This document provides information on several fungal and bacterial diseases that affect paddy/rice crops. It describes the symptoms, causal organisms, and management strategies for major diseases like blast caused by Pyricularia oryzae, brown spot caused by Helminthosporium oryzae, sheath blight caused by Rhizoctonia solani, and bacterial leaf blight caused by Xanthomonas campestris pv. oryzae. It emphasizes the importance of integrated disease management, including use of disease-free seeds, removal of weed hosts, fungicide application, and optimizing fertilizer use to reduce susceptibility.

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INTEGRATED DISEASE MANAGEMENT IN PADDY
Dr. M.R.Ravikumar
Professor of Plant Pathology
College of Agriculture
Hanumanamatti
UAS , DHARWAD– 585 101.

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• Paddy /Rice
• Staple food crop
• Grown on 43 million ha
= one third of total area under food
grains in the country.
• Cultivation practices differ with locality.
• Nearly 30 important fungal diseases

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ON LEAF
• Blast : Pyricularia oryzae
• Brown spot : Heliminthosporium oryzae
• Narrow brown leaf spot : Cercospora oryzae
• Leaf smut : Entyloma oryzae
• Stack burn disease : Alternaria padwickii
• Leaf Scald : Gerlachia oryzae
(Rhynchosporium oryzae)
• Eye spot : Helminthosporium
gigantea
• Rust : Uromyces coronatus
Puccinia graminis oryzae

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ON STEM & LEAF SHEATH
• Stem rot : Sclerotium oryzae
• Bakane disease : Fusarium moniliforme
: Gibberella fujikuroi
• Sheath blight : Rhizoctonia solani
: Thanatophorus
cucumeris
• Sheath rot : Sarocladium oryzae
• Myrothecium blotch : Myrothecium
verrucaria

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GRAIN
• False smut / Green smut :Ustilaginoidea
virens
Claviceps oryzae
• Kernal smut :Tilletia barclayana
• Udbatta : Balansia oryzae
(Ephilis oryzae)
• Grain discoloration :Curvularia spp.

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Blast
Pyricularia oryzae
Widely distributed & destructive.
Blast is also called as Rice fever disease in China
(1637),
Japan, (1704)and Brusone in Italy.(1828)
Metcalf (1907) called this as BLAST in English
In India first reported from Tanjore -1918.
Loss in severe case is to the extent of 70 – 80 %..

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Symptoms
• On all above ground except sheath.
• Reddish brown, spindle shape with ashy
gray centre.
• 1.5 cm length → 0.5 cm breadth.
• Seedling blast
• Leaf blast
• Nodal blast
• Neck blast / Neck rot

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Leaf blast of Paddy- Pyricularia oryzae

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Nodal Blast
NECK BLAST STEM BORER

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Pathogen : Pyricularia oryzae
Subdivision : Deuteromycotina
Order : Moniliales
Family : Moniliaceae
Perfect Stage- ascomycete
Magnaporthe grisea,

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Pathogen :
pyriform,
3 celled,
septate, hyaline,
RH > 93 % Conidia on leaf,
night dispersal of conidia
Conidiophore simple, rarely branched,
2-4 septate, or in fascicles emerging from stomata,
olive, swollen at base, tapering at tip, conidia at
tip, with a distinctly protruding basal hilum.

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- Toxins produced
- Picolinic acid -
Piricularin
Pyriculol
.

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Epidemiology
• After 6 days of inoculation 2000-6000
conidia / day
• 2-6 AM spore production, for 14 days.
• Dew is required for spore production.
• Infection with light & darkness 12 hr
• Spread air borne conidia.
• Temp - 20-320C .

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• Susceptibility inversely related to soil moisture
• High air humidity leads to more infection.
• High N2 induce susceptibility & less silicification
• Split application of nitrogen reduces
susceptibility.
• Increase in potassium reduces disease.

