Ceratocystis wilt in Chukrasia tabularis in Vietnam: identification, pathogenicity and host tolerance

Abstract

Chukrasia tabularis is a rare and valuable tree in the mahogany family (Meliaceae) which has been planted with fruit trees in home gardens in Vietnam more than 60 years. Recently, households have become concerned with sporadic trees wilting and dying. In this study we explore this new tree decline. The trunk of diseased trees, with cankers and wilt symptoms, and soil from around roots were sampled and cultures of Ceratocystis were obtained. The causal agent was identified as C. manginecans based on a phylogenetic species hypothesis of β-tubulin. Five C. manginecans isolates from diseased trees and five soil isolates were pathogenic in C. tabularis seedlings in a nursery trial. We used one isolate to explore the tolerance of 59 one-year-old C. tabularis families to inoculation. Of these, 33 families exhibited very strong tolerance (no lesions, no death). This suggests that there are opportunities to employ resistant families in breeding programs and to increase disease tolerance of C. tabularis through genetic gain.