You may be a soybean grower looking at kudzu bugs in your full-season soybeans.
As a fact, many fields in North Carolina are near threshold levels. That is one nymph per “swoosh of the net”
There are also a lot of fields that look like they will not exceed this threshold. So, what is your best approach?
One disclaimer that needs to be put on this threshold is that it is not a true economic threshold.
An economic threshold is a break even point, where the cost of control equals the yield loss caused by the insect.
Our one nymph per sweep threshold is the point at which you should not experience yield loss.
It is conservative and does not take into account the cost of driving over soybeans (depending on row spacing, tire spacing and yield potential, this could be as high as 4 bushels per acre), the cost of diesel, or the cost of the insecticide.
Therefore, it might pay to wait and see with some of these situations that are near threshold.
How can you predict what might happen to your population? One way is by assessing the level of adults versus nymphs in the field and by scouting eggs (covered in this article).
If you are at one nymph per sweep, with lots of adults and unhatched eggs, chances are you will exceed threshold and will benefit from a spray, even with drive-down and insecticide costs. If you have mostly nymphs, with few adults and eggs, you should probably hold off on your spray.