brown spots of rice

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Page 1: Brown spots of rice

Muhammad Ammar 03356337082

Page 2: Brown spots of rice

BSc. (Hons) Agriculture Muhammad Ammar

BROWN SPOTS OF RICE

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Host: Oryza sativa L. (rice)Disease name: Brown leaf spot or sesame leaf spotPathogen name: Bipolaris oryzae (Breda de Haan) Shoemaker

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Introduction

Brown leaf spot occurs in all rice-growing areas and was responsible for

the Bengal famine in 1942. The disease attacks the crop from the

seedling stage in the nursery to the milk stage in the field. Spots vary in shape and size and appear on the

coleoptiles of the leaves, leaf sheath, and glumes

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SymptomsBrown spot symptoms initially appear as smallcircular to oval spots on the first seedling leaves. Leaf spots are observed throughout the growing season and may vary in size, shape and color depending on the environmental conditions, age of the spots, and the degree of susceptibility of the rice variety. Small spots are dark brown to reddish brown while large spots have a light, reddish-brown or gray center surrounded by a dark to reddish brown margin

Muhammad Ammar 03356337082

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Symptoms

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Symptoms

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Epidemiology

Disease development is favored by high relative humidities (86-100%) and temperatures between 68° to 78° F. Leaves must be continuously wet for 8 to 24 hours for infection to occur.

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SPREAD OF THE DISEASE

• Bipolaris oryzae is seedborne. It can also survive• on infected rice straw and stubble. It spreads from• plant to plant in the field by airborne spores. Species• of some 23 grass genera have been reported to be• susceptible to infection by Bipolaris oryzae. It is not• known how many of these species may act as• alternative hosts in the spread of the disease to rice.

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Disease Management

•Preventive measures:•Use of resistant varieties – Rasi, IR 36, Jagannath.•Proper crop nutrition•Avoid water stress•Clean cultivation

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Cultural practices

Use disease free seeds for sowing.Do not use high nitrogenous fertilizer

Use resistant variety Amruth

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Chemical control

If the disease observed in the field than spray 1g of ediphenphos or 2g mancozeb or 2.25g Zineb in 1liter of

water.

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•THANK YOU

Muhammad Ammar 03356337082