Efficacy of the rotary knife in the control of potato ring rot

Abstract

Two factorial experiments in the control of ring-rot spread were carried out to test the effectiveness of 1) the rotary cutting knife, 2) two mercuric chloride cut seed dips, and (3) the ultra violet light. In both experiments the rotary knife produced higher yields of both healthy and total tubers than any of the other treatments tried. It also led to a statistically significant reduction in the amount of ring-rot diseased tubers. In both experiments mercuric chloride seed piece dips gave the greatest control of ring-rot spread, but at the same time led to the smallest crop of healthy and of total tubers. Either the extent of the field layout or the differences obtained, or both, were too small to show results of statistical significance in the control of ring-rot by the use of the ultra violet light. Analyses of covariance showed a high correlation between stand and yield, indicating that the yield of total tubers (healthy + diseased) was dependent on the effect of the particular treatment on emergence. The picker planter in the field led to an apparent spread of ring-rot, but the increase under conditions of the experiment may have been due to random variations as the difference was not statistically significant.