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COLLEGE OF 

 AGRICULTURE 

 UNIVERSITY OF 

 ILLINOIS AT 

 URBANA-CHAMPAIGN 

 AND NATURAL 

 HISTORY SURVEY 

 URBANA. ILLINOIS 



NSECX WEED & PLANT DISEASE SURVEY BULLETIN 



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



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..'. A L. .- 



rCD I lOyQ 

 FOR IMMEDIATE RELEASE No. 18, July 25, 1969 



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

 disease situation (fruit and commercial vegetables excepted) 3 along with suggested, ab- 

 breviated control measures. Each individual should check his own fields to determine 

 local conditions. 



INSECTS 



CORN INSECTS 



Armyworms are invading cornfields in western and northern Illinois . The moths , abundant 

 for the past 2 to 3 weeks, deposited eggs on grasses in cornfields, on oats in lodged spots, 

 and on oats and grasses in government acres. These worms have fed for some time, have 

 stripped the grasses, and are now migrating in search of food. If they migrate into a 

 cornfield, they often strip the plants, leaving only stalks and midribs. When corn is 

 small , this leaf loss may not be serious , but at this late date , it is as plants are under 

 stress during pollination and silking. Thus damage could be serious. Fat worms, 1-1/4 to 

 1-1/2 inches long, are mature and have already done their damage; but if you have many 

 small worms in a field, an insecticide for control may be wise. Above all, examine plants 

 land soil carefully for worms before treating. Be sure you have a problem and do not treat 

 just to be treating. Watch for shriveled or dying worms. Virus disease, wasp parasites, 

 and fly parasites may help control this pest. 



If you need an insecticide, use 1-1/2 pounds of actual toxaphene or carbaryl (Sevin) per 

 acre as a spray. Do not apply carbaryl [Sevin) near bee yards or on pollinating plants 

 frequented by bees. Do not apply toxaphene to, or adjacent to, fish-bearing waters. Do 

 lot feed toxaphene -treated com for ensilage or stover. 



Fall armyworm damage to corn is still visible but plants are recovering. Usually several 

 plants in one spot are affected. Leaves are fed upon, and plants have a ragged appearance. 

 3ut the worms have now matured and are conspicuous by their absence. A later generation 

 nay enter ears of late corn, alfalfa, or soybeans. However, this damage from the later 

 veneration is usually not severe except in extremely late corn. 



Control is not recommended when the worms are gone, but if you find these worms in the 

 diorl of the plants , you can control them with granules of either carbaryl (Sevin) or 

 ".oxaphene at 1-1/2 pounds of actual chemical per acre. Sprays provide erratic results, 

 ;o the granular form is preferred. Do not feed toxaphene- treated corn as forage to 

 lairy cattle. Do not feed toxaphene -treated corn as silage to livestock fattening for 

 slaughter. Corn treated with toxaphene granules may be fed as stover to livestock to 

 rithin 28 days of slaughter. There are no restrictions for carbaryl. 



]orn rootworms have begun to emerge as adults, but in the meantime the worms still present 

 n the soil are feeding on the roots; plants in many fields are tipping over because of 

 his root pruning. If moisture continues to be plentiful, the plants will partially re- 

 :uperate, but, if moisture becomes short, damage will be severe. 



