Faulty harvesting, handling and especially storage lead to agricultural product losses. Tubers, fruits, fresh vegetables, seeds and grain are subject to deterioration and spoilage during storage and transit due to a number of pathogenic and non-pathogenic agents. The loss in quality is accompanied by a less widely recognized loss in quantity. In many areas people have always been accustomed to products that are more or less spoiled by insects; often they do not understand that this is why products may only command low prices on world markets, or why in some cases they cannot be sold at all.
Food supplies could be augmented to an important extent through trying to minimize crop losses. A number of surveys have shown post-harvest losses of food grains reaching 20 or even as much as 40%, depending on crop and country. Losses occur all along the line: through poor management in harvesting; insect, rodent, and fungus damage in storage; poor quality sacks and other containers; inexperienced handling in transport; inefficient or poorly maintained milling equipment; and faulty distribution of milled products. The use of extremely low extraction rates to meet the presumed tastes of urban consumers means less food for humans and more feed for animals as well as a less nutritive end-product. Avoidable losses also occur in the handling and processing of other crops, such as oilseeds, where in many small factories an unnecessarily high proportion of oil is left in the by-products or where, alternatively, a part of the protein contained in the oilseed meal could be incorporated into foods suitable for human consumption. In the area of perishable fruit and vegetables, wastage in distribution quite often reaches 30 to 40%. These examples indicate the scope for increasing food supplies through reduction of losses. But they also suggest that no single programme would have a significant impact on the problem. Because the problems are various so too their solution must be sought through improvements in several directions. Some of the most important are: investment in modern storage for grains and other crops, both in villages and in larger centres; better packaging materials and transport facilities; modifications in the milling practices for cereals and oilseeds; and more effort to modernize the organization of wholesale and retail distribution.
The crops losses due to disease during transit and storage sometimes equal those that occur while the plants are growing. This is especially true of fresh fruit and vegetables, and seeds, such as those of wheat, corn, barley, soybeans and flax, which are stored in bulk for months or even years. Storage diseases are divided into those caused by nonpathogenic factors and those caused by living organisms. But damage beginning from nonpathogenic causes may be increased greatly by subsequent invasion of the tissues by bacteria and fungi able to cause rapid decay. Fruits and vegetables in storage also suffer from a number of physiological diseases caused by an excess of gases which are self generated. Common fungi, such as Botrytis, Penicillium, Rhizopus and Sclerotinia, invade and rot many fruits and vegetables. Losses of up to 25% between harvest and consumption are common in oranges, apples, peaches, pears, plums, potatoes, sweet potatoes, tomatoes and peppers. Bacteria, or a combination of fungi and bacteria, often rot stored potatoes and root vegetables. Grains stored in bulk are subject to invasion by a number of fungi, principally those in the genus Aspergillus. These reduce germinability of seeds, which is important in those to be used for planting or malting, and may reduce the quality of grains for processing.
Food spoilage and particularly the growth of pathogenic (food poisoning) bacteria are a major concern for food processing industries and community health and safety throughout the world. Losses, which may reach 100% when produce is entirely spoiled for lack of proper storage facilities, are estimated to average 25% globally. In 1990 it was estimated that 75% of the USSR potato crop (fruit and vegetable crop, 40%) never reaches consumers because of spoilage, exacerbated by inadequate transportation and storage. In all 25% of USSR farm production is lost in this way.