With cooler weather comes a new host of concerns for grape growers. Many diseases go dormant over the summer only to reappear as the season changes. Common fungal infections such as Botrytis bunch rot can resume growth and spread throughout your vineyard just before harvest. Preparing for the infection and providing the right treatment is key for keeping damaging diseases at bay.

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 brings an expanded portfolio of innovative solutions to keep your vineyard running strong, including ELEVATE^® and PH-D^® Fungicides for late-season Botrytis.

ELEVATE Fungicide (FRAC group 17) provides locally systemic activity and is excellent at controlling Botrytis bunch rot and powdery mildew. ELEVATE can provide post-infection activity when applied early in the disease life cycle and has been shown to enhance the efficacy of other fungicides when used in a powdery mildew spray program. With a zero-day pre-harvest interval, you can use ELEVATE up to the day of harvest.

PH-D Fungicide (FRAC group 19) is a broad-spectrum fungicide that offers a high degree of Botrytis and powdery mildew control in grapes. Its zero-day pre-harvest interval and 4-hour REI make it an excellent option for disease management sprays close to harvest. PH-D is the only product in FRAC group 19, making it an important resistance management tool.    

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 www.upl-ltd.com/us.

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