Pathogenicity of novel Monosporascus species in accessions of melon varietal groups

Abstract

The objective of this work was to evaluate the pathogenicity of the following Monosporascus species: Monosporascus brasiliensis, Monosporascus caatinguensis, Monosporascus mossoroensis, Monosporascus nordestinus, and Monosporascus semiaridus in comparison with Monosporascus cannonballus, as well as the reaction to these pathogens of the A-16, C-32, 'Goldex', and 'Hales Best Jumbo' melon accessions, which belong to the acidulus, cantalupensis, conomon, and inodorus varietal groups, respectively. Vine decline severity was evaluated based on root damage and on the root dry matter reduction index. All studied Monosporascus species caused damage to the melon accessions, but only M. brasiliensis, M. nordestinus, and especialy M. caatinguensis were considered virulent. The A-16 accession shows higher resistance to M. nordestinus, M. caatinguensis, and M. cannonballus, whereas 'Goldex' presents susceptibility to M. caatinguensis, M. nordestinus, and M. semiaridus. The M. brasiliensis, M. caatinguensis, M. mossoroensis, M. nordestinus, and M. semiaridus species present varying levels of pathogenicity and diferent levels of infection severity, with M. semiaridus having the highest severity, and M. cannonballus, the lowest.