Impact of Grapevine (Vitis vinifera) Varieties on Reproduction of the Northern Root-Knot Nematode (Meloidogyne hapla).

One of the most commonly encountered plant-parasitic nematodes in eastern Washington Vitis vinifera vineyards is Meloidogyne hapla; however, limited research exists on the impact of this nematode on V. vinifera. The objectives of this research were to determine the impact of M. hapla on Chardonnay and Cabernet Sauvignon vine establishment and to determine the host status of V. vinifera varieties/clones predominantly grown in Washington to M. hapla. In a microplot experiment, Chardonnay and Cabernet Sauvignon vines were planted into soil inoculated with different densities of M. hapla; population dynamics of M. hapla and vine performance were monitored over 3 yr. In greenhouse experiments, several clones representing five V. vinifera varieties, Chardonnay, Riesling, Cabernet Sauvignon, Merlot, and Syrah, were evaluated as hosts for M. hapla. In both microplot and greenhouse experiments, white varieties were significantly better hosts than red varieties. In the greenhouse experiments, Chardonnay and Riesling had 40% higher reproduction factor values than Syrah and Merlot, however, all varieties/clones screened were good hosts for M. hapla (reproduction factors > 3). In the microplot experiment, M. hapla eggs/g root were 4.5 times greater in Chardonnay compared to Cabernet Sauvignon 3 yr after planting but there was no evident impact of M. hapla on vine establishment.