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COLLEGE OF 

 AGRICULTURE 



UM\ E^Si^ O- 

 ILLINOIS AT 

 URBAMA -CHAMPAIGN 

 AND NATURAL 



HISTORY SURVEY 



URBAMA ILLINOIS 



v]SECT.\YEED& PLANT DISEASE SURVEY BULLETIN 



TE COUNTY LOCAL GROUPS U.S. DEPARTMENT OF AGRICULTURE COOPERATING 



FOR IMMEDIATE RELEASI 



No. 17, July 24, 1970 



This series ;; :v= : :!: bulletins provides a general loo~k at the insect, weed, and -plant 



disease situaticr, fv:-.:r tti .v~:-Ytt ' v vegetables excepted . along with suggested, 



breviated contro'i measures. Each individual s : :::-.'.i jheck his own fields to determine 

 local conditions. 







oofs 





Corn leaf aphid populations in general did not increase as much as expected during the 

 past week, although they are causing problems in occasional fields. Furthermore, popu- 

 lations in some fields apparently began to decrease, and dead aphids can be found in 

 unemerged tassels. 





Infestations are generally low or non-existent in fields already in full tassel, pres- 

 ent in very small numbers in fields in early tassel, and noticeably present in some 

 fields in the pretassel or late-whorl stage cd growth. However, only about 1 of 

 every 10 or 20 of these fields has enough aphids to pose a potential problem. 



Examine fields not yet in tassel t--.refv.llv every 5 days until after tassel emergence. 

 Tear open the whorls of 5 to 10 plants in each of 4 or 5 places in the field. If 50 

 percent or more of the plants are moderately infested with aphids . apply 1 pound of 

 malathion or diatir.tr. or 1 4 pound of methyl parathion per acre as a spray. Apply 

 just after the tassels begin tc show. Allow 5 days for malathion, 10 days for diazinon, 

 and Id days fox methyl parathion between treatment and harvest for grain, ensilage, or 

 stover. Methyl parathion should be applied only by experienced applicators. 



Tht res are ratter cus ir. ccrr. whorls. Dc not confuse them, -..-.t '-. the green aphids that 

 move about very slowly. Thrips are trim insects that move very rapidly and are black, 

 yellow, or orange. Nc centre 1 is 



IpanA/" 



Grasshcrrers can now be found in cornfields. If they are abundant and devouring leaves, 

 ears mav be smaller titan normal. If they feed em silks, the-." can affect pollination if 



emplete. 



it is met 



To control, apply carbaryl Aevin] , diactrc:.. malathion, er texarheme. dther insec- 

 ticides may do* the ; e'e . he met arm A - texarheme te eerm te he used for ensilage or 



tedder. 



Picnic "eeetl 



the elack beetles with the 4 Drange er yellow specs, are abundant in 

 seme ce:ttfields . Usually they feed in decaying organic matter er possibly teller.. When 

 they gc te the silks, thev de not affect pollination te any decree, but they met.- em 



