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Sweet Corn Pheromone Trap Network for Western New York,
This is a seasonal scouting report giving growers in the Western New York area information on the presence of sweet corn pests and recommendations on scouting and thresholds. The report is written by Abby Seaman, NYS IPM's Area Extension Educator for Vegetables.
Only a few CEW and FAW moths are still being caught at the remaining trapping locations. A processing field in the Penn Yan area was found to have large CEW and FAW worms in the ear tips today, reinforcing the need for short spray intervals in fresh market corn when CEW and FAW flights are high.
This is the last trap network report of the season. Many thanks to all the cooperators who faithfully check traps and call or email me every week. As you know, I couldn't do it without you.
The future of the trap network is in jeopardy. For the past 10 years I have funded the network through a combination of grants from the IPM program and in-kind and financial support from industry. As many of you know, the IPM program was not able to fund grants this year because of the line item veto of supplemental funding ($289,000) designated for the Program. The network was only possible this year because I was able to buy the lures with savings from previous years' funding. My little reserve of funds is now exhausted, and I'll need to come up with another source of funding if the budget situation for the IPM program does not change.
If your organization permits it and you would like to contact NY State Legislators and express your support for full funding of the NYS IPM Program, please let me know. We would provide you the necessary contact information. Letters and phone calls to legislators are important and would be appreciated.
To keep an eye on trap catches in the larger region go to Penn State Pest Watch.
Split field demonstrations have shown that applying insecticides to corn for worm control before tassel emergence does not produce better results than waiting until the usual tassel-emergence timing. Corn started under plastic or row cover is an exception to this rule.
Fields should be first scouted for ECB and FAW larvae at early tassel emergence. Even at a location with high ECB populations, insecticide applications in bare ground fields to whorl stage corn did not result in improved control when compared with one or two well-timed applications at tassel emergence. Larvae feeding in the whorl are protected from insecticide applications and mortality will not be as high as at tassel emergence, when larvae feeding in the emerging tassel are exposed to the spray. Larvae will leave the tassel as it opens up and no longer provides a moist, protected feeding environment, and move down the plant looking for protected places to feed. Insecticide applications need to be timed to kill larvae before they bore into a new feeding location where they will be again protected from sprays. In fields with very uneven development, two applications may be necessary, one when approximately 25-50% if the tassels have emerged, and again after 75-100% of the tassels have emerged, if the field is still over threshold.
The threshold for ECB and armyworms at tassel emergence is 15% infested plants. For corn borers, look down into emerging tassels for tiny larvae or frass (white to brown material about the size of fine sand). For armyworms look for ragged feeding holes and frass pellets the texture of coarse sawdust.
Before any insecticides have been applied, scouting is fast and easy because any sign of feeding is an almost sure sign of live larvae, so it's not necessary to spend time finding the larvae. After the initial insecticide application, feeding damage may be from a larva that has already been killed, so finding the critter is more important for an accurate estimate of the number of infested plants.
Once a field is silking, the threshold drops to 5% infested plants. Scout the ear zone (roughly from two leaves above and one leaf below the ears) for ECB egg masses and ECB or FAW larvae. Egg masses are found most frequently on the underside of leaves near the midrib, and consist of approximately 10-20 flattened eggs overlapping like fish scales. Eggs are white when first laid, turning cream colored after a couple of days, and show the black head capsules of the tiny larvae through the surface of the eggs when within 1 day of hatching (the "black head" stage). Egg masses can also sometimes be found on the flag leaves of the ears or on the husk itself. Eggs take approximately 100 base 50 degree days to hatch. When temperatures are in the 70's during the day and the 50's at night egg masses will take about a week to hatch. When temperatures are in the 80's during the day and the 60's at night, they could hatch in only 4 days.
Look down into the tops of the silks for newly hatched larvae, and pull the ear away from the stalk slightly to look for larvae feeding between the stalk and the ear.