The entomologist persuaded the grower to let him spray a small part of a field on a hill overlooking the grower's home as a test plot. When the rest of the field turned yellow from leafhopper damage, the initials stood out bright green and a foot taller. But timing the spray can be tricky, and it demands a lot from producers, Bledsoe says. They must start about mid-May, sampling the fields weekly with sweep nets to get an estimate of leafhopper populations. Then the growers have to weigh insect pressure against intended harvest dates and the cost of treatment.
Some growers spray fields after they notice the distinctive, yellow pattern on the leaves.
It's too late then. McCaslin, president of Wisconsin-based Forage Genetics Inc., says the leafhoppers had had it their way for way too long. There really wasn't an effective, foolproof method of handling the potato leafhopper. It was a huge gap in the package we were designing to help farmers get the best possible yields, persistence and forage quality. In an attempt to fill that gap, Shade and former Purdue agronomist Tommy Thompson began experimenting with 60 different species of alfalfa for insect resistance to the alfalfa weevil, pea aphid and, especially, the potato leafhopper.