Phomopsis cane & leaf spot
Phomopsis viticola
Black specks and cracked bark on the base of shoots, plus small spots on lower leaves.
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Description
Phomopsis (Phomopsis viticola) mostly damages the lower parts of shoots early in the season, when cool wet weather coincides with tender new growth. Its infections happen early but the tell-tale bleached, black-speckled canes often aren’t obvious until the following dormant season.
The disease lives in old infected wood, so pruning it out is central to control. Because infection is tied to early-season rain on young shoots, sprays are only useful in that narrow early window.
What to look for
- Tiny black spots with yellow halos on the lowest leaves and along veins.
- Black streaks and cracked, scabby bark on the base of green shoots.
- Weakened, brittle canes that can break in wind.
- Bleached canes dotted with black specks (fruiting bodies) after winter.
Treatment options
Cultural & prevention
Start here — habits that stop problems before they spread.
- Prune out and destroy old infected wood and bleached, speckled canes.
- Retain only healthy canes at pruning.
- Improve airflow to speed drying of new shoots.
Organic / low-toxicity
Gentler sprays and biologicals for active outbreaks.
- Copper or sulphur sprays as shoots begin to grow in cool, wet springs.
Conventional fungicide / pesticide
For severe cases. Always follow the product label.
- Protectant fungicides (e.g. mancozeb) at the 1–3 inch and 5–8 inch shoot stages.
Sources
This entry is based on the references below. Read them for full detail and for spray timings and rates valid where you live.
- Phomopsis Cane and Leaf Spot of Grape (PLPATH-FRU-47) — Ohio State University Extension (Ohioline)
- Phomopsis Cane and Leafspot - Grape Pest Management Guidelines — UC IPM
- Phomopsis Cane and Leaf Spot of Grape — Iowa State University Extension and Outreach