Mango Malformation Disease in South China Caused by Fusarium proliferatum

A total of 13 Fusarium isolates were obtained from samples of malformed mango seedlings from Yunnan and Sichuan provinces in China, and five morphologically similar isolates were confirmed causing the disease by satisfying Koch's postulates. One typical isolate (MG4) was selected for detailed morphological and molecular studies. Based on the following morphological characteristics, isolate MG4 was identified as Fusarium proliferatum: white aerial mycelium on PSA (potato sucrose agar: potato 200 g; sucrose 15 g; agar 18 g; distilled water 1000 ml) medium; hyaline reverse of colonies on PSA; production of pink pigment on rice medium and the production of conidia on branched conidiophore with monophialides bearing false heads of conidia. On carnation leaf agar medium, the microconidia were ovate to elongated ovoid, 0-1 septate, 3.1-10.2 x 1.5-2.2 mu m; the macroconidia were fusiform, 3-5 septate, 18-38 x 1.8-2.4 mu m, whereas chlamydospores and sexual structures were absent on all media used. The identity of the pathogen was confirmed by its high similarity (99.8-100%) in the sequence alignment of rDNA-ITS 1 and 4 with both isolates of F. proliferatum in the GenBank database.