The resistance of potato varieties to Heterodera schachtii Schmidt, the potato-root eelworm



The potato varieties Epicure and Doon Star permitted the production of fewer and smaller cysts of Heterodera schachtii on their roots than the varieties Golden Wonder and Majestic, when all were grown under standard conditions. Under the stimulus of potato-root excretion the number of larvae which emerged from Epicure and Doon Star cysts was less than that from Majestic or Golden Wonder cysts of the same volume. Accepting Lapage's (1938) criteria of resistance to nematode infestation in animals and applying them to plants, it is concluded that this deleterious effect of the variety on the eelworm is probably of the nature of a degree of resistance to eelworm attack specific to each variety and is physiological and not anatomical in action. Of the varieties tested, Epicure is judged the most resistant, closely followed by Doon Star. Majestic is fairly susceptible but not so much so as Golden Wonder on which the eelworm forms large cysts that are extremely productive of larvae.