Troubleshooting
Concord Grape problems — and how to fix them
Concord Grape (Vitis labrusca 'Concord') is generally forgiving once you match its basics, but a few issues come up again and again. Here is what each one looks like, why it happens, and the fix.
Black rot
A common fungal disease of labrusca grapes causing shrivelled, mummified berries. Prune for airflow, remove mummies, and apply preventive fungicide from bud break in wet seasons.
Powdery and downy mildew
Favoured by humid, crowded canopies. Open up the canopy by pruning, space shoots, and treat susceptible vines preventively.
Uneven ripening / failure to colour
From overcropping, shade, or too much nitrogen. Thin clusters, expose fruit to sun, and avoid heavy feeding.
Birds and wasps on ripe fruit
Concord's strong scent draws pests at ripening. Net clusters and harvest promptly once fully coloured and slip-skinned.
Prevent concord grape problems before they start
Most concord grape issues are care-mismatch, not bad luck. Dial in the basics:
Looking for concord grape in general rather than its problems? Read the full concord grape care guide — light, water, soil and feeding.
Concord Grape problems — FAQ
Why is my concord grape black rot?
A common fungal disease of labrusca grapes causing shrivelled, mummified berries. Prune for airflow, remove mummies, and apply preventive fungicide from bud break in wet seasons.
Why is my concord grape powdery and downy mildew?
Favoured by humid, crowded canopies. Open up the canopy by pruning, space shoots, and treat susceptible vines preventively.
Why is my concord grape uneven ripening / failure to colour?
From overcropping, shade, or too much nitrogen. Thin clusters, expose fruit to sun, and avoid heavy feeding.
Why is my concord grape birds and wasps on ripe fruit?
Concord's strong scent draws pests at ripening. Net clusters and harvest promptly once fully coloured and slip-skinned.