Foliage-feeding caterpillars are the insects peanut growers need to be most concerned with as harvest season approaches, according to Mark Abney, University of Georgia Extension peanut entomologist.
“The one that comes in every year and will probably eat the most peanuts and infest the most fields is velvetbean caterpillar. We started hearing about velvetbeans in southwest Georgia maybe a month ago now,” Abney said. “About two weeks ago we started seeing a lot of moths in my test plots around Tifton (Georgia). I’ve talked to some consultants and county agents over the last couple of weeks; they’re definitely increasing so growers need to be paying attention. If they’ve got a consultant or a scout, they’re going to catch them. If you don’t have a consultant or scout, now is the good time to be looking for velvet bean caterpillar.
“Soybean loopers are starting to pick up some now. Those are probably the two most common.”
Abney said the recommended threshold – or the barometer that must be exceeded before action needs to be taken – for caterpillars in peanuts is 4 to 8.
“People get confused a little bit about the thresholds on caterpillars because we say it’s 4 to 8 per row foot. They say, well what is it; four or eight or six or seven? I get it. It’s pretty simple, if you have peanuts that are stressed or haven’t lapped the middles yet or small, we’re going to be down on the low end of that threshold because we don’t want to lose leaves on peanuts that are stressed,” Abney said. “We might go four per foot. If you’ve got some peanuts that are knee high and they’ve had plenty of water and are growing good, you can afford to wait until you get to eight caterpillars per foot before you spray them.
“In reality, if they get to four or five, they’re going to spray them regardless of the condition of the vines because it looks scary.”
Abney said the window to protect your crop from damage is 70 to 100 days after planting. Growers really want to protect their peanuts from being defoliated. Peanut plants cannot tolerate a few leaves taken off.
“As we get past 100 days, if some foliage feeders get in there and you lose some leaves, it’s not going to be the end of the world. You still don’t want peanuts to get stripped. You can’t mature a crop if you don’t have any leaves,” Abney said. “That’s what velvetbeans can do to us. They can come in the last 30 days of the crop and take all the leaves off; you don’t have anything but stems and you’re pretty much done. Your maturity is what it is. That 70 to 100-day window is probably when we need to be looking really closely at peanut fields.”