WASTES IN RELATION TO AGRICULTURE AND FORESTRY 



51 



Treated seed in excess of current seeding needs 

 may be inadvertently fed to stock by farmers. 

 Poidtry and livestock sometimes are poisoned 

 from eating seed treated with mercury or other 

 fungicides. When fungicide-treated seed is de- 

 tected in shipments of food or feed grain, the 

 entire shipment is subject to seizure and destruc- 

 tion. Label directions on fungicides caution 

 against feeding fungicide-treated grain or inter- 

 mingling it with untreated grain. 



Nickel-maneb fungicides are being used to con- 

 trol rusts in grass seed fields. A significant amount 

 of nickel may accumulate in the soil following 

 repeated applications. This in turn can be taken 

 up by subsequently grown crop plants. Presently 

 available information shows no toxic effects on 

 sensitive plants from 200 pounds of nickel per acre. 



Herbicides 



In 1964, 97 million acres of agricultural land 

 were treated with herbicidal chemicals. They have 

 been tremendously effective in combating weeds. 



Herbicides applied to control weeds in one crop 

 may leave residues in the soil that prevent the 

 growing of certain crops immediately following 

 harvest of the treated crop. Losses are minimized 

 only by restricting subsequent crops to those that 

 are tolerant to the herbicides used. 



Diuron applied for weed control in irrigated 

 cotton in the western region leaves residues in the 

 soil which injure vegetable crops such as lettuce, 

 carrots, cabbage, and cucumbers when planted in 

 the winter following cotton harvest. Research in 

 Wyoming showed that residues from an applica- 

 tion of 2 pounds per acre of diuron persisted in the 

 soil for 2 years in amounts toxic to oats. 



Research in the Mississippi Delta shows that an- 

 nual applications of diuron for late season con- 

 trol of weeds can build up residues that would 

 damage soybeans and oats, but not subsequent cot- 

 ton crops. 



Atrazine, applied to control weeds in corn, re- 

 mains as a residue in the heavy soils of the north- 

 contral region and often causes severe injury or 

 prevents the growth of fall-seeded grain crops, 

 causes damage to spring-seeded cereal crops, and 

 may prevent the establishment of small-seeded 

 forage grasses and legumes. 



Phenoxy herbicides used to control weeds in tol- 

 erant crops such as corn, wheat, and rice and on 

 grazing lands are volatile and they drift. Damage 



may occur to nearby susceptible crops, such as cot- 

 ton, grapes, tobacco, and vegetables. The yield of 

 cotton can be reduced more than 50 percent by as 

 little as 0.01 pound of 2,4-D per acre. 



Spray drift of 2,4-D, and 2, 4, 5-T from applica- 

 tions on nearby forests, cropland, roadsides and 

 rights-of-way has damaged chemically sensitive 

 trees such as dogwood, paper birch, box elder, 

 chestnut, black locust, and other shade trees, 

 shrubs, and herbaceous ornamentals. Damaged 

 trees and shrubbery create long-lasting, unsightly 

 conditions on travel routes and in recreation areas. 



There are documentable instances in which spray 

 drift from aerial applications of the phenoxy her- 

 bicides without adequate precautions have caused 

 crop injury 10 miles or more downwind from tar- 

 get areas. In addition to major problems, smaller 

 incidents occur. For example, when a sprayer that 

 had previously been used to apply phenoxy herbi- 

 cides was used for insect control in cotton, more 

 than 200 acres of cotton in Washington County, 

 Miss., were damaged before the contamination of 

 the sprayer was detected. In another instance, a 

 formulation of the herbicide DNBP, applied as a 

 preemergence treatment for weed control in cotton, 

 volatilized and killed an extensive acreage of cot- 

 ton in the Mississippi Delta. DNBP is no longer 

 registered for this use on cotton. 



The use of herbicides for aquatic Aveed control 

 is subject to regulation and restrictions. No organic 

 herbicides are registered for use in potable water. 

 Certain herbicides are registered for use hi water 

 that is to be used for irrigation purposes. 



The control of aquatic weeds in irrigation 

 terns improves water conveyance. Many herbicides, 

 such as diquat, potassium and sodium salts of 

 endothall, simazine, sodium arsenite, silvox, 2,4-D, 

 an dichlobenil, do not injure fish at the concentra- 

 tions required to control most submersed aquatic 

 weeds. At higher rates they may become toxic to 

 fish, humans, livestock, wildlife, and crops. 



Dalapon and fenac do not harm fish oven at 

 concentration levels tar above those required for 

 aquatic weed control. 



Acrolein, chlorinated benzenes, xylene, and 

 amine salts of endothall are deadly or injurious to 

 fish at concentrations necessary to control aquatic 

 weeds and are not registered or recommended for 

 use in areas where protection of fish is required. 



