COLLEGE OF 

 AGRICULTURE 

 UNIVERSITY OF 

 ILLINOIS AT 

 URBANA-CHAMPAIGN 

 AND NATURAL 

 HISTORY SURVEY 

 URBANA. ILLINOIS 



NSECT WEED & PLANT DISEASE SURVEY BULLETIN 



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



RSlfBaiYQFrjIEB 



FOR IMMEDIATE RELEASE 



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No. 2, April 5, 1969 



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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 



FORAGE 



Alfalfa weevil development continues to be slow. It now appears that no insecticide treat - 

 ments will be needed in extreme southern Illinois until at least the week of April 13. 

 Small larvae are generally present; an average of 33 larvae and 100 eggs per square foot 

 were observed again this week. Feeding by these tiny worms is hardly noticeable, but it 

 will become more apparent with warmer weather. 



Further north, the hatch has been delayed and only an occasional small worm is present. 

 Continued cool weather may retard weevil development but may permit the alfalfa to grow. 

 This would reduce the number of sprays needed to protect the alfalfa. But as soon as 

 25 percent of the terminals show feeding, apply an insecticide unless the field is to be 

 harvested within a week to 10 days. 



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) 3/4 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 (3) 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, diaz- 

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



Clover leaf weevils resemble alfalfa weevil, but feed at night and hide in ground debris 

 during the day. Inspect red clover fields that have a heavy straw or mat covering. Slow- 

 growing plants may be injured by this worm. The leaves will be devoured and the plants 

 will look unthrifty- -often with almost no leaves. Although warm, humid weather favors a 

 disease that will kill these worms, severe problems could develop if the cool weather con- 

 tinues for any extended period. 



Clover can usually grow away from the damage. If the damage becomes severe and growth is 

 slow, a spray of 1 pound of malathion per acre is effective. This will also control pea 

 aphids, a few of which are now present in southern sections. 



