Screening of Efficient Fungicides for the Control of Citrus Anthracnose and the Discovery of Fungicide-Resistant Isolates

Five fungicides, namely 50% carbendazin WP, 80% mancozeb WP, 10% difenoconazole WG, 45% prochloraz EW and 25% azoxystrobin FW, were tested for their toxicities to citrus anthracnose pathogen Colletotrichum gloeosporioides isolates from different cirtrus varieties and different districts of Guangdong Province by using mycelial growth rate method. The results showed that prochloraz had the best antifungal effect, followed by difenoconazole. All tested isolates had certain degrees of resistance to azoxystrobin and mancozeb, and showed obvious sensitivity differences to carbendazim. Isolates CCMZ004, CCMZ004, CCST003 and CCST026 all had the strong tolerance (resistance) to carbendazim.Therefore, prochloraz and difenoconazole can be used as the preferable fungicides to control citrus anthracnose.