Tobacco (Nicotiana tabacumL.) cultivars showed different levels of tolerance to verticillium wilt: #x2018;Hicks#x2019; and closely related cultivars were very susceptible, #x2018;Yellow Gold#x2019; and #x2018;Kutsaga 51#x2019; showed slight, and #x2018;Waimea#x2019; marked resistance. Yellow Gold or Hicks plants inoculated either by standing the roots for 1 h in 1010or 106conidia/ml suspensions before transplanting or by planting the seedlings into soil containing 5000 or 50000 microsclerotia/ml later showed wilt symptoms in more than 90 of the leaves. Only 50 of Waimea leaves developed symptoms at the same inoculum levels. Less infection occurred in plants grown in soil inoculated with conidia. Infection did not affect growth markedly until after the plant had flowered. Isolates taken from Waimea plants showed a slightly greater pathogenicity than isolates taken from Yellow Gold or Hicks plants.
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