The inheritance of resistance to Ascochyta pisi Lib. in Pisum sativum L.

Abstract

A disease of peas caused by Ascochyta pisi is briefly described. The susceptibilities of over 200 varieties and strains of peas were tested by spray inoculation of the seedlings when they were six to eight inches in height. Austrian Winter was the least susceptible of the varieties tested. It was crossed with several other pea varieties and in all cases except one the F₁ generation, when spray inoculated in the late seedling stage, was shown to be as resistant as Austrian Winter. Segregation in the F₂ and later generations was such as to indicate that the resistance is due to a combination of three Mendelian factors, all of which are dominant. Other factors may have a modifying effect. A number of Austrian Winter hybrids were shown to possess considerable field resistance to the disease a t Warncoort, in the Colac district of Victoria. The resistant hybrids have all inherited some undesirable qualities from the Austrian Winter parent.