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COLLEGE OF 

 AGRICULTURE 

 UNIVERSITY OF 

 ILLINOIS AT 

 URBANA-CHAMPAIGN 

 AND NATURAL 

 HISTORY SURVEY 

 URBANA, ILLINOIS 



INSECT WEED & PLANT DISEASE SURVEY BULLETIN 



— <-■▼•- ~~ "■' — ^ n 



STATE/COUNTY/LOCAL GROUPS/U S DEPARTMEMT OF AGRICULTURE COOPERATING 



FOR IMMEDIATE RELEASE 



No. 6, May 2, 1969 



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 



FORAGE INSECTS 



Alfalfa weevil development is progressing slowly, but there is a gradual buildup. 

 Most alfalfa fields south of Highway 460 are being damaged. In the area between 

 Highway 460 and Highway 16, feeding damage is evident; some fields may need treat- 

 ment this week or by the following week (May 11) . Between Highway 16 and Highway 17 

 larvae can be readily found, but populations are still low. There may be need for 

 treatment in some fields in this area in another two or three weeks. 



When checking for alfalfa weevil, judge each field separately; there is a wide varia- 

 tion in weevil populations from field to field. If a field is within two weeks of 

 harvest, it probably would be best to cut early, remove the hay, and spray the new 

 growth. For most fields in the southern section, we will probably get by with a 

 single spraying on the first crop, but a second spraying may still be needed on the 

 new growth of the second crop. In the central section, early cutting and a spray 

 treatment, if needed, on the new growth of the second crop are likely to be sufficient. 

 If fields are more than two weeks from harvest and 25 percent or more of the terminals 

 show noticeable feeding, spray immediately. 



The insecticide recommendations are: 



1. Commercial applicators can apply 1/2 pound per acre of methyl parathion or azinphos- 

 methyl (Guthion) with good results. Use azinphosmethyl only once per cutting. Do 

 not harvest for 15 days after treatment with methyl parathion, 16 days for azinphos- 

 methyl. Wear protective clothing. 



2. Persons not equipped with protective clothing can use a mixture of (1) 5/4 pound of 

 malathion and 3/4 pound of methoxychlor per acre, (2) a mixture containing at least 

 1/2 pound of diazinon and 1 pound of methoxychlor per acre, or (5) 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 methoxychlor, 

 diazinon, or mixtures of them. There is no waiting period for malathion. 



Clover leaf weevil larvae are numerous in some fields of clover and alfalfa, particularly 

 in the western and northern sections of the state. Counts ranged from 4 to as high as 40 

 per square foot in some fields. The larvae are about a third grown. Although feeding is 



