David Owens, Extension Entomologist, owensd@udel.edu
Label Update – Chlorfenapyr
Chlorfenapyr (Pylon) has just been approved by EPA on various greenhouse pests and on various additional crops. This active ingredient is labeled for thrips, rust mites, spider mites, cyclamen mites, fungus gnats, and small Leps.
Watermelons
Two spot spider mite populations continue increasing in fields requiring treatments in several. A couple of reminders regarding miticides: abamectin containing products require an adjuvant, but do NOT use a sticker. This also goes for Kanemite and Zeal. These three products have translaminar activity. ‘Sticky’ fungicides like Bravo WeatherStik and sticker type adjuvants work against the translaminar properties of these miticides. In 2018-2020 spray trials, the fullest effect of these three miticides was not observed until about 10 days after treatment. While scouting for mites, pay attention to thrips. In plots at Carvel, thrips are also causing substantial feeding injury. We do not have a threshold for thrips feeding on leaves, but I would think that if you see a large number of small larvae and 10% or more of leaf feeding on the leaf undersides, you might want to consider a treatment, although this is not based on any research. Thrips materials include Assail (although cucumber beetles are pretty quiet), diamides, Radiant, and Torac. All three of these options are good worm materials. We have seen some yellow striped armyworm in fields. Be sure to begin scouting melon fruit for worm feeding injury as well.
Sweet Corn
Corn earworm counts are low. Many sites indicate a 4-5 day spray schedule. Silks that are wilting and turning brown are less attractive to moths than fresh silks. We have not been able to test very many moths this week in our lab bioassays. While early to mid-July is typically a quiet time for moths, be sure to check our site regularly for updates (https://agdev.anr.udel.edu/trap/trap.php). Thursday trap counts are as follows:
| Trap Location | BLT – CEW | Pheromone CEW |
| 3 nights total catch | ||
| Dover | 0 | 4 |
| Harrington | 0 | 12 |
| Milford | 1 | 4 |
| Rising Sun | 0 | 5 |
| Wyoming | 0 | 3 |
| Bridgeville | 0 | 4 |
| Concord | 0 | 10 |
| Georgetown | 0 | 4 |
| Greenwood | 0 | 24 |
| Laurel | 0 | 15 |
| Seaford | 1 | — |
| Lewes | — | 25 |
| Millsboro | 1 | 3 |
Pumpkins
If your winter squash or pumpkin seed does not have FI400 seed treatment, scout seedlings for signs of cucumber beetle, cutworm, and wireworm. Although cucumber beetle activity is very low right now, they can cause a great deal of damage to cotyledons. Wireworms feed below ground and will result in skips. They will sever the root from the cotyledons below ground.