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 many species of the genus Fusarium. This disease affects the seedbed and the establishment of maize crops because of seeds contaminated with different pathogens of this genus. Maize crops in the Ubate Valley, in the province of Cundinamarca, are currently infected by this disease, which reduces the yield and final quality of the maize seeds. This research evaluated the effects of thermal and fungicide treatments on pathogens of the genus Fusarium associated with maize seeds. Seeds were treated 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 the evaluated fungicides completely inhibited the radial growth of F. graminearum and only commercial doses of carboxin + captan and prochloraz + difenoconazole completely inhibited F. subglutinans growth. Germination inhibition of F. subglutinans and F. graminearum conidia was found with fludioxonil + metalaxyl-M at the three evaluated doses.

Keywords

• maize seed pathogens
• physical control
• chemical control
• Fusarium graminearum
• Fusarium subglutinans
• stalk rot