# Black foot & Petri disease

- URL: https://backyardgrapes.com/diseases/black-foot/
- Scientific name: Dactylonectria, Ilyonectria (black foot); Phaeomoniella (Petri)
- Category: Fungal
- Affects: Roots, Trunk & cordons
- Severity: high
- Favored by: Stress on young vines; infected or poorly grown nursery stock; wet, compacted, poorly drained soils.
- Easily confused with: Esca (trunk disease), Armillaria root rot, Root-knot nematode

**Summary:** Soilborne trunk-disease fungi that rot the base and wood of young vines, causing them to fail in the first years.

**What to look for:**
- Young vines that lag, leaf out weakly, and slowly decline instead of establishing.
- Blackened, sunken, rotted wood and bark at the base of the trunk and root crown.
- Sparse, sunken, or dead roots; a dark stain in the wood when cut open.
- Stunted shoots and small, pale leaves; vines may die within a few seasons.

**Treatment — Cultural / prevention:**
- Start with healthy, vigorous, certified nursery stock — the disease often arrives on weak young plants.
- Plant into well-drained soil; avoid waterlogging and compaction around the crown.
- Reduce transplant stress — proper planting depth, watering, and weed control help vines outgrow early infection.
- Remove and replace vines that fail to establish rather than nursing them along.

**Treatment — Organic / low-toxicity:**
- No cure once established; good soil and low stress are the real defences.

**Treatment — Conventional (chemical):**
- No practical curative spray for home growers; prevention through clean stock and site prep is key.

Black foot and Petri disease are the young-vine members of the grapevine trunk-disease
family — the same broad group as esca and the diebacks, but striking in the first few years
after planting rather than in old wood. The fungi rot the base of the trunk and the roots
(black foot) or plug and stain the young wood (Petri disease), so an affected vine simply
never gets going: weak shoots, pale leaves, and a slow slide toward death.

Because the infection often arrives on stressed or already-infected nursery plants and is
made worse by poor soil and transplant stress, the best defence is at planting time: buy
strong, clean stock, put it in well-drained soil, and keep the young vine unstressed so it
can establish quickly. There's no rescue spray, so a vine that refuses to establish is
usually best replaced rather than nursed.

**Image credits:**
- Longitudinal section of a rootstock base showing black-foot wood discoloration — [Photo: P. D. Abeywickrama et al., Pathogens (MDPI, 2021)](https://doi.org/10.3390/pathogens10121555) (CC BY 4.0)
- Longitudinal section of a grapevine rootstock showing dark-brown to black discoloration characteristic of black-foot disease — [Photo: C. Agusti-Brisach and J. Armengol (Phytopathologia Mediterranea, 2013), Phytopathologia Mediterranea (Firenze University Press)](https://oajournals.fupress.net/index.php/pm/article/view/5517) (CC BY 4.0)

**Sources:**
- [Grape (Vitis spp.) - Black Foot Disease](https://pnwhandbooks.org/plantdisease/host-disease/grape-vitis-spp-black-foot-disease) — Pacific Northwest Pest Management Handbooks (Oregon State, Washington State, Univ. of Idaho)
- [Black-foot disease of grapevine: an update on taxonomy, epidemiology and management strategies](https://oajournals.fupress.net/index.php/pm/article/view/5517) — Phytopathologia Mediterranea (peer-reviewed review)