Chrysoporthe cubensis ‐Induced Wilting in Eucalypt Mini‐Stumps: In Vitro Fungus and Disease Development

ABSTRACT Chrysoporthe cubensis was reported to cause wilting that later progressed to dieback and death in eucalypt mini‐stumps. This study aimed to evaluate the influence of various factors on the in vitro development of C. cubensis and to reproduce the wilting symptoms in eucalypt following artificial inoculation. Conidial production by C. cubensis varied depending on the combination of culture medium and temperature. The highest sporulation occurred on potato dextrose agar (PDA) and potato carrot agar (PCA) media containing eucalypt stem fragment on the surface, incubated at 28°C. In the absence of stem fragment, greater sporulation was observed on PCA and PDA, respectively, at 25°C and 28°C. The most favourable condition for mycelial growth was PDA at both 25°C and 28°C. After 12 h of incubation, higher germination occurred under continuous light. However, no significant difference in germination percentage was observed after 24 h of incubation, regardless of the light regime. Regarding temperature and incubation period, conidial germination increased with longer incubation periods. For the first time, Chrysoporthe ‐induced wilting symptoms were successfully reproduced in eucalypt plants, but only in those pruned with shears previously immersed in a conidial suspension or pruned and subsequently sprayed with the suspension. These results provide new insights into the C. cubensis ‐eucalypt interaction and highlight the role of wounds caused by periodic pruning of mini‐stumps as entry points for the pathogen.