Our final batch of corn earworm moths showed only 26% survivorship, down from last week. This season results showed a 37% survival rate for the seasonal total which exceeds all previous years. We are now up to 33 counties where brown marmorated stink bugs were/are present in soybean fields. Most are at pretty low levels compared with last year, but they are much more widespread. This week n some have been found in soybean fields in north central North Carolina. We are taking as much data as we can to help with answers for next season. And, the first kudzu bug nymphs were found in Charlotte County. We are nearing the end of this season in terms of insect pests and advisories…a long summer for sure.
Additional information: cew-cypermethrin-2011-2012-sept-13-2012-pptx

With our full complement of field scouts in place, more soybean fields are being found with BMSB infestations. We are up to 20 counties in Virginia (hit the ‘more’ button to see the map) spread over a very large area of the state. Infestations were a little slow to develop compared with last year but we are predicting that by the end of the season, many more fields will be infested compared with last year. So far, most infestations are at low to moderate levels (from 2-3 to 4-6 per 15 sweeps) but a few are in the high infestation range 8-10 or more/15 sweeps. We know that sweep netting is not the ideal way to sample for these insects, but there is no other method other than simply easing into the field edge and counting what you see. Basically, if you can stand in one spot, do a 360 degree turn and count more than 5 or 6, that area needs protection. So, how are they not ‘playing by the rules’? Last season, our first with treatable levels, bugs stayed on field edges and a single insecticide edge treatment provided season long control. This is true for many fields this year but in a few we are finding them deeper into fields, and, there are some cases where re-infestations are occurring in fields previously treated. The good news is that 1) based on our insecticide trials it is not difficult to kill them with several common products, and 2) many fields, especially the full season crop fields, are rapidly approaching the ‘safe stage’ which based on previous field cage studies happens after R6 (full seed) when pod walls begin to toughen. Many growers are treating field edges this year and we are going to follow as many as possible to determine if those treatments worked and held. More on this as we progress.
Additional information: herbert-bmsb-kb-va-aug-30-2012-pptx

Where much of the cotton crop is pretty much bug-safe, much of the Virginia soybean crop is in the most vulnerable growth stage, R5-early R6, to corn earworms and stink bugs. Both of these pests have a preference for the tender, developing seed (the R5 stage) and many fields are in or near that stage. The good news is that for the most part, corn earworm and native stink bug populations (green stink bug and brown stink bug) seem to be pretty light and spotty. Most reports are in the 1-3 worm/15 sweep range, certainly not excessive pressure, and the moth flight seems to be in decline. Native stink bug infestations are also very light to the point that and we cannot locate any field with a lot of native stink bugs. Although many growers have or are treating fields, if scouted, they are seeing that many fields are not at thresholds. We sometimes have another late summer/early fall corn earworm flight which could result in some new worm infestations, but it if this does happen, most fields will be in the bug-safe late R6-R7 stage.

A problem still exists with our adult pyrethroid vial test results. Last week’s sample reached 58% survivors, the highest level ever recorded for Virginia, and this week’s early sample was still at 50% survival. We have at least one report of lack of control in a soybean field treated with a pyrethroid (no need to mention any product names). If you are choosing a new product, a ‘brand’ you are not familiar with, be sure to check the label to see what you are buying/spraying. There are some products that are a mix of two pyrethroids (no help if you are concerned about pyrethroid resistance).

The problem story is with brown marmorated stink bugs. The more we look, the more we find. We are just now getting our scouts into the high risk counties in the northern and central areas. The reports show that many soybean fields in those counties (including Rockingham, Culpeper, Stafford, Madison and Orange Cos.) are infested at levels that need to be controlled. We do not have good thresholds or good sampling techniques for brown marmorated stink bug. It is almost impossible to get a good sample with a sweep net because they startle easily and drop to the ground quickly. But we do have data from last year that shows how damaging they can be to soybeans in the infested areas. The best we can offer now is that if you can visually ‘see’ several bugs on the upper leaves, there are MANY more down in the canopy feeding on seed. Like last year, field edge treatment seems to be all that is needed as the bugs are staying in the first 50 or so feet of the field edge. Edge treating (one spray boom width) was effective last year, and we are working to document the outcome (hopefully success) of this strategy again this year.

Kudzu bugs have not been reported in any new counties since our last pest advisory, but we do have reports of some egg masses in a couple of locations. We will likely see some nymphs soon in some fields, but time will tell if we get into any treatment situations. The later nymphs occur the lower the risk that they will develop into high populations, or that they will be able to cause any appreciable damage to plants. More next week as we progress with our scouting effort.