–by Dr. Jeff Whitworth and Dr. Holly Schwarting
Potato leafhoppers have been infesting alfalfa fields throughout north central Kansas for at least the last month. They continue to be very active, which is causing quite a bit of leaf yellowing, often called ‘hopper burn’, and even stem and whole-plant stress. Typically, swathing is sufficient to manage leafhopper populations. However, they have been actively reproducing and there are many nymphs, so it will be especially important to continue to scout these fields after swathing. If a stubble spray is deemed necessary after swathing, one application is often highly effective and re-infestation is unusual.
Alfalfa caterpillars are also quite common in alfalfa fields, where they feed on foliage, although they rarely do enough damage to warrant an insecticide application. They will eventually pupate and then turn into a yellow or white sulphur butterfly.