COLLEGE OF 

 AGRICULTURE 

 UNIVERSITY OF 

 ILLINOIS AT 

 URBANA-CHAMPAIGN 

 AND NATURAL 

 HISTORY SURVEY 

 URBANA, ILLINOIS 



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



NSECT, WEED & PLANT DISEASE SURVEY BULLETIN 



- - — -~ <***"** 



No. 8, May 11, 1973 



FOR IMMEDIATE RELEASE 



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 populations have reached their peak south of Interstate 70. Many lar- 

 vae are now pupating; but because of an extended egg-laying period by adult weevils, 

 larval populations will remain high for another week and then gradually decline. Wasp 

 parasites are evident, and will help to reduce larval numbers. South of 1-70, it would 

 be best to cut alfalfa as soon as possible and to spray the new growth, if needed. 

 Treat immediately if the new growth does not green-up in two or three days. 



In the area between Interstate 70 and a line from Paris to Decatur to Carthage, wee- 

 vil populations increased rapidly this week. Treatment was justified in most fields 

 within that area this past week. Treatments, if not already applied, should be made 

 now. Infestations were somewhat higher in the western part of this area than in the 

 east side. 



In the area north of a line from Paris to Decatur to Carthage and south of Interstate 

 74, watch fields closely this week and next. Weevil populations are expected to in- 

 crease rapidly. North of Interstate 74, it will be another one to three weeks before 

 infestations become serious. 



In general, alfalfa weevil development is slower than normal so far this year. In 

 many fields, it may be possible to take advantage of early cutting and to avoid the 

 use of insecticides --particularly in the central, north-central, and northern sections. 

 Harvesting first-crop alfalfa will often be as detrimental to the weevil larvae as ap- 

 plying an insecticide. So, use an insecticide treatment only when the field approaches 

 100 -percent tip feeding and when cutting is ten days or more away. For insecticide 

 recommendations, see last week's Bulletin, (No. 7, May 4). 



Spittlebug froth masses can be found now in most areas , particularly in new seedings 

 of clover and alfalfa. Populations are not expected to be damaging. 



CORN INSECTS 



Black cutworms could appear any time in the few fields of corn that have been planted. 

 These worms could show up any time during the next month. Watch corn closely for the 

 first signs of cut or missing plants. Dig around several of the damaged plants to find 

 the worms. Treatment is justified if you find 1 or more worms per 25 plants. 



