Download Nature and symptoms of damage ON LEAF

UNIVERSITY OF AGRICULTURAL SCIENCES
DHARWAD
Dr. M Bheemanna
Assocate Professor of Entomology
Regional Agricultural Research Station
Raichur-584102
Karnataka
Introduction
 Rice is grown in over 70 % of the area in Asia and it
forms a staple food for about 2.8 billion people.
 Wide spread utilization of HYV & adoption of
intensive practices of crop management, though
resulted in substantial increase in yield
simultaneously these practices improved the
conditions of several pests viz., insects, diseases
weeds, rodents and nematodes on the crop.
The yield loss in rice is about 24-35 % with a
loss to the tune of Rs. 100 crores/year.
About 1400 insects covering 100 species are
reported is the world to feed on this crop, of
which about 20 species are of Economic
significance from different parts of the country.
 In our state about 10-12 pests are important
causing significant damage.
PESTS OF PADDY
Yellow stem borer
Brown Plant hopper
Green leaf hoppers
Caseworm
Gall fly
White backed plant hopper
Paddy skipper
Rice leaf folder
Earhead bug
Horned caterpillar
Thrips
Other pests
Rice stem borer
There are 3-4 important stem borers of
which the major ones are
 Scirpophaga incertulas
 Sesamia inferens
 chilo suppersatis
Scirpophaga incertulas
Pyralidae : Lepidoptera
Rice stem borer is also
commonly known as the
paddy stem borer and
yellow borer of rice.
It is distributed in all
Asian countries.
It is a regular pest in all
parts of India.
Seasonal occurrence
 It occurs both in kharif and rabi/summer
seasons.
 Peak incidence is between April to May
 The pest affects the crop in the nursery, soon after
transplanting and also in the pre-ear head stage.
Yellow stem borer (Scirpophaga incertulas (Walk.))
Bright yellowish with brown forewing, long
(2 cm) and slender; Snout like labial palps
with a clear single black spot on each
forewing; Tuft of hairs are present at the
tip of abdomen in the female moth; moths
are attracted to light in the night
Pupa
Pupation inside the
stem in a silken
cacoon; pupal period
6-10 days
Newly hatched larva will be pale
white in colour with bark brown
head and prothoracis shield;
Later turn to pale yellow and
around 2 cm long; Larval period
30-40 days
Eggs are creamy white flattened,
laid in mass near the tip of
tender leaves and are covered
with hairs; Each egg mass
contains 15-80 eggs; IP – 5-8
days
Ecology
 Egg development takes place at about 160C with an
optimum temperature of 24 to 290C and relative humidity
of 90 to 100 percent.
 Hatching is drastically reduced at low temperatures of
130C and relative humidity of 70 per cent.
 The rate of larval development is positively correlated
to temperature range from 17 to 350C.
 The threshold for pupal development is 15 to 160C.
Nature and symptom of damage
Vegetative stage
Larvae feed on green tissue
of leaf sheath for 2 to 3 days.
Bore into the stem at the
nodal position and feed on
inner tissue of plant – Under
Severe conditions, it bores at
the base and move upwards
– Central leaf whorl does not
unfold, turns brown – dries
off.
Lower leaves remain green.
Heading stage
• Larvae bore at the
peduncle node.
• White heads are the
resultant effect.
• Damage is maximum
at this stage.
Yield loss
 Early planted crop 1-19%
 Late planted crop 38-80%
Brown Plant hopper, Nilaparvata lugens (Stal.)
Delphacidae:Hemiptera
Adults are brown in colour; 4-5 mm
long and more or less wedge shaped
Macropterans are strong fliers;
Hind tibia with a long movable spur
Biology: IP – 5 days; NP – 15 days
Brachypterans
are prolific
breeders
Eggs are elongated, cigar
shaped inserted by female in
two rows on wither side of the
midrib of the leaf sheath
Damaging symptoms
• Stage of attack:- Early growth
stage
but some times serious infestation
occurs at post flowering stage
• Damaging stages:- Adults
(especially brachypterans) and
nymphs
• Nature of damage:- Congregate at
the base of the plant causing
hopper burn
• Peak occurrence is between NovDec and not cause damage to
summer crop.
