شناسايي جدايه‌هاي مقاوم Pyricularia grisea به قارچ‌كش ادي فنفوس در استان مازندران و اثر تري سيكلازول بر آنها

Resistant Isolates of Pyricularia grisea to Edifenphos in Mazandaran Province and Effect of Tricyclazole on the Fungus

Rice Blast, caused by Pyricularia grisea is an important injurios fungal disease of Mazandran Province. To identify the fungusʹs resistance to Edifenphos fungicide, 50 isolates of the pathogen were sampled from some different parts of the province. The inhibition of hyphal growth in response to different concentrations (1-140 ppm in PDA) of Edifenphose and the EC50 of this fungicide for the isolates were determined after 5, 7 and 14 days following the start of the experiment. Then, the hyphal growth inhibition due to being disposed to different concentrations and as well as EC50 of Tricyclazole was measured for 11 semi-resistant and resistant against Edifenphos isolates, and after 5, 7, and 14 days from the start of the experiment. In a greenhouse experiment the effect of the fungicide was estimated on the control of leaf blast severity inflicted upon 2 resistant and 1 sensitive isolates of the pathogen, in Tarom commercial of rice cultivar. Results revealed 34% of the isolates as sensitive, 22% semi-sensitive, 30% semi-resistant and 14% resistant to Edifenphos, while all the semi-resistant and resistant isolates being sensitive to Tricyclazole. Also from the greenhouse experiment it was observed that this fungicide controlled the disease (caused by any of the isolates) more effectively than the fungicide Edifenphos. The seeming resistance against Edifenphos among the isolates of this pathogen, the sensitivity of the fungus to Tricyclazole and the more effectivity of this fungicide in the control of the disease is reported for the first time in the province.