-2- 



Use 1 pound of malathion or diazinon or 1/4 pound of methyl parathion per acre as a 

 spray. For best results, apply the spray just after the tassels begin to show. Allow 

 5 days for malathion, 10 days for diazinon, and 12 days for methyl parathion between 

 treatment and harvest for grain, ensilage, or stover. Methyl parathion should be 

 applied only by experienced applicators . 



Spider mites are present on the undersides of corn leaves in dry areas of the central 

 section. In general, infestations are not serious but should be watched. The lower 

 leaves are the area most likely to be attacked. Damaged leaves turn yellow or brown. 



If control is necessary, apply either 1 pound of carbophenothion (Trithion) or 1/2 

 pound of oxydemetonmethyl (Meta-Systox R) per acre. Allow 21 days for carbopheno- 

 thion and 30 days for oxydemetonmethyl between treatment and harvest of the corn as 

 forage. Do not apply either insecticide more than once per season. Both insecti- 

 cides should be applied only by experienced commercial applicators . For effective 

 mite control with insecticides , thorough coverage of infested leaves is important. 



Corn rootworm adults are beginning to emerge. Occasional northern and western corn 

 rootworm adults have been seen, but more will show up soon. Watch fields coming into 

 silk stage. These beetles attack the silks, causing a reduced kernel set. If there 

 is an average of five beetles or more per silk and pollination is just beginning, an 

 application of 1 pound of carbaryl (Sevin) malathion or diazinon per acre is profit- 

 able. Allow 5 days for malathion and 10 days for diazinon between treatment and har- i 

 vest as forage. There is no waiting period for carbaryl. 



A check this week in demonstrative plots for rootworm larval control indicated poorer 

 results than expected in some instances. The newer insecticides like BUX, Furadan, 

 Dasanit, Dyfonate, and Thimet sometimes do not last long enough when they are applied 

 as planter treatments to early planted corn. These insecticides have a relatively 

 short life in the soil, which is an advantage from the standpoint of avoiding residue' 

 problems. However, this same lack of persistency is a disadvantage in terms of ob- 

 taining full-season control of corn soil insects. 



Fall armyworms are appearing in whorl stage of corn, particularly in the southern sec- 

 tion. Plants appear ragged from the leaf -feeding. A series of plants in a row will 

 show damage, and these patches of infested plants will occur over the entire field. 



Early control while the worms are still small and exposed on the leaves is best. As 

 the worms become full-grown, they go deeper in the whorl inside the tightly rolled 

 leaves. Control of larger worms is generally poor. If 20 percent or more of the 

 plants are damaged and the worms are still present, control is justified. However, 

 if most worms are 1-1/4 to 1-1/2 inches long, an insecticide treatment would not 

 be justified since the worms are about through feeding. 



For control, apply 1-1/2 pounds of carbaryl (Sevin), Gardona, or toxaphene per acre. 

 Diazinon at 1 pound per acre is also effective. Direct the spray or granules into 

 the whorl. Granules are preferred for air applications. Do not feed corn sprayed 

 with toxaphene as forage to livestock. Corn treated with toxaphene granules may be 

 fed as stover to beef cattle within 28 days of slaughter. Allow 5 days for Gardona 

 and 10 days for diazinon between treatment and harvest as grain, ensilage, or stover. 

 Carbaryl has no waiting period. 



GENERAL INSECTS 



Grasshoppers are still thick in fence rows and ditchbanks, and along roadsides in man; 

 areas . They will stay in these areas as long as there is ample food. Control them b< 

 fore they move to more valuable crops such as corn and soybeans. 



