Soybean growers facing kudzu bug control decisions in May

Since the kudzu bug showed up on soybeans in Georgia, South Carolina and parts of our state in 2010-2011, there has not been a reported infestation on a commercially planted soybean field until the first generation kudzu bug adults have developed. 

From observations in previous years, kudzu bugs emerge from over-wintering and migrate to hosts.

In the spring of this year, we have had reports of kudzu bugs on all sorts of non-hosts (humans, houses, fig trees, grapes, wheat, cotton, and a magnolia tree, to name a few), hosts on which they feed and may or may not reproduce (e.g., legumes such as wisteria), and the major host of this pest, kudzu plants. 

In 2010 and 2011 adults moved from over-wintering sites through the landscape until they found kudzu and laid eggs, which developed as nymphs to the adult stage (first generation).  These first generation adults then moved onto soybeans, stayed on kudzu, or moved to other legume plants. They then laid eggs, which resulted in the development of a second generation of kudzu bugs for the year.

This year I have seen a glitch in this pattern, as kudzu bugs have been found in low densities on soybean seedlings in scattered areas of North and South Carolina (see previous blog post). These areas are all in areas where kudzu bug was confirmed as present in 2011. 

The recommendation has been to focus treatment on the kudzu bugs that arrived in soybeans and the resulting second generation of nymphs. A preliminary threshold of one nymph-stage bug per sweep (i.e., 15 nymphs per 15-sweep sample) is recommended and may help reduce the need for multiple sprays in reproductive stage soybean.