Phyllosticta leaf spot and dieback

Species of the fungus Phyllosticta are found quite commonly on fallen, dead leaves of a range of woody plants. In some cases they may reside within living leaves and wood without causing problems. Less frequently, they have been associated with leaf spotting and shoot dieback of plants such as holly, rhododendron and yew.

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Phyllosticta dieback on a holly hedge

Quick facts

Common name None
Scientific name Phyllosticta concentrica, P. foliorum, P. philoprina
Plants affected Holly, ivy, rhododendron, yew. Also found on a range of other woody plants
Main symptoms Brown leaf spots and blotches. Needle browning. Leaf loss and twig dieback
Caused by Fungus
Timing May be seen year-round

What is Phyllosticta leaf spot and dieback?

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.

 

Symptoms

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

Control

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

Chemical control

There are no fungicides available to gardeners with specific recommendations for use against Phyllosticta species. However, the fungicides tebuconazole (Provanto Fungus Fighter Concentrate), tebuconazole with trifloxystrobin (Provanto Fungus Fighter Plus, Toprose Fungus Control & Protect), and triticonazole (Fungus Clear Ultra) are labelled for the control of other diseases on ornamental plants, and could be used (at the grower's risk) to try and control Phyllosticta. There is no specific information available as to the efficacy of these products against Phyllosticta speciesIt would be prudent to apply a small amount of the chosen fungicide first, at a solution suggested on the packet for other problems, to ensure that the product will not cause plant damage.

Inclusion of a fungicide product does not indicate a recommendation or endorsement by the RHS. It is a list of products currently available to the home gardener.

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

Links

Chemicals: using a sprayer
Chemicals: using safely and effectively
Chemicals: storing and disposing safely

Biology

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 different strains, only some of which are capable of causing disease. This may be the case with other Phyllosticta species such as those described here.

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.

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