IN-VITRO STUDIES OF THE EFFECT OF ENVIRONMENTAL-CONDITIONS ON THE ANTHRACNOSE PATHOGEN OF BANANAS, COLLETOTRICHUM-MUSAE

In vitro studies were undertaken to determine the effect of pH, temperature, water availability and carbon dioxide (CO2) concentration on germination and growth of Colletotrichum musae, the causal pathogen of anthracnose of bananas. The optimum pH for germination and growth varied between 4.0 and 5.0 depending on temperature. At low pH (<3.0) and 15 degrees C, both germination and growth were significantly reduced, with a marked increase in the lag time, in days, prior to growth. C. musae germinated and grew over a wide range of water activities (a(w); 0.995-0.94 and 0.995-0.92, respectively) at 20, 25 and 30 degrees C. In all cases where germination occurred appresoria were subsequently produced. Optimum growth occurred at 30 degrees C and 0.995 a(w), although this changed to 0.98 a(w) at 35 degrees C. Increasing CO2 concentration to 15% or reducing oxygen concentration to 1% resulted in a significant (P<0.05) reduction in growth, but did not inhibit growth completely.