Multiline Cultivars for Disease Control

Abstract

Pure-line cultivars and multiline cultivars for disease control Recently, plant breeders have begun to pay atten-tion to the multiline-cultivar concept fcr controlling disease losses in self-pollinated crops. In the past, strict genotypic and phenotypic uniformity was required for the agronomic traits of cultivars, and disease resistance was no exception. When the pure-line cultivar with a single genotype for resistance was widely grown, new races of a patho-gen, that could parasitize this resistance, became selectively more prevalent, and the effectiveness of the newly developed commercial resistance was quickly lost. Plant breeders were forced to search for different resistance genes that were effective against the virulent races. This type of cycle was repeated frequently in the breeding of most self-pollinated crops. Genetic uniformity fcr disease resistance in the host population caused the uni-formity of new virulent reces in the pathogen population. Consequently, the life of a new crop cultivar was oftentimes as short as 3 to 5 years.