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Pls help ID

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Pls help ID

Postby Greenthumb » Apr 27, 2008 5:55 am

My neighbour has this tree in their backyard. Please help us ID what exactly is growing on the branches and what to do to iradicate. Thx very much.
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Postby Ian » Apr 27, 2008 7:50 am

Looks like Black knot fungus Apiosporina morbosa.
There is no chemical control other than pruning off the affected twigs to lessen the spread of the disease.

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Postby GardenGeek » Apr 28, 2008 12:39 pm

I second Black Knot. We have a MayDay in our yard and I just cut out two branches that were affected this spring.

I was told to cut the affected branch back, but to make sure that you get rid of at least 8 inches of good branch so it stays away. Best to prune it in the colder months or spring time so that the fungus doesn't spread into open branches. Try to cut it out with pruners rather than a saw as the shaking of the tree could also cause some of the fungus to go into the air.

Also, throw the branch out in the trash (bag it). Do not burn it as this might also cause it to go back into the air.

When we first moved into our house, or poor Mayday had a lot of it. We cut it out the first year, then only had two branches affected last year.

After you cut it out, leave it for the summer, and when the leaves fall off in the fall, check it again. Black Knot is easier to detect when there is nothing else on the tree.

Edited to add: Black Knot doesn't affect every type of tree. The most common types are Cherry, plum and chokecherry (or trees closely related to those - like MayDays).

Here is a site with more info: ... _knot.html

Best of luck.

"My green thumb came only as a result of the mistakes I made while learning to see things from the plant's point of view." ~H. Fred Ale
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Postby Irondog » Apr 28, 2008 5:17 pm

I have nothing hugely valuable to add... I think it is Black Knot too... but a funny aside, our Cherry Tree in Nova Scotia had this disease when I was a kid, and I used to ask my dad why dogs kept pooping in the tree.

We eventually had to cut it down. :(

Good luck with getting it taken care of though!
Julie and her Lawn Trolls (Pookie and Karmalina)
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