They are also vectors of grassy
stunt virus disease.
Causes for outbreak
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Use of heavy doses of nitrogenous fertilizers
Heavy irrigation with constant standing water
Use of heavy pesticides specially pyrethroids resulting
in resurgence
Continuous cropping of paddy (in both the seasons)
(monocropping)
Close planting will result in prevention of aeration &
light.
Use of susceptible varieties.
In low lying areas severity is more
White backed Plant hopper, Sogatella furcifera
Delphacidae:Hemiptera
The body colour is creamy white;
adult measures 3.1-4.0 mm in
length; the forewings are uniformly
hyaline with darker veins. There is a
conspicuous black dot around the
middle of the posterior edge of each
forewing; the pronotum is pale
yellow
Brachypterans are
prolific breeders
Eggs are elongated, cigar
shaped inserted by female in
two rows on either side of the
midrib of the leaf sheath
Leaf Folder Cnapholocrocis medinalis (guenee)
Lepidoptera : Pyralidae
 The rice leaf folder, earlier
considered as a minor and
sporadic pest of rice in many
Asian countries, appears to have
become increasingly important
with the spread of high yielding
rice varieties and accompanying
changes in cultural practices.
 It is distributed in many rice growing
countries like India, Pakistan, Bangladesh,
China, Burma, Bhutan, Indonesia, Japan,
Nepal, Malaysia, Kerala, Vietnam,
Srilanka, Taiwan, Thailand, Afghanistan
and Australia etc.
 In India it is a serious pest in Karnataka,
Madhya Pradesh, Orissa, Andhra Pradesh
& Tamilnadu.
Paddy Leaf Folder, Cnapahalocrosis medinalis (Guen.)
(Pyralidae;Lepidoptera)
These are small brownish orange
coloured moths and have
respectively two and one distinct
dark wavy lines on the brownish
fore and hind wings which have a
dark brown to gray band on their
outer margin.
Larvae are pale yellowish
to green in colour; They
fold leaf margin
longitudinally and feed
the rolled leaves; larval
period is 15-27 days;
Pupation takes place
inside the leaf roll (6-8
days); Total life cycle is
26-42 days.
Eggs are laid singly
or in pairs on the
under surfaces of
tender leaf blade;
Incubation period is
4 – 7 days
Seasonal Occurrence
 The pest is reported throughout the year
although they are most abundant during
wet season.
 Infestation usually higher during late
growth stages of the crop.
Ecology
 High humidity and optimum
temperatures are conducive factors for
the rapid multiplication of the pest.
 It occurs in abundance where ‘N’
fertilizer dose increase.
Damaging Symptoms
•Damaging stage:- Larvae
•Site of damage:- leaf blade
•Nature of damage:- Leaf margins are folded
longitudinally and feed the rolled leaves by
scraping
chlorophyll. The affected leaf dries up.
In a severely infested field the whole crop
gives a sickly appearance with white
patches. The infestation at boot leaf stage
results in heavy loss of grain yield
Gundhi Bug Leptocorisa oratorius
Hemiptera : Alydidae
 Gundhi bugs are also called
stink bugs as a characteristic
foul odour is produced by
scent glands present on the
abdomen
 These stink bugs are
distributed in all the tropical
and sub-tropical regions.
Seasonal occurrence
The population build up is usually noticed
at the end of rainy season and declines
rapidly during dry months when
temperatures are unfavorable.
The maximum population is usually
observed during September to November
months.
Paddy ear head bug, Leptocorisa acuta (Thumb)
(Alydidae; Hemiptera)
Adults are brown coloured with prominent
legs and antenna; Female lays eggs on the leaf
blade in long rows of 10 -15 eggs. The nymphs
are slender and greenish; Both nymphs and
adults emit a foul smell after disturbance.
