Ohio alfalfa growers should be on the lookout for potato leafhopper, warns Ron Hammond, entomologist with Ohio State University Extension. The bright-green, wedge-shaped insect can cause a significant economic impact, reducing yield and quality.
Potato leafhopper is an annual spring pest in Ohio as it migrates north from Gulf Coast states, carried on winds in storm systems, he notes. “In alfalfa, potato leafhopper is definitely our No. 1 pest. It’s an insect that, if allowed to go past threshold and develop young populations, can lead to damage such as stunting.”
For second-crop scouting, Hammond recommends sweep-net sampling once alfalfa regrowth reaches sufficient height. In glandular-haired leafhopper-resistant alfalfa, the economic threshold is three times the normal threshold, or three leafhoppers per inch of growth. In 6”-tall alfalfa, the threshold would be 18 leafhoppers.
“However, if the resistant alfalfa is a new planting this spring, growers might want to use thresholds meant for regular alfalfa during the very first growth from seeding. After the first cutting, growers can then use three times the normal level threshold.”
More on potato leafhopper, including how alfalfa-growing conditions might affect the threshold, can be downloaded here.
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