-2- 



be treated- -but not until the tassel ratio is at least 35, preferably 40 to 50. 

 The percentage of infested plants required to justify treatment can be reduced 

 with higher tassel ratios. 



Use 1 pound of actual diazinon in granular form per acre, or 1-1/2 pounds of car- 

 baryl (Sevin) as granules. For spraying, use the same amount of actual insecticide 

 per acre, and direct the spray to the upper third of the plant. Aerial applications 

 should be as granules , not sprays or dusts . Allow 10 days between treatment and the 

 ensiling of corn when applying diazinon; carbaryl has no waiting period. Commercial 

 applicators may prefer to use parathion at 1/2 pound actual per acre, which will pro- 

 vide good control of the corn borer. Parathion has a 12-day waiting period between 

 treatment and harvest. 



Garden symphylans or garden centipedes . Damage has been found in two fields of 

 corn in the central section. These insect relatives are small (1/16 to 5/16 of 

 an inch), white, and have many legs. They move rapidly in the soil, attacking the 

 roots. They prefer the root hairs and tender new roots, but they will reduce the 

 root system to a stub if the infestation is severe. Infested plants are stunted 

 and may be killed. These pests feed throughout the season, moving closer to the 

 surface when conditions are moist and going deeper when they are dry. 



To check for centipedes, look in areas where the stand is irregular. Locate plants 

 that appear stunted. Dig up the plant with a spade full of soil, and place this on 

 a sheet of plastic or cloth. Examine the root system for feeding injury. Carefully 

 sort through the soil, breaking up the clods and watching for the white, moving 

 centipedes. It usually takes a hundred or more garden centipedes per hill to cause 

 noticeable injury. Do not become alarmed if you find 5 to 10 in each hill. This 

 number is common in many cornfields. 



If the plants are being seriously affected, we suggest an application of granular 

 Dyfonate on a trial basis. Band 1 pound of actual Dyfonate per acre at the base 

 of the plants, and cover the granules by cultivation. Rain following the treat- 

 ment will enhance the possibility for success. If corn is to be replanted this 

 year or planted in this same field next year, apply 1 pound of actual Dyfonate 

 per acre as granules in a 7 -inch wide band just ahead of the press wheel. 



Corn rootworms . Egg-hatch has started, and will continue for several weeks. It 

 is too soon to predict the severity of the problem. Damage is likely to be the 

 worst north of a line from Carthage to Bloomington to Joliet. 



If you suspect a rootworm problem in your fields and did not use an organic phos- 

 phate or carbamate insecticide at planting time, apply one within the next two 

 weeks. Use granules applied at the base of the plants. Cover with cultivation. 

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

 phorate (Thimet) . Use the rate of 1 pound of actual chemical per acre. 



Corn leaf aphids . These were found in corn whorls in the south- central and south - 

 ern sections of Illinois this week. The aphids are just getting started, and it 

 is too soon to make predictions. 



White grubs . A few reports of damage to corn and soybeans have been received from 

 the central section. These grubs vary in size, but are mostly small. They will 

 continue to feed throughout the growing season. Attempts to control white grubs 

 with basal applications off the cultivator have failed. If soybeans are to be 



