Black Growths on Tree
These black spots or growths are on my tree in the front yard. How do I treat them?
The black growths on the stems are caused by black knot fungal disease. This disease attacks 24 species of Prunus, but is most often found on wild and cultivated varieties of plum and cherry.
The stem swellings, or 'knots', can girdle (stop flow of water and nutrients) limbs and stunt the plants growth. The fungus overwinters in these knots, then after a period of warm and wet weather in the spring the disease spores are released to infect other plant tissue or susceptible plants. This usually happens about the time of bud break.
Prune out and destroy limbs bearing knots now, before bud break, to prevent new infections. Cuts should be made at least 6-8 inches BELOW the knots. Disinfect your pruning tools after every cut to prevent spreading the disease. Rubbing alcohol or a solution of one part bleach to nine parts water will work too. Clean your tools after pruning to minimize the adverse effects of bleach. This is the best control THOUGH NOT 100% EFFECTIVE since there are likely other diseased plants in nearby natural and cultivated landscapes that serve as a source of future infection.
Related
Article
Upcoming Live Events
& Webinars
March 27, 2024
FREE WEBINAR
How to Start a Garden for Beginners
Register now
April 3, 2024
Garden Trends
Franklin Public Library, Franklin, WI
April 10, 2024
FREE WEBINAR
Container Gardening Throughout the Year
Register now
April 11, 2024
FREE WEBINAR
7 Steps to Managing Water Where it Falls in Your Yard
Register now
April 17, 2024
Landscaping for Birds:
A Gardener’s Perspective
Glendale, WI
April 18, 2024
Be a Waterwise Gardener
Golden Rondelle Theater, Racine, WI
Register now
April 20, 2024
Pruning Hydrangeas and Other Shrubs
Pasquesi Home & Gardens, Lake Bluff, IL
April 27, 2024
Ridges & Rivers Book Festival
Viroqua, WI
April 28, 2024
Flowering Trees and Shrubs
Ebert's Greenhouse Village, Ixonia, WI
May 1, 2024
FREE WEBINAR
Ornamental Fruits and Vegetables
Register now
May 9, 2024
FREE WEBINAR
How to Plant Your Rain Garden
Register now
WATCH ON-DEMAND WEBINARS
Learn More