Co-Authors:
Raviv, M., Dept. of Environmental Horticulture, Newe ya'Ar Research Center, Agricultural Research Organization, P.O.B. 1021, Ramat Yishay 30095, Israel
Abstract:
Although most soilless media are initially pathogen-free, infestations by root pathogens during the course of crop growing cycle are frequent. Some commerciallyavailable peat moss types are especially conducive to spread of several soil-borne pathogens. Unlike peat, many compost types suppress a wide range of soil-borne diseases. Disease suppressiveness is clearly linked with compost's degree of maturity, although excessively stabilized composts with low content of organic matter have lower suppressiveness capacity (SC). The causal agents of suppressiveness 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. Another important source of resumed activity after sterilisation is a fast recolonization of composts once exposed after the sterilisation process. 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 effective application rates. Examples of compost suppressiveness against a wide variety of microorganisms are described and putative mechanisms are discussed. Required future research is highlighted.