Pathogen isolation and identification of mango stem-end rot and in-door fungicide screening for disease control

【Objective】This study aimed to identify the fungal pathogen responsible for stem-end rot in mangoes in Leye County，Baise City，Guangxi，and assess the efficacy of various fungicides against the pathogen indoor. This study provided a scientific basis for the field management of mango stem-end rot.【Method】 Mangoes exhibiting typical symptoms of stem-end rot were collected from Baian Village，Youping Township，Leye County，Baise City. The isolation and purification of potential pathogenic fungi from these samples were carried out，followed by pathogenicity tests using Koch's method. The pathogens were identified based on morphological characterization，and genetic analysis involving ITS，β-tubulin and EF-1α gene sequences. Additionally，twenty-one commonly used fungicides were evaluated for their efficacy against the identified pathogen in vitro.【Result】 The fungal agent of mango stem-end rot was identified as Botryosphaeria dothidea，utilizing a combination of traditional fungal morphology，taxonomic classification，and molecular analysis（ITS，β-tubulin and EF-1α gene sequence） . The results of fungicide inhibited mycelial growth of pathogenic bacteria showed that，the most effective fungicides were 50% carbendazim，400 g/L flusilazole，40% dimethachlon，250 g/L pyraclostrobin，430 g/L tebuconazole and 450 g/L prochloraz，followed by 5% carvacrol，80% mancozeb，20% kasugamycin and 10% difenoconazole. Conversely，23.4% mandipropamid，350 g/L metalaxyl-M，and 30% flumorph displayed the least efficacy. The results of laboratory virulence test showed that among the 21 fungicides tested，the inhibition effect on pathogenic bacteria of 50% carbendazim，250 g/L pyraclostrobin，and 400 g/L flusilazole was fine，inhibited medium concentration（EC₅₀）of the three were less than 0.1000 mg/L，followed by 430 g/L tebuconazole，450 g/L prochloraz， 10% difenoconazole，40% dimethachlon and 240 g/L thifluzamide，whose EC₅₀ values ranging from 0.1000 mg/L to 1.0000 mg/L. The inhibition effects of 23.4% mandipropamid，350 g/L metalaxyl-M，8% ningnanmycin，and 30% flumorph were bad，with EC₅₀ values exceeding 100.00000 mg/L.【Conclusion】The pathogen responsible for mango stemend rot in Leye County，Baise City，Guangxi is B. dothidea. Fungicides such as 50% carbendazim，250 g/L pyraclostrobin and 400 g/L flusilazole demonstrate the highest efficacy against B. dothidea and are recommended in the field trials as primary treatment options. Alternatively，430 g/L tebuconazole，450 g/L prochloraz，10% difenoconazole，40% dimethachlon and 240 g/L thifluzamide could serve as secondary agents. However，fungicides like 8% ningnanmycin， 350 g/L metalaxyl-M，23.4% mandipropamid and 30% flumorph，which exhibit poor bacteriostatic effects，are not recommended for further testing or control measures.