COLLEGE OF 

 AGRICULTURE 

 UNIVERSITY OF 

 ILLINOIS AT 

 URBANA-CHAMPAIGN 

 AND NATURAL 

 HISTORY SURVEY 

 URBANA, ILLINOIS 



MSEC! WEED & PLANT DISEASE SURVEY BULLETIN 



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



JUL 



FOR IMMEDIATE RELEASE 



,"\- „ .^ 





No. 



, May 21, 1971 



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 determine local conditions. 



INSECTS 



SMALL GRAINS 



Armyworms . Six to nine armyworms per linear foot of drill row were found in a barley 

 field in south- central Illinois this week. They were about 5/4 of an inch long, 

 or approximately half grown. One or two worms per linear foot of drill row in 

 wheat fields was common in the same area. Although these armyworms are still 

 small, they will grow rapidly this week and will be noticeable in some fields. 

 As yet, the situation is not alarming. 



To count armyworms in a grain field, look first in the thick, lodged spots. Army- 

 worms will hide in the dead leaves and other trash at the base of the plants. If 

 you find lots of worms, make a count in several places in the field and figure 

 the average number of worms per foot of drill row. If you find no worms or only 

 an occasional one in the thick or lodged spots, there is no need to look further. 

 Chemical control is justified if there are 6 or more armyworms per foot of drill 

 row, as an average over the field. 



An armyworm will eat 59 linear inches of wheat leaf in its life as a worm. How- 

 ever, the leaf loss is usually not too important. So, do not become too alarmed 

 if you find a few armyworms in a wheat field. They often feed only on tne leaves, 

 and damage is usually minor. When they begin to cut off the wheat heads, however, 

 damage can be severe. 



Eighty percent of the total food consumed by an armyworm during its lifetime is 

 eaten during the last 20 percent of its life as a worm. Normally, you can wait 

 until many of the armyworms are 5/4 of an inch long before starting treatment. 

 This will give weather, armyworm diseases, and wasp and fly parasites a chance 

 to kill many of them. Chemical control may not be necessary. However, once the 

 worms are two- thirds to three- fourths grown and the population is high, chemical 

 control may be needed. 



Applications of 1 to 1-1/4 pounds of malathion, 1 pound of trichlorfon (Dylox) , 

 or 1-1/2 pounds toxaphene per acre will control armyworms. Do not feed forage or 

 straw treated with toxaphene to dairy cattle, livestock being fattened for slaugh- 

 ter, or poultry. After using trichlorfon, do not forage or feed the wheat within 



