Camellia leaf blight

These fungal diseases of camellias cause the leaves to brown, premature leaf loss and twig or branch dieback. They are most damaging on young plants or newly propagation material.

Camellia leaf blight

Quick facts

Common name Camellia leaf blight
Scientific name Monochaetia karstenii and Pestalotiopsis guepini
Plants affected Camellia spp.
Main symptoms Brown leaves, premature leaf loss and twig or branch dieback
Caused by Fungi
Timing Following prolonged wet periods throughout the year

What is camellia leaf blight?

Camellia leaf blight is a fungal disease caused by one of two fungal pathogens: Monochaetia karstenii and Pestalotiopsis guepini. The development of the disease is favoured by wetness on the leaves and any factors that weaken or damage the foliage.

Symptoms

You may see the following symptoms:

  • Discoloured patches develop on the leaves. These soon turn brown, giving the lesions a scorched appearance
  • Numerous tiny, black fruiting bodies of the fungus develop over the surface of the lesion (damaged area). In wet or very humid conditions these may be seen to exude a black tendril of spores
  • Infected leaves often fall prematurely. The infection can spread down the petiole and into the branch, leading to dieback. Affected cuttings may decay completely

Control

Non-chemical control

  • Good hygiene can help, as do cultural control measures. These include removing affected leaves, twigs or cuttings promptly and destroy them. Where possible, keep leaves dry to prevent dispersal and germination of the spores
  • If pruning out affected twigs or branches, disinfect the pruning implement between each cut

Chemical control

There are no fungicides available to amateur gardeners with specific recommendations for the control of Camellia leaf blight. However, the fungicides myclobutanil (Bayer Garden Systhane Fungus Fighter* and other products), tebuconazole (Bayer Garden Multirose Concentrate 2) and triticonazole (Scotts Fungus Clear Ultra) are labelled for the control of a number of other diseases on ornamental plants, and may give some control of Camellia leaf blight.

The following four products contain a combination of both pesticide and fungicide enabling the control of both insect pests and disease: myclobutanil containing cypermethrin (Westland Rose Rescue); tebuconazole containing deltamethrin (Bayer Garden Multirose 2), and triticonazole containing acetamiprid (Scotts Roseclear Ultra and Scotts 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 pests are not a problem on the plants treated.

*NB: The following products are being withdrawn:

Myclobutanil (Bayer Garden Systhane Fungus Fighter concentrate and Bayer Garden Fungus Fighter Disease Control). These products cannot be sold after the 30th November 2015 and remaining stocks must be used or disposed of before the 30th November 2016.

Download

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

Links

Chemicals: using a sprayer

Biology

Large numbers of spores are produced by the fruiting bodies. The spores are spread by water splash, and will germinate to create new infections if the leaf surfaces stay wet. 

The fungi are generally regarded as weak pathogens, and are much more likely to colonise plant tissue that is damaged, dead or that has been weakened by stress factors.

Advertise here

Video exclusive for RHS members: expert advice on dealing with slugs and snails

Sign into the RHS website to watch video Sign in

Sign in

Did you find the advice you needed?

RHS members can get exclusive individual advice from the RHS Gardening Advice team.

Join the RHS now

Discuss this

for the site or to share your experiences on this topic and seek advice from our community of gardeners.