A Rapid and Simple Pathogenicity Test for Detecting Virulent Clones of Fusarium oxysporum f. cubense using Seedlings of Musa balbisiana

Abstract

RESEARCH on Fusarium wilt of bananas induced by F. oxysporum f. cubense (E.F.S.) Sny. and Hans. has frequently been hindered by the lack of a rapid and simple pathogenicity test. It is well known^1,2 that parasitic isolates of F. oxysporum from soil and roots cannot be distinguished from saprophytes except by pathogenicity tests which are a prerequisite to placing isolates of F. oxysporum in their respective formæ. Recently a relatively simple field or large tank pathogenicity test was developed for F. oxysporum f. cubense ^3,4. However, this test utilized large banana plants growing in the field or in large containers and required 6–16 weeks for results. Similar tests carried out in 12-in. pots containing small banana rhizomes artificially inoculated were also satisfactory, but greenhouse shelf space limited the number of replications and the rhizomes were frequently attacked by Pectobacterium carotovorum ⁵. In addition, above-ground symptoms usually were not evident and the plants soon became pot-bound.