May 22, 2015

Merivon, a new fungicide option for disease control in strawberries

Merivon is a pre-mix fungicide containing two systemic active ingredients: fluxapyroxad (succinate dehydrogenase inhibitors or SDHI, FRAC group 7) and pyraclostrobin (quinone outside inhibitors or QoI or strobilurins, FRAC Group 11). Fluxapyroxad is a new active ingredient, but growers are already familiar with pyraclostrobin from Cabrio and Pristine fungicides. FRAC groups refer to fungicides with the same chemical mode of action as assigned by the Fungicide Resistance Action Committee (FRAC). These group numbers can help growers in choosing fungicides for alternation to minimize the risk of fungicide resistance development.

Merivon was already labeled for use in stone and pome fruits, but in 2014 received a supplemental label for strawberries and vegetables.Michigan State University Extension advises growers that they must have the supplemental label on hand when using this product. If necessary, the supplemental label can be obtained at CDMS.net. The supplemental label will expire Sept. 30, 2016, but by that time strawberries will be on the full label.

Merivon has a fairly broad spectrum of activity as it is labeled for use against common leaf spot, powdery mildew, anthracnose and Botrytis gray mold in strawberries. We have not specifically evaluated this product for strawberry disease control in Michigan, but in Florida strawberries, Merivon is effective against Botrytis gray mold, including those strains with multiple resistance to boscalid and QoIs. In general, Merivon is considered similar to or slightly better than Pristine.

The application rate ranges from 4 to 11 fluid ounces per acre, depending on the disease and disease pressure. No more than three total and two sequential applications should be made before alternating to labeled non-Group 7 or non-Group 11 fungicides. Due to potential toxicity to aquatic animals and plants, drift and run-off to surface water and leaching must be avoided. Leaching into groundwater is a risk in areas with permeable soils and shallow water tables, and caution must be exercised with this product under those conditions. The restricted entry interval for Merivon is 12 hours and the pre-harvest interval is zero days. Merivon can be applied aerially or through sprinkler irrigation equipment, but is not allowed in greenhouse or transplant production.

— By Annemiek Schilder, Michigan State University Extension, Department of Plant, Soil and Microbial Sciences