Backyard Grapes Identify & treat grapevine problems
Fungal high severity

Black foot & Petri disease

Dactylonectria, Ilyonectria (black foot); Phaeomoniella (Petri)

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

Longitudinal section of a rootstock base showing black-foot wood discoloration Photo: P. D. Abeywickrama et al. Pathogens (MDPI, 2021) 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) CC BY 4.0

Description

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.

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 options

Cultural & prevention

Start here — habits that stop problems before they spread.

  • 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.

Organic / low-toxicity

Gentler sprays and biologicals for active outbreaks.

  • No cure once established; good soil and low stress are the real defences.

Conventional fungicide / pesticide

For severe cases. Always follow the product label.

  • No practical curative spray for home growers; prevention through clean stock and site prep is key.

Sources

This entry is based on the references below. Read them for full detail and for spray timings and rates valid where you live.

  1. Grape (Vitis spp.) - Black Foot Disease — Pacific Northwest Pest Management Handbooks (Oregon State, Washington State, Univ. of Idaho)
  2. Black-foot disease of grapevine: an update on taxonomy, epidemiology and management strategies — Phytopathologia Mediterranea (peer-reviewed review)