INFLUENCE OF TEMPERATURE, PH AND SELECTED GROWTH MEDIA ON GERMINATION, GROWTH AND SPORULATION OF ASCHERSONIA-PLACENTA AND HYPOCRELLA-RACIBORSKII

Tween 70 at 0.1% provided the best conditions for germination of Asche rsonia placenta. Optimum germination and growth of the germ tube occur red over a temperature range of 25-30-degrees-C and a pH range of 5.0- 6.0. A temperature of 30-degrees-C resulted in the longest germ tube a t 45 mum. Apparently, temperature and pH did not affect the type of ge rmination, with polar germination being consistently recorded for in e xcess of 60% of conidia. In general, growth and sporulation seemed to be much better in semi-solid than in liquid media. Amongst several pla nt media tested, pumpkin consistently gave the most mycelial growth an d sporulation. The ability of A. placenta to sporulate on the surface of liquid culture has increased the possibilty of its mass production for the purpose of formulating a microbial pesticide against the indig enous scale insects of tropical fruits such as durian and guava in Mal aysia.