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/U.S. DEPARTMENT OF AGRICULTURE COOPERATING 



FOR IMMEDIATE RELEASE 



No. 7, May 19, 1972 



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

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

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

 to determine local conditions. 



INSE0T*^ RM " OFtHE 

 JUN 14 \ 



SMALL GRAINS 



, r ILLINOIS 



True armyworms can be found in thick, rank stands of wheat, barley, rye, and various 

 grasses in the south-central and southern sections of Illinois. All sizes of worms 

 can be seen. They are mostly small ones--around 1/4-inch long. Some fields may be 

 heavily infested. Counts averaging as high as 6 to 12 per linear foot of row were 

 observed in fields this week. Larger, more mature worms are present in the grasses, 

 because the moths deposit their eggs first there. Insecticides should not be ap- 

 plied until most of the worms are about 3/4 of an inch long, since they are only 

 damaging after they reach this size. Small armyworms are susceptible to diseases, 

 parasites, and predators. Many of these 1/4-inch size armyworms will never reach 

 maturity. 



Look in thick or lodged spots first when checking for armyworms. They will be 

 hidden 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 determine the aver- 

 age number of worms per foot of drill row. If you find no worms or just an oc- 

 casional one in the thick or lodged spots, there is no need to look further. How- 

 ever, check the field again in about a week, since there could be additional egg 

 hatch by then. 



Do not confuse the striped armyworms with the transparent yellow to green sawflies . 

 An armyworm has five pairs of abdominal prolegs; sawflies, six or more pairs. Saw- 

 flies were also present along with the armyworms in the fields this week. Sawflies 

 do not damage wheat plants enough to require control. 



Treatment is justified if there are 6 or more armyworms per foot of drill row as an 

 average over the field. Apply 1-1/2 pounds of toxaphene per acre. Do not feed the 

 straw to dairy cattle, animals fattening for slaughter, or poultry. There is no 

 restriction on the use of the grain. One and one-half pounds of malathion per acre 

 may be used to within 7 days of harvest, or 3/4 pound per acre of trichlorfon (Dylox) 

 to within 21 days of harvest. 



Cereal leaf beetles are coming out of hibernation in the regulated portions of Illi- 

 nois, according to officials of the State Department of Agriculture. Populations 

 of this insect are still low, and economic damage is not likely to occur this year. 



