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COLLEGE OF 

 AGRICULTURE 

 UNIVERSITY OF 

 ILLINOIS AT 

 URBANA-CHAMPAIGN 

 AND NATURAL 

 HISTORY SURVEY 

 URBANA, ILLINOIS 



NSECT WEED & PL ANT DISEASE SURVEY BULLETIN 



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



FOR IMMEDIATE RELEASE 



No. 6, May 7, 1971 



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

 ■plant disease situation (fruit and oommeroial vegetables excepted) , along with 

 suggested, abbreviated control measures. Each individual should check his own 

 fields to determine local conditions. lA/^y 



INSECTS 



JUL 2 



lagj 



FORAGE INSECTS 





"■UNOJS! 



Alfalfa weevils . Development in the central section of the state has probably been 

 slowed down by the cool weather, but many alfalfa fields between Highway 13 and 16 

 are being damaged. The number of fields needing treatment is greater in this area 

 and to the south of it than last year. Wasp parasites are also present in this area, 

 with the percentage of parasitism of larvae ranging from 20 in Pulaski County to 60 

 in a field in Lawrence County. 



The weevil population should have reached its peak this week in the area south of 

 Highway 460, with parasites reducing the population. In that area, it would be 

 best to cut the alfalfa, remove it, and treat the new growth- -if needed. 



Watch the fields between Highways 16 and 136 for weevil damage next week. 



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 - Commercial 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 mixtures of them. There is no waiting period for malathion. Do not apply 

 Imidan more than once per cutting. 



3 - Using ground equipment . Apply a minimum of 20 gallons of finished spray per 

 acre, or 4 gallons by air. 