Biology: Fecundity; 250-300 eggs with
incubation period of 8 days; Nymphal period
id 12-15 days and adults live for about 3 – 4
months.
•Stage of attack:- Before flowering stage and
up to to milky stage
•Damaging stages:- Both adults and nymphs
•Nature of damage:- Suck the sap of the
peduncle, tender stem and milky grains.
•Symptoms:- Grains become chaffy; At the spot
of the puncture water soaked spots appear and
become brown with white center; The quality
of the affected grain gets deteriorated. Apart
from rice, they also breed on other grasses.
Back
Ecology
 All the stages of the pest are vulnerable to changes in
temperature and humidity.
 Favourable conditions:
1. Temperature 27 –28° C Relative Humidity 80-82%
2. Flowering stage warm and cloudy weather and
frequent drizzles favour population build up.
3. Extensive weedy areas near rice fields and staggered
rice planting favour high population.
 Unfavorable conditions:
Heavy rains reduce population.
Confirmation
 The presence of the insect can be easily
determined by an offensive smell. The
grains are small, shrivelled, spotty, or
deformed. Some grains are also empty.
Economic threshold level (ETL)

1 or 2 bugs/Sq.mt or per hill
Paddy green leaf hoppers
(Cicadellidae; Hemiptera)
N. virescens
The black spots
in the forewing
do not extend up
to the black distal
portion
N. nigropictus
Male has two black
spots extending up
to the black distal
portion on the
forewing
N.cincticeps
No black spot
distal ends of
the wings
transparent
The leafhoppers attack all the aerial parts
of rice plant.
This pest is distributed in Bangladesh,
Burma, Hongkong, Indonesia, Malaysia,
Pakistan, Philippines, Taiwan and India.
In India it is severe in Andhra Pradesh,
Madhya Pradesh, Orissa and moderate to
low in other rice growing states.
Seasonal Occurrence
The hoppers remain active year round
In general two population peaks can be
observed one in first crop season and the
other in second crop season.
The insects are usually more abundant
during dry season than during wet season.
Life History
Adult female inserts
their eggs in rows under
the epidermis of leaf
sheath in groups of 5-20,
up to 100-135 eggs.
 Eggs hatch in 5-7 days.
 Nymphal stage
completed in 14-21 days.
Ecology
 The abundance of Green hoppers has been
correlated to high temperature, low rainfall
and abundant sunshine.
 The rate of nymphal development is faster
at high temperatures. (14.1 days at 35° C
and 37.3 days at 20° C).
 The rapid build up of pest population was
observed at tillering and panicle initiation
stages of rice crop.
 The insect can withstand long periods of
starvation. They are highly attracted to
light at nights.
Nature and symptoms of Damage
 The nymphs and adults cause direct damage to rice
crop by sucking sap from leaf sheaths and blades.
 The feeding marks predispose plants to fungal and
bacterial infections.
 The affected leaves and plants turn to yellow colour
and growth is retarded.
 They indirectly acts as vectors by transmitting virus
diseases such as Tungro and Yellow dwarf.
 They also feed on some grasses like Cynodon dactylon,
Echinochloa crussgalli and Eleusine indica, etc.,
Economic threshold level (ETL)
 Planting to Pre-Tillering 2 insects/hill in
Tungro endemic area.
 10 insects/hill in other areas.
 Mid-Tillering, Panicle Initiation to
Tillering20 insects/hill.
Rice Case Worm Nymphula depunctalis guen
(Lepidoptera : Pyralidae)
 The rice case worm is an important
pest of irrigated and rainfed wet land
rice in South and Southeast Asia.
 Besides rice it infests various other
grasses and millets.
It is existing in low population in all
rice growing areas.
Seasonal occurrence
 In South India, moth population reach
two peaks, one during November to
December and another during May to
June.
 These peaks coincide with periods of
high rainfall and high humidity.
 Beyond November, they migrate to
grassy areas.
