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COLLEGE OF 

 AGRICULTURE 

 UNIVERSITY OF 

 ILLINOIS AT 

 URBANA-CHAMPAIGN 

 AND NATURAL 

 HISTORY SURVEY 

 URBANA. ILLINOIS 



;nsect weed & PLANT disease survey bulletin 



iTATE/COUNTY/LOCAL GROUPS/U.S. DEPARTMEMT OF AGRICULTURE COOPERATING^ 



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=0R IMMEDIATE RELEASE 



No. 8, May 16, 1969 



Tiis series of weekly bulletins provides a general look at the insect, weed, and plant 

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

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

 \ocal conditions. 



INSECTS 



■ORAGE INSECTS 



llfalfa weevil populations continue at a high level , and damage is evident in fields south 

 »f Highway 16 . In the area between Highway 16 and Highway 136, damage is approaching 

 economic levels. Some fields may need treatment this week. North of this line, feeding 

 .s noticeable but is not yet severe. Larvae are just beginning to pupate in the central 

 iection; pupation is progressing rapidly in the southern sections. However, eggs are 

 -.till hatching; so, populations are expected to remain high for another 2 to 3 weeks, 

 '.arval populations should now begin to level off and gradually decline, as pupation con- 

 :inues and the incidence of parasitism increases. (In several fields, an extreme of 

 30 to 95 percent of the larvae were found parasitized by a wasp this week.) 



Continue to watch alfalfa fields in the southern half to two -thirds of the state for 

 /eevil problems. In fields that are untreated and as yet uncut, it would be best to cut 

 ±e alfalfa, remove the hay, and spray the neiv growth of the second crop. Cutting will 

 )ften reduce the weevil population, since many eggs are removed and a good many larvae 

 ire either killed or forced to pupate by exposure to the sun. If the crop has already 

 )een cut but the new growth has not been sprayed, watch it closely for evidence of 

 /eevil damage. If it does not green up in 2 to 4 days and if worms are still present, 

 ipply treatment promptly. When the second-crop growth is considerable, apply an insec- 

 :icide as soon as 25 percent or more of the terminals show noticeable feeding. This 

 minly applies to the southern sections of the state. 



.Tie insecticide recommendations are : 



l. Commercial applicators can apply 1/2 pound per acre of methyl parathion or azin- 

 phosmethyl (Guthion) with good results. Use azinphosmethyl only once per cutting. 

 Do not harvest for 15 days after treatment with methyl parathion, 16 days for 

 azinphosmethyl. Wear protective clothing. 



Persons not equipped with protective clothing can use a mixture of (1) 5/4 pound 

 of malathion and 3/4 pound of methoxychlor per acre, (2) a mixture containing at 

 least 1/2 pound of diazinon and 1 pound of methoxychlor per acre, or (3) 1-1/4, 

 pounds of malathion per acre on days when air temperatures will be above 60° F. 

 for several hours after application. Do not harvest for 7 days after treatment 

 with methoxychlor, diazinon, or mixtures of them. There is no waiting period for 

 malathion. 



