-2- 



To determine need for treatment, examine 50 to 100 plants for signs of 

 "borer feeding on the whorl leaves. If 75 percent or more of the plants show recent 

 whorl feeding, check the tassel ratio. Measure from the base to the tip of the 

 plant with the leaves extended. Split the plant lengthwise, and measure from the base 

 of the plant to the tip of the developing tassel. Divide tassel height by plant 

 height, and multiply by 100. Take an average for five representative plants per 

 field. This is the tassel ratio. The corn will warrant treatment if the tassel 

 ratio is 30 or above, but if possible do not treat until the ratio is at least 35 and 

 preferably k^ . However, treatment after borers have drilled into the stalk proper 

 will not be effective. 



DDT is still the most common insecticide for corn borer. Apply 1 1/2 lb. 

 per acre as a spray or $/k to 1 lb. per acre as granules. 



Other insecticides approved for use against corn borer are endrin and 

 toxaphene. Do not feed ensilage or stover of corn treated with DDT or toxaphene to 

 dairy cattle. Endrin may be used provided label restrictions are followed. 



Chinch bugs , although not generally present, are migrating from wheat to 

 corn in a few instances in eastern Illinois. Where this is occurring, apply 1/2 lb. 

 of dieldrin per acre to a strip of grain a few rods wide and into the corn as far as 

 the bugs are doing damage. Do not harvest treated grain for one week after treatment. 



Stable flies on cattle may be more severe this year than for the past 

 several years. For dairy cattle, apply 1 to 2 oz. daily of an oil-base spray con- 

 taining tabatrex, R-326, or DDVP daily. For beef cattle, spray every 3 or h weeks 

 with 0.5$ toxaphene water base spray at the rate of 1 to 2 <jt. per animal. Allow 

 28 days between treatment and slaughter when using toxaphene. 



Caution : Before applying insecticides, read the labels carefully, and 

 follow all precautions. This not only will insure personal safety, but will also 

 eliminate insecticide residue hazards. 



■*##*#■*•*#*# 



This weekly report was prepared by H. B. Petty, Illinois Agricultural 

 Extension Service and Illinois Natural History Survey, in cooperation with the USDA 

 Agricultural Research Service, Plant Pest Control Branch, from information gathered 

 by entomologists and cooperators who send in weekly reports from their own localities. 



HBPrdl 

 6/22/62 



