and be prepared to make timely applications when needed. As always, if we can ever be of any help, or if you would like to provide input on the situation in your area, please don’t hesitate to reach out (Scott Graham: 662-809-3368; Ron Smith: 334-332-9501).

For more information on thresholds and insecticide recommendations, visit the Alabama Cotton IPM Guide (IPM-0415). To stay up-to-date on the Alabama cotton insect situation, subscribe to the Alabama Cotton Shorts Newsletter, Alabama Crops Report Newsletter, and the Syngenta Pest Patrol Hotline.