Current Alfalfa Weevil Situation

May 5, 2000
Not much more needs to be said about alfalfa weevils. The larvae are active throughout the state (refer to Figure 2 for heat units accumulated from January 1 through May 2, 2000), and insecticides have been and will be applied to control some of the heaviest infestations in several years. Dave Feltes, Extension IPM educator at the Quad Cities Extension Center, has indicated that the potential for weevil damage in northern Illinois is higher than it is has been for the past several years. Everyone should be scouting for alfalfa weevil larvae and looking for evidence of infection by the fungus Zoophthora phytonomi. The presence of Bathyplectes spp. cocoons also might suggest that natural control is ongoing.

Figure 3 shows projected heat units from January 1 through May 16, 2000, which takes us well into weevil season and beyond for southern Illinois. We will discontinue producing these maps now that everyone is up to date on weevil activities. Thanks for your reports over the past few weeks. Don't hesitate to let us know if anything changes or if something significant happens in your area. Be especially alert for weevils feeding on regrowing buds after harvest. Heavy infestations and significant damage can result in slow recovery and, ultimately, reduced yields.--Kevin Steffey

Author: Kevin Steffey