What is in this article?:
- Kudzu bugs found in Alabama soybeans
- Feeding results similar to drought
• The kudzu bug has spread rapidly since it was first detected and now has been found in 7 Southeast states.
• The kudzu bug had been found previously on kudzu in 25 Alabama counties, but this is the first report on soybeans.
• Economic yield losses in soybeans due to kudzu bug feeding have been reported in Georgia.
Feeding results similar to drought
The effects of kudzu bug feeding on soybeans is similar to drought. Excessive feeding weakens and stresses the plant which can result in fewer pods per plant, fewer seeds per pod, and reduced seed size.
Over-wintering adults survive under pine bark and ground debris. Key reproductive hosts of kudzu bugs include kudzu, wisteria, clover and soybeans.
Adults begin laying eggs on kudzu shoots in mid-April and continue laying eggs on kudzu for several weeks.
Time required to reach the adult stage is about 6-8 weeks. These new adults then disperse to soybeans and other reproductive hosts beginning in mid-June and continuing through mid-July.
Soybeans become attractive to kudzu bug adults when plants are 8-10 inches tall. Early planted soybeans appear to be at greater risk for kudzu bug infestation compared with later planted soybeans.
Adults will begin laying eggs on the underside of soybean leaves and a generation requiring about 6 weeks will be completed on soybeans.
Initial field invasions tend to be more concentrated on field margins, but will eventually spread throughout the field. In many situations we will begin to see immature kudzu bugs in soybeans at about the R2-R3 stage.
Kudzu bugs can be scouted using a 15-inch diameter sweep net.
Kudzu bug populations can be extremely high. Georgia entomologists are suggesting a threshold of one immature kudzu bug per sweep. This suggested threshold is based on 2011 field trials where a single properly timed insecticide application preserved soybean yield.
If insecticides are applied when adults are still actively migrating from kudzu to soybeans (late June and early-mid July); additional applications may be needed.
Research is ongoing to verify and refine management and treatment thresholds for kudzu bugs in soybeans.
Multiple classes of insecticides have shown activity on kudzu bugs. Insecticide treatments containing bifenthrin, cyhalothrin, zeta-cypermethrin, carbaryl, or acephate provided greater than 80 percent control 2-5 days after treatment.