Comparisons of Pathogenicity and Cultural Characteristics Among four Isolates of Ceratocystis Ulmi and Some Variants

SUMMARY

Four isolates of Ceratocystis ulmi of known pathogenicity produced culturally distinct variants. Even though the cultural characteristics of the variants differed from their parent isolates, inoculation trials indicated the parent isolates and their variants were generally equally pathogenic in American elm. Cultural characteristics of isolates and variants reisolated from inoculated trees occasionally differed from those inoculated into the trees.