Life history
o The adult moths are white in color &
about 6 mm long with a wing expansion of
15 mm.
o Eggs are laid in one or two adjacent rows
in batches of 10 to 20 on the lower surface
of leaves or on the leaf sheath near the
water surface.
o The egg period vary from 2 to 6 days.
o The newly hatched larva is pale green and
measures 1.2 mm long.
Symptoms
1. Leaf cases floating on water
2. Leaves cut at right angles as
with a pair of scissors
3. Leaves with papery upper
epidermis that were fed on
4. Skeletonized leaf tissues
usually appear ladder-like
Asian Gall Midge, Orseolla oryzae
Diptera : Cecidomyiidae
 The gall midge is primarily a pest
of low land irrigated rice but has
been reported in upland and deep
water rice also.
 The extent and severity of gall
midge infestation has significantly
increased since 1970’s.
 The cultivation of high tillering
varieties, intensive management
and are low parasitization
conducive to the rapid
multiplication of this pest.
 It is distributed in almost all rice growing
Asian countries.
 In India it occurs as a serious pest in
Madhya Pradesh, Manipur, Orissa,
Andhra Pradesh, Bihar, Karnataka and
Kerala.
About three bio-types were identified in
different states.
Seasonal Occurrence
 The gall midge attacks rice crop from the
nursery to the end of tillering stage.
 The pest remains inactive as a pre-pupa in
wild rice or weeds during dry season.
The incidence is usually high during months
of July and August during which period the
maximum tillering takes place.
Life History
• Adult gall midge is similar to female mosquito in
appearance.
• Eggs are laid in singles or groups on the under side
near the base of the rice leaf or on leaf sheath.
• Single female is capable of laying 100 – 200 eggs.
• Adults are nocturnal in habit and attracted by light.
• Male mostly die in 12-18 hours after emergence – while
female live for 3 days.
• Eggs are shinning white or pinkish, red or yellow in
colour – elongated tubular and measures 0.55 mm long.
• Newly hatched maggots are grey white and fairly
stout with a pointed anterior end.
• Larval period is 15-20 days with 3 larval instars.
• Pupation takes place inside the galls near the base
of the plant.
• Pupae have abdominal spines which enable it to
wriggle its way to the tip of gall.
• Pupal period varies from 2-8 days .
• Adult emergence generally takes place at night or
early morning.
• Entire life cycle takes about 25-38 days.
Ecology
 The pest require high humidity for proper
development and hatching of eggs.
 The favorable condition for fly development
is 26 to 300C and 82 to 88 % relative
humidity.
 Heavy rains or storms cause high mortality.
Nature and symptoms of damage
 Damaged tillers turns into
tubular galls which dry off
without bearing panicles.
 Main external symptom is
SILVER SHOOT or GALL
which resembles onion leaf.
 Fully developed gall is a
silvery white hallow tube 1 cm
wide and 10 – 30 cm long.
 Attack to rice seedlings leads
to profuse tillering and these
new tillers often become
infested.
 Larvae develop only on growing
primordia.
 Yield loss is 0.5% for every unit
percent increase in incidence.
 Three bio types are noticed in
India – Which are capable of
damaging cultivars, resistant to
other populations of the same
species.
Economic threshold level (ETL)
 Nursery - One Silver Shoot / Sq.mt.
 Planting to Pre-Tillering One gall /m2
(endemic areas) or 5 % affected tillers (Nonendemic areas).
 Mid-Tillering 5 % affected tillers.
Paddy skipper Pelopidas mathias F.
Hesperidae;Lepidoptera
It is common but minor
pest.
Adult butterfly is dark
brown with two white spots
on the forewings.
Damage
They skeletonize the leaf by
eating the entire leaf margins
and leave the midrib uneaten.
Hispa Dicladispa armigera (oliver)
Coleoptera : Chrysomelidae
 This pest was reported to cause
considerable crop losses in many
Asian countries.
 It was observed to cause heavy
losses even to the extent of 55%
in Bangladesh.
