Olive Care Guide - Caring for Olive Tree Topiary

How to Care for Olive Trees

We would like your olive tree (Olea europaea) to be happy and healthy and last for years to come.

On this page you will find our care advice specifically for olive trees that will let you know what your plant needs.

We have also included our recommended products, products that we use ourselves, that will help you keep your plant looking at its very best.

 

 

Olive Tree Care Instructions

Common name	Olive Tree
Latin name	Olea Europaea.
Description	An elegant, slow-growing evergreen plant. The olive tree has grey-green leaves and tiny, fragrant, creamy-white flowers followed by edible, green fruits which slowly turn black in the autumn.
General care	Water well in the summer but sparingly in the winter.
Pruning	Trim or pinch out shoots during the summer months to retain a balanced shape.
Feeding	Feed 2-3 times during the spring and summer with a general purpose fertilizer.
Soil	Fertile and free drained soil.
Aspect	Prefers a sheltered spot in full sun.
Hardy	Established olive tree plants are generally tolerant of light frosts and temperatures down to freezing and olives are able to live outdoors all year in milder parts of the UK. Winter protection may be required during prolonged cold spells. Move into a sheltered area for protection. Can also be brought indoors and placed in a light, airy, well lit spot such as a conservatory or greenhouse.
Flowering	Flowering period - summer. Flower colour – cream, small flowers are lightly scented. Flowering is followed by the olive fruits.

Olive Tree Problems

Yellowing Leaves or Leaf Loss

Causes

Olives will naturally shed older leaves in the spring as new growth develops. Container grown olives may suffer leaf loss or yellowing due to dry conditions. Additionally, olives are not full hardy, they can suffer frost damage if temperatures fall below -10°C (14°F) causing leaves to drop. Equally waterlogged plants can suffer diseases such as verticillium wilt and Phytophthora root rot that cause leaves to yellow and wilt (see below).

Control & Prevention

Ordinarily olives cope with dry periods but with regular watering will do better throughout the growing season. Container grown olives will need regular watering and feeding with a liquid fertiliser such as Phostrogen. Plenty of drainage holes with a loam based compost mixed with 20% horticultural grit for additional drainage will help to prevent water-logging. In colder climates or northern regions, olives do best in pots where they can be moved to a greenhouse or conservatory for winter protection.

Scale Insects

What are they?

Scale insects are sap sucking insects that suck the sap from a wide variety of plants. In the UK there are over 25 species ranging from 1mm to 1cm in diameter. During their growing phase they are fairly mobile, once they reach maturity and grow their hard shell, they become sedentary fixing themselves to one spot and feeding on the sap on the host plant.

Symptoms

If you have an infestation the damage will be clearly seen on plants, leaves will turn mottled and yellow before dropping off. Other symptoms include, scales or bumps on leaves and plant stems, these are the scale insect covering; small white, waxy clusters protecting scale insect eggs and found in the early summer; a sticky substance known as honeydew on the upper surfaces of leaves. Heavy infestations may result in poor growth and plant health.

Treatment

If infestations are small, they can be removed by hand by picking them off or by gently wiping the insects with a cloth soaked in alcohol or neem based product. Pruning and disposing of infected stems or branches can solve the problem if caught early enough.

If the problem is on outdoor plants, introducing natural predators such as ladybirds, parasitoid wasps or birds will prey on and eat scale insects and their young larvae.

Organic sprays, fatty acids, and plant oils can give good control but will require reapplication as they have a short persistence. Additionally these products are unlikely to affect larger insects and predators such as ladybirds.

Other more persistent contact action insecticides and systemic neonicotinoid insecticides are available but must be used with caution on and around edible plants

Honey Fungus

What is it?

Honey fungus is a fungal infection in woody and perennial plants within the genus Armillaria. It is the most destructive fungal disease in UK gardens, it spreads underground attacking the roots and decaying the dead wood.

Symptoms

Above ground symptoms to watch out for are the die back of the upper part of the plant and a failure to flower or an unusually heavy flowering and subsequent crop of fruit. Leaves may appear paler and small then average and there maybe a premature autumn colour. During the autumn and if conditions are suitable, mushrooms or toadstools may appear indicating an infection.

At ground level honey fungus causes a white fungal growth to appear between the bark and wood of the infected plant. Just below soil level, decaying roots may be present along with a strong smell of mushrooms.

Control

There is no chemical control to treat honey fungus. The most effective way to control spread and prevent further outbreaks is to remove and destroy all infected plant material and create physical underground barriers to stop the spread of rhizomorphs.

Olive Scab

What is it?

Scab diseases are caused by a fungi which enjoys wet weather in the spring and summer. Apple scab is one of the most important diseases of apple trees and their fruit but other hosts such as the olive is commonly affected.

Symptoms

Olive scab causes purple to dark brown ring-spots with a green centre on the leaves. This is followed by yellowing and defoliation.

Control

There are no chemical fungicides available to control scab diseases. Non chemical control involves the pruning and disposal of affected shoots. General pruning opens up the canopy and aids air circulation enabling the foliage to dry more quickly after rainfall.

Verticillium Wilt

What is it?

Verticillium wilt is caused by a soil-borne fungi Verticillium dahliae and V. alboatrum. It invades plants through their roots and spreads upwards into its water conducting tissues causing wilting.

Symptoms

It is hard to detect as the disease mimics other plant diseases and environmental problems. Symptoms include the yellowing and shrivelling of lower leaves. These eventually turn brown and drop off with stems and branches dying back. As it travels up through the plant, it leaves dark streaks in the tissue under the bark. Circles of brown marks can be seen in the cross section if the branch is cut transversely.

Treatment

Once a plant is infected with Verticillium Wilt it can't be cured. It is best to remove and destroy smaller plants that can be easily replaced. As the disease remains in the soil, it is best not to replace with another susceptible plant.

Treatment of more established trees and shrubs with Verticillium Wilt can be focussed on building up their resistance with regular watering and afternoon shade where possible. Applying a low nitrogen, high phosphorus fertiliser at regular intervals and pruning of dead and dying branches will help to preserve affected plants.

Phytophthora Root

What is it?

Phytophthora Root Rot is a soil borne pathogen that infects trees, woody plants and sometimes vegetables. Sometimes called water mould it spreads through infected water and often indistinguishable from signs of water-logging. It penetrates root systems, causing rot which denies the plant of necessary nutrients.

Symptoms

Phytophthora causes a weakness and slow collapse in affected plants. Most plants appear to be drought stressed despite adequate watering, wilting and dying during the first warm spell after infection. Some symptoms are seen as a scattered browning from the centre of the tree and out towards its branches although this is found mainly in conifers.

Treatment

The best treatment of affected plants is remove and destroy making sure to disinfect tools and containers. Replacement of the top soil and ensuring proper drainage will enable you to replant with less susceptible strains.

However, similar to Verticillium Wilt, some plants can be saved with proper control. Removal of the soil around the base all the way to the main roots allowing them to dry completely will slow the spread of Phytophthora.

 

Further Reading

The RHS website has further information of pests and diseases that can affect olive trees: https://www.rhs.org.uk/advice/profile?pid=138