بررسی روش های به زراعی در کنترل بیماری بلاست برنج Pyricularia grisea

Rice is one of the three main food in the world. in Iran 80% of the areas under rice cultivation are situated in the northern provinces. Rice blast is a devastating disease which causes considerable damage to rice. In this study, Tarom-Hashemi cultivar after 20-25 days in nursery was cultivated in paddy. To strengthen plant growth in the nursery ,800 g of urea, 20 cc of amino acid wokozim, and 500 g of potassium mono phosphate were treated to each nursery of 30 square meters. Experiment was conducted in a completely randomized blocks with three replications in comparison with control. Cultivation processes were performed according to the usual method in all blocks. One day before transplantation in the main paddy land, 100 kg of potassium chloride, 100 kg of triple super phosphate, 35 kg of urea per hectare were treated. Seven days after transplantation, one kilogram of humic acid was added coupled with one liter wokozim and 40 mg of urea per hectare. The type and severity of leaf infection caused by blast were measured simultaneously using 0-9 criterion. Forty-five days after transplantation, 15 kg of potassium sulfate and 30 kg zinc per hectare were fed to promote grain filling. 20 kg wokozim was treated at heading time. the number of tillers in each mass was counted and 10 plants were randomly selected. spike length, spike weight, 1000 grain weight, number of filled and unfilled grains per spike, straw weight and final yield were calculated. Results showed that in the nursery seedlings growth and color freshness of treated plant increased with respect to the control plants. Analysis of variance revealed that productivity in terms of quantity in comparison with the control had a growth of 1.375. The severity of the disease decreased as a result of using potassium at proper time although that was not significant at 5% level. Interaction of decrease in disease severity and increase in productivity was significant. In this study, Diazinon insecticide and tricyclazole fungicide were applied once in lower dose and had a higher performance that control samples.