mj- 



COLLEGE OF 

 AGRICULTURE 

 UNIVERSITY OF 

 ILLINOIS AT 

 URBANA-CHAMPAIGN 

 AND NATURAL 

 HISTORY SURVEY 

 URBANA, ILLINOIS 



NSECT WEED & PLANT DISEASE SURVEY BULLETIN 



: ATE/COUNTY/LOCAL GROUPS/US. DEPARTMEMT OF AGRICULTURE COOPERATING 



FOR IMMEDIATE RELEASE 



No. 1, April 3, 1970 

 v 



This series of weekly bulletins provides a general look at the insect, weed, and 

 plant disease situation (fruit and eommercial vegetables excepted) , along with sug- 

 gested, abbreviated control measures. Each individual should check his own fields 

 to determine local conditions. 



THE LIBRARY OF THE 



INSECTS 



FORAGE 



JUN 1 8 1970 



iiMlvFRjirY Ot- ILLINOIS 

 U A T 1V U%ANA.CHAMPAIGr4 



Alfalfa weevil development is slow because of the cool weather. There are about 

 the same number of eggs per square foot in southern Illinois alfalfa fields now as 

 a year ago. Further north, in central Illinois, egg counts are higher than last 

 year. If the alfalfa begins to grow before weevil hatch, alfalfa growers may be 

 able to get by with only one spray application; also, the later the hatch, the 

 larger the number of parasitic wasps to attack and kill the alfalfa weevil larvae. 



In 1969, the first applications of insecticides began the week of April 18 in 

 southern Illinois. Unless temperatures moderate rapidly, this year will be like 

 last year- -both in the timing of the insecticide applications and the intensity 

 of the attack. Although some alfalfa fields required an insecticide application 

 in 1969, many others needed no insecticides at all. The weather during the next 

 few weeks will be very important in determining the importance of the alfalfa 

 weevil to the 1970 alfalfa crop. 



Clover leaf weevil larvae, green worms with a white stripe down the back, resemble 

 the alfalfa weevil larvae --except that the head of the alfalfa weevil is black and 

 that of the clover leaf weevil is brown. Furthermore, the clover leaf weevil feeds 

 at night and hides in the ground debris during the day, and the alfalfa weevil lar- 

 vae are on the plants all day long. 



If red clover is covered with straw and other debris and growth is retarded, these 

 clover leaf weevil larvae can cause severe damage during extended periods of cold 

 weather. On the other hand, warm, humid weather promotes plant growth as well as 

 a fungus disease that kills these pests. Clover can usually grow away from damage; 

 but if growth is slow and leaf feeding is severe, a spray of 1 pound of malathion 

 per acre (or mixtures of malathion or diazinon and methoxychlor) will reduce the 

 insect population and allow the plants to grow. Malathion alone is most effective 

 when the air temperature approaches 60° F. 



CORN INSECTS 



European corn borer winter survival is higher than usual. At this time of year, 

 20 to 30 percent of the borers found in the old corn stalks are usually dead. This 



