After once again battling bird nests in our blacklight trap and a lot of rainfall for most of May in Painter, we have finally gotten some usable information. This week’s trap catch included 0 European corn borer moths, 12 Corn earworm moths, and 205 green stink bugs. It is early for corn earworm moths, so a catch of 12 moths is interesting and should be monitored closely in future weeks. A catch of 205 green stink bugs per week in May is both high and early for that pest. This is another insect that should be monitored closely for in the coming weeks on the Eastern Shore.

Click on More for the new Danitol Supplemental Label, which contains the new uses that were recently approved by the EPA. Danitol is now labeled for use on stone fruit, olive, tree nuts, and tropical and sub-tropical fruit. Danitol is also labeled for use on caneberries (under the berries section). Last, additional pests were added to the fruiting vegetables, grape, pea, and pome fruit labels and they are included on this label. All of your states have been notified of this new Supplemental Label and it is ready to be used by growers on these new crops. Additional information: danitolsupplementallabel2009-pdf

Some potato growers on the Eastern Shore of Virginia are wondering about whether or not to spray insecticides for European corn borer, a pest which damages potatoes by boring into stems and causing the whole stem to wilt and die. The practice of spraying for this pest in potatoes has a long history on the Eastern Shore. Growers have traditionally sprayed products like Penncap-M, Furadan, pyrethroids (Asana, Baythroid, or Warrior), or SpinTor for this insect pest. However, there are very few other regions in the U.S., where potato growers spray insecticides for corn borer, including our neighboring state, North Carolina (according to my colleagues).
I am making a strong suggestion to growers that it is time to stop this traditional insecticide spraying in May for this pest on potatoes. Here are my reasons:
1. Many potato growers are using the systemic insecticide Regent at-planting for wireworm control. This insecticide is very efficacious to corn borer larvae. Our research has shown that you will have almost no corn borer tunnels in potato plants treated with Regent in-furrow.
2. There is very convincing evidence from historical moth catch data at blacklight traps that European corn borer densities regionwide have dropped tremendously over the past decade (click on More to see data graphs of historic European corn borer pest pressure in Painter Virginia on different crops). The adoption of Bt corn on the Delmarva is likely a major contributor to this decline in ECB populations. Bt corn provides virtually 100% kill to ECB. Any eggs deposited on corn (the preferred host) will essentially be a deadend for the population. This has been demonstrated in the Corn Belt states as well.
3. There is strong research evidence that potato plants can tolerate a lot of ECB tunneling before economic yield loss occurs. The potato plants may look bad in an infested field, but the damage often comes late when plants are ready to dry down any way.
4. This year, we’ve not caught any ECB moths in our blacklight trap at Painter.
So, I realize that many growers are probably spraying fungicides for late blight on potatoes currently. You’re probably convinced that adding an insecticide in the tank makes economical sense. But, if you don’t need it, then it really doesn’t make sense. The only other damaging insect pests of potatoes on the Eastern Shore are Colorado potato beetle and potato leafhopper. Both of these insects should be controlled by the at-planting applications of a neonicotinoid such as Admire, Platinum, Venom, Tops MZ-Gaucho, or Cruiser.

Sincerely,
Tom Kuhar
Associate Professor of Entomology
Virginia Tech
Additional information: ecb-infestation-over-time-graphs-docx