A second report on the effect of agronomic practices on the incidence of rhizoctonia and scab of potatoes

Abstract

The results obtained in three rotation experiments in New York State in 1939, confirm the report made in 1938. They are as follows: More potato tubers bore sclerotia ofRhisoctonia where potatoes were grown continuously than where they were grown in longer rotations. Where potatoes were grown continuously, the largest percentage of tubers were affected withRhizoctonia where they were grown without commercial fertilizer, manure or cover crop. The addition of fertilizing material in any of these forms reduced the percentage of tubers affected, and the greatest reduction was secured on plots where all of these fertilizing materials Were used together. At the only location where the pH of the soil was such as to favor scab, the largest amount occurred on plots which received no fertilizer, manure or cover crop. At the other locations small increases in scab occurred on plots Which had been previously limed for clover. The largest increases were obtained on plots which received both manure and lime. Manure alone has caused a small increase at Malone.