Fruit production: Why some trees and vines don’t bear fruit

Farmers often find that some of their fruit trees bear poor quality fruit, or do not produce any fruit at all. Instead of removing these trees, farmers should rather determine the reasons for the poor performance.

There can be many reasons why fruit trees or vines are not producing optimally.
Production might be low because trees are too old, or because of incorrect soil preparation, fertilisation, irrigation or pruning.
It might also be because of pollination or pest problems.
The causes for poor fruit bearing in orchards, can be the same for vineyards.

AGE OF TREES

Some types of fruit trees and cultivars yield fewer fruit as they grow past a certain age. A farmer, for this reason, should have a sound tree replacement strategy whereby a certain percentage of old trees are replaced by new ones every year to ensure his farm produces to its full potential.

PLANT MATERIAL

Remember that it takes four to five years for grafted trees to come into full production.
Trees established from seedlings will only bear fruit from the seventh year after planting. Grafted trees bought from a certified nursery, will have suitable rootstocks and produce fruit within 2 to 3 years.
Don’t allow too many fruit to reach maturity during the first 3 years after establishment, as this will inhibit the trees’ development and future production.
Homogenous trees are a must for commercial production.

SOIL PREPARATION

Tree development and production will be repressed if the soil is unsuitable for the specific cultivar or tree type; or because of improper soil preparation.
The sides of the planting hole should be uneven to allow the roots to penetrate into the soil.
Root growth and development would be inhibited if the hole is too small or limiting soil layers are present.
Do a soil analysis to measure the soil’s nutrient status and obtain expert advice on fertiliser application rates before you start preparing the soil.
Phosphate and lime should be applied during soil preparation for healthy root development.
Compost can be added, but it must be thoroughly mixed with the soil.
Compost improves the soil’s water-holding capacity.

FERTILISATION

Insufficient available nutrients in the soil will lead to poor fruit growth.
For example, flowers won’t form if potassium quantities are inadequate and without flowers, trees won’t produce fruit.
Boron is needed for the growth of pollen tubes.
A shortage will hamper pollination and subsequent fruit development.
Excessive nitrogen will stimulate vegetative growth at the expense of fruit growth.
So take soil samples and have them analysed to determine the nutrient status of the soil.
Get expert advice if the nutrient balance needs to be rectified.

IRRIGATION

The soil’s water-holding capacity and the trees’ water requirements must be taken into account to ensure that the correct quantities of water are applied at the correct intervals. So obtain expert advice.
Inadequate irrigation will inhibit tree growth and fruit development.
Over-irrigation is an even bigger problem, as it can lead to water-logging.
Trees producing poor-quality fruit, or no fruit at all.
Such trees have a poorly developed root system.

POLLINATION

Cold weather during pollination can have a negative effect on fruit production, as the pollinating insects aren’t very active then.
Trees sometimes bud in spring without any later fruit development; this could be because pollination did not occur.
Certain fruit trees have “perfect” flowers – both style (male reproductive organ) and stigma (female reproductive organ) are present.
These trees are called self-pollinators.
Some other fruit trees are cross-pollinators.
They can’t manufacture their own pollen, but need the pollen from another cultivar of the same fruit type for pollination.
When trees don’t produce fruit, it may be caused by the absence of a cross-pollinator in their vicinity.
Grafting a cross-pollinator onto one or two of the top branches of the tree could solve this problem.
In pome (apple and pear) orchards, it’s the practice to include pollinator trees at regular intervals within the rows.

PRUNING

Trees are pruned to shape them, ensure a strong framework, increase the quality and quantity of fruit, and to ensure a satisfactory annual production.
A tree has to be pruned and trained so that enough sunlight can reach the leaves and shoots. Without sunlight, the branches stop growing, die back and don’t produce flower buds and, as a result, no fruit.
Some trees produce a lot of fruit one season, and little – or none – the following season. (This is called alternate bearing.)
It happens, because the large crop load in the one season inhibits bud development for the next season.
Fruit thinning and a sound fertilisation programme is necessary to manage alternate bearing.

DISEASES

Blossom blight occurs mainly in apricots and peaches.
This fungal disease can be identified by the small, brown spots on the stems of the blossoms. The blossoms eventually turn brown and wilt, and no fruit is formed.
Rainy weather during blossoming favours the development of this fungus.
To limit future infections, remove and burn dead and wilted blossoms.
Use fungicides and pesticides for commercial production.

INSECTS

Uncontrolled insect infestations can inhibit tree growth, as well as fruit development.
Pests can cause internal damage and superficial lesions to fruit, leaves and buds.
Borers and some nematode species damage tree wood and roots.

CLIMATIC ENVIRONMENT

Fruit trees require sufficient sunlight to produce fruit.
To ensure the trees won’t be in the shade, plant them far enough apart and not near any buildings.
They require long, cold periods during winter to achieve rest-breaking.
If the cold period is too short, rest-breaking will only be achieved partially and delayed blossoming might occur.
Apple trees should only be planted in regions where winters are cold, as they have a great cold requirement.
Make sure, then, that purchased fruit trees are suitable for the intended cultivation area. Excessive cold damages flower buds, and so does frost.
In areas where there is frost during blossoming, take care to limit frost damage.

Also read: Fruit farming is a long-term investment

This article was written by Odette Beukes and first appeared in Farming SA.