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Weeds as hosts : Panicum repens,
Leersia hexandra
Resistance : ↑ Silica content
↓ N2 application ↑ R
Oxidation of polyphenols
↑ Peroxidase
↓ Catalase activity
Resistance genotype – TKM – 1, ADT – 25, Tetep,
Tadukan, IR – 8, 36
INTAN & IR 64 ---Earlier Resistance Now Susceptible

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Management
1.Disease free seeds
2.Seed treatment with carbendazim @0.1%
3.Seed s soaked in P.f 10g/lit of water for 30min.
4.Spray carbendazim 0.1% or tricyclazole 0.06% or
propiconozole 0.1%
5.Reduce the application of Nitrogen's fertilizers
6.Remove weed hosts
7. Increase the K fertilizers

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Sheath blight
• Rhizoctonia solani
(Thanatephorus cucumeris - Perfect state)
• This disease is more important in recent years
because
• Increase in fertilizers usage
• High yielding cultivars
• Increase in tillers
• Increase in humidity

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Symptoms
• Spots on leaf sheath
• Oval in shape
• Grayish white with brown margin
• Cover larger area, above portion of lamina
dies on water line surface,
• 20 % reduction in yield.

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Sheath blight of Rice – Coticium sasaki

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Pathogen
• Rhizoctonia solani S.D . Deuteromycotina
• Order – Mycelia sterilia
(Thanatephorus cucumeris - Perfect state)
• Septate,
• branching with constriction at branching.
• formation superficial globose sclerotia
• Sclerotia float on water
• 181 hosts 32 families.
• High humidity & high temperature ↑ disease.

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Management
1. Reduce the application of Nitrogen's
2. Spray with validamycine 0.1% or hexaconozole
0.1% or Difenconozole 0.1%
3. Avoid the movement of water from field

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Brown spot / Sesame leaf spot /
Helminthosporiose disease
• First report in India by
• Sundararaman – (1919) from Tamil Nadu.
Symptoms : In early stage it cause seedling
blight.
• Leaf spot like sesamum seed size, at
maturity coalesce to form large patches.
• Brown spots on glumes.

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Brown leaf spot of Paddy- Cochliobolus miyabinus

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Causal organism : Helminthosporium oryzae
{Drechslera oryzae} {P S – Cochliobolus miyabeanus}
(Subdivision : Deuteromycotina
Order : Moniliales
Family : Dematiaceae)
Perfect State –
Perithecia globose,ostiolar beak.
Asci cylindrical slightly curved.
Ascospore hyaline, 6-15 septate,
conidia singly and successively at regular intervals.
Conidiophore sympodial manner brownish spore.

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Epidemiology :
Survives in plant debris but not
soil borne
• Young seedlings show infection leading to
seedling blight.
• optimum temperature is 25 – 300C

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Collateral hosts :
Digitaria sanguinalis,
Leersia hexandra,
Echinochloa sp
Pennisetum typhoides,
Setaria italica.
Infected hay stacks serves as the source of inoculum
Air carry the spore
Spread is very fast at maturity.

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Management
Spray carbendazim 0.1% or Mancozeb 0.25%
Remove the weed hosts

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Foot rot – Bakane disease
First report by Thomas (1931) in India from
Godavari district of old Madras state
Symptoms :
Disease occurs in nursery & main
field.
• Chlorotic, pale, thinner and abnormally elongated
nodes.
• Tall and lanky plants in the field.
• Adventitious roots from the nodes near the ground.
• Pinkish brown sporulation at the base of plant.

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Bakane disease of rice – Gibberella fujikuroi

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Fusarium moniliforme
(Subdivision : Deuteromycotina
Order : Moniliales
Family : Tuberculariaceae)
P.S. – Gibberella fujikuroi
• Mycelium is both inter & intra cellular.
Produce Microconidia, Macroconidia and
Chlamydospores.

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Micro conidia single/ two celled, hyaline, round to
oval in nature.
Macro conidia are sickle shaped, many celled, hyaline
and pointed at both ends.
Chlamydospores are hard and formed either terminally
or intercalary
Produces Gibberellic Acid
Various type of symptoms of elongation on host
plant.

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• Fusaric acid which is a non specific toxin.
• Disease cycle : Seed & soil borne
Temperature : 25 – 350 C

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Stem rot : Sclerotium oryzae
• Very severe in Punjab
• It was described in detail by Butler in 1918.
• Symptoms :
• Disease at later stage of crop growth.
• More number of tillers
• At the base of tiller rottening
• Black irregular lesion at the water line.
• Slowly it spreads in vertical manner
• Mycelial mat & sclerotia inside the sheath.
• Leading to drying of leaves, with lighter grains.

