Sinclair W A, Griffiths H M, Whitlow T H
Department of Plant Pathology.
Department of Floriculture and Ornamental Horticulture, Cornell University, Ithaca, NY 14853.
Plant Dis. 1997 Apr;81(4):395-398. doi: 10.1094/PDIS.1997.81.4.395.
Growth responses of different ash (Fraxinus) species and rootstock-scion combinations to ash yellows (AshY) phytoplasmas were compared in greenhouse experiments by expressing each measurement as a proportion of the final average value of the variable in noninoculated, own-rooted control trees. Phytoplasmal infection suppressed shoot growth of white ash (F. americana) and green ash (F. pennsylvanica) beginning when buds opened, but did not suppress velvet ash (F. velutina) until after 60 days of growth. AshY-associated growth losses in height, stem diameter, and root volume, averaged across two experiments, were 80, 93, and 98%, respectively, in white ash; 60, 57, and 79% in green ash; and 23, 0, and 12% in velvet ash. Growth in height, but not in stem diameter or root volume, of diseased white ash on velvet ash rootstock was significantly greater than growth of diseased own-rooted white ash. White ash witches'-brooms grafted onto healthy velvet ash continued to grow but did not produce vigorous, dominant shoots. Growth of diseased velvet ash on white ash roots was severely suppressed in comparison with that of diseased own-rooted velvet ash. Management of AshY through the use of tolerant genotypes may require tolerance in both scions and rootstocks.
在温室实验中，通过将每种测量值表示为未接种、自根对照树中该变量最终平均值的比例，比较了不同梣属（白蜡树）物种以及砧木-接穗组合对梣黄化植原体（AshY）的生长反应。植原体感染从芽开放时就开始抑制美国白蜡树（F. americana）和绿梣（F. pennsylvanica）的新梢生长，但直到生长60天后才抑制绒毛白蜡（F. velutina）。在两个实验中，美国白蜡树与AshY相关的高度、茎直径和根体积的生长损失平均分别为80%、93%和98%；绿梣分别为60%、57%和79%；绒毛白蜡分别为23%、0和12%。绒毛白蜡砧木上患病美国白蜡树的高度生长显著大于患病自根美国白蜡树，但茎直径和根体积的生长并非如此。嫁接到健康绒毛白蜡上的美国白蜡扫帚病枝条继续生长，但没有产生旺盛、优势明显的新梢。与患病自根绒毛白蜡相比，白蜡树根上患病绒毛白蜡的生长受到严重抑制。通过使用耐性基因型来管理梣黄化病可能需要接穗和砧木都具有耐性。
