The old adage, "they breed like rabbits," may be replaced by the Potato Leaf Hopper. Unfortunately, it's no joke. Jeff Miller with Cornell Cooperative Extension is concerned about the number of PLH's he's found while scouting Central New York alfalfa fields.

Jeff says the adult female pest can lay up to 200 eggs in it's lifetime. They hatch in 10 days, become adults in days and start laying eggs again. You don't even need a calculator to know that's a lot of Potato Leaf Hoppers. So what do you do? Here's his suggestions.

First sweep your fields if you find more than 9 PLH in a field that is 3" high, you have a problem. In a field that is 10 inches or higher, 75 or more is trouble. Jeff's sweeps of various fields found between 66 and 100 and they all were adults. If your over the limit you have two options:

  • If it's within 10 days of harvest, do it know.
  • Outside the harvest window, Jeff suggests applying an insecticide like Baythroid, the only product currently labelled for mixed swards of alfalfa and grass.

Potato leaf hoppers do lots of damage, reducing yields by ½ ton an acre, reducing protein levels in the harvest as well as overall damage to future yields. Get more information on Potato Leaf Hoppers in this fact sheet or call Jeff at 315-736-3394 extension 120.


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