Abstract
The relationship of exchange acidity y1, soluble silica and scab severity index of potato common scab was investigated. From a result of soil analytical data, potato common scab was suppressed with 7 to 8 of exchange acidity y1, that is a practical measure of exchangeable aluminum, by decreasing soil pH. However, potato common scab was not at high level suppression when the Si/Al mol ratio, values of the coefficients of correlation between soluble silica and soluble aluminum, were more than 0.5 at 7 to 8 exchange acidity y1. It comes to a conclusion that soluble silica influences the disease development of potato common scab to control a level of exchangeable aluminum in soil.
