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.

Leaf rust may not be the most commonly encountered barley disease, never the less it is widespread and can be seen every season.

Look out for:

Brown rust pustules scattered across the surface of the leaf.

Risk Factors:

Warm conditions

Leaf rust is wind dispersed, placing all barley crops at risk.

Leaf rust favours warm conditions and therefore is more of a problem in early to mid-summer.

Severe infections can lead to significant yield losses.

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.

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.

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.

Ear Disease Complex

Ear disease complex is a term used to describe a range of weak pathogens that attack the ear, predominately of wheat, causing the ear to turn black. Due to the black colouration these fungi are often referred to as sooty moulds. While overall these fungi do not lead to high yield losses they do produce an unsightly crop and they can reduce grain quality. The problem tends to be worse in wet summers and when harvest is delayed.