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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 



FOR IMMEDIATE RELEASE 



No. 7, May 14, 1971 



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, ab- 

 breviated control measures. Each individual should check his own fields to determine 

 local conditions. 



INSECTS 



JUL 



FORAGE INSECTS 







Alfalfa weevils . These pests continue to damage alfalfa in the southern half of Illi- 

 nois^ Fields needing treatment were observed as far north as Route 136 this week. 

 Heavier populations were observed further north along the west side of the state than 

 along the east. Feeding is evident north of Route 136. Treatments could be needed 

 in some fields this week or next. 



In the southern third of Illinois, it would be best to cut the alfalfa, remove the 

 hay, and spray the new growth if needed. Treat immediately if the new growth does 

 not green-up in two or three days . 



In the central third of the state, many fields were treated this past week. Alfalfa 

 is rapidly approaching the point of harvest. It might be best to consider cutting 

 the crop, removing the hay, and spraying the new growth of the second crop. 



For the most part in the southern half of the state, alfalfa weevil larvae are pu- 

 pating rapidly. Wasp parasites are prevalent and are helping reduce the number of 

 larvae. New spring adults are beginning to emerge now. However, eggs are still 

 hatching and damage can be expected for another two to three weeks. 



There is a considerable variation in weevil population between different areas and 

 fields. Check each field separately to make judgments. Do not apply insecticides 

 unless they are needed. Treatment with an insecticide is justified when 25 percent 

 of the tips show feeding and the field is more than two weeks from harvest. 



The insecticide recommendations are: 



1. Co mmercial applicators . Apply 1/2 pound per acre of methyl parathion or azin- 

 pHosmethyl (Guthion) for good results. Use azinphosmethyl only once per cut- 

 ting. Do not harvest for 15 days after treatment with methyl parathion, or 



16 days for azinphosmethyl. Wear protective clothing. 



2. Persons not equipped with protective clothing . Use: (1) Imidan at 1 pound per 

 acre; (2) a mixture of 3/4 pound of malathion and 3/4 pound of methoxychlor per 

 acre; (3) a mixture containing at least 1/2 pound of diazinon and 1 pound of 

 methoxychlor per acre; or (4) 1-1/4 pounds of malathion per acre on days when 

 air temperatures will be above 60° F. for several hours after application. Do 

 not harvest for 7 days after treatment with Imidan, methoxychlor, diazinon, or 



