Last week I reported that survivorship of corn earworm in North Carolina adult vial tests was low- 18% (see previous article here). This has not changed for this location. Survivorship of adult male moths in this location was 12%. At this point, we would not consider this a resistant population. However, moths were collected and tested from a trap 4.5 miles away (~100 individuals in the sample). Survivorship of moths from this location was a whopping 41%. Remember that we start considering a population tolerant/resistant at anything over 30% point. Dr. Ames Herbert measured 44% survivorship from his population in Suffolk, Va this week (results here).
As a result, I am very comfortable with the statement that I made last week that we have geographical pockets where resistance prevalent and pockets where resistance is not as prevalent. Based on the widely different results from a population separated by a few miles, I cannot predict where this resistance will occur. I urge you to consider applying Belt, Steward, or Blackhawk (the new name for Tracer) for corn earworm. These are effective on almost all the worms in our system. Another option is to tank mix a pyrethroid with 1/2 lb. acephate. This tank mix will kill “resistant” corn earworm and tobacco budworm, stink bugs, and kudzu bugs, but will probably not take care of loopers or beet armyworms.