Yucca Leaf Spot

Yucca adds dramatic architectural effect to borders and courtyards with its bold sword-shaped leaves and panicles of bell-shaped flowers. Tender species make good house or conservatory plants.  Until recently it had been largely free from foliar disease problems but a fungal disease causing leaf spots on outdoor plants has now become common and widespread.

Yucca Leaf Spot (Coniothyrium concentricum)

Quick facts

Common name: Yucca leaf spot
Scientific name: Predominantly Coniothyrium concentricum (syn. Microsphaeropsis concentrica)
Plants affected: Yucca and some other succulents including Agave and Dracaena
Main symptoms: Brown leaf spots, scorched appearance to leaves 
Main causes: Fungi
Timing: Year round, as Yucca retain their leaves  

What is Yucca Leaf spot?

Yucca leaf spot is a fungal disease of Yucca species, and some other succulents including Agave and Dracaena.  
Coniothyrium concentricum (syn. Microsphaeropsis concentrica) is the most common cause of Yucca leaf spots in the UK.  Others have been recorded, including Colletotrichum species, but they are much less common.  All of these fungal species cause grey-brown spotting on the upper surface of leaves, and leaves can often appear scorched.


You may see the following symptoms:
  • The infection first appears as tiny clear spots in the older leaves. The lesions initially turn yellow and finally purple/brown as they mature. The lesions are generally oval and scattered across the upper leaf surface.
  • With a Coniothyrium concentricum infection, after about 4 months, tiny black fruiting bodies of the fungus form in concentric rings on the sunken lesions. 
  • Leaves can often appear scorched, especially at the tips.


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 heavily infected leaves if feasible to prevent the spread of spores to new foliage. 
  • Reduce overhead watering and/or provide protection from rain, which can help to reduce spores being splashed to new leaves.
  • The fungus most likely persists on fallen leaf debris, so clear the area of fallen leaves, and destroy the leaves rather than adding them to your compost.
  • Many plants suffer from more severe leaf spot infections when they are under general stress. Ensure that the plant is appropriately watered and fed to help improve its' overall health.

Chemical control

The fungicide tebuconazole with trifloxystrobin (Provanto Fungus Fighter Plus, Toprose Fungus Control & Protect) has a recommendation for the control of leaf spots on ornamental plants. Additionally, the fungicides tebuconazole (Provanto Fungus Fighter Concentrate) and triticonazole (Fungus Clear Ultra) are labelled for the control of other diseases on ornamental plants, and could therefore be used legally on Yucca (at the owner’s risk) to try and control the leaf spotting.

The following products contain a combination of both insecticide and fungicide, enabling the control of both damaging invertebrates and disease: triticonazole containing acetamiprid (Roseclear Ultra, Roseclear Ultra Gun). When a proprietary product contains an insecticide as well as a fungicide it would be preferable to use an alternative product if invertebrate damage is not a problem on the plants treated.

There is no specific information available as to the efficacy of these products against yucca leaf spot, however. It 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.

Success is more likely if it is combined with cutting out of the worst affected leaves.
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.


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


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


The precise conditions for spread of the leaf spot disease are unknown, but it is favoured by wet weather conditions. Spores are likely to be splashed around by rain droplets, germinating to produce new infections if the leaf surface stays wet for an extended period. The fungi probably persists on fallen leaf debris.

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