Troubleshooting
Cabernet Sauvignon grape problems — and how to fix them
Cabernet Sauvignon grape (Vitis vinifera 'Cabernet Sauvignon') 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.
Powdery mildew (Erysiphe necator)
White fungal coating on leaves, shoots, and berry skins, causing cracking in severe cases. More resistant than some vinifera cultivars but not immune. Apply preventive sulphur sprays from bud break; ensure canopy airflow through shoot-thinning and hedging.
Delayed ripening / green tannins
Cabernet Sauvignon is late-ripening and needs a long warm season. In cool or short-summer climates, fruit may not fully ripen, producing harsh, pyrazine-heavy wines. Choose a warm, sun-exposed site; consider leaf removal around clusters in August to maximise sun exposure.
Phylloxera (Daktulosphaira vitifoliae)
Root-feeding louse that destroys own-rooted Vitis vinifera. Always plant on phylloxera-resistant rootstock (e.g. SO4, 101-14, 3309C). Own-rooted vines remain viable only in sandy soils where phylloxera cannot establish.
Prevent cabernet sauvignon grape problems before they start
Most cabernet sauvignon grape issues are care-mismatch, not bad luck. Dial in the basics:
- Common vitis vinifera problems — the species this cultivar belongs to
- What's wrong with my plant? — the diagnosis apps compared
- Cabernet Sauvignon grape watering schedule
- Cabernet Sauvignon grape light requirements
- Best soil mix for cabernet sauvignon grape
- Cabernet Sauvignon grape temperature & humidity
- Full cabernet sauvignon grape care guide
Looking for cabernet sauvignon grape in general rather than its problems? Read the full cabernet sauvignon grape care guide — light, water, soil and feeding.
Cabernet Sauvignon grape problems — FAQ
Why is my cabernet sauvignon grape powdery mildew (erysiphe necator)?
White fungal coating on leaves, shoots, and berry skins, causing cracking in severe cases. More resistant than some vinifera cultivars but not immune. Apply preventive sulphur sprays from bud break; ensure canopy airflow through shoot-thinning and hedging.
Why is my cabernet sauvignon grape delayed ripening / green tannins?
Cabernet Sauvignon is late-ripening and needs a long warm season. In cool or short-summer climates, fruit may not fully ripen, producing harsh, pyrazine-heavy wines. Choose a warm, sun-exposed site; consider leaf removal around clusters in August to maximise sun exposure.
Why is my cabernet sauvignon grape phylloxera (daktulosphaira vitifoliae)?
Root-feeding louse that destroys own-rooted Vitis vinifera. Always plant on phylloxera-resistant rootstock (e.g. SO4, 101-14, 3309C). Own-rooted vines remain viable only in sandy soils where phylloxera cannot establish.