Disease control

Some diseases common in conventional crops, such as the cereal foliar diseases, are not so serious in organic crops. This is partly because maity organic crops are thinner than the conventionally grown crops and this reduces the risk of the spread of rain splash diseases. The thin crops also lead to more air movement and less of a microclimate within the crop canopy. Lush crops tend to be those most prone to damage by diseases. It is suggested that a balanced soil and crop nutrient status will help to reduce the incidence of some diseases. Application of manure has been shown to reduce disease possibly due to affecting the soil micro-flora. 

Good crop hygiene is very important for otganic farmers to help reduce disease incidence. Seed and storage diseases can be serious organic growers should only sow, or plant, disease-free seed or transplants and only disease free crops should be stored. 

Rubber trees are affected by a number of diseases involving roots, stems, and leaves. However, effective control measures have been evolved for all these diseases, except the South American Leaf BUght, caused by the fungus Microcyclus ulei, which has caused extensive damage to rubber plantations in South America. Fortunately Asia and Africa are free from this disease 

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Centers for Disease Control, Morbid. Mortal Weekly Rep. 45, 29 (1996). 

NIOSH Alert, Requestfor Assistance in Preventing Adverse Health Effectsfrom Exposure to Dimethjlformamide (DMF), DHHS (NIOSH) PubUcation No. 90-105, Center for Disease Control, U.S. Dept, of Health and Human Services, Washington, D.C., Sept. 1990. 

Mechanism of Action. The mechanisms by which antibiotic adrninistration at subtherapeutic levels enhance growth rate and efficiency of gain in growing animals have not been clarified. Possible modes of action include disease control, nutrient sparing, and metaboHc effects. There is extensive evidence that the principal benefit from subtherapeutic use of antibiotics results from the control of harmfiil microorganisms. 

The alimentary symptoms may be overshadowed by neuromuscular dysfunction, accompanied by signs of motor weakness that may progress to paralysis of the exterior muscles or the wrist (wrist drop), and less often, of the ankles (foot drop). Encephalopathy, the most serious result of lead poisoning, frequendy occurs in children as a result of pica, ie, ingestion of inorganic lead compounds in paint chips this rarely occurs in adults. Nephropathy has also been associated with chronic lead poisoning (147). The toxic effects of lead may be most pronounced on the developing fetus. Consequendy, women must be particulady cautious of lead exposure (148). The U.S. Center for Disease Control recommends a blood level of less than 10 p.m per 100 mL for children. 

R. J. Lewis, Sr. and R. L. Tatkin, eds.. Registry of Toxic Effects of Chemical Substances, 8th ed.. National Institute for Occupational Safety and Health, Pubhc Health Service Center for Disease Control, U.S. Government Printing Office, Washington, D.C., 1979. 

Biology and Control ofMedes aegypti, Hector Topics No. 4 and Dengue Surveillance Survey No. 9, U.S. PubHc Health Service, Centers for Disease Control and Prevention, Adanta, Ga., 1979 and 1983. 

Chemical treatment of diseases is not common, because of legislative controls and costs caused by the difficulty of appHcation through the leaf canopy. Breeding of resistant varieties is the main weapon for disease control. Some diseases, chiefly ratoon stunting disease, are controlled by hot water treatment of cane (6,8). 

Vaccines are used in either the general population of children or adults or for special groups. Recommendations for vaccine usage are made by the Advisory Committee on Immunization Practices (ACIP) of the Centers for Disease Control. The Committee on Infectious Diseases of the American Academy of Pediatrics (Redbook Committee) also makes recommendations for infants through adolescents, and the American Academy of Family Physicians makes recommendations for adults. An excellent review of vaccine history, development, usage, and related regulatory issues is available (2). 

Gonorrhea. Gonorrhea, caused by Neisseriagonorrheae is the most commonly reported communicable disease in the United States. Approximately lO cases were reported to the Center for Disease Control (CDC) in 1979, but actual cases could be two to three times higher (99,100). In addition, an increasing number of strains are becoming resistant to penicillin, the antibiotic that is usually used to treat this disease. 

Mobidity and Mortality Weekly Report (MMWR) Vol. 44, RR 5, Centers for Disease Control, Adanta, Ga., June 1993. 

Eegistry of Toxic Effects of Chemical Substances, NIOSH, U.S. Dept, of Health and Pubhc Services, Pubhc Health Service, Centers for Disease Control, Cincinnati, Ohio, (CCINFO disc as format), 1995. 

Suggested Health and Safety Guidelines for Public Spas and Hot Tubs, U.S. Department of Health and Human Services PubHcation No. 99-960, Centers for Disease Control, Atianta, Ga., 1985. 

Malaria affects an estimated 270 million people and causes 2—3 million deaths annually, approximately one million of which occur in children under the age of five. While primarily an affliction of the tropics and subtropics, it has occurred as far north as the Arctic Circle. The disease essentially has been eradicated in most temperate-zone countries, but some 1100 cases of malaria in U.S. citizens returning from abroad were reported to the Centers for Disease Control during 1990. Malaria is seen today in Southeast Asia, Africa, and Central and South America. It is on the increase in Afghanistan, Brazil, China, India, Mexico, the Philippines, Sri Lanka, Thailand, and Vietnam. Escalation of the disease is because of the discontinued use of the insecticide DDT which effectively kills mosquito larvae, but has been found to be toxic to Hvestock and wildlife. Also, chloroquine (6), a reUable dmg for the prophylaxis and treatment of falcipamm malaria, is ineffective in many parts of the world because of the spread of dmg-resistant strains. 

Gainesville (Florida) Sun, quoting Pierre Payment, Institute Arm an d-Frappier (Montreal), Judy Lew and Christine Moe at Centers for Disease Control, Adanta, and Phillip Berger, EPA, 5A, Dec. 8, 1990. 

The fungicides are among the chemicals of wide use as plant diseases control agents in intensive agriculture. At the same time these pesticides could have toxic effects, when accumulated in man and animals. Because of general society concern about fungicides use, they should be monitored in waters, soils and crops. 

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