Crop losses

Animal, Field crop loss and Field crop loss and Fluorosis of... 

Injury to plants and vegetation is caused by a variety of factors, of which air pollution is only one. Drought, too much water, heat and cold, hail, insects, animals, disease, and poor soil conditions are some of the other causes of plant injury and possible plant damage (3). Estimates suggest that less than 5% of total crop losses are related to air pollution. Air pollution has a much greater impact on some geographic areas and crops than others. Crop failure can be caused by fumigation from a local air pollution source or by more widespread and more frequent exposure to adverse levels of pollution. 

Why is air pollution damage important when estimates suggest that it accounts for less than 5% of total crop losses in the United States ... 

CBA relies heavily on the costs of environmental impacts. Some impacts may be easily expressed in monetary values, like crop loss or even increased morbidity among people. Others, like impact on biodiversity and the depletion of natural resources, are more difficult to describe in terms of monetary values. Large time scales and global impacts also complicate the methodology and confuse the understanding of the results. Some of the environmental consequences of today s activities appear only after several hundred or thousand yeats. Even low interest rates tend to diminish these types of impact, even if they are very large. 

Furthermore, significant amounts of food are lost to pests. Worldwide preharvest crop losses to pests (insects, diseases, and weeds) are estimated to be about 35% each year (10). These major pest losses are occurring despite the application of about 2.5 million metric tons of pesticide, at an annual cost of 18 billion (11). Even after crops are harvested, an additional 20% of the food is lost to pests (12). Overall about 48% of all potential world food supply for humans is lost to pests despite all efforts to protect it. 

Crop Losses to Pests and Changes in Agricultural Technologies... 

Future studies must focus on those specific agricultural technologies that have contributed to the increased use of pesticides during the past 40 years, and why crop losses to pests continue to Increase. Research needs not only to identify the detrimental technologies, but, more Important, develop ecologically sound practices that farmers can use as profitable substitutes (15). 

Estimated Crop Losses from Weed Competition... 

Commodity market value and monetary loss were constructed from information given in "Crop Losses Due to Weeds in Canada and the United States", 1984 J.M. Chandler, A. S. Hamill, and A.G. Thomas, Special Report. Weed Science Society of America, Champaign, IL. 

Abernathy, J. R. "Estimated Crop Losses Due to Weeds with Non-chemical Management " D. Pimental (Ed.) Handbook of Pest Management in Agriculture, Vol I, CRC Press, Boca Raton, Floridy, 1981 p 159-167. 

Signs Lesions appear on the leaves of rice plants and vary in size. They are usually diamond shaped and have a gray or white center with a brown or reddish-brown border. Crop loss of 50-90% has been reported. Lesions also appear on the rice head but are brown or black in color. Rice grains do not develop properly. In severe neck infections, the stem will break and the head will drop off. The fungus can infect the roots and also invade the plant s vascular system blocking the transport of nutrients and water from the roots. ... 

Prior to World War II, which ushered in a new era of pesticidal chemistry and more new products than we can satisfactorily evaluate, the Latin American grower fought his pests singlehandedly for the most part, utilizing the few products that were available with little or no technical assistance. Only the more prosperous grower could afford to purchase chemicals and the equipment to apply them. The underprivileged, because of inadequate knowledge as well as lack of material means, constantly faced the threat of one crop loss after another. A situation of this kind... 

Among the determined diseases which might assume prominence at any time are the so-called Buba or cushion gall of Nicaragua (52), several types of soft pod rot, a gray mold that attacks cacao leaves, a black rot of the interior of the pod, and undoubtedly other diseases. In general, it is possible that cacao crop losses due to diseases and pests are greater than those reported by Hale (20). 

Oshima has developed a methodology for evaluating and reporting economic crop losses that involves continuous air monitoring, chamber exposures, and monitoring plant species. He has attempted to weld these into a comprehensive method of determining yield reductions. He has reported yield reductions for some species, but has not folly clarified the procedure. He presented no economic values in either report. This type of approach needs to be considered further. 

Howell, R. K., and E. J. Koch. An experimental design for open-top field chambers to estimate crop losses caused by air pollution, (in press)... 

Oshima, R. J. Development of a System for Evaluating and Reporting Economic Crop Losses Caused by Air Pollution in California. 1. Quality Study. Sacramento California Department of Food and Agriculture, 1973. 

Calkins (1) reported a conservative estimate of 59 million dollars for chemical controls, 38 million dollars for quarantine and fumigation, and 260 million dollars in crop losses. However these figures are small conq>ared to the estimated 15 billion dollars of fruits and vegetables grown per year in California alone. Now that the importance of controlling these fruit flies has been shown, some control methods and efforts to keep these flies from spreading are presented. Some attractants, such as hydrocarbons from kerosene and essential oils, are discussed. 

Ozone and related oxidants are estimated to be responsible for about 95% of the annual 130 million crop loss caused by air pollutants in the United States. Reports have indicated that ozone can seriously damage important crops such as spinach, beans, petunias, citrus, tobacco, soybeans, and alfalfa, and forest trees such as Eastern white pine and Ponderosa pine. 

One factor contributing to crop losses caused by ozone is the development of abnormal pigments which are viewed as discolored areas on foliage of ozone-sensitive cultivars. Such discoloration is esthetically unacceptable on leafy food crops and probably causes a reduction in the nutritional value of all foliar components used for food and feed. Biochemical and physiological reactions responsible for ozone-induced discolorations have not... 

Ot and photo-oxidants Pulmonary oedema, emphysema, asthma, eye. nose, and throat irritation, reduced lung capacity. Vegetation damage, necrosis of leaves and pines, stunting of growth, photosynthesis inhibitor, probable cause of forest die-back, suspected cause of crop loss. Attack and destruction of natural rubber and polymers, textiles and materials. 

Weeds cause significant crop loss by direct competition for moisture, nutrients and light. In addition, they often harbour pests and diseases that can invade the crop, they may be poisonous and their seeds may reduce the quality of the grain or, if sown with the harvested seed, cause weeds to spread around the farm or between farms. In many cases, the presence of weeds in a crop at harvest will reduce the efficiency of the harvester and, thereby, increase the costs to the grower. 

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