Several have called to ask about determining need for this basal application. If 

 the field was treated with aldrin or heptachlor last year, the corn lodged badly, 

 and the roots were devoured, then you probably had resistant rootworms. If you 

 found green beetles feeding on the silks of each ear, you have a rootworm problem. 

 Corn planted in these fields this year will probably be damaged, and you should 

 be ready to apply or already have applied control measures. But you can make a 

 basal application even after rootworm hatch has begun, providing you can get 

 through the field with your equipment. Ideal time for application is now, not 

 after the damage has been done. It will be too late 2 to 3 weeks from now. 



Black cutworms continue to appear in a few fields but only a few are present. 



For emergency control, applications of 3 pounds of toxaphene, 2 to 3 pounds of 

 carbaryl (Sevin) , 2 pounds of diazinon (use granules) , or 1 pound of trichlorfon 

 (Dylox) per acre --directed as a spray at the base of the plants --will control 

 small worms. For best results, use at least 20 gallons of water per acre; cul- 

 tivate immediately to cover the spray deposit. A rain following the treatment 

 will greatly improve control. 



White grubs are now being reported from a few corn and soybean fields. These 

 fields are usually those where beans Avere grown in 1967. The June beetles, adults 

 of the white grubs, deposit their eggs in bean fields in a continual corn-soybean 

 rotation. The eggs hatch and by the following year the grubs are about 1/4 inch 

 long. We are in the second year of this cycle, and these grubs will feed all 

 summer. 



If the field is in soybeans, we have no chemical control after the beans are up. 

 In corn, it might help to apply a spray of 1 pound of aldrin or heptachlor. Direct 

 the spray at the base of the plant. Cultivate immediately and throw dirt over the 

 sprayed area. This will provide some help but control will not be perfect. 

 Whether or not this specific use has label approval is open to question, but the 

 corn should not be used for ensilage or stover. The grain should be free of any 

 contamination, however. This should not be applied after early July. 



First-generation European corn borers are not expected to be a general problem 

 this year even in the more advanced fields in an area. However, it would be wise 

 to check the most advanced fields to be sure that a localized situation has not 

 developed. 



Based on borer development, time for treatment in west -southwest and west-central 

 Illinois will be the week of June 24 and for north-central and northern Illinois 

 the week of July 1 . 



To decide whether an insecticide can be profitably applied, measure the tassel 

 ratio of the field and determine the percentage of the plants with recent feeding 

 in the whorl leaves. To determine the tassel ratio, measure the height of the 

 plants with leaves extended; split the stalk open and measure from the tip of the 

 developing tassel to the base of the plant; divide the tassel height by the plant 

 height; and multiply by 100. That figure is the tassel ratio. If the tassel 

 ratio is at least 55 (preferably 40 to 45) and at least 75 percent of the plants 

 show whorl feeding, treatment is justified. Use 1 pound of actual diazinon in 

 granular form per acre or 1 1/2 pounds of carbaryl (Sevin) as granules. For 

 spraying, use the sane amount of actual insecticide per acre, and direct the spray 



