In vitro efficacy tests against Fusarium spp. causing garlic dry rot

Garlic is cultivated worldwide and, according to FAOSTAT, in 2016 1.5 million hectares were destined to this culture. Starting from 2002, Fusarium proliferatum was signalled as the main causal agent of garlic dry rot during storage, but with infections starting during the growing season. Seed sanitation seems crucial to prevent pathogen spread. In the context of preparing guidelines for farmers to prevent/control dry rot in field and during storage, this study was designed. Fusarium proliferatum (MPVPG29) recovered from garlic during the 2017 growing season was used in in vitro trials. Six fungicides, all including triazoles, alone or in mixture, and 4 competitor/antagonist biocontrol agents (BCA; Trichoderma gamsii, Fusarium oxysporum IF23, Bacillus subtilis, Streptomyces griseoviridis K61) were considered. Spiked media for chemicals (4 concentrations (1-1000 ppm) and dual cultures for BCAs were used. Inoculated dishes were incubated at 3 temperatures (10-15-25° C) and the percentage of growth inhibition was recorded after 7-14-21 days. All chemical products were able to stop fungal growth at 100 ppm concentrations and Procloraz+Propiconazole showed a 94% reduction followed by Tebuconazole (57% reduction) even at 1 ppm. Regarding BCAs, T. gamsii was the most effective in reducing F. proliferatum growth (mean reduction=84%), followed by S. griseoviridis (mean reduction=60%). Results are very promising and a field trial is ongoing to verify the performances of BCAs in garlic crops.