Scientists point out resistance of Colletotrichum fungi to fungicides in China

They tested the sensitivity of these isolates to commonly used fungicides, including carbendazim, iprodione, fluopyram and propiconazole.

05.07.2024 | 16:39 (UTC -3)
Cultivar Magazine
Efficacy in the control of carbendazim for sensitive and resistant isolates of and . (A, B), after 5 days of inoculation, highly resistant (HR) isolates of and moderately resistant (MR) isolates of developed anthracnose symptoms in detached fresh peaches, while sensitive isolates of both species did not. exhibit any symptoms. Control efficacy test showing significant differences (P<0,05) between sensitive and resistant isolates - doi.org/10.1016/j.pestbp.2024.106006
Efficacy in the control of carbendazim for sensitive and resistant isolates of C. fructicola e C. siamense. (A, B), after 5 days of inoculation, highly resistant (HR) isolates of C. fructicola and moderately resistant (MR) isolates of C. siamense developed anthracnose symptoms on fresh detached peaches, while susceptible isolates of both species did not show any symptoms. Control efficacy test showing significant differences (P<0,05) between sensitive and resistant isolates - doi.org/10.1016/j.pestbp.2024.106006

Peach production, one of the most popular and economically important fruit crops in China, is facing serious challenges due to anthracnose. This disease, caused by fungi Colletotrichum fructicola e Colletotrichum siamense, has caused significant economic losses for producers. Recently, a study revealed worrying levels of resistance of these fungi to several fungicides.

Researchers collected 39 isolates from C. fructicola and 41 of C. siamense in several Chinese provinces. They tested the sensitivity of these isolates to commonly used fungicides, including carbendazim, iprodione, fluopyram, and propiconazole. The results showed high resistance to carbendazim in isolates of C. fructicola from Guangdong province, while those isolated from Guizhou proved to be sensitive. For C. siamense, isolates from Hebei showed moderate resistance, while those from Shandong were sensitive to carbendazim.

Furthermore, all isolates from both species showed high resistance to the fungicides iprodione (DCF) and fluopyram (SDHI), but were sensitive to propiconazole (DMI).

Resistance to carbendazim has been correlated with mutations in the β-tubulin 2 (TUB2) gene. In the case of C. fructicola, the E198A mutation was identified as responsible for high resistance, while in C. siamense, the F200Y mutation was associated with moderate resistance. Positive cross-resistance was observed between carbendazim and benomyl, both from the methyl benzimidazole carbamate (MBC) group.

Widespread resistance to traditional fungicides highlights the urgent need for new management strategies. Researchers suggest using demethylation inhibitor (DMI) fungicides such as propiconazole or prochloraz, especially in areas where pathogens have already developed resistance to carbendazim and other fungicides.

About anthracnose

Anthracnose, caused by species of Colletotrichum, is a common fungal disease in several plants. The gender Colletotrichum is one of the ten most important groups of phytopathogenic fungi globally. Peach anthracnose is generally caused by Colletotrichum acutatum e Colletotrichum gloeosporioides. Colletotrichum truncatum has also been identified in peach. Studies have shown that C. acutatum e C. gloeosporioides are species complexes with more than 30 and 22 species, respectively. Colletotrichum fructicola e Colletotrichum siamense, belonging to the species complex C. gloeosporioides, have been identified as causing anthracnose in peaches in several locations, including the USA, South Korea, Uruguay and China. Recent study found Colletotrichum godetiae, from the species complex C. acutatum, and Colletotrichum karsti, from the species complex C. boninense, in peaches, being the first time that these species have been reported in this fruit.

The scientists published an article highlighting aspects of their research. It can be seen at doi.org/10.1016/j.pestbp.2024.106006

Efficacy test of DMI fungicides with recommended field doses (1ml/1L of prochloraz, 2ml/1L of propiconazole, 0,17g/1L of tebuconazole and 0,67ml/1L of hexaconazole) for carbendazim-sensitive, highly resistant (HR) isolates ) of and moderately resistant (MR) isolates of , where the control was treated with water. Data were collected 5 days after inoculation. Prochloraz and propiconazole showed >90% control efficacy, while tebuconazole and hexaconazole showed much lower control efficacy.
Efficacy test of DMI fungicides with recommended field doses (1ml/1L of prochloraz, 2ml/1L of propiconazole, 0,17g/1L of tebuconazole and 0,67ml/1L of hexaconazole) for carbendazim-sensitive, highly resistant (HR) isolates ) in C. fructicola and moderately resistant (MR) isolates of C. siamense, where the control was treated with water. Data were collected 5 days after inoculation. Prochloraz and propiconazole showed >90% control efficacy, while tebuconazole and hexaconazole showed much lower control efficacy.
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