Fall is just around the corner, and with cooler weather comes a new host of concerns for grape growers. Many diseases go dormant throughout the summer only to make a re-appearance as the season changes. Common fungal infections such as Botrytis bunch rot can resume growth and spread throughout your vineyard just before harvest. Keep damaging diseases at bay by preparing for the infection and providing the right treatment.

Grapes that escape bloom-time infection may become infected at or near harvest under favorable environmental conditions. Late-season infections, including Botrytis, are most severe when temperatures range from 58 °F to 82 °F, relative humidity exceeds 92 percent and free moisture is present on the fruit surface.

Botrytis growth can begin on the plant’s leaves, stems and bud axils, but the grapes themselves are increasingly suspectable to infection as they mature. This is partially because ripe fruit attracts fruit flies, which help spread Botrytis on their bodies from plant to plant. Ripe berries that have experienced damage from insects, birds, machinery, etc. may become infected at any time as the juice in the berry can provide the necessary water and nutrients for fungal growth.

The fungal infection colonizes on the surface of plant tissue and invades the top layers of epidermis cells. Infected grapes may appear gray and velvety — a result of epidermal cracks in the fruit where fungal growth produces mycelium and spores. At first, the infected grapes will appear soft; however, they will shrivel with time before falling off the plant.

UPL offers a complete line of grape protection that includes ELEVATE® and PH-D® Fungicides. These two products offer the needed protection against Botrytis bunch rot and are a great fit with any disease management plan. Despite seasonal changes, the right products at the right time can keep grapes healthy and fungus-free up until harvest.

To control Botrytis fruit rot, Group 17 fungicide ELEVATE gives grape growers high-quality protection. It features a unique active ingredient, fenhexamid, which has no effect on most beneficial insects and no known cross-resistance to other commonly used fungicides. With its one-day pre-harvest interval, ELEVATE can be used within one day of harvest.

A broad-spectrum, Group 19 fungicide, PH-D provides excellent knockdown of Powdery mildew, Botrytis and other secondary rot-forming fungi such as Cladosporium. Its unique mode of action makes it a perfect addition to your resistance management tool box. PH-D features a 4-hour re-entry interval (REI) and a zero-day PHI, and can be applied preventatively in grapes when climatic conditions exist for the development of disease infection.

Don’t stand for late-season disease in your vineyard. With UPL, you can count on dependable disease control and a staff dedicated to keeping your vineyard protected all season long. To learn more about the UPL portfolio of crop protection products, contact your local UPL sales representative or visit the company website.

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