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Rice sheath blight and its causal agent Rhizoctonia solani AG-1 IA are associated with intensive and high input production systems. To our knowledge, resistant varieties have not been introduced for this disease, thus good crop management is expected to be among viable disease control methods. The aims of the present study were to determine the effect of different rates of nitrogen fertilizer, planting spaces and inoculum densities on sheath blight incidence and severity, including grain yield loss. Additionally we aimed to identify those developmental stages that are more susceptible to the disease. Field experiments were conducted over two consecutive years, in 2017 and 2018 in the Guilan province of Iran. Results indicated that higher N rates, denser planting and higher initial inoculum density resulted in greater disease development. Among five different growth stages, inoculation of plants at booting and flowering stages, resulted in maximum disease severity and grain yield loss. Taken together, reasonable use of nitrogen fertilizer, optimum planting space and reduced inoculum density obtained by spraying fungicide at the booting and flowering stages of rice are suggested as the best options to control sheath blight epidemics in rice.

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Zagros oak (Quercus spp.) forests (ZOF) cover approximately 4 million hectares of the Zagros Mountains in Iran. Oak charcoal disease caused by Biscogniauxia mediterranea and Obolarina persica has recently increased in some regions of ZOF. Detection of these fungi in host tissue and identification of the anamorphs by traditional methods have limitations and difficulties which were overcome using two primers, OP1 and OP2, based on rDNA sequences of O. persica and used along with the specific primers MED1 and MED2 for B. mediterranea to develop a multiplex PCR. This method was used to correctly identify 1 pg of fungal DNA per 1 mg of inner bark tissues of Quercus brantii, Q. infectoria and Q. libani.