L*l7 



COLLEGE OF 

 AGRICULTURE 

 UNIVERSITY OF 

 ILLINOIS AT 

 URBANA-CHAMPAIGN 

 AND NATURAL 

 HISTORY SURVEY 

 URBANA, ILLINOIS 



NSECT, WEED & PLANT DISEASE SURVEY BULLETIN 



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



•£q£ 



FOR IMMEDIATE RELEASE 



May 



***<*** 



No. 6, April 27, 1973 



This series of weekly bulletins provides a general look at the itnsectj 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 



FORAGE INSECTS 



Alfalfa weevil populations increased rapidly in the counties south of Interstate 70 

 this past week. The heavy rains slowed the feeding activity and may have killed some 

 larvae; but, in general, did not reduce the problem. Larval populations are general- 

 ly higher and the damage more severe in the western half of the area south of 1-70 

 than the eastern part. Some fields in Jackson, Perry, and Washington counties had an 

 average of 80 larvae per sweep; fields in Clinton, Madison, and St. Clair counties, 

 8 to 25 larvae per sweep. Adult weevils are abundant in all fields. 



Many fields south of Interstate 70, and particularly south of Route 50, will require 

 treatment this week (April 30-May 5) . Examine and evaluate each field on an individ- 

 ual basis. If 25 percent or more of the tips are being skeletonized, treat immediate- 

 ly. Fields south of Route 50 with high populations of weevils, if left untreated, can 

 be expected to take on a silvery appearance as damage progresses. 



Soggy, wet fields may prohibit the use of ground equipment in some areas, particularly 

 where alfalfa weevils are numerous. Rather than waiting a few extra days or a week for 

 the fields to firm-up, it would be advisable to spray these fields by air now. 



Between Interstate 70 and Route 36, alfalfa weevil populations are low- -except for an 

 occasional field in the western area. North of Routh 36, very few larvae have been ob- 

 served; adult weevils average about 40 per 100 sweeps. 



Crop Residues and Planting 



The prospect of late planting and fuel shortages prompts questions about insect damage 

 when corn is planted without plowing under the old stalks or bean stubble. In emergen- 

 cies such as we face, getting the corn planted is the most important thing. Some in- 

 sects may be a bit more numerous when old stalks are not plowed under. The number of 

 borers is low at present, and is not to be feared. If a field has a northern corn root- 

 worm problem, you should at least straddle the old rows- -since the beetles deposited 

 their eggs mainly at the base of those old stalks last August and September. NOTE: Do 

 not expect soil insecticides to be as effective on unplowed ground as on plowed soil. 



