Infection process of Curvularia gladioli on gladiolus leaves

Curvularia leaf spot, caused by Curvularia gladioli, is an important disease of gladiolus. Inoculated leaf samples of the Gladiolus grandiflorus ‘T-704’ and ‘Veronica’ varieties were obtained 1 to 192 h after inoculation (hai). There was no difference in the percentage of conidial germination and appressorium formation on the leaves of both varieties. Conidia exhibited polar germination, and most conidia produced one to two germ tubes. Protoappressoria were observed at 1 and 3 hai in ‘Veronica’ and ‘T-704’, respectively. The most common form of fungal penetration was direct. Both intracellular and intercellular colonization of the fungal hyphae were observed in ‘T-704’ (96 hai) and ‘Veronica’ (192 hai). However, there was less hyphal development in ‘Veronica’. Fungal sporulation occurred in both varieties 7 to 8 days after inoculation. Conidiophores were observed emerging through the papillae and stomatal openings in both gladiolus varieties, but were visually more abundant for ‘T-704’. This study provides insights into the infection process of C. gladioli on gladiolus leaves.