Update on soybean insect pests in Virginia

In mid July we initiated our annual soybean insect pest survey, our black light trapping program, and our corn earworm pyrethroid resistance monitoring program. Following are short updates.

BMSB (brown marmorated stink bug): So far this summer, only a TOTAL of 4 BMSBs have been found in soybeans—one in a field in Amelia Co. and 3 in a field in Bedford Co. (see the attached BMSB occurrence map). This breaks all records for the fewest for this time of year. Was it the cold winter, or those unusually hot days in June (BMSB does not do well when temperatures exceed the mid 90s)? We will continue posting our field survey results but all indicators point to a season with very low risk to BMSB infestations in the Virginia soybean crop.  BMSB_map_30_July_2015

Kudzu bug: As of the end of July, kudzu bugs have been found in soybean fields in 21 southern/eastern counties (see the attached kudzu bug occurrence map)—but in all cases, these have been adults only, and at very low numbers. Most counts reported by our scouts were 1 or fewer adults in 15 sweeps, and occasionally 2 per 15 sweeps. These numbers are way too low to be a threat to fields and DO NOT warrant treatment. These adults represent the first generation that will set up the nymphs that could cause concern later, but only if numbers increase a lot. Our best guess based on what we are seeing in fields now, and the lower number that successfully overwintered compared with last year, is that not many, if any, fields that will reach the nymphal threshold.  KB_map_30_July_2015

Corn earworm moth activity: We are seeing an increase in CEW moth activity just in the last week and what we think is the beginning of the flight from field corn. Our local pheromone traps have gone from just a few caught in a week, to averaging in the teens and twenties. We are just beginning to see moths fly up in crop fields as we walk the rows, and some local growers are seeing the same. On a separate advisory we have posted the results of the annual corn earworm field corn survey—which showed a statewide average of only 17.5% ears infested. This is even lower than the numbers reported in 2014 (20%) and 2013 (18%)—both years with very few cotton, peanut or soybean fields being infested with treatable numbers of worms. So far, all indicators point to another year with few fields reaching thresholds. We will continue monitoring and posting updates.

Corn earworm pyrethroid resistance: To date we have tested 255 moths (see the attached line graph). We started the season with about 15% survivorship at the end of June and as of the end of July are up to 40% survivorship. This level, this early in the season is cause for some concern. We will be posting updates often.  Vial_tests_30_July_2015