In vitro inhibition of grapevine root pathogens by vineyard soil bacteria and actinomycetes

Soil contains significant populations of microorganisms with the ability to attack or suppress plant pathogenic fungi (1, 2). Fungistasis has been shown to be strongest in soils with high organic matter content and microbial activity, and soil bacteria have been implicated as the major cause of such fungistasis (2). Disease suppressive soils capable of controlling plant pathogens have been reported for a number of crops (1, 3, 4, 5) but this aspect of natural biocontrol has not yet been investigated in viticulture.Soil microbial communities with high population and diversity are likely to have a larger number of candidates with the ability to compete with pathogens and to be disease suppressive (1). This study investigated the effect of mulch and organic matter from herbicide treated weeds (6) on the populations of vineyard soil bacteria and actinomycetes able to suppress grapevine fungal root pathogens in vitro.