Phyllosticta is a fungus that is often found on dead leaves and twigs under plants such as holly, rhododendron and ivy. When found on old dead leaves that have been shed naturally by the plant this is not a worry for gardeners. However, it can also be an occasional pathogen, capable of attacking previously healthy leaves and shoots to cause leaf spots, needle browning and dieback.

You may see the following symptoms:

• Irregular brown spots and blotches on the leaves of holly, ivy and rhododendron
• Needle death of yew. Affected leaves may remain attached to the twigs for a considerable length of time
• Numerous tiny, black fruiting bodies (visible as black dots) are produced within the affected tissues
• Twig or branch dieback may also occur on any of these hosts

The RHS believes that avoiding pests, diseases and weeds by good practice in cultivation methods, cultivar selection, garden hygiene and encouraging or introducing natural enemies, should be the first line of control. If chemical controls are used, they should be used only in a minimal and highly targeted manner.

Non-chemical control

• Remove and destroy affected leaves, or twigs with dieback, together with fallen leaves at the base of the plant
• Encourage the production of vigorous, healthy growth by feeding, mulching to conserve moisture, and watering of plants during periods of extended drought

Fungicides

The RHS recommends that you don't use fungicides. Fungicides (including organic types) may reduce biodiversity, impact soil health and have wider adverse environmental effects. If you do intend to use a fungicide, please read the information given in the link and download below to ensure that use, storage and disposal of the product is done in a responsible and legally compliant manner.
  
The products listed in the ‘Fungicides for gardeners’ document below are legally available for use by home gardeners in the UK. This information is provided to avoid misuse of legal products and the use of unauthorised and untested products, which potentially has more serious consequences for the environment and wildlife than when products are used legally. Homemade products are not recommended as they are unregulated and usually untested.

There is no specific information available on the efficacy of any home garden fungicide against Phyllosticta leaf spot and dieback.

Download

Fungicides for gardeners (Adobe Acrobat pdf document outlining fungicides available to gardeners)

Link

Chemicals: storing and disposing safely

There is very little information available on these fungi and how they cause disease. It is likely that in many cases they may reside within the leaves and wood of a plant without causing problems (in this case the fungus is known as an endophyte), only becoming visible and producing fruiting bodies when the leaf or twig dies naturally. However, on the host plants described in this profile Phyllosticta species are sometimes capable of acting as plant pathogens. It is known that some species of the fungus (e.g. Phyllosticta citricarpa, the cause of black spot disease of citrus fruit) exist as a number of genetically-distinct strains, only some of which are capable of causing disease. This may be the case with other Phyllosticta species such as those described in this profile.

The taxonomy of this fungal genus is currently the subject of revision. At present, the species found on yew (the plant affected most commonly by dieback caused by the fungus) is known as Phyllosticta foliorum, that on ivy is P. concentrica and the species found on holly is P. philoprina.

On plants where the fungus causes leaf spots or twig/branch dieback, spread of the disease is likely to occur via rain-splashed spores. Plant stress or physical damage may render a plant more susceptible to attack.