Pansy leaf spots

Pansies and violas may be attacked by various leaf spot diseases that disfigure the plants. Plants in containers and those in the ground can be equally affected.

Pansy leaf spots

Quick facts

Common name Pansy leaf spots
Scientific name Various
Plants affected Pansies
Main causes Fungus and fungus-like (Oomycete) organisms
Timing Winter until early summer

What are pansy leaf spots?

Spots and blotches on the leaves of pansies are caused by the fungal pathogens Ramularia lactea, R. agrestis and Mycocentrospora acerina.

Pansies also suffer from downy mildew caused by the fungus-like (Oomycete) organism Peronospora violae.

Symptoms

Symptoms vary, depending on the disease that is to blame;

Ramularia lactea:

  • Dark greasy spots appear on the leaves becoming brown in the centre

Ramularia agrestis:

  • Pale tan spots and blotches similar to chemical scorch appear on the leaves

Mycocentrospora acerina:

  • Very dark blotches appear on the leaves, and the crown of the plant may rot

Peronospora violae:

  • Yellowish blotches appear on the upper leaf surface, corresponding to a grey, fuzzy, fungus-like outgrowth on the lower surface

Control

Non-chemical control:

  • Avoid repeat planting on the same site to prevent build-up of these pathogens in the soil
  • Spores of the fungal spots are not wind-borne or seed-borne, so be aware that the most likely source of infection is plants which are already infected when bought in. Do not buy plants that show any signs of leaf spot
  • Wild pansies and violets may be sources of infection for garden pansies

Chemical control:

There are no fungicides available to gardeners with specific recommendations for the control of pansy leaf spots. However, the fungicides tebuconazole (Bayer Fungus Fighter Concentrate), tebuconazole with trifloxystrobin (Bayer Fungus Fighter Plus), and triticonazole (Scotts Fungus Clear Ultra and Scotts Fungus Clear Ultra Gun) may be used on pansies and will probably give useful control of leaf spot diseases. They will not control downy mildew.

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.

Download

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

All of these pathogens produce spores on the leaves that are spread by rain over short distances (leaf spots) or by wind over long distances (downy mildew). Mycocentrospora acerina and Peronospora violae also produce tough resting structures in the dead tissues which can contaminate the soil for several years, and the Ramularia spp. probably also do this.

The Ramularia spp. and Peronospora violae only infect pansies and violets, but Mycocentrospora acerina affects a wide range of plants and also causes storage rot in carrots.

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