Strawberry crown rot (SCR) is a serious disease that is generally referred to as seedling anthracnose due to its association with Colletotrichum spp. Presently, SCR is the main cause of death of strawberry seedlings. However, management strategies, including fungicides targeting Colletotrichum spp., have failed to obtain satisfactory results. Therefore, identifying the exact pathogen species causing SCR could guide its management. A total of 287 isolates were obtained from SCR-diseased plants. Based on the culture, morphology, and phylogenetic characteristics, the above 287 fungal isolates of SCR pathogens were identified as 12 different species, including Colletotrichum siamense, C. fructicola, Fusarium oxysporum, F. commune, F. equiseti, F. solani, F. tricinctum, Epicoccum sorghinum, Stemphylium lycopersici, Clonostachys rosea, Phoma herbarum, and Curvularia trifolii. Pathogenicity results showed that most isolates were pathogenic to strawberry seedlings and exhibited different degrees of virulence. In severe cases, poor growth on the ground, yellowing of the leaves, and even death of seedlings occurred. In mild cases, only black disease spots appeared on the stems of the strawberry seedlings, and a few withered leaves became necrotic. The inoculation experiments showed that the most virulent species were C. siamense and F. oxysporum, followed by F. equiseti, P. herbarum, Cl. rosea, S. lycopersici, and C. fructicola, which had disease incidences above 50%. E. sorghinum, S. lycopersici, Cl. rosea, P. herbarum and Cu. trifolii were reported to cause SCR for the first time herein. In conclusion, SCR is a sophisticated disease caused by a diversity of pathogenic fungi. This work provides new valuable data about the diversity and pathogenicity of SCR pathogens, which will help in formulating effective strategies to better control of the SCR disease.

In 2017 and 2018, a total of 294 Fusarium fujikuroi isolates were collected from bakanae-diseased rice plants in Jinhua, Shaoxing, and Jiaxing in Zhejiang Province, China. Phenamacril sensitivity of these isolates was determined by the 50% effective concentration value or minimum inhibitory concentration methods. Our results indicated that the phenamacril resistance frequency of F. fujikuroi increased from 18% in 2017 to 47% in 2018, and rice plants infected with F. fujikuroi-resistant isolates could not be protected effectively with 50 mg/liter of phenamacril. Phenamacril-resistant F. fujikuroi isolates obtained from rice fields showed stable resistance, because their fitness levels (i.e., mycelial growth, sporulation, and pathogenicity) were similar to the phenamacril-sensitive isolates. In addition to the point mutation at codon 219 in the myosin-5 gene that conferred resistance to phenamacril, our results also showed another point mutation at codon 218 (AAG→ACG) in myosin-5 that also conferred resistance to phenamacril. In this study, we found rapid development and persistence of diversified genotypes of phenamacril resistance, highlighting the importance of proper use of phenamacril in rice fields. Our results may also help researchers develop new fungicides or new control strategies using combinations of different fungicides in the control of phenamacril-resistant F. fujikuroi isolates.

Alternative oxidase (AOX) is a ubiquinol terminal oxidase that is involved in fungal mitochondrial oxidative phosphorylation. In this study, we analyzed the roles of AOX in Botrytis cinerea by generating BcAOX deletion mutants. The mutants exhibited defects in mycelial growth, sporulation, spore germination, and virulence. Furthermore, the sensitivity of the mutants to quinone outside inhibitor fungicides and oxidative stress were increased. All phenotypic variations could be restored in the complemented strain. In summary, these results showed that BcAOX is involved in the regulation for vegetative development, adaptation to environmental stress, and virulence of B. cinerea.

Anthracnose is a devastating fungal disease in strawberry nurseries. Multiple Colletotrichum species are responsible for strawberry anthracnose. In this study, 105 Colletotrichum isolates were obtained from strawberry seedlings with anthracnose symptoms in fifteen nurseries located in Zhejiang province, China, and were classified based on multilocus sequence and morphological characteristic analyses. Analysis of ITS, ACT, CAL, CHS-1, and GAPDH revealed that four species within C. gloeosporioides species complex, including C. siamense (56 isolates, 53.3%), C. fructicola (37 isolates, 35.2%), C. gloeosporioides (7 isolates, 6.7%), and C. aenigma (5 isolates, 4.8%), were detected in diseased seedlings. Thiophanate-methyl is one of the benzimidazole fungicides, and has long been used to control strawberry anthracnose in China. Here, thiophanate-methyl resistance of Colletotrichum isolates was determined by the minimum inhibitory concentration (MIC) method. Our results indicated that the resistance frequency was up to 96.2%, containing 94.3% of highly resistant isolates. Only four sensitive isolates (two C. fructicola, one C. gloeosporioides, and one C. siamense isolates) and two moderately resistant isolates (one C. aenigma isolate and one C. siamense isolate) were detected. Our data indicated that the high resistance was mainly caused by the E198A mutation in the β-tubulin protein. In addition, F200Y (TTC→TAC) in the β-tubulin protein were detected in two moderately resistant isolates. Based on the point mutation at codon 198 (GAG→GCG) in the β-tubulin gene of Colletotrichum isolates, we developed a loop-mediated isothermal amplification (LAMP) assay to rapidly detect the E198A mutants. Collectively, our study indicated that four species within the C. gloeosporioides species complex were associated with anthracnose symptoms in strawberry nurseries in Zhejiang province, and serious resistance was widespread in each Colletotrichum species.

Anthracnose is a fungal disease that seriously threatens grape production and quality. Multiple Colletotrichum species are detected in anthracnose grapes in vineyards. In this study, diseased grapes were collected in four counties in Zhejiang, and 43 Colletotrichum isolates were obtained. Multi-genes (ITS, TUB2, ACT, CHS-I, and GAPDH) and morphological characteristic analyses showed that C. fructicola (40 isolates, 93%), C. aenigma (two isolates, 4.7%), and C. pseudoacutatum (one isolate, 2.3%) were the cause of grape anthracnose in Zhejiang. Among the three Colletotrichum species, C. fructicola was the prevalent and dominant species in all sampled counties; C. pseudoacutatum was first identified as the pathogen responsible for grape anthracnose. There were significant differences in the sporulation among the three Colletotrichum species, as well as in the spore germination. Pathogenicity testing showed that all species can infect grapes, resulting in anthracnose. On the other hand, the virulence of species was varied and may be associated with their spore germination. This is the first study to characterize the Colletotrichum species causing grape anthracnose in Zhejiang Province and reveal that C. fructicola is the dominant species. The determination of Colletotrichum species associated with grape anthracnose may contribute to the study of epidemiology and development of an efficient strategy for controlling anthracnose in the vineyards.