Postiva fungicide is a systemic fungicide engineered for broad-spectrum, long-lasting disease control and suppression of bacterial pathogens in ornamental production. It features a combination of active ingredients from two distinct FRAC groups, utilizing ADEPIDYN technology.
Chemical Composition and Formulation
The active ingredients are pydiflumetofen, a succinate dehydrogenase inhibitor (SDHI) from FRAC Group 7, and difenoconazole, a demethylation inhibitor (DMI) from FRAC Group 3. The product is formulated as a suspension concentrate (SC). The EPA registration number is 100-1661.
Functional Mechanism and Design
Pydiflumetofen (Group 7) inhibits fungal respiration by blocking succinate dehydrogenase in mitochondrial Complex II. Difenoconazole (Group 3) inhibits C14-demethylase in sterol biosynthesis, disrupting fungal cell membrane integrity. This dual-mode-of-action design provides preventative, systemic, and curative activity. The formulation is rapidly absorbed into plant tissue, creating a rainfast barrier.
Target Applications and Performance
Postiva is labeled for preventative and curative control of a wide range of fungal diseases including those caused by Fusarium spp. (wilt, root rot, crown rot), Botrytis cinerea (gray mold), Rhizoctonia solani, powdery mildew, and numerous leaf spot pathogens (e.g., Alternaria, Cercospora). It also provides suppression of bacterial diseases caused by Pseudomonas spp. and Xanthomonas spp. It is approved for use on ornamental plants grown in greenhouses, shadehouses, nurseries, and container-outdoor production.
Application Specifications and Protocol
Applications can be made via foliar spray, soil drench, chemigation, or cold fogging systems. Standard application rates for foliar and drench applications range from 1.0 to 2.0 fluid ounces per 100 gallons of water. For drench applications targeting Fusarium root and crown rots, the label specifies a rate of 2.0 fl oz/100 gal. A re-treatment interval of 14 to 28 days is recommended. The product must be agitated during application. Specific use rates and intervals depend on the target pathogen, crop, and application method as detailed on the EPA-approved label.
Handling and Safety
This product bears the signal word "CAUTION" on its label. Applicators must wear long-sleeved shirt and long pants, shoes plus socks, and chemical-resistant gloves during handling, mixing, loading, application, and repair of equipment. For greenhouse applications, a posted warning sign is required. The re-entry interval (REI) is 12 hours for all uses except greenhouse ornamentals, which have a 24-hour REI. Do not apply where runoff may reach aquatic systems.
