Ifa I 



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 IMvlEDIATE RELEASE 



No. 5, April 30, 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. 



INSECTS 



FORAGE INSECTS 





Alfalfa weevils developed very fast this past week, and feeding damage is notice- 

 able in fields within the southern third to half of the state. Infestations appear 

 to be heavier than last year. However, wasp parasites of weevil larvae are increas- 

 ing, and they will help curb the weevil populations. 



Fields needing treatment were observed as far north as Highway 16. Between Highway 

 16 and Highway 136, some fields may need treatment this week. It will be another 

 one to three weeks before infestations are serious north of Highway 136. 



In the extreme southern section (south of Highway 13) , damage is already severe and 

 the best time for insecticide treatment is past. Consider cutting and removing the 

 hay and spraying the new growth, if needed. Larvae are already beginning to pupate 

 and wasp parasites are taking their toll in this area. Larval populations have prob- 

 ably already reached their peak, and will now decline slowly during the next three 

 to four weeks. 



There is considerable variation in weevil populations between different areas and 

 fields. So check each field separately to make judgments. Do not apply insecti- 

 cides 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: 



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

 phosmethyl (Guthion) for good results. Use azinphosmethyl only once per cutting. 

 Do not harvest for 15 days after treatment with methyl parathion, or 16 days for 

 azinphosmethyl. Wear protective clothing. 



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. 