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Stem rot - Leptosphaeria salvinii

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• Causal agent : Sclerotium oryzae
(P.S. Leptosphaeria salvinii)
• Subdivision : Deuteromycotina;
• Order : Mycelia sterilia
• Disease cycle : Sclerotia soil borne
• Present in soil debris.
• Through irrigation water sclerotia spreads
• Float on water.
• Spread of the disease is seen in unusual dry period and
or accompanied with insect damage at base of plant.
Excessive nitrogen enhances the disease.

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• Udbatta disease : Ephelis oryzae
It is an endemic and minor disease in India. It is
more severe in South India.
Symptoms : Panicle emerges from the leaf sheath a
straight, dirty coloured, hard cylindrical spike much
resembling an agarbatti or Udbatta hence the name.
No grains are formed in the panicle.

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Management :
Use of disease free seeds
Hot water seed treatment
40

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False smut / Green smut
Ustilaginoidea virens
First report from Tirunelveli in Tamil Nadu in
1878.

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Symptoms
• Ears individual ovaries are transformed into
large velvety green masses.
• These are round to oval attain a size of 10mm.
• Only few spikelets are infected
• Glumes are not affected but covered by a
membrane.
• Color changes when it is exposed by breaking
of membrane.

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False smut - Claviceps oryzae
(Ustilaginoidea virens)

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Management:
Hot water Seed treatment
Remove the alternate host
Spray carbendaizim 0.1% or
Propiconazole 0.05%
45

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Bacterial diseases
Earlier bacteria can affect only foliar parts.
But NOW bacterial diseases observed from
seedling to maturity
So far 11 bacterial diseases of rice on leaf Been
reported.
Among them bacterial leaf blight and bacterial
leaf streak are important.

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Bacterial leaf blight of paddy
Xanthomonas campestris pv. oryzae.
• In Fukuoka -1884.
Proved as bacterium by Ishiyama (1922).
In India Srinivasan et. al., in 1959.
Due to introduction of high yield strains like Tai Chung Native – 1
Susceptible to this disease it spread to a large area.

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Loss
Loss is 20 – 30 % in
Japan
In India 6 – 60 %.
The higher loss in India.
Stage of crop affected

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Symptoms
• Yellowing of leaves mainly tip leaves
• Tiny water soaked lesion at margin of fully
opened leaves.
• Spots enlarge, turn yellow and roll when
leaves are green and later dry.
• Wavy Margin on leaf is noticed.
• In severe case seedling die leading to
“KRESEK” symptoms.
• Bacterium spreads through Xylem vessels and
reaches glumes, awns.

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• On the surface of young lesions milky/opaque
dew drops may be observed in the early
morning later dry as yellowish spherical beads
• Chaffy grain, broken grain, poor quality
grains.

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51. Pathogens
• The bacterium is strict aerobe, gram negative, non spore
forming, rod shaped with size ranging from 1-2 x 0.8-1.0um
with monotrichous polar flagellum of 6-8 um.
• Colonies are circular, convex with entire margins, whitish
yellow to straw yellow later and opaque.

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Epidemiology
• Survival in soil is 1 – 3 months
• On seed it survives for three months.
• Rice stubbles/roots, pathogen survives for 3 months
• Entry through natural openings or
• Wounds → through roots at transplanting or chaffing of
leaves.
• Heavy rain, irrigation water & wind increase the disease.
• Kresek symptoms in 20 days at 310 C &
• 40 days at 210C (i.e. high temp quickly Kresek symptom is
seen.)

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Weeds/wild host
Leersia hexandra,
Cyperus rotundus

54. Management
• Burn the stubbles.
• Use optimum dose of fertilizers.
• Avoid clipping of tip of seedling at the time of
transplanting
• Avoid flooded conditions
• . Remove weed hosts.
• Grow resistant cultivars like IR 20 and TKM 6.
• Spray Streptocycline 300g + Copper oxychloride 1.25
g/ha.

