Review: Identification of Resistance and Tolerance to Potato Cyst Nematodes and Their Practical Implications

Abstract

The efficient utilization of resistant and tolerant cultivars as a means of control of potato cyst-nematodes requires that proper consideration be given to those factors which affect the reaction of the plants in their relationship with nematode populations and environment. The external and internal factors that affect a plant's reaction in the presence of a nematode infestation are discussed. The influence of the physiological condition of the plant, environmental factors, and other organisms are emphasized. The necessity of a proper identification of the nematode pathotypes and variants to which material tested is either resistant or tolerant is emphasized. Some comments are made on the pathotype classification schemes now utilized. Because of the danger of selecting other pathotypes or more aggresive variants, it is advisable to consider, in most cases, the use of resistance and tolerance only as part of integrated control programs. Because of variability in nematode populations a