Dealing with an Unfruitful Tree

Every now and again you may find that one of your fruit trees fails to produce fruit and this may well happen after several years of good fruiting. This is not terribly unusual and can happen at any time and there are usually very good reasons for this. Alternatively a tree may not want to start fruit production at all so let’s consider what you might do to get your tree into a fruiting habit.

I am assuming:

1. that you have not planted a tree without any suitable pollinators
2. that your tree is not very young and has been in the ground for at least three years as some top fruits can take at least two years before they start fruiting. You may have to be more patient with some varieties and several such as the apple ‘Blenheim Orange’ can take up to seven years before fruiting will commence.
3. that the tree in question is not having an ‘off’ year as some fruit trees can fruit only biennially. Good examples are the apples ‘Laxton’s Fortune’, ‘Ellison’s Orange’ and ‘Blenheim Orange.’

 

Weather

As it is not possible for us to control the weather in our gardens (as yet!) it is important to recognise that it can have an effect on our fruit trees. In severely cold weather flower buds can be destroyed before they even open and during blossoming a drop to -2℃ (29℉) can destroy the viability of any pollen. This will generally not be a regular problem unless you have planted your tree or trees in a shady, cold area or in a frost pocket. Looking at the opposite conditions a prolonged summer drought can cause a very poor formation of fruit buds and this can lead to the formation of very few or no flower buds the following spring. In severe summer conditions, therefore, it can be wise to irrigate fruit trees.

If, without realising, you have planted your tree or trees in a frost pocket you might be inclined to move them to a less difficult location if you can. If not, you will need to be ready to protect your trees in times of frost.

 

Feeding

Although it is not generally necessary to feed trees, provided they have been planted well, this may be required if a tree is either not cropping or cropping very poorly. Possible reasons here are nutrient deprivation caused by very poor soils, thin soils which have nutrients washed out after a heavy rainfall or growing the trees in grass or other plants which compete for nutrients. In all cases feed with a very good handful of Fruit Tree Feed or blood, fish and bone in March and June and lightly fork this into the soil. Remove any competing weeds and plants and cut back grass to ensure a circle of at least 90cm (3ft) around the tree. Trees should only be grassed around if they are growing on strong rootstocks such as MM106, Quince A and St. Julien A.

Don’t overfeed your trees as this may lead them to grow excessive leaf which in itself will inhibit fruit bud formation. Avoid using fertilisers which are high in nitrogen such as chicken manure  and chicken manure pellets as the high nitrogen content will also cause excessive leaf growth and inhibit bud formation.

 

Pruning

Fruit trees are pruned on an annual basis to ensure that a balance is struck between growth and fruiting. In the case of fruit trees grown as restricted forms – and that will generally apply to all of the fruit trees that we are growing – annual pruning is essential and if missed even for one year this can lead to excessive growth of laterals and little production of fruit buds. In the case of stone fruits you should be pruning in June/July, pears in late July and apples in August.

Be aware of the tip bearing apple trees which produce the majority of fruits bud at the end of laterals. A good ‘haircut’ can remove the majority, if not all, of the following year’s fruit! Strike a balance between restricting growth and preserving shorter laterals.

 

Festooning

Festooning fruit trees consists of training young branches to grow into gaps to improve the shape of the tree by creating hoops of branches. This can be done by bending the branches and securing them to the trunk with string. Another approach to festooning is to tie plastic buckets to the branch and fill with water until they bend into the shape that is needed. The age and thickness of the branch will determine which approach is used.

Essentially this method is used to counter the apical dominance of the tree by bending the branches down to as near the horizontal as possible. The threat to apical dominance will worry the tree and start forming fruit buds on these horizontal branches. Commercially fruit farmers used to use lead weights attached to clothes pegs which were attached to the laterals and branches but these are out of fashion now that new fruit growing methods are being used commercially. Once tied down for a period of time the branches and laterals will set and whatever medium was used can be removed.

