VIABILITY OF PYRENOPHORA GRAMINEA CULTURES AFTER SUNLIGHT EXPOSURE UNDER FIELD CONDITIONS
M.I.E. Arabi, E. Al-Shehadah, M. Jawhar
Conidia of Pyrenophora graminea, the causal agent of barley leaf stripe, were simultaneously exposed outdoors to direct solar radiation or placed in an adjacent ventilated enclosure in the dark for four months. After exposure, conidia were placed on water agar in closed Petri dishes and allowed to germinate for 24 h. Shaded conditions were always more favourable to conidia germination and mycelial growth than sunlight conditions. Significant decreases (P<0.05) in conidia germinability (60.6%) and mycelial growth (41.46%) were detected in light-exposed conidia in comparison with the non-exposed control. Exposure also decreased the pathogenicity of fungus on different cultivars. The possibility that sunlight exposure may reduce conidia germinability over the hottest four months and aerial transport distances should be considered.