Friday, June 24, 2022

Alabama Insect Situation: June 24, 2022

Cotton Situation

The past two weeks have been HOT and DRY across Alabama. We have gotten some scattered storms across the state, but we have also seen a couple of days in the triple digits and a good bit of our crop could use a good drink.

Blasted Square from TPB feeding
We have gotten reports from all cotton producing areas of Alabama this week and the biggest thing going is plant bugs. As more fields begin to square, more adult plant bugs are being found and more fields are needing to be treated. The good news is that most of the reports that we got this week was the fields that were treated the week prior did not have threshold levels of plant bugs this week and only “new” fields needed to be sprayed. Of course, we still need to check fields that have had an application because they can show back up. Our older cotton fields are beginning to bloom and will likely start to have immature plant bugs show up soon. We have not gotten any reports of this yet, but we know they are just around the corner.

With the beforementioned weather, we have the potential for the spider mite situation to “blow up” on us quick. One observation that has been reported from multiple regions of Alabama is that spider mites are worse in fields that were treated with acephate back during the thrips window. In some cases, this may have been as many as 3-4 weeks ago. That is not to say they can’t be found in fields treated with other chemistries or fields that weren’t treated for thrips, but make sure to look for mites in fields that were treated with acephate. With that being said, I would strongly consider the potential to flare spider mites when making a plant bug insecticide decision (note: not a spray decision, if plant bugs are at economic levels, we need to get them). In other words, choose a product that is less likely to aggravate mites.

Soybean Situation

Adult RBSB
We did some sweeps in R2 soybeans near Tallassee and found redbanded stink bugs. We were averaging about 2 adults per 25 sweeps (threshold = 4/25 sweeps). This is an unwelcomed but not unexpected find. We picked up RBSB this spring in clovers when we were sampling and the somewhat mild winter allowed for some survival. Normally, we don’t recommend a pyrethroid with an R3 fungicide trip, but I would consider a piggy pack application if adults are in the field. If we get behind on RBSB, it can be extremely difficult to get back ahead. They are likely not in every field and I would be surprised to see some in north Alabama right now, but now is the time to start looking in central and south Alabama if beans are in the reproductive stages.

As always, if we can be of any help, please let us know.

Thursday, June 16, 2022

Alabama Cotton Insect Situation: June 16th, 2022

We still have some thrips going in spots here and there, but we are mostly through that window. Plant bugs and spider mites are the biggest calls and reports that we are getting.

As more cotton is starting to square across the state, we are receiving more reports of adult plant bugs moving into fields. Remember our thresholds are 2 adults per 25 sweeps (8 in 100 sweeps) or 80% square retention in the upper 2 or 3 nodes of the plant.

One important thing keep in mind is that thresholds are more of a guideline than a hard and fast rule. The proper term is “economic threshold” which obviously means economics play a role (both commodity and input prices). Due to the fluctuation and variations of prices, we don’t change our thresholds each year, but we can adjust a little bit “on the fly” if we need to. With cotton prices hovering over a dollar, we can afford to be a little more aggressive with insect management. This is because even though the insects are “eating the same amount of cotton” they are eating “more money” because that cotton is worth more. This is not to say that scouting and thresholds aren’t important in years with high prices, an application with no insects in the field is still a waste, just that pulling the trigger a little sooner may provide a higher return. Of course, in years where prices are low, the opposite is true.

Early spider mite symptoms

We got some storms across Alabama yesterday, and that may help the spider mite situation a little bit, but I wouldn’t bet on it. With the temperatures across the state right now and projected to be even hotter next week, every insecticide application should consider spider mites. We are in a situation where they could blow up quick. I am not saying don’t treat plant bugs if you have economic infestations for fear of spider mites but try to choose something less likely to flare them. Our threshold is to treat when 30% or more of plants are infested with spider mites and damage is evident. Sometimes we may watch the forecast and see if an imminent rain can help us before we make an application. I am not sure I would do that with the current outlook. I think being a little more proactive on these building populations with upper 90’s and even into the 100’s temperatures impending would be prudent.

