Jsl. 



COLLEGE OF 

 AGRICULTURE 

 UNIVERSITY OF 

 ILLINOIS AT 

 URBANA-CHAMPAIGN 

 AND NATURAL 

 HISTORY SURVEY 

 URBANA, ILLINOIS 



NSECT WEED & PLANT DISEASE SURVEY BULLETIN 



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



FOR IMMEDIATE RELEASE 



No. 19, August 11, 1972 



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

 ■plant disease situation (fruit and commercial vegetables excepted) , along with sug- 

 gested, abbreviated, control measures. Each individual should check his own fields 

 to determine local conditions. 



THE LIBRARY OF THE 



INSECTS THE 



SEP 6 1972 



CORN INSECTS 



UNIVERSITY OF ILLINOIS 



Corn rootworm adults . If they are numerous iA T aM , S^M' t now, this could mean a root- 

 worm problem if the field goes back into corn in 1973. As a guideline, if a field 

 averages 4 or more rootworm beetles per plant now or 1 or more per plant for four 

 consecutive weeks, a rootworm problem could develop if the field is planted with 

 corn in 1973. Late-maturing fields are probably going to have the highest beetle 

 counts in the rootworm problem area; consequently, the most egg- laying. 



The western corn rootworm has been found for the first time in Montgomery County. 

 This species continues to move south and east in Illinois. 



A survey of 370 fields was completed this week, to determine the adult northern 

 and western corn rootworm populations. In general, populations are higher than 

 in 1971. Interpreting this information to predict potential rootworm problems in 

 1973 is difficult. There are too many unknowns involved. However, "one should 

 find the most eggs where there are the most chickens." 



Following are the results of surveys on the abundance of adult rootworms conducted 

 in 1971 and 1972: 



No. of 

 Area of fields 



Illinois surveyed 



Northwest 60 



Northeast 30 



West 50 



Central 40 



East 50 



Southwest 80 



Southeast 60 



Number of rootworm beetles 

 per 100 plants 



1972 



1971 



98 

 36 



109 



111 



73 



5 



64 



106 



64 



55 



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