# Winter & frost injury

- URL: https://backyardgrapes.com/diseases/winter-injury/
- Category: Disorder
- Affects: Trunk & cordons, Shoots & canes
- Severity: high
- Favored by: Hard winter freezes, sudden cold snaps after warm spells, tender late-season growth, low-lying frost pockets, and cold-tender varieties.
- Easily confused with: Eutypa dieback, Botryosphaeria dieback, Esca (trunk disease)

**Summary:** Cold damage that kills buds, splits bark, and kills trunks — a frequent look-alike for trunk disease.

**What to look for:**
- Buds that fail to break in spring, or patchy, delayed, uneven bud break.
- Split, cracked, or blackened bark on the trunk and cordons after a hard freeze.
- Dead cordons or whole trunks, with new growth only from the base.
- Spring frost: newly emerged green shoots suddenly blacken and wilt.

**Treatment — Cultural / prevention:**
- Grow varieties and rootstocks rated for your winter lows — the most important decision.
- Train two or more trunks per vine as insurance; if one dies back, another carries on.
- In cold regions, hill soil over the graft union in late autumn and remove it in spring.
- Avoid late-summer nitrogen and late watering that push tender growth into autumn.
- Delay pruning until late winter, and after damage, retrain a new trunk from a healthy sucker.
- Site vines off low frost pockets; cold air pools in dips and hollows.

**Treatment — Organic / low-toxicity:**
- No treatment reverses freeze damage — recovery is about retraining live wood and preventing the next injury.

Winter and frost injury is pure cold damage, but it earns a place here because the
aftermath — dead spurs, dead arms, split bark, patchy bud break — mimics the wood-rotting
trunk diseases so closely that growers routinely confuse the two. Two things help tell them
apart: winter injury appears suddenly across a vine (or across many vines at once) right
after a known cold event, and a cut through cold-killed wood shows a browned ring or a clean
dead zone rather than the wedge-shaped canker of a trunk-disease fungus.

There's no cure for tissue the cold has already killed, so the whole game is prevention and
recovery. Choose varieties hardy enough for your winters, carry more than one trunk per vine
as insurance, protect the graft union in cold areas, and avoid the late feeding and watering
that leave a vine soft going into winter. After a bad freeze, retrain a new trunk from a
living sucker rather than trying to save damaged wood. Spring frost — which blackens
newly emerged shoots — is a related risk best managed by site selection and, in small
plantings, covering vines on frost nights.

**Image credits:**
- Young shoots browned and collapsed after a spring frost (South Tyrol, April 2016) — [Photo: Südtiroler Beratungsring für Obst- und Weinbau, Wikimedia Commons](https://commons.wikimedia.org/wiki/File:2016_Sp%C3%A4tfrost_%C3%9Cberetsch_(10).JPG) (CC BY-SA 3.0)
- Garden grapevine after a late-April frost: new shoots shrivelled and browned — [Photo: StromBer, Wikimedia Commons](https://commons.wikimedia.org/wiki/File:Frostschaden2017April20.JPG) (CC0)

**Sources:**
- [Assessing Grapevine Bud Damage](https://extension.umd.edu/resource/assessing-grapevine-bud-damage) — University of Maryland Extension
- [Winter Cold Injury](https://ag.missouristate.edu/Winery/Hardiness/winter-cold-injury.htm) — Missouri State University, Darr College of Agriculture
- [Introducing A Grower-Friendly Tool for Assessing Grapevine Cold Damage Risk](https://extension.psu.edu/introducing-a-grower-friendly-tool-for-assessing-grapevine-cold-damage-risk) — Penn State Extension
- [Update on Potential Cold Injury to Grapevine Buds](https://blogs.cornell.edu/flxgrapes/2022/01/24/update-on-potential-cold-injury-to-grapevine-buds/) — Cornell Cooperative Extension, Finger Lakes Grape Program