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Plum fruit is Oozing Sap #797945

Asked June 26, 2022, 4:06 PM EDT

My community garden has a young plum tree -- about 3 years on site. This year, I noticed that some of the plums are drying up and turning hard black while other plums are developing normally. Thank you for your help with this.

Hennepin County Minnesota

Expert Response

You can see the little sugar crystals.  I believe there are some plums that are still very green.  I am seeking to know the cause of this fruit issue.  Hopefully, it won't impact our entire plum crop this year.

The Question Asker Replied June 26, 2022, 4:57 PM EDT
Hi there, thanks for your question. I'm currently consulting with colleagues on your question and will reply once I hear back. Thanks for your patience!
Catherine B University of Minnesota, Master Gardener Replied June 29, 2022, 11:09 PM EDT
Hi, a couple of follow-up questions:
1. Have you noticed brown spores on any of the fruit?
2. What do you see on the inside if you open up the dried up/damaged fruit?

Catherine B University of Minnesota, Master Gardener Replied June 30, 2022, 12:16 PM EDT

I have not noticed brown spores on any of the fruit.  I also looked at our sour cherry tree and found similar issues.  Some of the cherries look like just the seeds with a black leather coat.  I picked some of them but did not photograph them. 

The Question Asker Replied June 30, 2022, 7:40 PM EDT

I recall seeing some webs on one of the branches and spraying the hose around the tree in May or so...

I also have been leaving quack grass encircling it about 3 feet from the trunk--a sort of mulch if you will.  Hopefully, that isn't our undoing for these trees.

The Question Asker Replied June 30, 2022, 7:44 PM EDT
Hi, thanks for your patience! After consulting with an Extension Educator, the issue you're facing may be brown rot. It's been known to affect plums and cherries and is caused by the proliferation of fungi, resulting in "mummified" fruit.

Take a look at the link below to see if this matches what you're noticing with your trees:
https://conservancy.umn.edu/bitstream/handle/11299/198102/Stone%20Fruit%20Home%20IPM.pdf?sequence=1&isAllowed=y

If it is brown rot, the link also has some information on how to manage the disease (you'll want to clear any plant debris under your tree).

Let us know if you have any questions, thanks!
Catherine B University of Minnesota, Master Gardener Replied July 04, 2022, 10:49 PM EDT

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