CEW moth activity is definitely beginning to increase. We are now catching 20-30 per night in our traps compared to 4 or 5 per night last week. We are not sure how this will progress. A lot will depend on the weather, and eventually, corn harvest. We will keep posting updates.
PEANUTS: We are beginning to find just a few worms in peanut fields—way below any reasonable threshold (See the advisory I posted on the peanut/worm situation for more details).
SORGHUM: A few worms are beginning to show up in sorghum heads (See the advisory I posted on sorghum head worms).
SOYBEAN: We are getting reports of a few worms in soybean fields but not at threshold levels, and not threatening the seed.
COTTON: Although we have found a few CEW eggs, we are finding almost no worms. This could be year when the BG2 and WideStrike provide enough protection, without additional foliar sprays.
PYRETHROID RESISTANCE: Keep in mind that I use the term ‘resistance’ loosely. We cannot prove/disprove actual resistance using the AVT (Adult Vial Testing) method, only determine the percent that survive the pyrethroid challenge. So, where do we stand this year? If you open the file (‘more’ button) you can get a quick comparison of where we are compared to last year—so far we are seeing only about 30% survivorship. But also notice that the number of moths tested to date is very low, which could bias our results. Is 30% survivorship enough to warrant a shift to a non-pyrethroid—my answer is, it depends. My rule of thumb is—if a field is at or just above the threshold (check that for each crop), a pyrethroid applied at the highest labeled rate, using a spray system that achieves good plant coverage, will do well. But, if a field is 3 to 4 times the threshold, or higher, a non-pyrethroid will be needed.
Additional information: cew-avt-results-aug-13-pptx

As of this week, we are starting to find a few corn earworms in sorghum grain heads. We suggest that you should begin sampling any sorghum fields that have heads entering the milk stage—and many in Virginia are in that stage. Using the ‘bucket/shake’ method is the best way to determine the average number of worms per head. We recommend doing a series of 10-head samples in each field. Shake 10 randomly selected heads into a white 5-gallon bucket and count the worms/10=average per head. Do several 10-head samples in each field taking samples from areas with any obvious differences (different head maturities, areas next to corn, etc.)—then calculate an overall worm/head field average. Recommendations are pretty variable across states, but an average of 2 worms per head, or more, should trigger a spray. Use a spray boom/nozzle/gpa/psi system that delivers as much product to the heads as possible. Spraying leaves is a waste of product—the more product hitting the heads, the better. Directing sprays to the heads is even more important in varieties with compact heads (vs loose heads). When heads are compact, worms tend to burrow to the center, are not easily seen, and are not as vulnerable to sprays. Remember, the insecticides used for worm control depend on direct contact.

What insecticides should you use? Sorghum has fewer labeled insecticides than many commodities, but there is a pretty good selection with different modes-of-action. Pyrethroids include Tombstone, Mustang Maxx, Karate/Warrior, and Asana XL, and others. Non-pyrethroids include Belt, Blackhawk (was Tracer), and Lannate. There are a few others that combine active ingredients like Stallion (Mustang + Lorsban) and Consero (Prolex + Tracer). Note that we have not evaluated these products so cannot make comments about control, but have experienced lack of control with pyrethroids, alone, when worm populations were high or worms were a large size (harder to kill) when sprays were applied.

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.

CEW activity is low compared to this time in previous years. We have not captured many moths in our pheromone traps and even fewer in black light traps. We know that CEW populations are usually low in generally wet years, which is what we are experiencing this year, so the pattern seems to fit. This can change—quickly, depending on weather patterns.

We are initiating our annual field corn survey to document the infestation level, which will help predict the infestation level growers can expect in subsequent crops. Many VCE Ag Agents across much of eastern/central Virginia are cooperating on this survey and we hope to have it completed by the end of July.

The situation with pyrethroid sensitivity is developing quickly. To date we have tested 188 moths with the AVT (adult vial test) pyrethroid challenge with an overall survival rate of about 17%. This is a relatively high level for this early in the season. How will this progress? Time will tell.