Seasonal variation in spore numbers of Pithomyces chartarum in 1960 and 1961 in the Waikato

In 1960 and 1961 surveys were made on grassland herbage of paddocks in the Waikato region of New Zealand * with a mobile volumetric spore trap to determine the nature and magnitude of the fluctuations in estimated spore numbers of P. chartarum , the fungus implicated in facial eczema disease of sheep and cattle. The relation between these fluctuations and the weather conditions as recorded at a reference centre was examined. The trends in spore counts on the herbage of reference paddocks can give reliable indications of the trends in counts on paddocks in the surrounding farming district. The count levels at any one lime on different paddocks may vary considerably. Trends in estimated spore trap counts are markedly influenced by weather conditions. Major peak counts occurred in dry weather following moist warm conditions. Although estimated spore trap counts do not directly indicate spore load on grazed herbage, it is considered that the presence of a danger period for grazing animals is indicated when a rapid upward trend in spore counts occurs following a moist warm period.