The Influence of Soil Moisture on Infection of Peas by Pythium Ultimum

Abstract

The mode of action of soil moisture in influencing infection of peas by P. uUimum is examined. It is concluded that soil moisture per unit volume, soil moisture per unit weight, and moisture tension do not affect disease incidence directly. Experimental results indicate that the importance of soil moisture is in its influence on the amount of sugar exuded from pea seeds, and this determines disease incidence. Loss of sugar is also influenced by soil type (more sugar being exuded from peas in a non-aggregated sand than from those in aggregated soils) and by soil bulk density.