J- /K I 



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. DEPARTMENT OF AGRICULTURE COOPERATING 



FOR IMMEDIATE RELEASE 



16 1973 



FY OF ILL' 

 AT Ul AIGN 



No. 7, May 4, 1973 



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- 

 nriyie local conditions. 



INSECTS 



FORAGE INSECTS 



Alfalfa weevil populations did not increase greatly south of Highway Route 50 (Law- 

 rence vi lie to St. Louis) during the past week, but those present have grown and their 

 appetites have increased. As a consequence, severe damage is apparent in unsprayed 

 fields. Some of this spring's larvae are already pupating, while some overwintering 

 adults are still depositing eggs. The number of larvae should begin to decrease in 

 about 10 days. Alfalfa is maturing, and it might be best to consider cutting the 

 alfalfa for hay rather than spraying. 



From Route 50 north to a line through Mattoon and Carlinville, larval populations 

 are still increasing and damage is becoming more apparent. Adult weevils are com- 

 mon and are still depositing lots of eggs. Insecticide applications in severely 

 infested fields wall still be profitable. 



There is tremendous variation in weevil populations and feeding and alfalfa vigor 

 from one field to another. Judge each field on its own merits before deciding to 

 spend money on insecticide applications. 



As alfalfa weevil larvae are hatching and alfalfa plants are still small in the 

 spring, we use 25-percent tip feeding as an indication of need for treatment, but 

 as the larvae and the alfalfa become larger, we can adjust the percentage upward, 

 As harvest approaches, even 100 -percent tip feeding does not warrant use of an in- 

 secticide. So from now on, before applying insecticides take into consideration 

 amount of tip feeding, size and number of larvae, and nearness to harvest. When 

 using insecticides, record the date of application so you can follow the required 

 interval between application and harvest. 



The insecticide recommendations are: 



1. Comme rcial applicators . Apply 1/2 pound per acre of methyl parathion, azinphos- 

 methyl (Guthion) , or Supracide--or 1/4 pound of carbofuran (Furadan) . Use azin- 

 phosmethyl only once per cutting, and do not harvest for 16 days. Do not har- 

 vest for 15 days after a treatment with methyl parathion, 7 days after using 1/4 

 pound of carbofuran, or 10 days after using 1/2 pound of Supracide. As a general 

 precaution, wear protective clothing. Higher dosages of carbofuran will require 

 longer waiting periods. Do not apply carbofuran more than once per season. 



