Brown Leaf Spot
Brown leaf spot is one of the most common and damaging rice diseases that can develop in areas with high relative humidity (86-100%) and temperatures between 16-36°C. Commonly seen in unflooded areas and nutrient deficient soil or soils that accumulate toxic substances.
The fungus causing brown spot in rice is Helminthosporium oryzae can survive in the seed for more than four years and infected plant debris which serves as a source of inoculum in the field
Source: http://www.knowledgebank.irri.org/training/fact-sheets/pest-management/diseases/item/brown-spot Source: http://www.knowledgebank.irri.org/training/fact-sheets/pest-management/diseases/item/brown-spot
What are the symptoms
Typical symptoms appear as numerous spots (small, circular, yellow brown or brown lesions) on the leaves that extend up to coleoptile, leaf sheaths, panicle branches, glumes and spikelets. When infection occurs in seed, unfilled grains, and discolored seeds are formed.
Impact to the Crop
The infection leads to unfilled and discolored grains that directly affect the yield. Up to 50% yield loss has been recorded for severe cases.
How to Control
The disease can be controlled by improving soil fertility, use of resistant varieties, use of fungicides as seed treatments such as iprodione, propiconazole, azoxystrobin, trifloxystrobin, and carbendazim, seed treatment in 53-54°C for 10-12mins.
Source: http://www.knowledgebank.irri.org/training/fact-sheets/pest-management/diseases/item/brown-spot
