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Root-knot nematodes are a chief pest of vineyards across California and the United States, but aggressive and virulent nematode populations can feed on and damage many important rootstock varieties. The USDA ARS grape rootstock breeding program tests the root-knot nematode resistance of rootstocks and wild grape species and combines nematode resistance and other useful traits through hybridization. They then evaluate the pest resistance, viticultural performance, and other important qualities of the new seedlings to identify candidate rootstocks. Three improved root-knot nematode resistant rootstocks (Kingfisher, Matador, Minotaur) were released from the USDA ARS breeding program in 2010. Kingfisher resulted from selection of a seedling in a population derived from controlled hybridization of the Vitis hybrid rootstock selection 4-12A (seed parent) with Vitis riparia (pollen parent). 4-12A is a cross of V. x champinii Dog Ridge and V. rufotomentosa. Kingfisher is easily rooted from dormant cuttings and bench grafted to Vitis vinifera scions. Kingfisher was identified as a seedling on December 24, 2002 due to its complete suppression of root-knot nematode reproduction in greenhouse evaluation. Root-knot nematode resistance was confirmed in replicated tests of cutting grown plants. The nematode population used to confirm resistance was an N-virulent nematode population capable of feeding on and damaging N-allele grapevine rootstocks, such as Harmony and Freedom. Dormant cuttings collected from plants grown in a California vineyard were evaluated for rooting ability; 100% of dormant cuttings of Kingfisher successfully propagated and produced callus, shoots, and roots. The original Kingfisher vine was planted in 2002. In addition to nematode resistance and propagation evaluations, Kingfisher has been evaluated grafted to Syrah in a rootstock trial in California. Kingfisher was grafted to Syrah and planted into a rootstock trial at UC KREC, Parlier, California in 2005. When four years of fruiting data and three years of pruning weight data are considered, Kingfisher rootstock showed a fruit to pruning weight ratio of 6.53; the check rootstock, Freedom, showed a fruit to pruning weight ratio of 6.14, demonstrating the improved production efficiency of Kingfisher rootstock compared to Freedom.
Minotaur, Matador, and Kingfisher rootstocks were bred by USDA ARS as a part of a research project that received grant funding from the American Vineyard Foundation, California Table Grape Commission, California Raisin Marketing Board, California Grape Rootstock Improvement Commission, and California Grape Rootstock Research Foundation in addition to appropriated funds. These three rootstocks were released as public varieties, with no intellectual property protection. For more information about these varieties and the USDA ARS grape rootstock improvement program, please contact Peter Cousins ([email protected]). |
