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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 



OR IMMEDIATE RELEASE 



No. 19, August 7, 1970 



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

 iisease situation (fruit and commercial vegetables excepted) , along with, suggested, 

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

 mine local conditions. 



INSECTS 





VRN 



■ 



: all armyworms are damaging late -maturing corn, particularly in the southern sections, 

 fhese dark-brown-to-gray to dull-green, smooth- skinned worms feed in the whorl, giving 

 )lants a ragged appearance as the leaves emerge. A series of plants in a row will 

 ;how damage, and these patches of infested plants will usually be over the entire 

 field. The worms this week were one-third to one-half grown with another 7 to 10 days 

 )f feeding time left before they mature. Additional generations could still present 

 further problems in late-maturing fields. After corn has pollinated, fall armyworms 

 /ill attack the developing ears (like earworms), and some larvae will be present in 

 ;ars until frost. 



'reatment is justified in fields in which 20 percent or more of the plants are in- 

 fested. Before applying insecticides be sure the worms are still present and that 

 ,ost of them are not more than 1-1/4 inches long. When they reach about 1-1/2 inches, 

 hey are mature; at that size they stop feeding, drop to the ground, enter the soil, 

 nd pupate. 



or control, apply either carbaryl (Sevinj or toxaphene at 1-1/2 pounds of chemical 

 er acre. Granules are preferred, especially if air applications are made. Ground 

 pplications with the spray directed into the whorl will provide fair to good results, 

 epending on the size of the worms. The larger worms that are deep in the whorl are 

 ore difficult to reach with an insecticide, and control is poor. Smaller worms, 

 any of which are on exposed leaves, are readily killed. 



o not feed toxaphene -treated corn as forage to dairy cattle. Do not feed toxaphene- 

 reated corn as silage to livestock fattening for slaughter. Corn treated with toxa- 

 hene granules may be fed as stover to beef cattle to within 28 days of slaughter, 

 here are no restrictions for carbarvl. 



econd-generation flea beetles are numerous in corn, particularly in southern Illinois. 

 ;iese shiny-black beetles (slightly larger than a pinhead) that jump when disturbed 

 3ave white scratch marks on the leaves. Some extremely late fields of corn (8 to 12 

 iches high) are being damaged by these insects. The beetles can also be found feeding 

 ; i more mature corn, but the damage is not serious and no control is needed. Carbaryl 