55. Bacterial leaf streak
Xanthomonas campestris pv.orizicola
• First reported in china 1957
• Fine translucent streaks are formed on the veins and
the lesions enlarge lengthwise and infect larger veins
and turn brown.
• On the surface of the lesions, bacteria ooze out and
form small yellow band-like exudates under humid
conditions.
• In severe cases the leaves may dry up.

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Bacterial leaf streak Xanthomonas oryzicola oryzicola

57. • Bacteria spread through irrigation water, rain
water
• Bacteria survive in the seed(glumes)
• Favourable conditions
• High humidity
• Temp.20-26c
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Virus diseases
• Seventeen virus and virus like diseases.
• Rice dwarf the first plant virus disease
demonstrated to be transmitted by an insect.
• It was first cause of a virus to be passing from
one generation to next through eggs.
• The severity of disease differs with locality.

59. Tungro disease
• Infection occurs both in the nursery and in the main
field.
• Plants are markedly stunted.
• Leaves show yellow to orange discoloration and
interveinal chlorosis.
• Yellow discoloration is commonly seen in
“Japonica” varieties,
• while “Indica” varieties show orange discoloration.
• Young leaves are often mottled with pale green to
whitish interveinal stripes.
61

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The plants may be killed if infected early.
Tillering is reduced with poor root system.
The infected plants have few spikelets and panicles are
small with discoloured grains.
Tungro infected plants can be chemically identified by
lodine Test.
Ten cm long leaf tip is cut in the early morning before 6
A.M. and dipped in a solution containing 2 g lodine and
6 g Potassium lodide in 100 ml of water for 30 minutes.
Tungro infected leaves show dark blue streaks.

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Rice yellow dwarf
Vector – leaf hoppers

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Rice Tungro
Vector leaf hopper

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“Virus and related diseases of rice can be
distinguished based on the following”
Stunting Plants No stunting of
plants : Rolling &
discoloration of
Orange leaf
Reduced tillering, leaves Profuse tillering
Show dis colouration
Tungro
Pale, drooping of leaves Leaves erect
Yellow dwarf showing rusty specks.
Grassy stunt.

64. Pathogens
• It is a composite disease caused by two morphologically
unrelated viruses :
• Rice tungro bacilliform virus (RTBV)
• Rice tungro spherical virus (RTSV).
• RTBV has a bacilliform capsid 130 x 30 nm made up of a
single species of coat protein of MW 36 K and a single
molecule of circular double - standed DNA of 8.3 KbP.
• RTSV has a isomatric capsid,30 nm in diameter comprising
two to three polypeptide species and a single speices of
polyadenylated single - standed RNA of about 10 KbP.
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65. Management
• Summer deep ploughing and burning of stubbles.
• Destory weed hosts of the virus and vectors.
• Grow disease tolerant cultivars like IR50 and Co45.
• Control the vectors in the nursery by application of
carbofuran 170 g/cent, 10 days after sowing.
• Spray Phosphamidan 500 ml or Fenthion 500 ml or
Neem oil 3 per cent in the main field 15 and 30 days
after transplanting to control leaf hoppers.
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66. Nematode diseases
White tip of Rice- Aphelenchoides besseyi
Phylum :Nematoda
Order :Tylenchida
S. Order :Aphelenchina
S.F : Aphelenchoidoidea
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67. Distribution :
India, USSR
Dastur 1934- Reported from Madhya Pradesh
Yokoo 1940- Japan
1949 - USA
1955 - Bangladesh
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68. Symptoms
*Infected seeds emerge late in seed beds and produce smaller
seedlings
*The upper 2-5 cm leaf tips turn white or pale yellow in
tillering stage then turns to brown and necrotic
*Flag leaves are characteristically shortened and twisted at
their apical portion
*Stunting of Plants
*Panicales are shorter and spiklets reduce in numbers
*Deformed Kernals
Panicles delayed in Maturity_
* 70

