Pathogenicity of six Calonectria species isolated from five soil layers in a Eucalyptus plantation

Abstract

AbstractThe genus Calonectria includes species that are pathogens of many plants. Calonectria leaf blight is a serious threat to Eucalyptus plantations in China and elsewhere in the world. Some Calonectria recovered from the surface layer (<20 cm) of soils can cause typical leaf blight symptoms on Eucalyptus trees. However, pathogenicity tests of Calonectria species from deeper soil layers have not been conducted. We tested the pathogenicity of 42 isolates of Calonectria aconidialis, C. chinensis, C. hongkongensis, C. ilicicola, C. kyotensis and C. orientalis obtained from 0–20, 20–40, 40–60, 60–80 and 80–100 cm soil layers in one Eucalyptus plantation in southern China. All the Calonectria isolates were pathogenic to two Eucalyptus genotypes. For isolates of the same Calonectria species from different soil layers, there was no evidence of correlation between their pathogenicity and soil depth. The pathogenicity of some isolates found in deeper soil layers was stronger than isolates in shallower soil layers. This may increase the challenges of controlling the diseases caused by these fungi. This study performed the first pathogenicity test for C. chinensis, C. kyotensis and C. orientalis on plants, and the first pathogenicity test for C. ilicicola on Eucalyptus. Research results in this study helped to clarify the potential threats of Calonectria species in deeper soil layers posed to Eucalyptus plantations.