On June 28, I visited a research site in Stephenson County that was designed to allow us to study potato leafhoppers in "normal" and glandular-haired alfalfa. David Feltes, Extension Educator/IPM at the Quad Cities Extension Center, and Jim Morrison, Extension Educator/Crop Systems at the Rockford Extension Center, have established the trial and gathered lots of data thus far. My objective was to see firsthand the impact of potato leafhoppers in untreated alfalfa, "normal" alfalfa treated with an insecticide, and glandular-haired alfalfa, some of which was not treated and some of which had been treated with an insecticide.|
I was impressed with the level of damage caused by leafhoppers in the trial. In untreated plots of both "normal" and glandular-haired alfalfa, the plants were obviously stunted and yellow. The typical wedge-shaped yellowing known as "hopperburn" was quite evident. On the other hand, plots that had been sprayed according to published economic thresholds looked marvelous. The plants in treated plots were considerably taller, and there was no evidence of leafhopper injury.
The data have not been analyzed, and it is too early to make any sweeping conclusions. However, it was obvious to me that glandular-haired alfalfa did not provide the level of leafhopper control afforded by the insecticide used in the trial. Nevertheless, leafhopper injury in untreated glandular-haired alfalfa was less obvious than it was in untreated "normal" alfalfa. Much remains to be learned about this new leafhopper-resistant alfalfa. Stay tuned as Dave and Jim begin to generate more conclusive data.--Kevin Steffey
Potato leafhopper injury to alfalfa plants.