Ramularia Leaf Spot

Ramularia collo-cygni

Ramularia leaf spot (Ramularia collo-cygni) is a common disease of barley which can result in significant yield loss if not controlled. While both winter and spring planted barley can be affected, the impact of Ramularia is usually greater on winter planted crops. Ramularia is seed borne and once the fungus has infected the plant it grows within the plant, not producing visible symptoms until around ear emergence. Symptoms consist of small brown lesions which under the right conditions can rapidly increase and coalesce together.

Initial symptoms of Ramularia leaf spot (RLS) are small brown spots. These then develop into larger, reddish-brown lesions, which can have a yellow margin. RLS lesions penetrate through the leaf. Symptoms can develop very rapidly when conditions are favourable.

Look out for:

Small, brown spots
Larger, reddish-brown lesions

Risk factors:

Infected seeds
Barley stubble
Spring rainfall
High light intensity following flowering

RLS has a complex life cycle starting with infected seed. (None of the available seed treatments control RLS). The disease then grows unseen within the plant before it causes symptoms, usually after barley flowers.

If trash from a previous barley crop is present spores from this source can infect a crop during the season.

Spring rainfall and also periods of high light intensity following flowering favour RLS.

Yield losses of 20% have been recorded.

Related Pests

Scald

Rhynchosporium secalis

Scald (Rhynchosporium secalis) is a common disease of barley which can result in significant yield loss if not controlled. Scald is favoured by cooler, moist conditions with the initial source of inoculum being infected straw debris. The first symptoms often appear during winter or early spring, initially as pale greyish lesions which then develop a more straw coloured appearance with a defined dark edge to the lesion.

Net Blotch

Pyreophora teres

Net blotch (Pyreophora teres) is a common disease of autumn sown barley (much less commonly spring sown barley) which can result in significant yield loss if not controlled. Charateristics net type lesions give the disease its common name but lesions can also take the form of dark stripes and streaks and when infection is severe in large dead areas of leaf. Infection sources are either seed or crop debris, which is borne out by second year barley crops being likely to carry infection. Net blotch development is favoured by cool, moist conditions.

Leaf Rust - Barley

Puccinia hordei

Leaf rust (also known as brown rust) is a disease of barley. Whilst occurring less frequently than leaf rust in wheat it can result in significant yield loss if not controlled. Leaf rust is favoured by warmer, drier conditions with the initial source of inoculum being infected volunteer cereals. Under favourable conditions leaf rust can develop very quickly. Spores are scattered at random on the leaf and are often surrounded by a pale chlorotic halo.

Spot Blotch

Cochiobolus sativus

Spot blotch (Cochiobolus sativus) is an uncommon expression of net blotch, a common disease of autumn sown barley (much less commonly spring sown barley). Spot blotch lesions are dark-brown and elliptical in shape.