This is an update of an article from last year as a reminder about managing kudzu bug infestations in soybean.
Kudzu bugs adults and egg masses are now easy to find in some soybean fields as adults migrate from kudzu. It’s currently too soon to spray, but this is something we need to be tracking from this point forward. I’m hopefully that Beauveria bassiana, a fungus that attacked and killed many kudzu bugs last year, will again help us out this year. If you need a refresher, please read below.
- Adults and immature life stages (pictured below) feed on the sap of soybean. They are not seed feeders. Thus, it takes time and numbers to cause economic injury.
- Spraying only for adults as they migrate into fields is almost always a waste of time and money. If you spray too early, you’ll just get to spray again. It is best to let the population establish and start reproducing before an insecticide application is made.
- The recommended threshold for kudzu bug is 1 IMMATURE kudzu bug per sweep (25 nymphs/25 sweeps). This may occur 2-3 weeks after the adults started infesting a field.
- Infestations are often much higher on edges, so make sure you take representative samples throughout the field. Given a choice, they typically prefer flowering soybean.
- One well timed application is usually enough if you don’t spray too early. Recommended insecticides include several pyrethroids and acephate, but the data show that one of the bifenthrin products (e.g., Brigade, Fanfare, Sniper, Tundra) at 5-6 oz/acre are hard to beat, but we saw really good control with Karate/Warrior last year in our test plots as well.
- Infestations may occur anywhere is Tennessee. The more kudzu in an area and the closer it is to soybean fields, the greater the risk. However, kudzu bugs are good fliers and can infest soybean several miles away from infested kudzu.