Grape

Table of Contents

1. Berry Moths
2. Black Rot
3. Grape Flea Beetles
4. Downy Mildew
5. Powdery Mildew
6. Related Links

Berry Moths

Berry moths are a problem only in areas where grapes are grown commercially. The adult is a 6 mm brown-bodied moth with blue-grey wings that have cream spots near the tips. The larvae are initially cream-coloured with a brown head but become green and then purple when mature. The first generation larvae web together buds, flowers and newly set berries and chew them. The second generation burrow into green berries near the stem. Berries usually shrivel or fall off.

Treatment

Cultural control: Remove nearby wild grapevines. Bury leaf debris.

Chemical control: If wormy fruit has been a problem, spray after blossoming period and repeat as indicated on the product label.For up to date recommendations on pest management options consult local horticulturalists, Master Gardeners or your local garden supply centres.

| Top of Page |

Black Rot

Black rot can be a serious problem on many grape varieties including Catawba, Concord, Agawam and Niagara. Raised black lesions develop on cluster and leaf stems and on new shoots. Infected berries develop a reddish-brown ring and shortly before harvest shrivel into blue-black mummies.

Treatment

Cultural control: Remove infected debris before the start of the growing season. Cultivate early in season to bury infected mummies and remaining debris.

Chemical control: Preventive sprays have to be applied just before, and again shortly after, bloom. For up to date recommendations on pest management options consult local horticulturalists, Master Gardeners or your local garden supply centres.

| Top of Page |

Grape Flea Beetles

The grape flea beetle is a shiny, metallic, greenish-blue beetle that attacks opening buds in spring. It is 4-5 mm long and jumps when disturbed. The adult chews through the ends and sides of swelling buds. Larvae are black-spotted grubs which feed on leaves.

Treatment

Cultural control: Examine vines in May. If practical, knock the adults off into a pail of soapy water.

Chemical control: Examine vines in May (as buds swell) for adults. Spray if numbers warrant. For up to date recommendations on pest management options consult local horticulturalists, Master Gardeners or your local garden supply centres.

| Top of Page |

Downy Mildew

Downy mildew appears early in the season and affects leaves, tendrils, shoots and fruit, covering these with heavy, white, downy fungus underneath and localized pale yellow areas on top surfaces. Fruit clusters may curl or be completely destroyed. The disease is more serious in wet seasons and in sheltered areas with poor air movement.

Treatment

Cultural control: Prune to allow good air movement. Collect and destroy infected plant material. Cultivate in spring to bury any remaining infected tissue. Agawam, Delaware, Fredonia, Niagara and Van Buren varieties are especially susceptible. Plant other varieties to avoid the need for fungicides.

Chemical control: Spray just before bloom but after flower clusters have expanded. Additional sprays may be necessary, depending on weather and disease conditions. For up to date recommendations on pest management options consult local horticulturalists, Master Gardeners or your local garden supply centres.

| Top of Page |

Powdery Mildew

Powdery mildew usually appears later than downy mildew but may be present just after bloom. Blossoms wither and drop, whitish patches appear on upper leaf surfaces in shaded areas of the vine, and fruit may crack and fail to ripen. If the fruit stem is infected, berries drop. Prolonged humid conditions favour its growth.

Treatment

Cultural Control: Prune to allow good air circulation and to reduce shading. Agawam, Buffalo, Concord, DeChaunac, Fredonia, Foch, New York Muscat and Seneca varieties are especially susceptible. Plant more resistant cultivars if possible.

Chemical Control: Spray thoroughly just after bloom (mid-to-late June) and repeat again during the first week of August or when mildew appears. Further applications may be necessary. For up to date recommendations on pest management options consult local horticulturalists, Master Gardeners or your local garden supply centres.

| Top of Page |

Related Links

• Diseases
• Insects
• Grapes
• Master Gardeners
• Landscape Ontario

| Top of Page |