This disease is caused by a bacterium. Legionella longbeachae occurs in soil and compost. Infection with this agent can lead to a respiratory disease.

The more common L.pneumonophila occurs naturally in water courses but can multiply in standing water to potentially harmful levels when the water temperature is between 20 and 45degrees c.

Precautions should be taken when opening bags of compost or turning composts heaps especially when they are dry and dusty. Avoid using compost in enclosed areas and do not store in greenhouses where contents may get very dry and hot. Damp down your compost heap if it gets very dry. Consider using a mask when
turning the heap.

Empty hose pipes of water after use to avoid water standing in pipes which heat in the sun. Water butts should preferably not be in full sun. This is not always possible but they can be painted white or insulated to counteract overheating.

The tetanus bacterium is found in soil and gains entry to the body via cuts and grazes. Tetanus is a particularly nasty illness and can cause death in 10% of cases.

Tetanus vaccination is very successful and it is routinely given in childhood. Those who work regularly in contact with soil should ensure that their vaccinations are up to date. It is recommended that boosters are given every ten years. Any injuries such as cuts or scratches on hands should be covered when working in the garden. Serious injuries in the garden should be taken to a doctor and consideration given
to giving another tetanus vaccination. Wearing gloves is recommended.

This is a bacterial infection which can be carried by rodents (rats and mice). The bacterial agent is carried in water or wet vegetation contaminated by urine from rats. Rat urine can also carry salmonella bacteria. The bacterium can enter the body via uncovered cuts and scratches.

Tops of compost bags should be rolled over to prevent entry by rodents. Meat, fish and egg remains should not be placed in garden compost containers unless vermin can be excluded. Water butts should be covered. Wearing gloves is recommended.

Affects some species more than others. Subsection Cinnabarina is particularly susceptible as are the Fortunea. Infection causes pale green, reddish purple or yellowish spots on the upper surface of evergreen rhododendrons. Deciduous species may show white powdery fungus on the leaves. This isn’t usually fatal for the plant but unsightly and some years are worse than others. It is not recommended to remove affected leaves or plant could be defoliated!

Causes buds to go brown and remain attached. Later buds may turn silvery grey before becoming covered in small black bristles. This should not be confused with frosted buds which remain brown and can be knocked off easily. Remove and destroy affected buds of bud blast promptly.

Spots appear on petals in wet conditions. These spread rapidly and cause petals to collapse in a slimy mess.

This is usually found on ‘azaleas’ and leaves become pale, swollen and distorted then covered with a bloom of white fungal spores. Remove galls promptly when seen before the spores appear and spread the disease.

Purple or brown roundish spots on upper leaf surfaces usually of evergreen species.

Rust (Chrysomyxa rhododendri) seen as discoloured spots on the upper leaf surface which correspond to pustules on lower surface containing dusty orange spores. Rhododendrons can also be attacked by more generalist diseases:

Sudden wilting and collapse of whole plant or slower and more gradual decline.

Bodies of fungus sometimes seen developing on dead or dying parts.

This can cause dieback of the branches with fruiting bodies sometimes developing on dead or dying parts. It affects the wood of the plant and is often spread by infected pruning tools. The silver appearance of the leaves is due to the top layer of leaf cells separating from the one below as a reaction to the fungus in the bark. Light is then reflected differently.

These small oval shaped insects attach to the stems and leaves of rhododendron plants. They feed on the sap and can cause yellowing, wilting and stunted growth. Excretions of honey dew from these insects attracts a black fungal growth of ‘sooty mould’ which is very unsightly. It is difficult to eradicate without chemical control of the insect. If the air circulation around the plant is improved, there may be less sooty mould.

Lace bugs (Stephanitis takeyai and Stephanitis rhododendri) were first recorded in the UK in 1998. They are tiny sap sucking insects native to Japan. They were introduced to the USA and Europe via the horticultural trade. The south east of England was affected initially but incidences have been recorded from Leicestershire, Rutland, Nottinghamshire and parts of Wales . Rhododendron growers in the USA complain bitterly about the problems caused by these pests and find that some rhododendron subsections are more affected by lace bugs than others. They are named for the lacey appearance of their wings.

Adults cause characteristic semicircular notching of the leaves of rhododendrons. In late summer and over the winter, larvae eat the bark, usually circling the stem just above the ground and causing the plant to die.
(A lot of very useful information is to be found on the Glendoick website under the heading ‘What is
wrong with my rhododendron – ‘Rhododendron problems, pests and diseases)

This was originally seen in the United States but first reported in the UK, including Scotland, in 2014 and 2015. It affects the genera Cedrus and Tsuga; cedars and hemlocks. Symptoms are severe shoot blight and defoliation. Dead needles have a characteristically pink colour and later go brown. There can be cankers and bleeding of resin from the bark. Spread is via rain splash and high winds. There is no effective control other than biosecurity and plant hygiene. More information

Marion Kinns, 2022

Of less concern to us is a new Stink Bug originating from China and Japan. This has been highlighted by the RHS. The brown marmorated stink bug, Halyomorpha halys spread to the USA in the 1990s and is now found in various European countries. So far only adults have been discovered in the UK and no breeding populations.

They differ from native stink bugs with pale bands on the antennae, a row of pale dots on the body and a rectangular head. They appear to overwinter in houses.

The main threat is to orchards where a small number can cause great damage. Gardeners are asked to watch for them. If you find them, capture them and report suspects to bmsb@niab.com or via the RHS gardening advice service rhs.org.uk/myadvice . More Information

Marion Kinns, 04/02/22

This soil and water born fungus affects our native juniper which is already rare so there is some real cause for concern. It affects and damages roots leading to death. Discolouration of the foliage is seen which is either a uniform bronze following root damage or patchy from lesions on stems or branches. Tongue or flame shaped lesions up to 50cm can be seen under the bark and sometimes resin pockets. There is no natural resistance but plants on drier sites may survive. More Information

Marion Kinns 04/02/22