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trio of sick Tart cherry trees #923969

Asked January 27, 2026, 4:42 PM EST

Hi there! I have 3 beautiful, mature and bountiful tart cherry trees who came down with black knot last year. I trimmed off afflicted branches but apparently I didn't get them all because this past year the black knot came back with a vengeance. Is there anything I could do to save them? I was thinking of pollarding them and treating with a systemic fungicide(?) If I remove them is there any danger of spreading black knot to new trees? I'm open to any and all ideas. Thank you for your time and consideration of our dilemma, Sincerely, Jo Schultz

Erie County Ohio

Expert Response

Established orchards or backyard trees should be scouted or examined each year for the presence of black knot, and infected twigs should be pruned out and destroyed or removed before bud break. Chopping prunings with a flail mower (to strip infected bark and knots from wood) is an alternative method of destroying infected prunings if burning or burying is impractical. It is important to prune at least 2 to 4 inches (5 to 10 cm) below each knot because the fungus grows beyond the edge of the knot itself. If pruning is not possible because knots are present on major scaffold limbs or the trunk, they can be removed by cutting away the diseased tissue down to healthy wood and out at least ½ inch (1 cm) beyond the edge of the knot.

Pollarding may be an option. Here are 3 links:

https://ohioline.osu.edu/factsheet/plpath-fru-31

https://extension.umn.edu/plant-diseases/black-knot

https://extension.psu.edu/stone-fruit-disease-black-knot/

Tom deHaas

An Ask Extension Expert Replied January 27, 2026, 6:18 PM EST

Question answered and closed

Thomas deHaas

OSU Extension - Erie County Agriculture/Natural Resource Educator

2900 Columbus Ave.

Sandusky, Ohio 44870

“During the Growing Season I will be in and out of the office on site visits. I will return phone calls and e-mails within 24 hours, except weekends.”

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An Ask Extension Expert Replied January 31, 2026, 8:10 AM EST

trio of sick Tart cherry trees #923969

Expert Response

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