69. Life cycle:
A. besseyi is carried beneath the hull of the rice kernel
Nematodes survive up to 3 years
Survive : Seeds and weeds
* When the infected seeds are sown in the moist soil, they
become active and emerge from the seed within 3days
and infect the germinating seedlings
*They move to the growing points of the stem and leaves
and start feeding ectoparasiticaly at the axil of leaves in
between the leaf sheath
*Eggs are deposited in leaf axils or in panicles and
generation occur in each season ( Life cycle 8-10 days)
9-13 generations are usually complete within one cropping
season
• *
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70. Management:
*Soak the seed in hot water at 51-56c for 10-15mints
*Seed treatment with carbosulfan, aldicarb sulfone
*Burning and cleaning of straw, weeds and wild rice
*Application of carbfuran 6-8kg a.i/ha
*Resistant varieties –chinoor, Nira
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71. Rice stunt nematode (Ufra disease)
Phylum :Nematoda
Order :Tylenchida
S.O .Tylenchina
S.F: Tylenchoidea
F : Anguinidae
Genera : Ditylenchus angustus
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72. Distribution :
India, Bangaladesh, Burma, Malasia, Thialad
Symptoms :
Chorosis/ streaks on the upper leaves
a) Swoolen ufra- panicle enclosed within the leaf sheath
* Penduncle dark brown
*Flowers on the lower part remain unfertile
*Stunting and wilting
b) Ripe Ufra –panicle emerge and produce normal
grains
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73. Life Cycle
*At maturity of the crop , the adult and fourth stage juveniles
of the nematode cease feeding and coil up in dried
part of rice plants
Survive 6-15 months
*During humid periods , they become active, climbing up on
the stems and invade the growing points
*They feed ectoparasitically
*Female produce 50-100eggs
*Eggs are laid on rice stem
• *
75

74. Host range –Leersia hexandra
Spread : Seed, Water
Management :
*Crop rotation with jute
*Good drainage
*Destruction of stubbles
*Elimination of voluntary plants
*Using nematode free seeds
*Application of carbofuran or phorate 6-8kg a.i/ha
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75. Rice root knot : Meloidogynidae incognita
Phyum :Nematoda
Order :Tylenchida
S.O. :Tylenchina
S.F. :Heteroderoidea
F : Meloidogynidae
77

76. Distribution :
USA, Thailand, Bangladesh, India
India : West Bengal, Karnataka (Shimoga,Mandya,
K.R,pet, Mercara,Mangalore)
Symptoms:
* Yellowing of leaf, curling of leaves along the midribs
*Infestation by second stage juveniles in roots cause
disruption and hypertrophy of cartical cells and their
migration, movement and salivary sacretion
78

77. *Galls formation in the roots
*Reduced tillering
*Flowering is poor and delayed
*Death of seedlings or plants
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Life cycle:* Invasion and establishments of
juveniles inside roots was completed in 5 days
*The duration of 3rd and 4th stage juveniles was 3 and
7days,
*Male developed in 8days and females developed and
produce egg mass in to a gelatinous matrix
extruding into cortex inside roots within 11days
*The life cycle completed in 24days-27days in
summer ,
16days in July to November

79. Soil temp.18-23.5c at 5cm depth was found to be
congenial for root knot formation
Host range :
Echinocloa colonum
Sweet potato, cowpea, castor, sun flower, Sesamum
Management:
*Soaking seeds in 0.02% carbosulfone for 12hours
*Root dips in the solution of 0.2% carbosulfone
*Flooding the soils and destruction of alternate weed host
*Crop rotation with beans , jute,
* Soil application of neem cake
81

80. Rice root rot : Hirschmarmiella oryzae
Cyst nematode : Heterodera oryzae
Lance nematode :Hoplolaimus columbus
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81. Non infectious disease:
Khaira disease/Zn deficiency
Symptoms :
*The disease appears 10-15 days after transplanting
*Leaves of diseased plants show chlorosis at the base
*Large number of small brown or bronze spots appear on the
lamina surface
*These coalesce to form bigger spots and ultimately the entire
leaf turns bronze coloured and dries
*Stunted growth
* Root growth is restricted and main roots turn brown
*No panicles formation
83

82. Management :
*Two sprays of a mixture of 2kg Zinc sulphate and 1kg
of lime in 400lits. of water per acre
*First spray is given as soon as early symptoms of the
disease are noticed
*Second spray is given 10 days later
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83. 85
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