Field Resistance of 20 Strawberry Cultivars to Black Root Rot

Abstract

Black root rot (BRR), a non-specific disease typified by blackening of roots, with associated poor growth and yield, is common in perennial strawberry plantings worldwide. Although the causal.agent of blackening is often unknown, Pythiumspp., Rhizoctonia fragariaeHusain & McKeen and Pratylenchus penetrans(Cobb) Filip. and Stek. have been identified in association with BRR. Distinct cultivar differences in tolerance to BRR can be observed in commercial fields, suggesting the possibility that management can be achieved by cultivar selection. Twenty cultivars from various breeding programs throughout North America were planted in the spring at two field sites (with and without a history of BRR) in western New York and root health was assessed during harvest the following year. The cultivars most resistant to BRR were 'Tristar,' 'Earliglow,' and 'Midway,' while 'Allstar' NY113 and 'Selva' were least resistant. When cultivar rankings at these sites were compared with those of two other studies, correlations were nonexistent to negative. These data suggest that the causes of BRR can differ among locations, and cultivar selection will be of no value unless the causal organism at a particular site is known. Chemical names used: N-(2,6-dimethylphenyl)- N-(methoxyacetyl) alanine methyl ester (metalaxyl).