Cinnabar Polypore on fruit trees - how to treat

fredh

I have what looks like Cinnabar Polypore conks growing on last year's pruning cuts on Sweet Cherry trees. The trees seem to be otherwise healthy. What is the best thing to do? I want to physically remove the conks to prevent further spread. Should I prune out some more wood and apply a fungicide - if so what? Obviously copper-based fungicide is a possibility but I can't find any info as to what other fungicides might be more specific or effective - also whether something systemic is needed.

Sean Freeman

Fredh, my advice to you is to focus on maintaining and improving the health of your trees rather than what is to me a somewhat pointless activity of trying to workout what chemical is going to kill Pycnoporus cinnabarinus.

As a plant pathogen Pycnoporus cinnabarinus is not generally regarded as being capable of overwhelming healthy trees. We generally encounter it as a saprophite, rather than a parasite...ie colonises deadwood and digests damaged compromised and dysfunctional wood tissues. It certainly has been noted by CSIRO in commercial timber crops as a pathogen, but not certainly not one of the worst.

Possibly there was a large volume of fungal spores in the atmosphere at the time of your pruning....nearby deadwood?

I would suggest getting your soil tested for basic indicators of physical, chemical and biological health...boost the soil biology, and unless your trees have an underlying health and vigour problem they should be capable of out-growing the decay fungi.

For future pruning I would suggest you investigate the benefits of applying treatments of antagonistic fungi such as Trichoderma sp...also ensure that general good hygene practices are being followed during pruning works.

Eric Frei

Source: Pests & Diseases | Management of Stone Fruit Diseases SA

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fredh

Thanks for the above responses. Sean - you are right about the probable cause - there was a pile of prunings nearby which didn't get burned in time when the fires season abribtly started a month early. This growth can be seen on any pruning which get inadverently left behind but I've never seen it on a live tree. I am reassured to accept that it is probably only attacking dead wood.

As I recall the weather was hot and dry when the pruning was done and the painting was done promptly - maybe sunburn was part of the cause and they got infected later - most of the infected spots are open to full sun.

The trees in general are bursting with vigour but the pruning method, which has not given any problems over many years now, requires that vertical limbs get severely shortened and a stump is always left so that the main part of the tree (which has really been converted into a bush) won't get infected if the original cut does. Anyway there's always going to be a stump - you couldn't ge the saw into the crotch even if you wanted to.

BTW - congrats to all involved - what a fantastic site.

I'm not sure on the painting or not painting debate - so far I have always painted bigger cuts.

What I think I'll do is, when there promises to be a run of fine weather (and before any more other pruning):

1. Remove the conks and take them away and burn them.
2. Likewise any trash lying around.
3 Where the conk was on a stump:
a: shorten the stump another inch
b: apply something fungicidal
c: ? paint maybe.

I use WD40 a lot to disinfect snips etc - I'm thinking I may put that on - especially if there is dead dry wood there - it should soak in well.

Maybe it would pay to vary the approach across a few trees - see what works and redo the others that way if they get reinfected.

Just a note on cherry trees - the main things we fear from pruning wounds are bacterial canker (pseudomonas syringae) and silverleaf (chondrostereum purpureum - a fungus) - so far I've escaped both, the key approach being to only prune actively growing trees in fine weather and to paint all bigger cuts.

Any improvements on the proposed approach?

Eric Frei

You can read this thread.

In the second post is some PDF's read them.

Trichoderma | wound dressing | wound painting | Biological controls

I understand that orchardists use wound paint and spraying often.

A few of the issues with why wound paints fail long tem is, tree or environmental moisture cannot and does not drop below 20% to stop fungi and re-application. We cut, paint with copper oxychloride. Immediate protection but for how long? Now in orchards they do not prune accurately, in fact they get mechanical pruning machines and drive down the isle and whack the lot of them.

However there's a spraying regime, they spray for all sorts of stuff, all the time so the prevalence of fungi is low and the chemical reapplication is high.

Also it's a crop, has a use by date and succession planting is planned.

Sounds to me like you have some sort of pollard thing going on, best option if so. watch the fruiting cycle, some fruit on current years growth and some fruit on 2 years growth and so on, but as we dont have fruit tree (cherry especially) I'm not sure of the fruiting cycle. When trees are grown for fruit they are exempt from AS4373 as far as pruning standards go, you prune for productivity and access (picking the fruit).

In amenity arboriculture if a large dia cut was made and painted, who's coming back every 3 months and repainting? So over say 4 years of open wound the fungi wins.

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