Competition Between Typhula incarnata strains as a Source of Variation of Typhula blight in Winter Barley

Abstract

AbstractSeveral crosses between monokaryotic strains of Typhula incarnata Laschex Fr. have given rise to hypoaggressive dikaryons under laboratory conditions. Winter barley plants, preinoculated in cold chamber by these strains, were, fully protected against the harmful effects of the aggressive strains inoculated 15 days later. The experiments have stressed the role of plant cold‐hardening on their susceptibility to Typhula. Under field conditions, when inoculated to winter barley seedlings, a mixture of aggressive and nonaggressive strains produced an attack which was intermediate between the severe one of the former and the almost indiscernible one of the latter strain.Moreover, in cold chamber, mixed sclerotia from two equally aggressive strains induced as much damage as each strain inoculated separately.Insofar as the extent of barley infection by T. incarnata can be measured by the dry weight of the infected plants before stem elongation and by the number of ears at harvest, our results indicate the determinant role of the first infective strain upon the ultimate degree of the attack. The eventual role of crosses between strains is discussed.