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Inherited old plum trees with brown rot and black knot

Posted by Mad.Hatter 6b (My Page) on
Sat, Jul 20, 13 at 1:55

Hi there,

This is my first post so i hope i am following the guidelines.

Anyways, so we moved into a property about 4 years ago. It was an old Italian couples home. Part of the reason we chose it was because it had a garden plot and many different fruit trees (i will post separate questions for those). There was two plum trees. At the time i did not think to get the common or latin names of the trees.

Anyway, since the year we moved in i have not eaten a single plum due to numerous plant diseases. I have battles black knot every year, to the point where the tree now looks like ridiculously strange. I have been cutting the limbs off below where the infected branch was which has resulted in the loss of some major branches and a strange growth pattern. One of the trees contracted black knot near the base of the trunk and i didnt think all the hassle was worth trying to surgically dig in around it to prevent it constricting the trees vascular system. I usually burn the removed parts, but there must be other trees in the area that have it as it comes back every year relentlessly.

Secondly, is the brown rot. This hits hard right around now. It has rained quite heavily infrequently. We had a rain fall that was a record for the amount we received, even surpassing a previous hurricane. Anyway, literally almost every plum is covered with this stuff. I know i should be getting rid of the infected ones but its just about all of them, and i cant even reach the highest branches as the tree is well established and the massive pruning i have taken to it has caused it to skyrocket for the heavens.

I guess my question to those familiar with plums is: is it worth it? Should i cut them down? or is there any hope? In ontario we have strict regulations or fungicides, herbicides, and pesticides. So those are out of the picture. Pretty much all i have left is dormant or horticultural oils. To my knowledge they wont protect from black knot or protect the fruit. Can sulfur be applied to the fruit when the tree has leafed out already?

I can post pictures of the tree to display some of the features if it better helps to diagnose treat. The fruits usually start to produce this yellowish sap then go all moldy looking. The black knot, is well black knot. Brown growth that turn to black. I sterilize between cuts.


PS. There will be other question to follow in regards to some seriously huge apricot trees with canker as well.

Follow-Up Postings:

RE: Inherited old plum trees with brown rot and black knot

Once black knot is set in the trees it is difficult to control and all you can do is cut it out the moment you see it and spray the wounds with chlorathalinal. Cut deep and clean to unstained wood.

Getting fruit will probably require 2-4 sprays a season with the right materials at the right time.

RE: Inherited old plum trees with brown rot and black knot

Unfortunately here in Ontario we have quite strict regulations on pesticides, herbicides, and fungicides. It is the brown rot that really gets the fruit. Im not sure what i can do to quell it besides a dormant spray or serenade.

I suppose that at this stage the tree may be so worn down and infected it may not be worth it. Is there a limited time span on plum trees?

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