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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 



TATE/COUNTY/LOCAL GROUPS/US DEPARTMEMT OF AGRICULTURE COOPERATING 



i i oft! 





r- - 



)R IMMEDIATE RELEASE 



No. 14, June 27, 1969 



lis series of weekly bulletins provides a genera Trvdhli at the insect, weed, and plant 

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

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

 jcal conditions. ,, . i L .•,;.,■,.•• 



INSECTS 



JRN INSECTS 



le first generation of European corn borers has almost been eliminated as a general threat 

 d early corn this year. 



lthough first -generation borers may not present a general problem, some fields that 

 3re planted early will be damaged. This is particularly true in the area bounded by the 

 llinois River on the east, Route 136 on the south, and Route 6 on the north. The rain 

 id wind storms of the past week apparently whipped egg masses off leaves and killed a 

 reat many moths, because it is now difficult to find either moths or eggs in early corn, 

 f we have misjudged the effect of these storms, egg laying will begin with the first 

 ight that is warm and quiet. Such nights enable moths to fly and deposit eggs without 

 3ing disturbed. 



s an insurance, continue to examine early planted fields in western and northern Illinois 

 or signs of whorl feeding for another week. It will pay to treat fields with an insecti- 

 ide if tassel ratios are over 30 and if 75 percent of the plants show whorl feeding, but 

 o not apply insecticide until the tassel ratio is at least 35, preferably 40 to 50. Higher 

 assel ratios require a lower percent of plants with whorl feeding to warrant insecticide 

 ontrol. Naturally, the earliest fields will now have the highest tassel ratios. 



d determine the tassel ratio, dig up a plant and measure from the bottom of the plant to 

 tie tip of the longest leaf. Split the plant and find the developing tassel. Measure from 

 tie bottom of the plant to the tip of the tassel. Divide the tassel height by the plant 

 eight and multiply by 100 . 



org rootworm larvae have not yet been reported, but they should appear this week. If you 

 now or suspect that you have a rootworm problem and did not use an organic phosphate or 

 arbamate insecticide at planting time, apply one of the recommended chemicals now as a 

 asal treatment. Do not wait to count the larvae. In many fields- -especially early planted 

 nes--the corn will be too tall for a basal treatment by the time rootworms are large enough 

 o be found and counted. 



he insecticides suggested for basal treatment are diazinon, phorate (Thimet) , BUXten, disul- 

 oton (DiSyston) , or parathion (Niran)--at the rate of 1 pound of actual chemical per acre; 

 nd carbaryl (Sevin) , at the rate of 2 pounds actual per acre. 



