INSECT 



SURVEY 



BULLETIN 



College of Agriculture 



University of Illinois 



and Natural History Survey, 





tate / County / Local Groups / U. S. Department of Agriculture Cooperating 



FOR IMMEDIATE RELEASE 



June 21, 1968 



ILLINOIS INSECT, D ISEASE, A ND WEED SURVEY BULLET IN NO. 15 



This series of weekly bulletins provides a general look at the insect, plant dis- 

 ease, and weed situation (fruit and commercial vegetables excepted) , along with 

 suggested, abbreviated control measures. Each individual should check his own 

 fields to determine local ^"^fjffc^'ft^inv nr rur 



Corn Insects 



jul rtW 



WKWMitlT tt RUNS* 



Corn rootworms are of primary concern this week. We have found a few newly - 

 hatched western rootworm larvae and had a report of northern rootworm egg hatch 

 on June 2TT! Rootworms should be found commonly within the next 10 days. 



All western corn rootworms in Illinois are highly resistant to aldrin and hepta- 

 chlor"] The area of moderate to severe western corn rootworm infestation is bounded 

 in Illinois by the Mississippi River on the west and a line from Carthage to Peoria 

 to Dixon to Galena on the south, east, and north. In this area, third-year corn- 

 fields are likely to be damaged and second-year fields may very well be severely 

 damaged by western rootworms, particularly in Mercer County and adjacent areas. 

 Over 50 percent of the fields infested by northern corn rootworms in 1967 showed 

 varying degrees of rootworm resistance to aldrin and heptachlor. Although these 

 northern corn rootworms are present throughout the state, they are expected to be 

 more severe in the northern half of Illinois than in the southern half. Fields 

 planted to corn for 3 or more years continuously are most likely to be damaged, 

 but severe damage to second-year corn may occur. The farther north and west the 

 more common the northern corn rootworm is and the more resistant it has become. 



At planting time, many farmers used one of the phosphate or carbamate insecticides 

 in places of aldrin or heptachlor to control these rootworms. Many other farmers 

 have planned to use one of these phosphate or carbamate insecticides as a basal, 

 cultivator, or lay-by application. The insecticide is directed at the base of the 

 plant and the cultivator throws dirt over the chemical . We recommend 1 pound of 

 diazinon, disulfoton (Di-Syston) , or phorate (Thimet) per acre. BUX ten, Dasanit, 

 and dyfonate do not have label approval for this purpose. Parathion and carbaryl 

 (Sevin) , although not recommended in Illinois for this purpose, do have label ap- 

 proval and are recommended by some states . 



For convenience, this can be done any time in the fore part of June, but the ideal 

 ti^e to apply these chemicals as basal treatments is when the first rootworm eggs 

 begin to hatch and that is now. Another week and it will be impossible to get 

 through some fields. For those farmers who have already made these applications, 

 the control should be very good. 



