Time of year for tree pruning

[aesmith]

Hi,

 

I've generally thought that significant pruning should be done in winter, when the tree's not in leaf and before the buds start to open. However I saw a comment in another thread saying that Cherry should be pruned when in full leaf, so I was wondering if that applies to any other trees.

 

The sort of pruning I'm referring to involves cutting branches from a few inches thick upwards. One example would be after storm damage where I want to cut back to a suitable side shoot. Other examples would be where the branches are crossing. Or where the branches are in the way, or looking top heavy.

 

Trees include Oak, Beech, Ash, Rowan, Cherry (or other Prunus), Sycamore and Maple, Elder, Lilac, Willow.

 

From what I've seen Cherry should be pruned in summer, Lilac immediately after flowering, but are there any others I've named that shouldn't pruned in winter?

 

Thanks,

 

Tony S

[sandspider]

As I recollect, plum trees (prunus sp) shouldn't be pruned in winter due to silver leaf disease?

[farmer rod]

I am happy to be corrected but I was led to believe that cherries should be pruned after flowering, something to do with canker

[woodyguy]

I think the idea is that plums and cherries that are both prone to infections should be pruned when actively growing, so that the cuts heal quickly and are less likely to get infected. But... in reality that could equally apply to any tree and the established wisdom of winter pruning has no real evidence behind it. What is most important is not cutting right back to the trunk and allowing the tree to compartmentalise the cut surface quickly. Some trees like sycamore and birch will "bleed" profusely if cut back in spring when the sap is rising. That's the only problem I've ever come across.

[Paul Cleaver]

- do not prune just as the leaves are opening and just as they are falling generally ok to prune any other time (except on certain species to follow)

I would also avoid pruning in spells of extreme hot and cold weather to avoid sun scorch and frost cracks

 

the best time for pruning prunus trees is mid summer as said - walnuts late summer (bleeding) (other heavy bleeders already covered)

 

oh evergreens are best pruned after the chance of frost to avoid tender new shoots being damaged

 

I think that's covered it

[aesmith]

Sorry, forgot I'd not replied. Thanks for all the comments, I'm glad to hear there's no general reason not to prune while trees are in leaf. Some of our Rowan have dead branches that I'd like to cut back before they cause problems, and it's difficult to distinguish when the tree's dormant. Following comments above I'll wait until the leaves are fully open.

 

Other ones of concern are Lilac where there are some really top heavy stems that are going to fail if left. One already did so last year. I'll do these immediately after flowering.

 

Thanks again, Tony S

[brisbane trees]

Much more important than when is how. Poor pruning techniques really can murder trees. I know it wasn't the question, but the answer is tenfold more important.

 

I've been attending half a dozen trees suffering from caterpillar invasions where I live over the last week and every one of them except one had been badly pruned within the last two years. It was an eye-opener to me about stressors leading to other problems for the trees' health.

[Jesse]

Sounds like you have a lot of trees with good reasons to prune ?? why is that, all trees have their optimum size when mature, unless its for a good reason, and not just because you think your trees need pruning, or that your kind neighbour has told you to prune your trees, or for fruit propagation, best not to prune ( wound ) as it provides the ideal entry points for pathogens , and stimulates excessive regrowth , and a tree will endeavor to re assume its optimum size beyond the point of abscission and then some, what you could end up with is an unhealthy or vigorous tree, which will require ongoing management ( Which really means future expenditure and costs, thats if you intend to stay ) Just to put my point across. Think carefully before pruning, and only do it for a reason.

Edited April 28, 2015 by Jesse
bit more info

[Chris at eden]

Sounds like you have a lot of trees with good reasons to prune ?? why is that, all trees have their optimum size when mature, unless its for a good reason, and not just because you think your trees need pruning, or that your kind neighbour has told you to prune your trees, or for fruit propagation, best not to prune ( wound ) as it provides the ideal entry points for pathogens , and stimulates excessive regrowth , and a tree will endeavor to re assume its optimum size beyond the point of abscission and then some, what you could end up with is an unhealthy or vigorous tree, which will require ongoing management ( Which really means future expenditure and costs, thats if you intend to stay ) Just to put my point across. Think carefully before pruning, and only do it for a reason.

 

Spot on. I agree 100%.

 

Additionally in response to some of the questions. The old myth of only pruning in the winter was based on the Askanarzy curve, not sure on the spelling but the research was flawed in any case. It was based on testing starch levels immediately after bud break but they only tested winter flowering cherries from what I remember. These would obviously be depleted as they have put out flowers before they have any photosynthetic capacity so just on potential energy. Then to put out leaves is a bit much so pruning straight after is probably not a good idea.

 

If you pruning in summer the tree is actively growing so is able to form reaction zones to prevent colonisation by decay organisms. Additionally most decay fungi sporilate in the autumn so spores are at an all time low. The wound response of deciduous trees in the winter is pretty much zero and fungal spores are at a high.

 

I don't see the issue with bleeding either. its not like an animal bleeding where if it runs low it will die. Also if its pumping out water it means nothing can get in and cherries and some conifers produce gums and resins during the summer as a defensive compound.

 

I would say in most instances that summer pruning is best but then again I've never met a tree surgeon that has the winter off and most local authorities prune planes during the winter due to the irritant hairs. Realistically do many of these trees pruned in winter die? I wouldn't say so, not if done properly.

 

The paper in mentioned is called straightening out the askanarzy curve if you are interested in the research.

 

[aesmith]

Thanks for the comments. I agree that it might be a good idea to review whether or not pruning is actually necessary. For example one case is an Ash tree that was cut back by SSE to maintain clearance from the power lines, it looks ugly but could be left as-is. My main concerns are firstly a couple of other Ash that have had storm damage leaving jagged and split branches. My thought was to cut these back to a sound branch (sort of equivalent to smaller scale pruning where you cut just by a bud).

 

The other issue is a Lilac which has a couple of very long stems with no leaves or branches except at the end, after maybe 10 or 12 feet of bare branch. One of those broke off just below ground level a couple of years ago, and I think the others will do the same before too long. My thought there was to cut these off just above ground level in the hope that they'll grow new shoots.

 

I'll see if I can post a couple of photos.

 

Tony S