Ml 



7 



COLLEGE OF 

 AGRICULTURE 

 UNIVERSITY OF 

 ILLINOIS AT 

 U R B AN A-CH AM P AIG N 

 AND NATURAL 

 HISTORY SURVEY 

 URBANA. ILLINOIS 



NSECT, WEED & PLANT DISEASE SURVEY BULLETIN 



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



FOR IMMEDIATE RELEASE 



No. 16, July 21, 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 



THE LIBRARY OF THE 



SEP 6 1972 



GENERAL 



AT URBANA-' 



Grasshoppers continue to present a potential problem for hay crops, soybeans, and corn. 

 Right now the grasshoppers are still in the hay-crop fields, in fence rows, ditch banks, 

 and roadsides. Toxaphene can be used on fence rows, road sides, and ditch banks if 

 these are not adjacent to fish-bearing waters. If they are next to such waters, carbaryl 

 (Sevin) is preferred. 



In the hay-crop fields, mow the hay but leave a few uncut strips where the grasshoppers 

 will concentrate. If the crop is in blossom, spray these with malathion or naled (Di- 

 brom) after bee activity is completed for the day. You may also use carbaryl or diazi- 

 non if the crop is not blossoming. Since the grasshoppers will migrate into fence rows 

 as the hay is cut, spray these areas when you spray the uncut strips of hay. 



No time interval is required between spraying and harvesting when malathion or carbaiyl 

 are used. Naled requires 4 days, and diazinon 7 days. 



When soybeans are in the blossom to early pod stage, leaf- feeding by grasshoppers is 

 serious and affects the yield if 40 percent or more of the leaf surface is consumed. 

 So begin to apply toxaphene when 25 percent of the leaf surface is gone. Leaf-feeding 

 after the pods have begun to fill is seldom serious; but grasshoppers start to eat the 

 pods, that can be dangerous. If this happens, estimate the number of pods that are 

 damaged. This will determine the need for treatment. 



CORN INSECTS 



Com rootworm adults are emerging in numbers throughout central and western Illinois, 

 and some will be emerging in northern Illinois this week. They feed on the silks, and 

 can interfere with pollination if it has just begun. Begin now to examine fields. If 

 the field has fewer than 50 percent of the ears pollinated and about 5 beetles per ear, 

 apply carbaryl or malathion immediately. 



We were called to one field in central Illinois this week where the beetles were so 

 numerous that the silks were being cut off and were dropping into piles on the leaf 

 below. Pollination had just begun, and this silk-feeding by the beetles was going to 

 be critical for three to five days. We might add that a rootworm soil insecticide had 

 been used in the field. 



