Field resistance to leafroll infection in potato varieties

Summary

In recent years the leafroll disease of potatoes has become a major problem in the production of potatoes for seed and table stock in Washington. In order to find a substitute for the very susceptible variety, Netted Gem, variety tests were undertaken at three representative locations in the state. Data representing exposure to natural infection in the field in 1944 and 1945 indicate that the variety, Katahdin, is the most resistant of the twenty-three varieties tested, while Sequoia showed considerable resistance. The varieties, netted Gem, Chippewa, and Burbank, were the most susceptible under the conditions of these tests. The daily maximum temperature appeared to be of great importance in affecting the rate of field spread of leafroll at the different locations and during the two seasons through its effect upon aphids flights. The relative humidity was a limiting factor for field spread in only a few instances.