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Corn rootworms. The growth and development of rootworm larvae is progressing rap- 

 idly in the problem areas. Pupation of the larvae that hatched early has started, 

 and some adults will begin to emerge soon. For fields planted extremely late, a 

 basal application during cultivation may still be applied if rootworms are present. 

 The insecticides suggested for basal treatments are BUX, Dasanit, Dyfonate, or 

 phorate (Thimet) . A series of rootworm "digging and counting" meetings in demon- 

 stration plots to evaluate various insecticide treatments for rootworm control are 

 scheduled in six counties between July 6 and 9 and July 12 and 13. The locations 

 are given near the end of this newsletter. Bring a pocketknife for examining roots. 



European corn borers . This coming week will be the last one for profitable treat- 

 ment of first -gene rat ion corn borers in most areas of Illinois. There may be a 

 few exceptions in the northernmost counties. After the borers leave the whorl and 

 tunnel into the side of the stalk, control measures are of little value. (See last 

 week's bulletin for control recommendations.) 



SOYBEAN INSECTS 



Mites. A few more reports have been received of spider mite damage to soybeans. 

 The affected plants show stunting, yellowing, and browning of leaves. The infes- 

 tations are usually spotty, appearing first in rows along grassy roadsides or 

 grass waterways, then gradually expanding in size. The mites appear as small 

 specks on the undersides of the leaves. A fine web is usually apparent. Shaking 

 the leaves over a piece of white paper will dislodge the mites onto that surface. 

 The small specks that move are probably mites. The recent hot, dry weather in 

 many sections has been ideal for the development of mites. If the dry weather 

 continues, the problem will probably become worse. 



Severely affected fields may be sprayed with 1/2 pound of azinphosmethyl (Guthion) 

 or 3/4 pound of carbophenothion (Trithion) per acre. Only experienced applicators 

 should do this work. Azinphosmethyl has a 21-day waiting period between application 

 and harvest; carbophenothion, a 7-day waiting period. Do not feed soybeans sprayed 

 with either of these insecticides as forage to dairy animals or livestock being 

 fattened for slaughter. 



SORGHUM INSECTS 



Com leaf aphids . Several reports of this insect being present in the whorls of 

 sorghum have been received. Research conducted in other states indicates that 

 these aphids seldom affect sorghum production. If the infestation is heavy, mal- 

 athion will control them. 



Greenbugs . They can damage sorghum from the seedling up to the early pre -boot 

 stage, and will often cause plant death. As greenbugs suck the plant sap, they 

 inject a toxin into the leaves that causes a reddish discoloration to develop 

 around the point of feeding. We have not had any reports of greenbug damage to 

 sorghum in Illinois so far. Greenbugs are yellowish or bright green, with a 

 reddish tinge on the back of the body. Only the tips of their cornicles aid an- 

 tennae are black. They usually feed on the undersides of the lower leaves. Corn 

 leaf aphids, by contrast, are usually found in the whorls. Whenever greenbugs are 

 causing the death of more than two normal-sized leaves, they should be controlled. 



The sprays that can be applied by commercial applicators are demeton (Systox) , di- 

 sulfoton (Di-syston), or ethyl parathion. Do not use methyl parathion because of 

 possible injury to some sorghum varieties. The sprays that producers can apply 

 with ground equipment are diazinon, dimethoate (Cygon) , or malathion. 



