-4- 



To control rootworms on early-planted corn, the entomologists of several Midwestern 

 states have shown that a basal application of insecticide during cultivation will 

 provide protection against rootworm attack. A special applicator on the cultivator 

 directs organic phosphate insecticide granules at the base of the plant. This kills 

 rootworms for about 6 inches on each side of the plant, allowing roots to establish 

 themselves and secure the plant. The three most effective insecticides for basal 

 applications appear to be phorate, diazinon, and disulfoton granules. 



Several organic phosphates and carbamates are being sold for planting- time appli- 

 cation for rootworm control. Of the ones tested in Illinois, only those above gave 

 consistent and satisfactory results. Others failed to provide root protection to 

 the corn when conditions were slightly adverse. Fertilizer- insecticide mixtures 

 are discouraged at this time; band fertilizers are generally applied to only one 

 side of the row and results from such treatments have been no better than untreated 

 plots. 



POLLINATION INJURY BY ROOTWORM BEETLE FEEDING 



Corn rootworm beetles feed on silks. When these beetles are numerous during pol- 

 lination, kernel set can be affected, particularly in late-planted fields where 

 silking has just begun. If beetle emergence occurs during dry silk, then polli- 

 nation is not seriously hurt. Control will be profitable when 5 to 10 or more bee- 

 tles per ear are present and not more than 50 percent of the plants have silked. 



CONDENSED SOIL INSECTICIDE SUGGESTIONS 



General non- dairy farms : In a normal rotation, continue to use aldrin or hepta- 

 chlor broadcast and disked- in before planting (or in the row at planting time) to 

 control white grubs, wireworms, grape colaspis, and seed- infesting insects. Broad- 

 cast applications generally control cutworms. But if a row treatment is used, plan 

 to apply a post-planting or emergency application of carbaryl, diazinon, toxaphene, 

 or trichlorfon for cutworms if necessary. (See page 5, 1968 revised Circular 899 

 for details.) 



Dairy farms : Use an organic phosphate or carbamate insecticide as described for 

 rootworm control. For early-planted corn, use a planter-box seed treatment to sup- 

 plement early- June basal applications ; but take precautions not to interfere with 

 the seeding rate. In some instances, you may have to apply a post-planting or emer- 

 gency application of one of the insecticides listed in the table for cutworm control. 



Soybeans : Do not apply aldrin, chlordane, dieldrin, endrin, or heptachlor as a 

 soil or foliar treatment for soybean insects. If you have applied aldrin or hep- 

 tachlor annually for 5 or more years for corn soil insect control, skip 1 year be- 

 fore planting soybeans. 



Continuous corn and control of resistant corn rootworms : When planting early , plan 

 to use a basal insecticide application in the fore part of June. With mid- season 

 plantings , you may wish to try a planting- time treatment of phorate or BUX ten 

 (0-5353) in a 7- inch band ahead of the press wheel. For late-planted corn, use 

 phorate, BUX ten (0-5353), or diazinon granules ahead of the press wheel. 



For early-planted corn, you may want to use an aldrin or heptachlor preplanting 

 or planting-time treatment, or at least a planter-box seed treatment. 



