The relative susceptibility of grapevine rootstocks to black foot disease is dependent on inoculum pressure

Black foot disease of grapevines is a major economic issue for the viticulture industry worldwide. The mainly associated with complex pathogen species within genera Dactylonectria and Ilyonectria. susceptibility six grapevine rootstock cultivars to black under field conditions was assessed. Callused rootstocks 101-14, 5C, 420A, Riparia Gloire, Schwarzmann 3309C were planted into soil containing low natural populations or inoculated isolates representing diversity in New Zealand. Disease incidence, severity dry weight accumulation assessed after 8 months growth. Root shoot weights not significantly affected by inoculation treatment, but differed among cultivars, cultivar 420A having lowest root weight, largest 5C weight. relative depending on whether they grown inoculum pressure higher artificially soil. Gloire least susceptible pressure, most In contrast, one levels high pressure. result study indicate that affect infection, may have implications selection planting.