Mating southern green stink bugs in corn

I also want to briefly mention stink bugs. We have been in corn fields in central and SE Alabama this week collecting corn earworms for Bt resistance monitoring. There is currently a ton of adult stink bugs in corn fields that are mating, and some nymphs are beginning to emerge as well. Corn is the perfect trap crop for stink bugs and cotton. A well-timed application will help corn and cotton as well. The best time to spray is at tassel, while the ears are forming, but stink bugs can damage corn through the R2 (blister) stage. Most labeled pyrethroids provide good control. If you haven’t, consider making an application in corn, it will help that crop and likely relive some pressure in cotton later in the year as well. For more information on managing stink bugs in corn, watch this video (link) with Eddie McGriff and Dr. Katelyn Kesheimer.  

We will also give a reminder that we have two more scout schools (link) this coming week. We will be at the TN Valley REC in Belle Mina on Tuesday the 21st with registration starting at 8 and the program beginning at 8:30. We will also be in Centre at McCord’s Fire Station #1 on Thursday the 23rd. That program will begin at 10 am.

As always, if we can ever be of any help, please let us know.

Monday, June 6, 2022

Alabama Cotton Insect Situation: June 6, 2022

Things were pretty quiet last week, but the Alabama Cotton Insect Situation seems to be picking back up this week. We have already gotten a few calls about threshold levels of adult plant bugs in squaring cotton in in Central and SW Alabama. If you remember last year, we had a big migration of adult plant bugs into cotton fields statewide around June the 15th. At this point, adults are moving into our oldest cotton (mid-April to first week of May) that is starting to put on squares. So, most of our fields aren’t at risk yet, but keying in on fields that are squaring is important. Much of the fleabane across the state has already or is starting to play out. This means plant bugs are looking for somewhere to go and a cotton field that is starting to square is a good place for them to settle in. Reports out of the TN Valley and NE Alabama are that not much cotton is squaring, and no threshold levels of plant bugs have  been observed.

Adult Tarnished Plant Bug
With input and cotton prices where they are, it’s going to be important to scout fields and be prepared to treat when necessary. Prior to bloom, our thresholds are 2 adult plant bugs per 25 sweeps or 80% square retention in the upper 2-3 nodes. One thing to keep in mind is that we may scout a field with high square retention, but also high numbers of plant bugs. That may mean that the bugs just moved into the field and that squares that were fed on haven’t yet had time to abort. That’s why we like to use these thresholds as an either/or and a both/and. In other words, if you hit one of the thresholds but not the other, we should go ahead and trigger a spray.

In terms of recommendations, we like to manage migrating adults as economically as possible, because there is always the potential for more to move in a few days after a spray. Unfortunately, nothing will provide much residual control of migrating adult plant bugs. I have heard some reports that some of our “June go-to’” products are hard to get. We have some options, such as imidacloprid (highest labeled rate), Centric (1.5-2oz), acephate (8-10oz) and depending on resistance in your region, bifenthrin (6.4oz). Keep in mind that per the label, Bidrin cannot be applied between pinhead square and first bloom.

Another thing to remember is that square retention is a good way to evaluate the efficacy of an insecticide on migrating adults. If you come back to a field 5 or 7 days after a spray and find as many or more plant bugs, good square retention will tell you your spray worked, and more bugs have moved into the field.

We should be through the thrips window for much of our cotton, some fields, particularly in north Alabama, may still need to be watched. As a general rule, we don’t see much value in spray cotton beyond the 4th true leaf stage, but we have seen some fields this year that would very likely benefit from a spray at the 5th or 6th leaf.

Early spider mite symptoms on leaves
The last thing I will mention is that we observed spider mites in a field in central Alabama today. It has been an interesting start to the season variable weather, most too dry and some too wet at times. These mites had likely been building on some weeds that were in the field and have moved into the cotton after a herbicide application went out. In dry areas, spider mites are another thing to consider when making insecticide application decisions. Hopefully the chances of rain across the state this week will materialize so we can get some reprieve and help get this cotton crop off and running.

The 63rd Alabama Cotton Scouting School is coming up. This year we have our 3 traditional locations: Tuesday, June 14th in Autaugaville, Wednesday June 15th in Headland and Tuesday, June 21st in Belle Mina. We will also have an in-season scouting update in Centre on June 23rd and a late season scouting update in Southeast Alabama in August. More information can be found here.

As always, if we can ever be of any help, please let us know.