.4i 7 



COLLEGE OF 

 AGRICULTURE 

 UNIVERSITY OF 

 ILLINOIS AT 

 URBANA-CHAMPAIGN 

 AND NATURAL 

 HISTORY SURVEY 

 URBANA. ILLINOIS 



NSECT WEED & PLANT DISEASE SURVEY BULLETIN 



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



FOR IMMEDIATE RELEASE 



No. 10, June 5, 1970 



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. >r , w __ TLIC . 



THE LIBRARY OF THE 



INSECTS 



CORN 



JUN 2 9 1 Q 70 



UNIVtKSlf* Oh ILLINOIS 

 AT URBANA-CHAMPAIGN 



Cutworms are the major insect problem this week- -primarily the black species, with an 

 occasional infestation of the variegated species. These worms have been cutting off 

 corn plants at or below the soil surface. They are not necessarily confined to the 



I low areas of fields as is usually the situation but are found throughout a corn field. 



'Also, the size of the worms in an infested field may range from ones almost full-grown 

 (about two inches long) to young worms (a half inch or less in length) . Where soil 



[moisture is low, the worms are feeding below the surface of the soil. Where the soil 



'surface is moist, however, the worms are feeding on or near the surface. 



In many instances, worms tunnel into the base of taller plants and kill them. Corn 

 ; plants cut off below the growing point will die. In general, corn that is less than 



12 inches tall will recover from cutworm damage. But if many small worms are present 

 j (as in many fields now) , cutworm damage could continue for another 10 to 14 days . 



I Some of the cutworm- infested fields were treated with a row application of either 

 aldrin or heptachlor at planting time. Decisions on applying emergency treatments 

 will vary from field to field. It is important to check the fields closely and to 

 carefully evaluate the damage being done. Some infested fields are wet, thus pre- 

 venting any ground application of an insecticide. Don't depend on aerial applications 

 I of cutworm emergency treatments to give consistent control. If the corn is more than 

 i 8 inches tall and 20 percent or more of the plants have been attacked, emergency treat- 

 ment is warranted. Use a spray- -directed at the base of the plants- -of carbaryl 

 ! (Sevin) at 2 or 3 pounds, diazinon at 2 pounds, toxaphene at 3 pounds, or trichlorfon 

 j (Dylox) at 1 pound of actual chemical per acre. It is best to use at least 20 gallons 

 of water per acre, and, if possible, to cover the spray band by throwing soil at the 

 I base of the plants with a cultivator. 



If replanting becomes necessary, the cutworms will probably still be present when this 

 j is done. Diazinon or Dyfonate granules will probably provide the best control. Use 

 them at 2 pounds of actual insecticide per acre, banded ahead of the planter press 

 wheel . 



European com-borer development continues to progress more rapidly than usual. Egg- 

 laying in the southern part of Illinois probably peaked during this past week. The 



