Other leaf spot diseases of pansy and viola

Several leaf spot diseases can affect pansies and violas. Understanding what they are, and how to spot the signs, will allow you to choose the best control strategies and minimise the risk of damage to your crops.

This information was last updated in 2014.

Leaf spot diseases

Alternaria violae and Cercospora violae (and possibly other species) can also give rise to symptoms of leaf spotting on pansy and viola crops, they can sometimes also be found in association with Ramularia on crops.

Spottting the symptoms

The initial symptoms of Alternaria violae are greenish yellow to light buff lesions which can be water-soaked, later the lesions develop a brown centre.

Concentric rings of light and dark brown become apparent as the spots enlarge and they can merge to form large necrotic areas.

In the case of Cercospora violae, symptoms appear as a dry brown or greyish spot; these darken with the production of spores and may have a purplish border. Lesions may coalesce into a larger necrotic area.

Plant clinic diagnosis is usually necessary for accurate identification of these diseases as control measures can differ from Ramularia.

Disease development, spread and survival

As for Ramularia, these pathogens are usually most prevalent during cool, wet weather and are most commonly found during the autumn period.

Controlling Alternaria and Cercospora

Crops need to be monitored regularly, especially during the early stages of production, for signs of leaf spotting on the older leaves.

Where found, application of a suitable fungicide is advisable to help prevent further disease development.

For up-to-date information on fungicide suitability, advice should be sought from a qualified consultant or representative or via the Chemical Regulations Division - https://www.hse.gov.uk/crd/.