Is there a way to discourage plum trees from fruiting so heavily?

Question

We have 9 mature plum (victoria I think) and a couple of damson trees in quite a small cottage garden. Our plums are very heavy croppers and really it's a frustrating fruit to have in such quantities. It stores poorly (unless you preserve it - which I'll come to) and bruises easily in transport, which makes it hard to give away to visitors. Yes, we eat (and even cook with) a few of them but the dent we make in the crop is negligible.

Its season is very short and intense. In fact it's the definition of an unwanted glut.

The fruit lie in great carpets across the lawn interfering with lawn-care/mowing and attracting wasps.

We don't want to grub out any of the trees since they add shade and character to the garden and we enjoy them for 11 months of the year. We don't have the facilities or storage space to pot/preserve/can this vast crop.

Pruning them back aggressively did help a few years back. But are there any other tricks to discourage this unwanted crop?

Answer 1

It is extremely hard to control the rate of fruit production precisely in a healthy manner. Pruning (good pruning cuts) in general encourage fruiting and over-pruning the tree or bad cuts can cause the tree to go into shock and not produce any fruit.

I would suggest thinning as an alternative. Thinning is when you selectively remove a few fruits to encourage the rest in a bunch to grow bigger and sweeter. You needn't wait for the fruit to form either, as you can thin early by removing buds just before spring sets in (or when they start to bloom). This might actually be easier as you won't have the leaves coming in your way.

With this, you only remove the flowers (and hence the fruits) and leave the leaves intact, thereby providing you with the same shade that it does now.

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Mike Perry has made a couple of suggestions that build on the above:

• Prune once every 2 to 3 years immediately after flowering has finished:

  • Open up the centre of the tree, get some air movement in there. Doing so will help prevent diseases getting hold.

  • Reduce its height, this will make future tree/fruit maintenance and fruit picking a little bit easier.

• When thinning, it's generally recommended to remove 50% of the fruit (very early in the fruit growing season, probably best to do around the same time as pruning or shortly afterward). Yes it's labour intensive and may seem like a lot to remove, but the benefits of doing so greatly outweigh not doing so.

• An additional thought about pruning. It might make the job a little more manageable seeing as we're dealing with 11 fruit trees in total:

  • Year 1: Prune 3 or 4 tress.

  • Year 2: Prune a different 3 or 4 tress.

  • Year 3: Prune the remaining 3 or 4 tress.

• Then repeat that cycle ie Each tree is on a 3 year pruning cycle. Unfortunately there is no way round the annual thinning of all the trees...

Have you considered contacting local food banks, churches, charitable organisations, nursing homes, plum wine makers, etc to see if they will come and take this fruity glut off your hands?

Also if you have the time and means, drying plums are a great way of storing them...

Answer 2

Another potential strategy (possibly in combination with the thinning and/or pruning mentioned in the discussion under yoda's answer) would be to set up nets (or other catchment -- old bed sheets?) under the trees during fruiting. Then give the tree a shake every day so that the ripe fruits fall down and you can gather them up easily.

Mike Perry's comment about asking a local food shelf or church to come in and gather fruits may be useful in combination with this -- pick or shake out enough fruit for yourself to eat fresh and put up, then call in reinforcements to finish most of the picking and the rest of the work you have to do will be reduced.

Answer 3

The easiest method is to chemically thin the flowers with one of the products available on the market.

Edit: The substances are sprayed on the flowers when the tree is 80% in bloom and about half of them won't set fruit, or are sprayed on the fruitlets when they have a maximum diameter of 10 mm, after which the fruitlets fall.