Morphological characterization and optimization of conditions for conidial production of Elsinoë ampelina, the causal organism of grapevine anthracnose

Abstract Grape anthracnose, which is caused by Elsinoë ampelina , is a disease that negatively affects grape production. This study aimed to investigate the effects of aeration, temperature, light, and preculture period on the formation of E . ampelina conidia and conidial germination and virulence. The colony morphology on potato dextrose agar ( PDA ) plates was more diverse than that in PDA bottles. The assessment of different culture methods, temperatures, light conditions, and preculture periods revealed that optimal conidial production occurred on 25‐day‐old colonies grown in PDA bottles at 21°C for 24 hr in the dark. The cultures in PDA bottles consistently produced approximately 5.0 × 10 6 conidia under these conditions. No conidial formation occurred when the cultures were kept at 25°C in the dark. The highest germination rate of E. ampelina was 80% at 25°C after 24 hr, whereas no germination was observed at 17°C after 12 hr. Pathogenicity tests revealed that symptoms of the disease were observed 4 days postinoculation (dpi) on leaves of Vitis vinifera cv. Red Globe. New conidia were observed on the lesions at 8 dpi. This study provides an effective method for the conidial production of E. ampelina that may also be applicable for other Elsinoë fungal species.