Issue No. 4/April 16, 2004
Alfalfa Weevil Update
With degree-days nearing 300 across much of Illinois, leaf feeding by alfalfa weevils should begin in the next two weeks. Degree-day accumulations and projections for five Illinois locations are provided.
Little Activity from Black Cutworms
Few reports were received this week, but as corn planting begins to coincide with black cutworm moth flights, itís important to scout fields that are especially attractive for egg laying. Fields or areas of fields in which early-season weeds were growing at the time moths flew into the area are at a higher risk than weed-free fields.
Diagnostics Is Key to Making Early-Season Decisions
It is critical to diagnose early-season crop problems so that unnecessary treatments are avoided. Watch for symptoms of insect injury--cut, missing, stunted, or wilted plants; discoloration; distorted growth; gouges in stems; leaf tissue missing; reduced plant populations--but realize many of these symptoms can be caused by other factors.
What Is Bt Corn?
Bt corn hybrids may differ in the proteins expressed to kill certain insects. It is important to be knowledgeable and specific about these transgenic products, how they work, and their insect resistance management requirements.
A Primer on Soybean Aphids
Topics discussed in this primer on soybean aphids include overwintering hosts and predicted first occurrences. Promoting the treatment of soybean fields for soybean aphids without regard for aphid thresholds, aphid densities, or knowledge of predator densities runs counter to the IPM philosophy.
Insect Fact Sheets Getting a Makeover
Insect fact sheets are being revised, with updates of information and photos on insect descriptions, life cycles, injury, scouting procedures, and management. The IPM Web site is the source for the updated fact sheets, with revised versions posted as they are completed.
Early-Season Wheat Virus Diseases
Viruses are mild and scattered this season. If viruses are going to be a problem, symptoms should be well evident by now. The most common virus diseases early in the spring are barley yellow dwarf virus, soilborne wheat mosaic virus, and wheat streak mosaic virus; modes of transmission, injury symptoms, and control measures are discussed.
Soybean Rust Information for Illinois
An Illinois perspective on soybean rust is outlined: how it could be moved into Illinois, how to scout for and diagnose it, and how it can be managed if it comes. A number of Internet resources for more information are listed.
Weed Control in Small Grains
Herbicides for control of weeds (mostly broadleaf species) in wheat require proper timing and have application restrictions based on wheat developmental stage. The nonbroadleaf species wild garlic can result in significant economic loss, especially in southern Illinois, if left uncontrolled.
Planting: How Early Is "Early"?
It makes little sense to ever plant soybean before corn planting is finished; the risk of not getting corn planted on time is simply greater than the risk for soybean. Other observations are specified on early planting regarding planting depth, soil moisture, and crusting.
Reports are provided this issue for east-central Illinois, northern Illinois, southern Illinois, and west-central Illinois.