Potato Leafhopper Management in Alfalfa
Purdue University Extension Entomologists are reporting that populations of potato leafhopper in alfalfa are booming in Indiana. There have been observations of high numbers of leafhoppers coming to lights at night. They attribute this explosion in potato leafhopper population to recent hot temperatures.
I expect that we may also experience high numbers of potato leafhoppers. Soon after cutting alfalfa, producers need to begin scouting for potato leafhopper. Purdue Entomologists Christian Krupke and John Obermeyer warn that once yellowing is seen on alfalfa, the damage is already done and it is likely too late for an insecticide treatment. (Read full story in Purdue Pest and Crop Newsletter: http://extension.entm.purdue.edu/pestcrop/2009/issue13/index.html)
To determine potato leafhopper numbers, take at least five sets of 20 sweeps with an insect sweep net, each set from a different area of the field. Open the net and count the number of potato leafhoppers, both adults and nymphs. After taking each set of sweeps, measure the height of a few stems in each area. After all sweeps and height measurements have been taken, determine the number of potato leafhoppers per sweep and the average stem height for the field. See the Purdue table for treatment guidelines: http://extension.entm.purdue.edu/publications/E-220.pdf