Berkeleyomyces basicola (black root rot)

Environmental conditions are important for disease management. Soil temperatures should be favourable for the growth of the host and overwatering should be avoided to limit disease development. Generally, black root rot is more severe in soils with a pH above 5.6 and lower in more acidic conditions (pH <5.2) (Harrison and Shew, 2001). In controlled studies, herbicides have been demonstrated to increase black root rot (Lee and Lockwood, 1977; Lewis and Papavizas, 1979).

Crop rotation is important to prevent the build-up and maintenance of high soil populations of the pathogen. Anderson and Welacky (1988) in Ontario, Canada, reported soil populations were related to frequency of soyabean (Glycine max) production and frequency of tobacco (Nicotiana tabacum) and soyabean in rotation. Holtz and Weinhold (1994) in California, USA, found higher populations in soil planted for 3 or more years to cotton (Gossypium) than fields rotated to other crops (safflower (Carthamus tinctorius), wheat (Triticum aestivum) or barley (Hordeum vulgare)). Fields having crop rotations of sorghum or small grains, or fallow had less blackhull on the subsequent groundnut (Arachis hypogaea) crop than rotation of cotton or groundnut (Hsi, 1966). Weed control may be important for reductions in populations of the pathogen (Gayed, 1972; Klimova, 1979; Villiers, 1987). The pathogen can be recovered from plant species that are showing no symptoms and are not considered hosts (Wills and Lambe, 1978; Yarwood, 1981). Incorporation of hairy vetch (Vicia villosa) as a green manure reduced black root rot on cotton because of reductions in the population of the pathogen from the release of ammonia from the decomposing residue (Rothrock et al., 1995; Candole and Rothrock, 1997).

Variation in susceptibility of cultivars or lines has been reported for a number of crops including cherry (Prunus) (Pepin et al., 1975), chickpea (Cicer arietinum) (Bowden et al., 1985; Bhatti and Kraft, 1992b), holly [Ilex] (Merrill et al., 1986), lettuce (Lactuca sativa) (O'Brien and Davis, 1994), pea (Pisum sativum) (Lloyd and Lockwood, 1963), soyabean (Anderson, 1984) and groundnut (Merwe et al., 1993). In tobacco, resistance is well characterized with complete single dominant gene resistance from Nicotiana debneyi and several sources of partial resistance (Clayton, 1969; Shew and Shoemaker, 1993).

Due to the variable regulations around (de-)registration of pesticides, we are for the moment not including any specific chemical control recommendations. For further information, we recommend you visit the following resources: