Corn earworm (CEW), kudzu bug, and stink bug update

The corn earworm situation is shaping up to be late and fairly light, at least that’s what we seem to be seeing so far. Our annual field corn/corn earworm survey is completed with 27 counties reported. Percent infested ear averages are very low compared to most years. The overall average across all counties is at an all time low of less than 18% ears infested. Even the southeastern counties which traditionally have had the highest infestation level are at just over 23% ears infested, when averages are normally in the 40-60% range. The moth movement from corn is also slow in developing. We have yet to see more than just a few moths in our local black light traps and we are not seeing moths fling from fields as we walk them, or at night. We can speculate about the reasons for this unusually low level, but the bottom line is that unless things change pretty drastically over the next few weeks, we may not see many soybean, cotton, peanut or sorghum fields infested this year.

Kudzu bug activity in soybean is increasing. From our statewide surveillance program, we are now up to 37 counties with infestations in soybean fields. The good news is that most of these infestations are at low or very low levels—well below the economic threshold—but there are exceptions. Heavy infestations are now reported for several of the counties close to the NC border. The heaviest infestations are in early planted fields that are flowering or beginning to form pods. We are now seeing second generation adults in many fields. We are not sure what this will mean in terms of the late planted fields, time will tell. In an earlier advisory we attached a table generated by entomologists at Clemson and UGA that listed the percent control provided by a long list of insecticides. We STRONGLY recommend that if a field treatment is needed that growers use products that are listed at the top of that table—those that provide the best control. We have learned that not following this guide can lead to having to retreat.

Stink bug pressure in cotton is turning out to be less severe than what we had predicted earlier, although we are seeing a number of fields at threshold. Cotton will remain vulnerable to stink bugs for a few more weeks—at least through the 6th week of bloom. If a treatment is needed this week (or has already been applied), we recommend re-sampling for new damage at about 7 days post-treatment—using our cotton stink bug threshold card. Additional treatments may be needed, especially if the ‘traditional’ bollworm treatment is not needed because of the very light CEW pressure discussed above. That ‘traditional’ bollworm treatment (if it included a pyrethroid) has been providing stink bug control as an added bonus. So a field that does not have to be treated for bollworm (use the 3% worm/fresh worm damaged boll threshold) may have to be treated again for stink bugs. So scout fields for fresh stink bug damage weekly for the next few weeks and abide by the recommended percent damaged boll thresholds.

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