Improving Fruit Harvests at Home
The fruit trees are beginning to burst into blossom. Yay, a sign of the bucket loads of fruit come harvest time. But, there are so many years in Dunedin the expectation and the results are significantly different.
Good fruit set in spring depends on several factors, including pollination, weather conditions, tree health, and proper care.
Hints for Good Fruit Set:
Position:
Fruit production may be affected by position. Wind, soil, sun or shade can be improved by moving the plant.
Sunlight:
Branches need UV exposure to develop flowering growth so plant trees in full sun for maximum cropping. They are more susceptible to pests and diseases in the shade too. A fruit tree should get five hours of direct sunlight in the middle part of the day - early morning and later afternoon sun is not as intense so not as useful.
Prune trees in to improve air circulation and sunlight penetration.
Compatible Varieties:
Identify wether the fruit tree is self-pollinating (e.g., peaches, apricots, berries). Or cross-pollinating (e.g., apples, pears, plums, blue berries) which require pollen from a different compatible variety. Even self-fertile varieties will fruit better when planted with another variety to improve pollination. At least two compatible varieties need to be planted nearby. Or a compatible variety can be grafted onto the tree as a new branch.
Encourage Pollinators:
Plant pollinator-friendly flowers that bloom in spring near the fruit trees.
Avoid using pesticides during bloom time, as they can harm bees and other pollinators.
And provide a water source (e.g., a shallow dish with water and pebbles) for bees.
Hand Pollination:
Use a small paint brush to transfer pollen from one flower to another. Gently touch the stamens of one flower and then the pistil of another.
Weather:
A lack of cold winter weather will reduce flower and fruit production for cold-climate trees such as apricots and cherries. Winter chill requirements are the number of hours below 7°C needed for fruiting growth. Match fruit and variety to the local conditions.
Fruit trees may have been stressed by summer drought, failing to develop flower buds for the following season. In a very dry summer, keep fruit trees well irrigated and mulched. Spring weather plays a critical role in fruit set: Most fruit trees require warm days and cool nights when in blossom. Pollination can be affected when it is too cold, too wet or both during flowering as bees prefer warm conditions.
Protect from frost with frost cloth or use sprinklers (the ice forms a protective layer over the blooms) as frost can damage blossoms and reduce fruit set.
Excessive rain can wash away pollen and prevent bees from being active.
High humidity can encourage fungal diseases (e.g., brown rot), which can damage blossoms.
Tree Health:
Healthy trees are more likely to set fruit successfully.
Remove dead, diseased, damaged or crossing branches.
Pruning:
Incorrect pruning can result in upright, vigorous unproductive growth. Remove only 20-30 per cent of the tree each year; if a hard prune is needed to reinvigorate or shrink a tree, do it over several years
Age:
Older trees can become unproductive due to an overall decline in health. Some can potentially be rejuvenated with a hard prune, but often they are just past their prime.
Sometimes the solution is simply patience, as some varieties will take three or four years to fruit well after planting.
Biennial Bearing:
Some varieties produce a large crop one season, and nothing the next. (common for plums and pears). Thinning to only two fruit per bunch helps, as it allows them to grow to full size without placing a heavy burden on the tree.
Nutrition:
Apply a balanced fertiliser in early spring to support blooms and early fruit development.
Avoid applying too much nitrogen, as it can promote leafy growth at the expense of flowers.
Watering:
Keep soil consistently moist but not waterlogged during bloom and fruit set. Drought stress can cause flowers and immature fruit to drop.
Prevent and Manage Pests and Disease:
Pests and diseases can weaken trees and reduce fruit set
Thin Immature Fruit Early:
If the tree has set too much fruit, it can lead to small, poor-quality fruit or lead to fruit drop. Thin fruit 4–6 weeks after bloom when fruits are about the size of a pea.
So in general, I would recommend planting at least two different varieties of each fruit type to get the best results.
Fruit Varieties
Apples and Pears
Apple and Pear trees are grouped into pollination groups based on their bloom time. Plant at least two varieties from the same or overlapping groups to ensure pollination. Crabapple varieties are useful pollinators, as most types have a long flowering period and produce a lot of pollen.(Bear in mind apples and pears, although closely related, cannot pollinate each other).
Peaches and Nectarines:
Most are self-pollinating, but some varieties benefit from cross-pollination from another variety that flowers at the same time planted nearby.
Plums:
Most require cross-pollination. Plant at least two compatible varieties. Bear in mind European plums (Prunus domestica) and Japanese plums (Prunus salicina) cannot pollinate each other because they are different species.
Apricots:
Most are self-pollinating, but cross-pollination can improve fruit set.
Cherries:
Most require cross-pollination. Plant at least two compatible varieties.
Raspberries:
Raspberries are self-pollinating, but pollinators like bees can improve fruit set.
Strawberries:
Strawberries are self-pollinating, but pollinators like bees can improve fruit set.
Blueberries:
Blueberries require cross-pollination for optimal fruit set. Plant multiple varieties to improve pollination and fruit quality.
Currants:
Currants require insect pollination to set fruit, some cultivars are self-fertile, but most currant varieties benefit from cross-pollination by a different cultivar
Feijoas:
Feijoas are different to most fruit trees, as they are pollinated by birds who spread the pollen around on their beaks and chests. They are mostly self-pollinating, but cross-pollination can improve fruit set and give larger, more fleshy fruit.
Grapes:
Most grapes are self-pollinating, but some varieties benefit from cross-pollination.
Citrus:
Most citrus trees are self-pollinating, but cross-pollination can improve fruit set.
More on the importance of winter chill and cold temperatures can be read about in the blog: -
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