-2- 



at least 1/2 pound of diazinon and 1 pound of methoxychlor per acre (2 1/2 to 

 5 quarts of the commercially prepared mixture Alfatox) . You may also use 

 1 1/4 pounds of malathion per acre (1 quart of the 5-pounds-per-gallon con- 

 centrate) in the morning on days when air temperatures will be above 60° F. 

 Do not harvest for 7 days after treatment with methoxychlor, diazinon, or 

 mixtures of them. There is no waiting period for malathion. 



The quantity of finished spray applied per acre is also important. Use no less 

 than 4 gallons per acre by air or 20 gallons per acre by ground machine. The 

 exception is on stubble, where 10 gallons per acre by ground will be sufficient. 



A few clover leaf weevils can be found in every alfalfa and clover field but as 

 yet no damaging populations have been reported. 



White grubs are moving up from the subsoil to feed on grass and weed roots and 

 later on the roots of corn and soybeans. The common three-year-cycle grub caused 

 problems in corn and soybeans in the central sections in 1965 and is expected to 

 be a problem in some fields this year. The grubs are about half grown in this 

 second year of their development and will feed throughout the growing season. 

 Watch for grubs when plowing or during other tillage operations, and if many are 

 present or if the field has a history of grub problems, plan to apply control 

 measures. If the field is to be planted to corn, apply 1 1/2 pounds of actual 

 aldrin or heptachlor and disk it in ahead of planting. Do not use either aldrin 

 or heptachlor on fields to be planted to soybeans. Ahead of soybeans, 4 pounds 

 of actual diazinon broadcast and disked in should provide get-by protection. 



English grain aphids are present in wheat fields but are not numerous enough to 

 be of concern. Predators, parasites, and diseases usually hold grain aphid num- 

 bers in check. We have observed some fields of wheat in poor condition, but dis- 

 ease (see report below), not aphids, was the cause. Aphids are of greatest con- 

 cern when the populations are high at the time wheat is heading out. No control 

 is needed at this time. 



Septoria leaf blotch is abundant in most wheat fields in Illinois. Extremely 

 favorable conditions for infection of young wheat plants occurred last fall. 

 Defoliation and invasion of crowns at that time produced weakened plants. Some 

 of these did not survive the winter. Spores are produced on the dead leaves in 

 pycnidia, and the disease can be expected to spread upward onto the new leaves 

 as long as cool, wet weather persists. 



The pycnidia appear as small black dots , and the resulting speckled appearance 

 of the dead tissue is a reliable symptom for identifying the disease. New infec- 

 tions appear as yellow to light-green areas. At first they are confined to tis- 

 sue between the leaf veins, but later spread to form irregular blotches. 



Septoria leaf blotch does its greatest damage to seedlings in the fall and to 

 tillers in the early spring. In some years the disease kills most of the rosette 

 leaves and up to 50 percent of the tillers. If most of the leaves of maturing 

 plants are killed before the grain reaches the soft dough stage, the grain is 

 lightweight and shriveled. 



