|Valdebenito-Sanhueza, Rosa Maria - EMBRAPA, BRAZIL|
Submitted to: Postharvest Diseases of Tropical Fruits and Vegetables
Publication Type: Book / Chapter
Publication Acceptance Date: November 18, 2005
Publication Date: August 14, 2006
Citation: Valdebenito-Sanhueza, R., Janisiewicz, W.J. 2006. Biological control. Postharvest Diseases of Tropical Fruits and Vegetables. Brazil: Embrapa Informacao Tecnologica. p. 119-144. Technical Abstract: The explanation of the mechanisms of biological control of postharvest diseases (BCPD) may allow modification of the antagonist environment on fruit, optimization of growth, formulation and application method, and genetic manipulation to increase the biocontrol potential of the antagonist. Until recently, the mechanism of biocontrol was seldom the subject of in-depth investigation in BCPD. Following the appearance of the first commercial products on the market, more research has been devoted to the improvement of BCPD for which knowledge of the mechanism of biocontrol is indispensable. Review of the putative mechanisms of biocontrol may be useful for understanding the variety of the potential mechanisms operating on fruit and its complexity. These mechanisms include antibiosis, competition for limiting nutrients, secretion of lytic enzymes, induction of resistance in fruit, parasitic attachment to the fungus, and interference with pathogenicity factors. BCPD generally has a narrower spectrum of activity and is more sensitive to environmental factors than synthetic fungicides. To overcome these problems, higher concentrations of the antagonist may need to be used, postharvest practices may require modification, and /or biocontrol should be combined with other alternatives to fungicides or reduced doses of fungicides. The alternative methods are generally less effective than fungicides or biological control; however, in combination with antagonists, these alternatives often result in an additive or a synergistic effect. A variety of Substances Generally Recognized as Safe (GRAS) have been successfully used in combination with biocontrol agents to improve decay control on subtropical, tropical, and temperate fruits. These GRAS substances include many food additives and preservatives such as sodium bicarbonate (baking soda), sodium carbonate, ethanol, potassium sorbate, glycochitosan, and nisin, as well as various other nutrients and nutrient analogs. Control of fruit decay was also improved by combining biocontrol with heat treatment (hot water dips or hot air) or low level of fungicides (often 10 x less than recommended). The presented examples clearly demonstrate that BCPD is amenable to manipulation, and many of its shortcomings may be successfully addressed by integrating it with other non-fungicidal methods.