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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 



TATE/COUNTY/LOCAL GROUPS/U S DEPARTMEMT OF AGRICULTURE COOPERATING ip'tV ' 



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FOR IMMEDIATE RELEASE 



USR0- 



No. 4, April 18, 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, ab- 

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

 local conditions. 



INSECTS 



FORAGE INSECTS 



Alfalfa weevil development, although still slower than normal south of Highway Route 50, 

 did speed up this week. Insecticide applications should be made now in the more-severely 

 infested fields. Fields that had feeding on 10 to 30 percent of the terminals last week 

 low show 40- to 50 -percent terminal feeding; 5 to 10 percent of the terminals had severe 

 feeding; 20 percent, moderate; and 20 percent, light. Although most larvae are small and 

 ^an be found only through close examination, they are growing rapidly. Expect more damage 

 to appear this week. 



In the area south of Highway 50, weevil adults are also more numerous. 

 160 per 100 sweeps of an insect net, compared with 20 to 90 last week, 

 creasing- -so will larval populations and damage. 



Populations reached 

 Egg- laying is in- 



Further north, weevil activity is just beginning. Here there was feeding on 5 to 20 per- 

 cent of the terminals, and there were 1 to 5 worms per infested terminal. Egg -laying and 

 natch will accelerate with warm weather. Those worms already there will grow and feed, so 

 insecticide control may be justified late in the week of April 21. 



fetch all alfalfa fields closely from now on. As soon as 25 percent of the terminals show 

 loticeable feeding, apply an insecticide- -unless the field is within two weeks of harvest. 

 In that case, cut early and treat the new growth. 



Die insecticide recommendations are: 



I. 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 azinphosmethyl. 

 Wear protective clothing. Slight discoloration of alfalfa may occur after the use of 

 parathion. 



I. 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, 

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



