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COLLEGE OF 

 AGRICULTURE 

 UNIVERSITY OF 

 ILLINOIS AT 

 URBANA-CHAMPAIGN 

 AND NATURAL 

 HISTORY SURVEY 

 URBANA, ILLINOIS 



NSEC7T, WEED & PL ANT DISEASE SURVEY BULLETIN 



fATE/COUNTY/LOCAL GROUPS/U.S. DEPARTMENT OF AGRICULTURE COOPERATING 



FOR IMMEDIATE RELEASE 



No. 17, July 28, 1972 



This series of weekly bulletins provides a general look at the insect, weed, and plant 

 disease situation (fruit and commercial vegetables excepted) , along with suggested, 

 abbreviated, control measures. Each individual should check his own fields to deter- 

 mine local conditions. 



INSECTS 



• T "E U B Ra Ry 



°F TH £ 



CORN INSECTS 



AUG 





I 7 19 



72 



European corn borers . Second-generation moths are laying eggs in the southern section 

 of Illinois. Moth emergence in the central area is underway , "but/ egg- laying is just 

 beginning. In the northern section, moth emergence is just getting started. Peak 

 egg-laying will probably not occur for another ten days in central Illinois and two 

 weeks in northern Illinois. Egg- laying will continue for two or three weeks or more. 



This is the time to check late -maturing fields for egg masses and feeding in the south- 

 ern half of Illinois, to determine whether treatments are needed. 



The moths will deposit eggs on corn at any stage of its development, but fields of 

 late-planted corn in the late-whorl to early silk stage are usually preferred. Look 

 for egg masses or small, newly hatched larvae. 



To determine whether treatment is necessary, look for egg masses or whorl feeding. If 

 the average is one or more eggs masses per plant, apply an insecticide after a few eggs 

 have hatched. If the corn is in the whorl stage and if 75 percent or more of the 

 plants are showing recent whorl feeding, apply carbaryl (Sevin) or diazinon granules. 

 Aerial sprays on tasseled corn are effective; but on whorl-stage corn, aerial applica- 

 tions should be granules not sprays. Use 1-1/2 pounds of carbaryl (Sevin), 1 pound of 

 diazinon, or 1/2 pound of parathion per acre. (Allow ten days for diazinon and twelve 

 days for parathion between application and silage removal.) Parathion should be ap- 

 plied only by experienced applicators. No waiting period is required for carbaryl. 



Corn rootworms . The adults are becoming more numerous as they continue to emerge from 

 the soil. The yellowish to pale-green northern rootworms, the yellow and black- striped 

 western worms, as well as the twelve -spotted southern corn rootworms, feed on fresh 

 silks. They can interfere with pollination and reduce kernel set. 



Continue to check fields coming into fresh silk, particularly in the northern half of 

 the state. If there is an average of 5 or more of these beetles per plant and if the 

 field is not over 50-percent silked, treatment is justified. Apply carbaryl (Sevin), 

 malathion, or diazinon at 1 pound of actual chemical per acre. There is no waiting 

 period between application and harvest for carbaryl. Allow five days for malathion 

 and ten davs for diazinon. 



