Resistance to mercury ofPyrenophora avenae(conidial stateHelminthosporium avenae) in New Zealand seed oats

摘要

Each of 53 samples of New Zealand seed oats harvested in the 1966#x2013;7 season was examined for the presence ofPyrenophora avenaeIto and Kuribay, before and after treatment with an organomercurial seed dressing. Colonies grew from 27 untreated samples and from eight treated samples. A number of isolates of the fungus were further tested for resistance to mercury by growing them on agar containing different concentrations of mercuric chloride, methoxyethyl mercury chloride, and phenyl mercury chloride. All colonies grew well at low concentrations, and in the case of mercuric chloride. grew better in the presence of small amounts of mercury than in its absence. Results of pot tests for infection after treatment agree well with those from agar plate tests.