THE USE OF COMPOST IN GROWING MEDIA AS SUPPRESSIVE AGENT AGAINST SOIL-BORNE DISEASES
Initially most soilless media are pathogen-free. However, an infestation during the course of the crop growing cycle is not rare. Peat moss, a common medium constituent, is especially conducive to spread of several soil-borne pathogens. Unlike peat, many compost types suppress a large range of soil-borne diseases such as those caused by Sclerotium, Rhizoctonia, Pythium and Fusarium. Compost is a term describing all organic matter that has undergone long, thermophilic, aerobic decomposition a.k.a. composting. Composts vary according to the raw material(s) used and to the nature of the composting process. Compost serving as a component of container media must be stable in order to avoid competition between microorganisms and plant roots for oxygen and nitrogen. Composts can be produced using numerous organic wastes and combinations thereof, such as sewage sludge, MSW, animal excreta, wastes of food industry, etc. Animal excreta are of special value for co-composting because they contain large, diverse populations of microorganisms, which accelerate the process. Compost disease suppressiveness is clearly linked with its degree of maturity, although excessively stabilized composts with low content of organic matter have lower suppressiveness capacity (SC). The suppressiveness causal agents are complexes of microbial and fungal populations, which invade the pile during the curing stage. Sterilization largely eliminates compost suppressiveness, suggesting that most of it results from biological activity, although some residual activity is probably related to fungistatic compounds occurring in the composts. The use of composts as constituents of growing media is discussed in relation to the nature of the raw materials, methods of compost production and practical application methods. Methods to assess microbial maturity are evaluated, as related to their SC. Examples of compost suppressiveness against several types of wilt diseases caused by Fusarium oxysporum are described.
Raviv, M. (2008). THE USE OF COMPOST IN GROWING MEDIA AS SUPPRESSIVE AGENT AGAINST SOIL-BORNE DISEASES. Acta Hortic. 779, 39-50
peat moss, suppressiveness, Phytophthora cinnamomi, Fusarium spp., Sclerotium rolfsii, Rhizoctonia solani, Pythium spp.