Willow with Anthracnose - Will it spread over winter?

[William Clifford]

Will Anthracnose spread through a Willow at this time of year whilst the tree is dormant?

 

I think the spread is too far gone and likely in the main stem, but was hoping to work on it when it comes into leaf to see what may be surviving and cut out any infection.

 

Thanks.

 

[JaySmith]

Have you got an pics? Anthracnose normally lies dormant doing winter months in the buds and twigs as well as fallen wood and leaves. Come the spring it then flourishes. My understanding is that it’s normally confined to rigs and leaves as opposed to the colonisation of timber. Anthracnose (or version of) is often cosmetic as opposed to fatal but can lead to the demise in all ready stresses trees or help with secondary colonisation such honey fungus

[openspaceman]

3 hours ago, JaySmith said:

Have you got an pics? Anthracnose normally lies dormant doing winter months in the buds and twigs as well as fallen wood and leaves. Come the spring it then flourishes. My understanding is that it’s normally confined to rigs and leaves as opposed to the colonisation of timber. Anthracnose (or version of) is often cosmetic as opposed to fatal but can lead to the demise in all ready stresses trees or help with secondary colonisation such honey fungus

Yes I thought the fungus largely re infects the current years growth from spores produces from the previous year's growth.

[William Clifford]

No, I haven't got any pictures. It's a domestic garden, 'pollarded' Willow around 15ft or so high with a 2.5ft ish diameter stem. The anthracnose is clear in my mind from the reported black twigs / patches on twigs, and curling and loss of leaves in early summer. Then what I can see of it now I would have diagnosed Anthracnose anyway. I came across a couple of trees 2 summers ago that were infected, and this one has been apparently showing signs since last summer. They're all within 5 miles of each other.

 

The other two trees that I came across we got to within a couple of weeks to see what we could prune out in the summer, but whilst there were live patches in one of the trees, it had spread very quickly. The necrosis and staining had gone down into the framework and main stem. The other tree was completely dead. Both had been 'pollarded' in the past. I put the staining down to the Anthracnose, it didn't look the same as dead / dying wood. More like chasing Silver Leaf staining out of a Cherry if you know what I mean? The dead Willow was just infected down to the collars of the regrowth, but it was (albeit much loved by the client), an old and rotting Willow pollard.

 

The client had already cleaned up any twigs and leaves when I visited yesterday. I guess the question really is whether to prune out now or in spring when we can see if / what comes back. If we do it now, I don't think there's going to be anything left. We could just re-pollard and possibly spray in Spring if it came back? Or Cut out anything that isn't shooting or is heavily infected in Spring, and possibly spray to limit the spread?

 

Thanks for the responses.

[JaySmith]

Normally the anthracnose is confined to the leaf and twigs, I’ve not seen it on main stems like you describe. As we know it lies dormant in the twigs/buds etc it may be worthwhile to remove the re growth (repollard) at this stage. This may then do one of two things, the tree puts on re growth in new growing season for essential processes or it sends it into further decline as it’s resources are insufficient for the tree to continue. Shame you haven’t got any pics as I’d be interested to see. Tricky decision but if the re growth is already compromised then repollarding at this stage may be a suitable option? Have you sounded the main stem with a hammer to see if there is further degradation or decay in the main stem, there could be other things at play in conjunction with the anthracnose. I’m not too sure about spraying the growth as I have no experience of this, I know companies such as Bartletts offer this but am unsure of success rates etc

[William Clifford]

I'll give the client the info and let them make the decision! There's pro's and con's to either way we go really. If spraying was 100% effective for example, it'd probably be best to go that route and prune to give any surviving shoots a chance. If it isn't (and I imagine it isn't), then probably best to re-pollard. I've not sounded the stem but I did have a good look and couldn't see anything else going on. It's young-ish relatively speaking, not full of cavities or anything. When I say 'on the stem' I meant the odd shoots growing straight out of the stem becoming infected and because of how the previous one had died back into the thicker wood and the staining went through it, I had put the 2 together. Possibly incorrectly and something else was also happening? The one we took down previously was stained all the way down to a couple of feet from the floor and seemed to start from the tips. There could have been something else going on in that instance, though I don't know what. I've known the tree for years, also re 'pollarded' it some years ago and it has always been a vigorous tree - until the summer when I got a call because it wasn't looking well and declined extremely quickly.

 

Thank you for the help 👍