Most trees will not need this treatment as the majority of them will develop a good balance of horizontal laterals as well as upward growing branches. However, some varieties of fruit have a tendency to upright growth – and many pears do this – and so tying down is a very valuable tool.

 

Root Management and Pruning

On occasion a fruit tree will happily grow away without thinking of producing future generations and needs to be shocked into fruit production. There are two methods of doing this via the root system and I have used both very successfully.

The first method is very applicable to younger fruit trees – say up to 10 years old and simply involves digging up the tree and replanting it in the same position. The tree becomes shocked and will start producing fruit buds the following autumn. For some reason this method is particularly effective on pears and stone fruits.

The second method – used for older trees – is to use root pruning. The effect is the same as for completely digging up a tree and replacing it. What needs to be done with this method is to dig a small trench around the tree to a diameter of around 90cm (3ft). Dig carefully so that the roots are not damaged and to achieve this I prefer to dig by hand. Once the roots are exposed cut around half of the big thick roots and remove a small section. When this is done replace all removed soil.

Both of these methods should only ever be undertaken in the dormant season (December until March). Afterwards, always apply a good handful of Fruit Feed or blood, fish and bone and water for the first part of the new growing season.

 

Bark-Ringing

This is a simple operation designed to restrict the growth of very vigorous fruit trees and bring them into bearing. The effect of bark-ringing is to limit the downward flow of sap, thus conserving the concentrated food supplies in branches and shoots. As a result, fruit buds are developed and strengthened and unfruitful growth is kept in check. Bark-ringing can be used on well growing apple and pear trees quite safely but do not use this method on any stone fruit tree. In the case of stone fruits, root pruning in autumn is much to be preferred to bark ringing as a means of encouraging fruiting. It is a very old method and has been practiced by gardeners for many years. In recent years it has been employed by commercial fruit growers and gardeners, particularly in Europe. The operation is carried out in the spring, usually in May, when the sap must be running freely so that the bark lifts easily and cleanly without tearing.

Bark-ringing can be an extremely helpful type of pruning. If done correctly and when utilized properly, this can limit the growth of trees enough to help focus the energy of the tree more on fruit production. However, if the procedure isn’t done correctly, then you can find yourself with a seriously damaged tree that could possibly die. Remember that this procedure should only be done around May, as this is when most trees begin to experience their growth spurts and it will be most effective then. I personally advise that you only use this method as a last resort as I believe that my previous options will more than likely suffice. But if you want to go ahead with this method you may prefer to do it in stages to avoid damaging the tree too much. This means that it will end up taking several years to get a complete ring out of the tree. Each year you will make a new cut, but offset at an angle. Eventually the bark-ring will look like a spiral around the tree.

You have had my health warning but if you would like to consider this method here goes!

1. Making your cuts: Using a measuring tape, mark off a spot on the trunk of your tree about 60cm (2ft) above the ground. This is where the ring will start. Make two cuts at an upward angle that go around half of the tree. The cuts should be between 6-13mm (¼-½in) apart from each other and equal in length. Make two smaller cuts at each end of the half spiral to form one long rectangular spiral.
2. Removing the bark: Take a knife, and begin removing the bark from the tree. Be careful when you do this though, since you only want to remove the bark down to the cambium layer of the wood. The cambium layer is the green coloured layer that you usually find right underneath the bark. Remove all of the bark in the marked area.
3. Covering the wound: Once you have removed all of the bark down to the cambium level, get some adhesive tape. This tape will be used to cover the wound you just made, and help prevent the area from completely drying out. Think of it as a bandage.
4. Repeat the process: At the same time the following year, repeat the process. This time though, continue on from the end of the last cut, still going on in a circling spiral upwards.

 

Gerry Edwards
29th July 2015

Gerry is an experienced amateur fruit grower who is Chairman of the RHS Fruit Group, a member of the Royal Horticultural Society’s Fruit, Vegetable and Herb Committee and also their Fruit Trials Panel. Gerry judges fruit nationally for the Royal Horticultural Society and is also a qualified National Vegetable Society judge.