Effect of thermal and in vitro fungicide treatments on pathogens of the genus Fusarium associated with maize seeds

Abstract

Stalk rot in maize plants is commonly associated with manyspecies of the genus Fusarium. This disease affects the seedbedand the establishment of maize crops because of seedscontaminated with different pathogens of this genus. Maizecrops in the Ubate Valley, in the province of Cundinamarca,are currently infected by this disease, which reduces the yieldand final quality of the maize seeds. This research evaluatedthe effects of thermal and fungicide treatments on pathogensof the genus Fusarium associated with maize seeds. Seeds weretreated at 50°C, 55°C and 60°C with dry heat and hot water. Mycelial colonization of seeds, germination percentage, seedling length, and fresh weight were evaluated as variables. In in vitro tests, the fungicides fludioxonil + metalaxyl-M, tebuconazole + trifloxystrobin, prochloraz + difenoconazole and carboxin + captan were evaluated at 0.5, 1.0 and 1.5 the commercial dose on the radial growth and conidial germination of Fusarium subglutinans and Fusarium graminearum isolates. The most effective heat treatments on Fusarium colonization of maize seeds were obtained with the two heat sources at 55°C without a significant reduction in the percentage of germination and seedling length and fresh weight. Commercial doses of theevaluated fungicides completely inhibited the radial growthof F. graminearum and only commercial doses of carboxin +captan and prochloraz + difenoconazole completely inhibited F. subglutinans growth. Germination inhibition of F. subglutinansand F. graminearum conidia was found with fludioxonil + metalaxyl-M at the three evaluated doses.