Document Type : Plant Pathology
Authors
member of scientific board/ Mazandaran agricultural and natural resources research centre
Abstract
Head rot is one of the most important diseases of sunflower in the world. During recent years, the disease was observed in Golestan and Mazandaran, northern provinces of Iran. A survey was done during 1999 to 2000 and infected sunflower head samples with the disease symptoms were collected from various regions of Mazandaran. A total of 25 fungal isolates were obtained from the collected samples on the culture media. Based on the morphological and growth properties, all isolates were identified as Rhizopus oryzae. Record cultivar was inoculated by obtained isolates under green-house and field conditions. The symptoms were seen to be similar under the two different conditions. Rhizopus colonies reisolated from plants in the two experiments. In the experimental field conditions the yield losses were evaluted 100 to 44.11 percents at 4.2 to 4.5, and 6.43 to 3.35 percents at 5.1 to 5.3 flowering growth stages, respectively. In commercial fields, infection rates varied between 6 (Ran co., Behshahr) to 18 percents (Khorshid, Neka), and the yield losses were estimated from 0.64 (Kelt, Behshahr) to 1.78 percents (Khorshid, Neka), based on the infection occurrence time.
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