n 7 



COLLEGE OF 

 AGRICULTURE 

 UNIVERSITY OF 

 ILLINOIS AT 

 URBANA-CHAMPAIGN 

 AND NATURAL 

 HISTORY SURVEY 

 URBANA, ILLINOIS 



NSECT WEED & PLANT DISEASE SURVEY BULLETIN 



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



FOR IMMEDIATE RELEASE 



No. 9, May 28, 1970 



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

 disease situation (fruit and oommeroial vegetables excepted) , along with suggested 

 abbreviated control measures. Each individual should check his own fields to deter- 

 mine local conditions. 



Because of the long weekend this bulletin is being written one day earlier than 

 usual. We hope no last-minute problems are overlooked. lbraryofthe 



INSECTS 



SMALL GRAINS AND GRASSES 



JUN 1 8 1970 



UNIVP&9ITY SF IWWINUIS 

 AT URiANA^HAMPAIQN 



Armyworms are now present in wheat fields in many areas . Some luxuriant fields of 

 wheat are infested as far north as central Illinois, but high temperatures are speeding 

 up worm development as well as a disease that may kill many of the worms. Parasites 

 are also present. The worms are still small in wheat fields along the east side of 

 the state and there are many of them. Populations are lower and the worms are more 

 mature in the western and southern sections. Although the time for maximum benefit 

 is about over, some fields may still warrant the use of an insecticide. 



To determine the need for treatment, strike the plants vigorously, then count the 

 worms on the ground or in the debris --even in the cracks and crevices in the row. If 

 the average count is 6 or more worms per linear foot of drill row throughout the field, 

 apply an insecticide when the worms are about 3/4 of an inch long. An armyworm eats 

 39 linear inches of wheat leaf in its lifetime, but 80 percent of that feeding occurs 

 after the worm is over 3/4 of an inch long. Leaf feeding is not serious when worm 

 populations are low, but an average population of less than 6 worms per linear foot 

 of drill row can still be damaging if the worms are cutting off the heads of the 

 wheat. Also if most worms are about 1-1/4 to 1-1/2 inches long and are fat, they 

 are through feeding. Do not use insecticides then; it is too late. 



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 found in many wheat fields this week. They do not damage wheat plants 

 enough to require control. 



Treatment is justified if there are six or more armyworms per foot of drill row, as 

 an average over the field. Applications of 1 to 1-1/4 pounds of malathion, 1 pound 

 of trichlorfon (Dylox) , 1-1/2 pounds of carbaryl (Sevin) , or toxaphene will control 

 armyworms. Do not apply carbaryl on small grains after the boot stage. Do not feed 

 forage or straw treated with toxaphene or trichlorfon to dairy cattle, livestock 

 being fattened for slaughter, or poultry. There is no waiting period between the 

 application of toxaphene and grain harvest; a week is required when applying malathion, 

 21 days for trichlorfon. 



Remember, toxaphene is very toxic to fish. Do not use it near fish-bearing waters . 

 If there are honey-bee colonies adjacent to fields to be treated, toxaphene is the 



