Initiation of Branching in the Germ Tubes of Peronospora Parasitica by Alcohol

SUMMARY

Low molecular weight alcohols (0.67 M, 0.89 M, 1.09 M methanol and 0.44 M, 0.67 M, 0.89 Methanol) initiate branching in the germ tubes of the conidia of Peronospora parasitica. Propanol and butanol inhibit germination at these concentrations (0.44-1.09 M) and with more dilute concentrations (0.01-0.03 M) of these higher molecular weight alcohols there is germination but no branching. All of the alcohols tested reduce the percentage of germination. Ethyl alcohol must be present continuously just after either the beginning or 2 or 5 h after the beginning of germination for branching to occur. The longer the delay in the application of alcohol after the beginning of germination, the greater the distance of the branches on the germ tube from the spore wall.