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/US. DEPARTMEMT OF AGRICULTURE COOPERATING 





I- - 



FOR IMMEDIATE RELEASE 



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No. 19, August 1, 1969 



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 determine 

 local conditions. 



INSECTS 



CORN INSECTS 



True armyworms in corn rate the insect -of -the -week award. The problem area lies north 

 of Route 36. They are damaging corn where grasses were thick in the row and cornfields 

 planted adjacent to government acres which contain grasses or oats. The worms strip 

 the lower leaves first, leaving only the stalk and midribs. Sometimes they chew silks 

 and work the tip of the ear. 



Worms of all sizes were found this week (the worm stage lasts 2-1/2 to 3 weeks), with 

 about 1/2 to 2/3 of them nearly full grown. The worms should begin to disappear as 

 pupation progresses rapidly. The next generation of moths will roll on northward and 

 should present no further problems in these same areas. 



Before applying an insecticide, examine the field closely for the presence of worms and 

 assess the prospects for further damage. In many fields, the damage is confined to 

 localized grassy spots. Virus diseases, wasp parasites, and fly parasites can reduce 

 populations quickly. So, watch for shriveled or dying worms on the leaves. Diseased 

 worms were observed in several fields this week. If the disease becomes widespread, 

 worm populations will disappear almost overnight. 



If worms are still present, particularly many small to half -grown ones, and feeding is 

 pronounced, apply 1-1/2 pounds of actual carbaryl (Sevin) or toxaphene per acre as a 

 spray. Malathion at 1 pound of actual per acre is also effective. Do not apply carbaryl 

 near bee yards or on pollinating plants frequented by bees. Carbaryl has no waiting 

 period. Do not apply toxaphene on or adjacent to fish-bearing waters. Do not feed 

 toxaphene -treated corn as ensilage or stover to dairy cattle or to livestock fattening 

 for slaughter. Corn may be fed as grain from toxaphene -sprayed fields. Do not harvest 

 corn treated with malathion as feed or forage for 5 days after treatment. 



Corn rootworm adults are beginning to emerge in cornfields, where they are feeding on 

 silks. Species include the tan or pale-green northern, yellow and black striped western, 

 and 12-spotted southern corn rootworms. Since adult emergence is just beginning, popula- 

 tions can be expected to increase. In many of the problem fields, the corn is lodged 

 (especially if rains and winds have occurred recently) and root damage is severe, due 

 to feeding by the larvae. 



