DISEASE OF FIELD CROPS

1. ANUJA GEORGE
111718012004

2. Sheath blight of Rice
Disease : Sheath blight
Pathogen : Rhizoctonia solani

3. Symptoms
 The fungus affect the crop from tillering to heading.
 Initial symptoms are ellipsodial or ovoid, greenish-
gray spot.
 The centre become greyish white with an irregular
blackish-brown or purple-brown border.
 Severly infected plant produced by poorly filled or
empty grains,especially on lower surface of leaves.

4. Pathogen
 The fungus produces septate mycelium which are
hyaline when young,yellowish-brown when old. It
produces large number of spherical brown
sclerotia.

5. LIFECYCLEOFSHEATHBLIGHT

6. Management
 Growt resistant varieties like mansarovar,
swaraudhan, pankajetc.
 Avoid excess dose of fertilizer.
 Proper spacing.
 Eliminate weed host.
 Spray of tilt(propinoconazole) @0% or
Hexaconazole @0.2% or validamycin@0.2%.
 Seed treatment with pseudomonas fluroescens of
10g/kg of seed.

7. False smut of Rice
Disease : False smut
Pathogen : Ustilaginoidea virens

8. Symptoms
 Individual rice grain transformed into a mass of
yellow fruiting bodies.
 The fungus transforms grains into greenish spore
balls of velvetty appearance.
 It become black in colour.

9. Pathogen
 Chlamydospore are formed as spore balls which
are spherical to elliptical,warty and olivaceous.

10. LIFE CYCLE OF FALSE SMUT
 Grasses and wild rice species are alternate
host.The main source of inoculum is air-borne
spores.
 Ascospores produced from sclerotia act as
primary source of infection while chlamydospore
are secondary source of infection.
 Chlamydospores are air-born,abundant at
heading stage.

11. Favourable condition
 Rainfall and cloudy weather during flowering and
maturity.
Management
 Removal and proper disposal of infected plant debris.
 Use of disease free seeds that are selected from
healthy plant.
 Seed treatment with carbendazium 2.0g/kg of seeds.
 Spray copperoxy chloride @0.3% at panicle
emergence stage.