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The number of corn leaf aphids is increasing this week. Some fields in the south- 

 southwestern part of the state have a few plants that are heavily infested. Both 

 winged and wingless aphids can be found on grasses and in the whorls of corn 

 plants. These insects suck the juices from the plant. Such damage usually oc- 

 curs just prior to and during tasseling. Check the whorls of corn plants for 

 these insects during the two-week period prior to tasseling. 



Early treatment is best. When the corn is in the late-whorl stage and 50 percent 

 or more of the plants have aphids (with a few plants heavily infested) , and if 

 the corn is under stress, treat immediately. Treatment is also justified in corn 

 in the early tassel- to-pollinating stage, if 15 percent or more of the plants are 

 heavily loaded with aphids. 



Spray treatments by ground or air with 1 pound of malathion or diazinon per acre 

 will provide control. When using malathion, allow 5 days between treatment and 

 harvest for grain, ensilage, or stover. There is no waiting period between treat- 

 ment and harvest for grain for diazinon, but allow 10 days for ensilage or stover. 

 If corn is still in the late-whorl stage, seed producers may prefer to use 1 pound 

 per acre of either diazinon or phorate (Thimet) as granules. To avoid potential 

 hazards to detasselers, use phorate only on male- sterile corn. 



Common stalk borers in border rows of corn are still causing concern, but should 

 soon disappear. Keep fence rows, ditch banks, grass waterways, and similar areas 

 mowed during August to help prevent infestations next year. This is where the 

 moths deposit their eggs. 



Black cutworms were found this week in a cornfield in south-central Illinois. 

 About 10 percent of plants had been hollowed out below the ground level, and 

 these plants were dead. It is too late for control when this has happened. 



True armyworms have been observed in grassy cornfields in the northern half of 

 Illinois. Watch such fields closely; the worms feed first on the grass and then 

 move on to the corn plant. For infestations, apply carbaryl (Sevin) or toxaphene. 



There is no waiting period between application and harvest of the crop for grain 

 or ensilage if you use carbaryl. If you apply toxaphene, there is no restriction 

 on use of grain, but do not feed treated forage to dairy animals. Do not feed 

 ensilage, fodder, or stover to livestock within 28 days of slaughter. 



Soybean Insects 



Bean leaf beetles are now present in southern Illinois, but not in damaging numbers. 



Very small, green cloverworms are present in soybeans in central and northern Illi- 

 nois. These pale, green worms with white stripes are the ones that feed heavily on 

 soybeans, usually in August. If the plants are jarred, they fall to the ground. 

 When touched, they twist their body rapidly- -almost as if they were a spring. The 

 severity of this problem remains to be seen, but a fly parasite lays tiny, white 

 globular eggs on the backs of these worms. When present in sufficient numbers, 

 they aid in control. 



