Jft /-. 



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/U S DEPARTMEMT OF AGRICULTURE COOPERATING 



L... 



OR IMMEDIATE RELEASE 



: , 



No. 10, May 29, 1969 



Ttis aeries of weekly bulletins -provides a general VtMMi at the insect, weed, and -giant 

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

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

 local conditions. 



INSECTS 



VRN INSECTS 



ieed-corn beetles and seed-corn maggots are both damaging germinating corn. The beetles 

 ire also hurting seedling plants. Missing plants (skips) or stunted plants are a sign of 

 ;eed damage by these insects. The slender seed-corn beetle (most common) is chestnut 

 )rown color. The striped seed-corn beetle is dark-brown with a tan border. Both are 

 ibout 3/8 inch long and move about in the soil readily. The seed-corn maggot is a pale, 

 /ellowish-white maggot about 1/4 inch long found in the seed. 



fhe beetles and maggots eat holes in the seed. The beetles also eat gouges in the devel- 

 oping sprout, sometimes cutting small sprouts completely. Plants with damaged sprouts or 

 dnor tunnelling in the seed are stunted. Many of these plants will still recover. Once 

 :orn reaches the three- or four-leaf stage, it will usually grow away from the damage. 

 lowever, the insects will continue to hurt germinating corn for another 2 to 4 weeks. 

 Damage is evident in untreated fields as well as in fields treated with aldrin, heptachlor, 

 Alordane, lindane, or dieldrin as seed or soil treatments, indicating resistance to these 

 insecticides. The control of these insects has been satisfactory, when a diazinon seed 

 treatment or an insecticide for resistant rootworms was applied at planting time. 



If replanting becomes necessary, use a diazinon dust on the seed for control. Take time 

 to check and clean the planter plates frequently. This will help prevent any reduction 

 in the seeding rate. 



Slack cutworms are reported to be causing damage in a few fields. Watch the low, wet 

 spots in the cornfields. If damage appears, use a spray directed at the base of the 

 Dlants of carbaryl (Sevin) at 2 or 3 pounds, diazinon at 2 pounds, toxaphene at 3 pounds, 

 )r trichlorfon (Dylox) at 1 pound of actual chemical per acre. It is best to use at 

 least 20 gallons of water per acre and to cover the spray band by throwing soil at the 

 )ase of the plants with a cultivator. 



European corn-borer moth emergence is progressing rapidly in the southern section. In 

 the central section, approximately 75 to 90 percent of the borers have pupated, and 

 emergence of moths is beginning. Pupation has started in the northern section, but no 

 noths have emerged as yet. Corn-borer development parallels that of 1956, when a high 

 overwintering population caused severe damage in the more -mature plantings in late June 

 aid early July. Much of the corn planted before May 10 in the northern half to two- 

 thirds of the state (except localized areas in the east-central section) may develop 

 pconanic infestations of first-generation borers. Watch fields in the south-central 

 'section beginning about June 12, in the central section about June 18, and in the 

 northern section about June 24 for damaging infestations. Plan to use insecticides if 

 leeded. 



