UGA Extension Cook County

Lessers in Peanuts, Spidermites in Watermelon, Spray Pecans Now

Hot dry weather = hot dry weather problems.  Check peanut fields for lesser cornstalk borers as they are starting to pop up in Cook and Berrien counties; and reports of findings from other counties.  Found a hit of spider mites in watermelons.  Also see below for info on spraying pecans now (before rain predicted in the next 5 days per weather reports). Tucker Price 507-8862

LCB found in Cook County.

Ideal Conditions for Lesser Cornstalk Borer in Peanuts.

UGA Peanut Entomologist, Dr. Mark Abney

Lesser cornstalk borer (LCB) is the most destructive insect pest of peanut in the Southeast, and it thrives in hot, dry conditions. It doesn’t get a whole lot hotter or drier in South Georgia than it has been the last couple weeks, and reports of LCB infestations in peanuts have predictably started to arrive.

What should growers do about LCB? The most important thing a grower can do is monitor fields regularly and take appropriate action if/when infestations are discovered. Three insecticide active ingredients are recommended by the University of Georgia for LCB management in peanut: chlorpyrifos, chlorantraniliprole, and novaluron. Chlorpyrifos (Chlorpyrifos 15G) can only be applied as a granular product banded over the row. It requires rainfall or irrigation for activation, and applications are often followed by outbreaks of caterpillars and/or mites. Chlorantraniliprole (Prevathon) and novaluron (Diamond) are applied as broadcast foliar sprays. Rainfall or irrigation after application may improve efficacy, but I have no data to support this, and both products have provided good control in UGA trials without additional water.

Severe LCB infestations are not common in irrigated peanut after the vines have lapped the row middles IF adequate irrigation is applied. However, LCB is often found in irrigated fields (especially those with sandy soils) prior to row closure when environmental conditions are favorable. LCB caterpillar feeding in the crown of seedling plants can reduce yield even if adequate water is available later in the growing season. It is important to remember that while LCB does not survive well in moist conditions, one or two rainfall events will not eliminate an established population, and we will probably not be able to “irrigate LCB away” prior to row closure.

The two mistakes that are most likely to be made when LCB infestations are on the rise are:
1. Treating fields with an insecticide when no insects are present. No matter how bad LCB gets in 2019, it will not be in every field.
2. Failing to treat or treating too late when thresholds are reached.
Scouting is the best way to avoid these mistakes. It is hot and dry and there are lesser cornstalk borers in some of our peanut fields, and we cannot do anything about any of that. What we can do is stay calm and make wise decisions that will protect our peanuts and maximize our return on investment.

Scout Watermelon Fields for Spider Mites

Spider mites in watermelons.

Spray (pecans) Now!

Lenny Wells, UGA Pecan Specialist

Most pecan growers in Georgia have been stretching out their scab sprays over the last several weeks since we have been hot and dry with no rain at all for about a month now. In the absence of any scab pressure this was the right thing to do but when you stretch your sprays out you really have to be watching the forecast closely.

Unfortunately, the forecast has changed dramatically and we now have rain scheduled at 50-60% every day for the next week or so. Therefore growers who have been stretching sprays out need to get a fungicide spray on as soon as possible. It is always best to get a fungicide spray on prior to the rain as opposed to waiting until the rain has passed. Since many growers most likely will not be able to get over everything prior to the rain, they need to start with spraying Desirables and any other scab susceptible varieties they may have first. Now that we are entering the nut sizing stage, a good option will be a group 3 + group 11 fungicide with a surfactant or go ahead and begin spraying with Elast or Elast/Tin. Stay on a 2 week maximum interval from this point on until shell hardening, rain or shine for susceptible varieties.