Spotting ramularia in barley, subject of new video

How ramularia leaf spot is assessed in Recommended Lists (RL) trials is the subject of a new video from AHDB.

Developed to help train RL trial managers, it features SRUC’s Neil Havis, who explains how to tell ramularia lesions apart from other foliar symptoms and how to score symptom severity.

In December 2018, AHDB announced it had suspended disease ratings for ramularia because of the strong and poorly understood influence of the environment on disease development in crops.

This year, AHDB plans to run specific ramularia trials to improve understanding of the disease. The training video will help standardise the disease assessment procedure.

Catherine Garman, who manages disease research at AHDB, said: “It’s essential that all RL trials are assessed in the same way. Ramularia is particularly difficult to identify and score. This video will help ensure our trials are assessed to the highest possible standards.”

Within the RL trial assessment process, ramularia disease severity is scored on a 1 to 9 scale. A score of 1 is recorded when crops show no visible ramularia symptoms. Conversely, a score of 9 is recorded when almost all leaves appear necrotic and lesions are present on all leaves.

The scoring data can be used to establish whether robust varietal disease ratings can be produced.

The video follows on from a ‘Ramularia leaf spot in barley’ publication issued by AHDB in 2018. The document includes information on the life cycle of ramularia and control options, as well as images to help with the assessment of disease severity.

The pathogen that causes ramularia – Ramularia collo-cygni – grows from infected seed and moves systematically within both winter and spring barley crops.

Symptoms, which often develop rapidly, appear on dying leaves throughout the season but occur most frequently on upper leaves after ear emergence.

As symptoms are frequently misdiagnosed, the publication illustrates how mature ramularia lesions can be distinguished from other foliar symptoms by applying the ‘5Rs’:

1. Rectangular shape
2. Reddish-brown colouration
3. Restricted by the leaf veins
4. Right through the leaf
5. Ringed with yellow margin of chlorosis

The video, publication and information on fungicide resistance management can be accessed via ahdb.org.uk/ramularia

A training video that outlines the disease scoring process for yellow rust and septoria tritici in wheat is also available from the RL protocols web page.

SRUC’s Neil Havis explains how to tell ramularia leaf spot lesions apart from other foliar symptoms and how to score symptom severity.

1. Rectangular shape
2. Reddish-brown colouration
3. Restricted by the leaf veins
4. Right through the leaf
5. Ringed with yellow margin of chlorosis