In vitro evaluation of fungicides against eucalyptus stem canker pathogens in Ethiopia

Field surveys of Eucalyptus camaldulensis diseases were conducted during 2019-20 and 2020-21 in Ethiopia. This species was the most commonly planted in the surveyed fields and exhibited stem canker diseases. Sampling was performed from diseased stems and branches displaying clear symptoms. Morphological and PCR assays of the ITS1 and ITS2 loci were conducted to identify the fungal pathogens. Lasiodiplodia theobromae and Didymella pinodella were identified as the fungal pathogens causing E. camaldulensis stem canker diseases. Four nationally licensed fungicides viz. Vitra (copper hydroxide), Ridomil Gold (metalaxyl-M + mancozeb), Liveshow (pyraclostrobin + epoxiconazole), and Sabozeb (mancozeb) were evaluated for their in vitro control efficacy against the identified fungi at different concentrations (500, 1000, 1500, and 2000 ppm). Vitra and Liveshow were found to be the most effective fungicides at 2000 ppm for the control and treatment of E. camaldulensis stem canker diseases. The identification of L. theobromae and D. pinodella as causal agents of E. camaldulensis is crucial for targeted disease management strategies. The evaluation of four fungicides at different concentrations provided valuable information for selecting the most effective treatment options for practical management practices of the diseases. This research serves as the first report on the management of Eucalyptus disease in Ethiopia, laying the foundation for future studies and contributing to the development of sustainable disease management practices. The findings of this research can guide policymakers, researchers, and agricultural practitioners in implementing targeted fungicide applications to mitigate the impact of stem canker on Eucalyptus plantations and improve their productivity.