Black Knot

Disease of apple and cherry.

Oct 1, 2020

Fort St. John, along with many other areas of British Columbia and Alberta, is experiencing a Black Knot fungus infestation. Black Knot, or Apiosporina morbosa, is a deadly tree fungal disease that attacks predominately plum and cherry trees. The fungus can put the tree’s health at risk, and without treatment, can eventually kill the tree.

Learn more at www.fortstjohn.ca/black-knot.

Jul 19, 2009

Hi, I'm James Blake, Director of the Clemson Extension Home & Garden Information Center. Today we're looking at a disease known as black knot.

Were along the edge of the Clemson University Experimental Forest looking at a wild black cherry with some strange black growths on the twigs. This disease is known as black knot caused by the fungus Apiosporina morbosa. It infects cherries and plums.

The fungus can infect green shoots but can also enter through wounds. Infection leads to these long, rough galls on the twigs and branches and can even infect the trunks of trees. These galls can range in size from an inch to more than 20 inches. These galls can form on one side of a branch or can encircle the entire branch. When infection circles the entire branch or twig it leads to death beyond the point of the gall.

The duration of the complete cycle of this disease is normally 2 years. After infection occurs in the spring, swellings appear in the fall on the current seasons growth. After being dormant during the winter, the fungus resumes growth in spring and the bark splits revealing olive-green fungal tissue covered with spores. These galls turn darker during the summer and fall and then turn hard and black during the winter. In the following spring, another spore stage is produced on the black knots that starts new infections.

Management of black knot begins with the selection of resistant cultivars. If any galls form on susceptible varieties these galls should be removed 4 inches below the point of the gall. All infected plant material should be destroyed.

For more information on gardening, landscaping, insect and disease problems on your plants, visit the Home & Garden Information Center web site at www.clemson.edu/hgic

May 26, 2020

In this video, plant pathologist Ed Zaworski discusses Black knot of plum and cherry trees. Check it out!

Published on Jan 7, 2013

Buckthorn versus cherry trees - black knot fungus grows on cherry trees but not on buckthorn. Learn to Identify and remove black knot fungus from native cherry trees in your woodland. Get rid of buckthorn - not cherry trees

Published on Mar 27, 2012

NOTE: 4 days after visiting the shelter good weather came by and started to really melt. Visited a forest that was facing South and not North like my shelter. What a difference. I fell upon something I felt I could share.

Showing that this fungus is not Chaga even though they look similar..Please visit our website http://bushcraftbartons.com/

Uploaded on Feb 25, 2010

Dr. Scott Enebak Auburn University School of Forestry & Wildlife Sciences, discusses the characteristics of common forest diseases.