Investigation on Casual Agents of Evening Primrose (Oenothera biennis L.) Root and Crown Rot and Decline in Green Space of Faculty of Agriculture of Gorgan University

Evening primrose scientifically known as Oenothera biennis belongs to Onagraceae family is an ornamental and medicinal plants with seed containing oil in which in some temperate regions is accepted as an alternative for oilseed plants by farmers. The seeds of plant contain 20-30% oil with unsaturated fatty acids like linoleic acid (more than 70%) and gamma linolenic acid (7-12%). Recently, root and crown rot together yellowing and necrosis and finely decline are appeared in evening primrose cultivated in green space of faculty of agriculture. To study the causal agents of observed disorders, 24 samples were transferred to laboratory and sterilized using hypochlorite 50% for 30 min. then samples were cultured in potato dextrose agar (PDA) medium. After one week a fungus with white grayish colony with black sclorut (55-115 µm) and oval colorless conidia (100-160 µm) was observed. The characters of isolated fungus were similar to Macrophomina phaseolina. The single hyphe of isolated fungus was propagated and inoculated to non-contaminated plants. One month later a black colony of fungus with a high number of sclorut was observed. Re-inoculation of pathogen showed the similar symptoms. The present manuscript is the first report of evening primrose root decline in Iran.