INFLUENCE OF TEMPERATURE AND HUMIDITY ON GERMINATION OF PHYTOPHTHORA INFESTANS CONIDIA
ARMY BIOLOGICAL LABS FREDERICK MD
Pagination or Media Count:
In observing spore germination, it was noticed that under similar conditions conidia germinated either in larger numbers or singly and the difference concerned the length of the shoots as well. Such variations were contributed to difference in the degree of maturity of spores. For this purpose experiments were carried out on germination of spores of 7- and 9-day cultures. The germination percentage in a 9-day culture lagged considerably behind the germination of conidia of a 7-day culture and the germ tubes were considerably shorter. It is interesting to note, that in a 9-day culture there was usually no formation of zoo-spores. In this regard there is a complete analogy with the results obtained by Rosenbaum with Phytophthore cactorum, by Uppal with Phytophthora colocasiae and Blackwell and Waterhouse with the same fungi. The more dubious seems the fact that DeBary obtained zoo-spores from conidia Phytophthora infestans, which persisted on slowly drying out leaves of the plant-host during three weeks after maturing. It is more probable that on these leaves continued formation of new conidia which produced zoo-spores.