Black Knot

Apiosporina morbosa

38 host plants · Fungal

Last updated

Data Maturity Structured

This profile synthesizes data from multiple published sources. Expert field review is in progress.

Large, black, warty growths develop on cherry or plum branches. Prune out knots below visible symptoms and destroy material. Scout adjacent areas.

Remove and destroy knots when observed on economically important crops. Scout adjacent orchards and wooded areas each winter for infected Prunus spp., which can act as a reservoir of spores.

Quick Reference

Agent Type
fungal
Causal Agent
Apiosporina morbosa
Host Plants
38
Favorable Conditions
Spring ascospore release from fruiting bodies on dead infected wood; infectio...

Management

Vulnerability Window

Spring (bud break through early summer, BBCH 10-20). Young shoots most susceptible.

What Triggers Infection

Spring ascospore release from fruiting bodies on dead infected wood; infection occurs during early shoot growth.

Cultural Controls

  • Remove and destroy knots when observed on economically important crops.
  • Scout adjacent orchards and wooded areas each winter for infected Prunus spp., which can act as a reservoir of spores.
  • Remove branches 2 to 3 inches below knots and burn or bury infected debris.

Host Plants (38)

Betula lenta Sweet Birch, Cherry Birch, Black Birch Malus robusta Cherry, Crabapple Prunus americana Wild Plum American (Red) Plum August Plum, Goose Plum Prunus armeniaca Apricot Prunus avium Sweet Cherry Prunus besseyi Sand Cherry, Western Sand Cherry Prunus blireiana Blireiana Plum Prunus caroliniana Carolina Cherrylaurel American Cherrylaurel Prunus cascade Prunus cascade Prunus cerasifera Cherry, Plum Prunus cistena Purpleleaf Sandcherry Redleaf Sandcherry Cistena Sandcherry Cistena Plum Prunus dream Prunus dream Prunus emarginata Bitter Cherry, Wild Cherry, Quinine Cherry Prunus first Prunus first Prunus fruticosa Steppe Cherry, European Dwarf Ground Cherry, Mongolian Cherry Prunus glandulosa Dwarf Flowering Almond Prunus ilicifolia Hollyleaf Cherry, Holly-leaved Cherry Prunus laurocerasus Cherry, Laurel Prunus lusitanica Portugal Laurel Prunus maackii Amur Chokecherry Amur Cherry, Manchurian Cherry Prunus mume Japanese Apricotc Japanese Flowering Apricot Japanese Flowering Plum Prunus newport Newport Flowering Plum Prunus okame Okame Flowering Cherry Prunus padus European Birdcherry Common Birdcherry Prunus prostrata Rock Cherry, Mountain Cherry Prunus sargentii Sargent Cherry, Sargent's Cherry Prunus serotina Black Cherry, Rum Cherry Prunus serrula Birchbark Cherry, Paperbark Cherry, Tibetan Cherry Prunus serrulata Japanese Flowering Cherry Prunus snow Prunus snow Prunus subcordata Klamath Plum, Sierra Plum, Pacific Plum Prunus subhirtella Higan Cherry Prunus subhirtella var. autumnalis Autumn Flowering Higan Cherry Prunus tai Prunus tai Prunus virginiana Prunus virginiana Prunus virginiana var. demissa Western Chokecherry Prunus virginiana var. virginiana Common Chokecherry, Eastern Chokecherry Prunus yedoensis Yoshino Cherry, Somei-yoshino Cherry, Tokyo Cherry