7. Barley Net Blotch

Author: Mariana Nakova

DOI: 10.22620/agrisci.2009.02.007


Barley net blotch is rare and not very well-known in Bulgaria. The disease first appeared on a large scale in the region of Yambol during 2005 on 5 000 ha of barley, on spots scattered in the field, sized from 0.2 to 0.5 ha during the tillering stage. The disease syndrome was quite complicated.
The first symptoms are found on plants growing from infected seeds. Light brown spots with dark fine lines and net appearance are found on the first leaves. Later in the plant development, small red-brown spots with a yellowish margin, resembling net blotch, develop. Spots soon merge and leaves start to wilt from the top and become necrotic.
Drechslera teres is identified as the causal agent on the basis of the observed symptoms and morphological characteristics of the isolated fungi. Conidiophores are in groups from 2 to 3, brownish, cylindrical (130-12 μm). Conidia are cylindrical, with roundish edges, 75-180 X 14-23 μm in size.
The pathogen overwinters as conidia in the seeds and with plant debris in the soil. Teleomorph is not found. The “In vitro” fungicide activity of the following active ingredients is tested: propiconazole, tebuconazole, triadimenol, spiroxamine, difeconazole, chexoconazole, copper oxychloride, metalaxyl + mancozeb, copper oxychloride and zineb, copper oxychloride, tiophanat methyl, triadimefon, carboxin, mancozeb.