COLLEGE OF 

 AGRICULTURE 

 UNIVERSITY OF 

 ILLINOIS AT 

 URBANA-CHAMPAIGN 

 AND NATURAL 

 HISTORY SURVEY 

 URBANA. ILLINOIS 



MSEC! WEED & PLANT DISEASE SURVEY BULLETIN 



<\TE/COUNTY/LOCAL GROUPS/US. DEPARTMEMT OF AGRICULTURE COOPERATING"»*(ft^U \ W» *&"'"' 



c 



)R IMMEDIATE RELEASE 



No. 1, March 28, 1969 



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

 ■sease situation (fruit and commercial vegetables excepted) , along with suggested, ab- 

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

 >cal conditions. 



INSECTS 



irage Insects 



falfa weevil development slowed this week due to the cold, wet weather. An average of 

 i larvae per square foot were found in the extreme southern counties. The worms are still 

 lall, more yellowish than green, and hidden in terminal leaf buds. Some tips are showing 

 ceding but no damage has yet occurred. A week to ten days of warm weather would cause a 

 idden hatch of many new larvae, resulting in the need for treatment in some fields. The 

 .rst insecticide applications will probably not be needed in the extreme southern counties 

 Ltil the week of April 6 or later, depending on the weather. Cool weather will prolong 

 ,g laying and hatch, allow the alfalfa to grow, and lessen the amount of injury. 



lis spring, the alfalfa weevil has the potential of inflicting severe damage to fields of 

 .falfa south of a line from Watseka to Hardin. Damage could be noticeable. Some treat - 

 aits could be needed in alfalfa fields in the area north of this line as well. 



: you intend to protect your alfalfa from weevil attack, begin to make preparations now. 

 an to apply an insecticide when 25 percent of the terminals show noticeable feeding and 

 irvae are still present. A second application may be needed about 2 or 3 weeks later as 

 >re larvae hatch. Even a third spraying might be needed in some southern areas to com- 

 .etely protect the first cutting and new growth of the second cutting. 



le insecticide recommendations are : 



Experienced commercial applicators who have the proper protective clothing will get 

 the best results with methyl parathion applied at 1/2 pound per acre, or a special 

 alfalfa weevil spray of azinphosmethyl (Guthion) at 1/2 pound per acre. Azinphos - 

 methyl can be applied only once per cutting . Do not harvest for 15 days after treat - 

 ment with methyl parathion, 16 days for azinphosmethyl . 



The person not properly equipped with protective clothing to use methyl parathion or 

 azinphosmethyl can use a mixture of 5/4 pound of malathion and 5/4 pound of methoxy- 

 chlor per acre (5 pints of a concentrate containing 2 pounds of methoxychlor and 2 

 pounds of malathion per gallon) , or a mixture containing at least 1/2 pound of diazinon 

 and 1 pound of methoxychlor per acre (2-1/2 to 3 quarts of the commercially prepared 

 mixture Alfatox) . You may also use 1-1/4 pounds of malathion per acre (1 quart of the 

 5-pounds-per-gallon concentrate) in the morning on days when the air temperature will 

 be above 60° F. Do not harvest for 7 days after treatment with methoxychlor, diazinon, 

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



