"Spider" wrote in message ...
On 01/02/2015 16:22, FrankB wrote:
"Spider" wrote in message
...
On 01/02/2015 15:47, FrankB wrote:
Yesterday I realised I'd made a serious error in sawing off a major
branch )about 5" thick) of a mature plum tree which had been giving the
tree
a lopsided look. I only found out today that you should never prune a
plum
tree in winter due to susceptibility to silver leaf disease. If I treat
the
cut tomorrow by painting with Bayer 'seal and heal' fungicide will that
prevent the problem arising or will 48 hours exposure to the elements of
the
wound already be too late?


It's already potentially too late. Anything nasty will have already
entered the wound. Using a wound treatment now will only seal disease
in. I suggest you wait until the summer and see how the tree reacts.
You may be lucky.

This stuff is a fungicide so by painting it on the wound any spores that
have already alighted there I would have hoped woud be wiped out or at least
rendered inactive. I mean it's possible that silver leaf spores could have
alighted on the wound seconds after cutting. So are you suggesting that the
fungicide sealant has little purpose anyway?



It's the "seal" part of the "seal and heal" which is the problem. If
you apply 2 days after the cut, you may be sealing disease in. Below is
a link to Bayer's description of its product. It is implicit that you
apply the paint immediately (though I would still have my doubts).
However, it also suggests you cut into the branch again to gain a clean
cut surface. It was on my mind to suggest this but, if you made the cut
correctly in the first place, you would have cut back to the 'collar'
(raised and often creased area between the trunk and branch), which
means there is no more wood left to cut out.

http://www.bayergarden.co.uk/Product...-and-Heal.aspx

Trouble is it's not my tree but a friend whose garden I've been slowly restoring. He won't be best pleased if I tell him I may have killed his plum tree. I'm wondering whether I should warn him in advance.

I''ve got about ½" of projected branch left that I can further saw back. The stuff I'm getting tomorrow isn't quite the same as your link but according to Bayer serves the same purpose from the description (below links). So I'll try that tomorrow and paint immediately. .

Here - http://tinyurl.com/n9lenaz
and
Here - http://tinyurl.com/q8h8uhc