EVALUATION OF SPRING BARLEYS FOR REACTION TO Fusarium culmorum SEEDLING BLIGHT AND ROOT ROT

Abstract

The effects of Fusarium seedling blight and root rot, caused by Fusarium culmorum, on plant emergence, harvestable tillers, grain yield and disease reaction in 12 spring barley cultivars were studied in greenhouse and field experiments at Bozeman, Mt. in 1984 and 1985. Atomization of F. culmorum macroconidia onto seed increased disease severity in greenhouse seedlings and mature plants in the field as compared with noninoculated seed. In the inoculated treatments the mean disease rating, based upon the extent of discoloration of the seedling coleoptile or the mature plant subcrown internode, differentiated resistant and susceptible two- and six-rowed cultivars. Among the 12 cultivars, seedling and mature plant disease reactions were not correlated. In 1985 field tests, F. culmorum inoculation reduced the plant emergence of all two-rowed, but only one six-rowed cultivar. Plant emergence in 1985 field tests was negatively correlated with greenhouse seedling and field mature plant disease reactions. To remove the effects of stand reduction by inoculation and determine the subsequent effect of infection on grain yield, the plant stand of a control treatment was hand-thinned to equal that of the inoculated treatment. Generally, F. culmorum inoculation had no effect on harvestable tillers or grain yield when compared with the hand-thinned control. The ease with which seed can be inoculated with the pathogen makes this technique a useful tool in evaluating the ability of a genotype to compensate for stand reduction and to tolerate root rot infection.Key words: Disease tolerance, dryland root rot