Powdery mildew-resistant summer squash hybrids having higher yields than their susceptible, commercial counterparts

Abstract

Attempts at breeding squash (Cucurbita pepo) resistant to powdery mildew (Sphaerotheca fuliginea and Erysiphe cichoracearum) have heretofore been unsuccessful due mainly to association of the resistance trait with reduction in yield. The goal of the present work was to determine if heterozygous hybrids expressing partial resistance could be potentially valuable for squash growers. One heterozygous hybrid each of zucchini, cocozelle, and vegetable-marrow squash was grown alongside a leading susceptible commercial hybrid cultivar of the same type, under standard field conditions. Although fungicides were applied at recommended rates every 6 to 13 days to suppress powdery mildew, the susceptible hybrids became heavily infested later in the season. The resistant hybrids were similar to their respective commercially available susceptible hybrids in fruit appearance and other horticulturally important traits. The resistant hybrids yielded at least as well as the commercial hybrids early in the season and outyielded them later in the season.