Diverse Foliar Resistance in Vitis spp. to Erysiphe necator

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• Variation Within and Among Vitis spp. for Foliar Resistance to the Powdery Mildew Pathogen Erysiphe necator

  Researchers conducted disease resistance screenings of various Vitis germplasm for powdery mildew caused by Erysiphe necator. They inoculated 1,025 Vitis accessions and compared results with natural epidemics in two vineyards. Around 33% of genotypes were resistant to a single isolate but susceptible to diverse isolates in either or both vineyards, possibly due to race-specific resistance. Correlation of ratings between vineyard and single-isolate ratings was moderate (r = 0.55 to 0.56), and no accession was immune in all three screens. Uniform testing in multiple environments is emphasized for durable resistance cultivar development.