Ramularia leaf spot - a potential threat to barley production in North Macedonia

Abstract

Ramularia collo-cygni (Rcc) is a causal agent of Ramularia leaf spot (RLS) that emerged as an economically important seed-borne disease in the last 30 years. RLS causes yield losses of up to 35 % and it is reported as a serious threat of barley production all over the world. Although the fungus co-exists with the host plant from early development stages the RLS symptoms occur late in the season as rectangular reddish-brown necrotic spots usually surrounded by a chlorotic halo. RLS symptoms are visible on both sides of the leaf blade and are very hard to be distinguished from other barley diseases or physiological leaf spots without using molecular techniques. Difficulties in distinguishing RLS from other abiotic and biotic factors of leaf spotting complex, asymptomatic phase of fungal development, and lack of regulations controlling RLS distribution through barley seed trade are major reasons that could jeopardize RLS management and barley production. During the visual inspection of barley production in 2016. in Kumanovo and Bitola the symptoms of RLS were observed on leaves, spikes and awns.