Fig. 7.

Pathogenicity test of maize stalk rot (MSR) fulfilling Koch’s postulates. A. Diagram of a three-leaf-old seedlings of maize. B. Typical symptoms of disease severity (0–4). C. Blank control treated with sterile water. D–U. Maize seedlings treated with different Fusarium suspensions. The conidial concentration (CC) of Fusarium strains and disease severity index (DSI) of infected plants were listed. DSI (%) = [sum (class frequency × score of rating class)/(total number of plants × maximal disease severity score)] × 100.