-Lav 7 



COLLEGE OF 

 AGRICULTURE 

 UNIVERSITY OF 

 ILLINOIS AT 

 URBANA-CHAMPAIGN 

 AND NATURAL 

 HISTORY SURVEY 

 URBANA, ILLINOIS 



;nsect, weed & PLANT disease survey bulletin 



STATE/COUNTY/LOCAL GROUPS/US. DEPARTMENT OF AGRICULTURE COOPERATING 



FOR IMMEDIATE RELEASE 



No. 9, May 18, 1973 



This series of weekly bulletins provides a general look at the insect t weed 3 and 

 plant disease situation (fruit and commercial vegetables excepted) s along with 

 suggested;, abbreviated, control measures. Each individual should check his own 

 fields to determine local conditions. 



INSECTS 



FORAGE CROPS 



*^# 



Alfalfa weevil larval numbers, although still high, are beginning to decline in the 

 southern third of Illinois. Small larvae are present, but many of the older larvae 

 are pupating. Overwintering as well as newly emerged adults are present in most 

 fields. 



Damage may be so severe in some fields that using insecticides would be a waste of 

 money. Cut the crop. If new growth is not noticeable in three to five days, examine 

 the new growth closely for alfalfa weevil larvae. If they are devouring the new shoots, 

 use an insecticide. 



This same thing will occur in the central third of Illinois within a week. From now 

 on this spring if the harvest of the crop is near, cut and treat the new growth in 

 cases of excessive weevil populations. 



SMALL GRAINS 



Armyworms will appear within the next two weeks if they are going to be a problem. As 

 yet , we have not found any damaging infestations in wheat, but have found a few in 

 tall grass. 



Look for armyworms in thick or lodged spots in wheat or barley fields. Shake the 

 lodged plants vigorously, and examine the ground and debris underneath these plants. 

 If you find no worms or just an occasional one in the thick or lodged spots, there 

 is no need to look further. However, check the field again in about a week, since 

 there could be additional egg hatch by then. 



Do not confuse the striped armyworms with the transparent yellow to green sawflies . 

 An armyworm has five pairs of abdominal prolegs; sawflies, six or more pairs. Saw- 

 flies were also present along with the armyworms in the fields this week. Sawflies 

 do not damage wheat plants enough to require control. 



Treatment is justified if there are 6 or more armyworms per foot of drill row as an 

 average over the field. Apply 1-1/2 pounds of toxaphene per acre. Do not feed the 

 straw to dairy cattle, animals fattening for slaughter, or poultry. There is no re- 

 striction on the use of the grain. One and one-half pounds of malathion per acre may 

 be used to within seven days of harvest, or 3/4 pound per acre of trichlorfon (Dylox) 

 to within twenty-one days of harvest. 



