Fusarium annulatum causes Fusarium rot of cantaloupe melons in Spain

Abstract

During the summer of 2018, there was high incidence of fruit rots of cantaloupe melons (Cucumis melo var. cantalupensis) in Murcia province, south-eastern Spain. The fruits showed development of whitish mycelium and pulp softening. Morphological and molecular analysis of the internal transcribed spacer (ITS), translation elongation factor 1-α (TEF1-α) and the second largest subunit of RNA polymerase (RPB2) genes confirmed Fusarium annulatum as the causal agent of the disease. A phylogenetic study indicated that F. annulatum is in the Fusarium fujikuroi species complex (FFSC). Pathogenicity of the isolate was determined on healthy fruit verifying Koch’s postulates. The first symptoms of fruit rot were observed 3 d after inoculations at 28ºC. Fruit infections only occurred in artificially wounded melons, and F. annulatum was re-isolated from the wounds. This disease appeared after fruit harvesting, and could generate substantial economic losses mainly in fruit destined for foreign markets due to long transportation times. This is the first report of melon fruit rot caused by F. annulatum in Spain.