<-/%!_ 



COLLEGE OF 

 AGRICULTURE 

 UNIVERSITY OF 

 ILLINOIS AT 

 URBANA-CHAMPAIGN 

 AND NATURAL 

 HISTORY SURVEY 

 URBANA, ILLINOIS 



NSECX WEED & PLANT DISEASE SURVEY BULLETIN 



rATE/COUNTY/LOCAL GROUPS/US. DEPARTMENT OF AGRICULTURE COOPERATING 



FOR IMMEDIATE RELEASE 



No. 10, May 25, 1973 



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 deter- 

 mine local conditions. 



INSECTS 



jHEUBRAW 



OF THE 



1973 



FORAGE CROPS 



Alfalfa weevil larvae are continuing to decline in number, and 4;ne alfaLf$ N 6CHitinues 

 to grow. Generally, it is too late now to treat with an inse^iieid^VJ^T^^st thing 

 to do is to cut the alfalfa and remove the hay. If the weevil larvae are seriously 

 damaging the new shoots, spray with one of the recommended insecticides. If you have 

 had lots of alfalfa weevil problems this spring, now is the time to start thinking 

 about a November application of an insecticide. This will kill the adults that would 

 otherwise overwinter and deposit their eggs in the late winter and spring of 1974. 



Alfalfa or potato leafhoppers are tiny, green, wedge-shaped insects that run sideways 

 when disturbed. They feed on the undersides of the leaves. As they suck the plant 

 sap, they secrete a toxic material causing the leaves to turn yellow or purple and 

 stunt the plant. These insects overwinter near the Gulf of Mexico and migrate north- 

 ward. The extent of this year's migration is unknown, but there seems to be a strip 

 across central Illinois where populations are light to moderate. If the adults are 

 quite noticeable on new growth of alfalfa after the first cutting, apply 1 pound of 

 carbaryl (Sevin) or malathion, 1/2 pound of dimethoate (Cygon, De-Fend, and perhaps 

 others), or 1/2 pound of methoxychlor per acre. When spraying alfalfa with carbaryl 

 or malathion, there is no waiting period between application and harvest. With di- 

 methoate, wait ten days; with methoxychlor, seven days. 



SMALL GRAINS 



Armyworms are becoming conspicuous by their absence in lodged spots in wheat fields 

 in the areas of Illinois that are usually infested. We are finding some, but the num- 

 ber is small. The largest armyworms are about half an inch long, which is about half- 

 grown. 



The number of armyworms is much lower than one year ago, but the delayed spring may 

 mean an infestation later than usual. Look for armyworms in lodged grain. If you 

 find lots of them in such spots, examine the remainder of the field. 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 with- 

 in seven days of harvest, or 3/4 pound per acre of trichlorfon (Dylox) to within twenty - 

 one days of harvest. 



