-2- 



Very severe infestations of aphids may result in barren plants and shriv- 

 eled ears. As a rule of thumb, value of control, except under extreme infestations, 

 is questionable if corn is pollinating or has pollinated. However, if corn is pre- 

 tassel or younger and 25 percent or more of the whorls are severely infested, control 

 may be profitable. 



In general, we believe that corn leaf aphids present a greater problem to 

 the seed producer than to the commercial grain producer. 



Eoth 1 pound of phorate (Thimet) and 1.25 pounds of diazinon as granules in 

 pretassel corn provided excellent control in tests this past week. Sprays of diazi- 

 non, malathion, mevinphos (Phosdrin) and parathion will control these aphids. Do not 

 use phorate if it was used as a soil insecticide, and even then do not apply later 

 than whorl stage. Mevinphos and parathion sprays should be applied only by operators 

 prepared to use protective clothing. Phorate granules can be used by the individual, 

 but extreme care must be taken when handling. Diazinon granules can be used to within 

 2 days of harvest, malathion to within 5 days, parathion to within 12 days and mevin- 

 phos to within 1 day. 



Corn borer moths have been depositing eggs in late cornfields in the south- 

 ern fourth of Illinois for some time. The average is about 15 egg masses per 100 

 stalks. In general, second- and third -generation borer populations will probably be 

 higher this year than last. 



Pupation of first -generation borers in the northern third of the state 

 varies from 25 to 75 percent, with emergence just starting. 



First -generation populations are lower than in previous years, so we do not 

 expect a second-generation corn borer problem. 



Spider mites are present in some soybean fields in south-central Illinois. 

 These tiny mites rasp the undersurfaces of leaves, giving them a mottled appearance. 

 In addition, they spin webs on the undersides of the leaves. These mites increase 

 during dry weather. The best control is carbophenothion (Trithion), which can be 

 used to within 7 days of harvest of beans as grain. 



Spotted alfalfa aphids are present in numbers in alfalfa fields in southern 

 Illinois. If dry weather continues, damage could become severe. One pound of mala- 

 thion, l/2 pound of diazinon or l/k pound of demeton can be used. Do not apply diazi- 

 non within 10 days of harvest. Do not apply demeton more than once per cutting or 

 within 21 days of harvest. 



Potato leafhopper damage has become more apparent in alfalfa fields. Some 

 reports of severe damage to this year's seedings have been received. Malathion or 

 methoxychlor will provide control. Unfortunately, it will do little good to kill the 

 leafhoppers after they have been feeding for some time, They inject a toxin into the 

 plant which produces the purpling, yellowing and stunting. 



Northern corn rootworm adults are becoming more numerous. They are the 

 green beetles that feed on corn silks. This insect is showing signs of general re- 

 sistance to the soil insecticides. 



White grubs are still feeding on soybeans, and patches of dead beans in 

 fields are getting larger. Little can be done to control this pest. 



