The cotton crop in Virginia seems to have made it past insect danger this year, but Virginia Tech entomologist Ames Herbert notes soybeans are now in their most vulnerable stage to corn earworms and stinkbugs, that is, the R5-early R6 stage. These pests love tender, developing seed, and Herbert notes many fields are in that condition.
The silver lining is that corn earworm and native stink bug populations appear to be light this year.
"Most reports are in the 1-3 worm/15 sweep range, certainly not excessive pressure," Herbert notes in his Virginia Ag Pest Advisory of August 23. "And the moth flight seems to be in decline. Native stink bug infestations are also very light to the point that we cannot locate any field with a lot of native stink bugs."
Brown Marmorated Stinkbugs Mounting In Virginia Soybean Fields
Herbert notes some growers are treating fields, even though these fields aren't necessarily at recommended thresholds for applications.
Sometimes there will also be a late summer/early fall corn earworm flight but even if this is the case this year, most fields will already be in the late R6-R7 stage; that is, beyond any danger.
Herbert notes more brown marmorated stink bugs are turning up in soybean fields. "The more we look, the more we find," he says.
Scouting reports indicate that many soybean fields in the northern and central Virginia counties (including Rockingham, Culpepper, Stafford, Madison and Orange counties) are turning up in numbers that need control. However, thresholds and sampling techniques are not fully developed in Virginia with this new pest.
"It is almost impossible to get a good sample with a sweep net because they startle easily and drop to the ground quickly," Herbert says. He suggests scouts inspect leaves and if they see several bugs on the upper leaves they can be assured there are more down in the canopy.
He recommends field edge treatments because the bugs "seem to be staying in the first 50 or so feet of the field edge."
Consult your local Extension agent for more details on treatment.