 It is common in wet-land
environments and sporadic out of
breaks have been reported from
many parts
 the pest usually occurs from
July to October.
Life History
 Adults are small shiny black beetles of 5.5 mm
long with spines on their wing covers Longevity of
female - 20 days and male - 15 days
 Female beetles lay eggs in singles with in the
epidermal layers of the ventral surface of rice
leaves.
 Newly hatched grubs mines to form bloches, pale
yellow in color and 2 to 4 mm long.
Ecology
 High humidity after rains and intermittent
bright sunshine appears to favor Hispa
development in South India.
 Heavy rainfall in July followed by unusually
low rainfall in August and September was
characteristic of epidemic years.
 The late planting in August suffers severe
damage with little chance of recovery.
Nature and symptoms of damage
 Both grubs and adult
beetles feed on rice
plants.
 Adults scrape chlorophyl
first between the veins
and the lamina.
 White parallel streaks on
the leaves.
 Feed on veins also
resulting in the
formation of blotches on
the leaves.
In severe infestations the affected
leaves turn to brown and the field
presents a dried-up appearance.
Economic threshold level (ETL)
Planting to pre-tillering stage : 1 adult or
1 damaged leaf/hill.
Mid-tillering stage : 2 adults or 2
damaged leaves/hill.
Paddy thrips
Stenchaetothrips biformis (Bagnall)
Thripidae; thysanoptera
 Adults are tiny elongated bark brown
insects with narro fringed wings. They are
usually seen at the tip of the leaves and
sheaths.
 The female lays eggs singly with in the
leaf tissue
Damage
The infestation is more in the
nursery and just transplanted
crop.. Both nymphs and adults
lacerate the leaf tissue and suck
plant sap with the result the leaf
margin and in sever cases
seedlings are killed.
The damage is severe under
water stress conditions. Late
planted crops are more prone
for damage. Damaged leaves
roll inwards along the margins,
feeding causes leaf drying
resulting poor crop growth.
Paddy horned caterpillar Melanitis leda ismene C.
Satyridae; Lepidoptera
The butterfly is dark brown
with large wings having a
black and yellow and eye spot
one on each of forewing
 It lays white round eggs
singly on the leaves
 Caterpillar is green
slightly flattened with two
red horn like process on
the head and two yellow
process in the anal end
 It pupates in a greenish
chrysalis which suspends
from the leaf.
Damage
• The larva feeds on the leaf blade.
• Each larva is capable of defoliating a
great quantity of leaf tissue during its 3week larval period
Whorl Maggot Hydrellia spp
Diptera: Ephydridae
• Several species of Hydrellia exist
in Rice ecosystem .
• The pest occurs in India,
Bangladesh, Indonesia, Taiwan,
Thailand and Phillippines.
• The pest is more abundant in
Rice crop grown with
continuous standing water.
• It is found as occasional pest in
Rice fields.
Life History
• The adult flies are dull-grey
coloured.
• Newly hatched maggots are
transparent to light cream in
colour and later turn to
yellow.
• Maggots migrate to un open
central leaves and remain
there during entire larval
period.
Nature and symptoms of damage
• The maggots attack the leaf
blades even before unfurling
and the initial damage is
characterized by the presence
of the blade margins. narrow
stripes of whitish arean
• Heavy infestation causes a
marked stunting of the plant
and reduction of tillers.
Seasonal occurrence
• The pest is abundant during early stages of crop
growth.
• The infestation ceases at the panicle emergence
stage.
Paddy swarming caterpillar and
climbing cutworm
Spodoptera mauritia and S.litura
Noctuidae: Lepidoptera
 It is a miner post in the region
 The pest is active from July-Sept.
Occurs both in nursery and main crop
and swarm from field to field.
 The adults are stout dark brown moth
with conspicuous marking on the
forewing. Female lays eggs is mass of
200-300 and cover with grayish hairs.
• Incubation period lasts for 3-5 days,
larvae are green as they grow they
become grayish pale green with
reddish and yellowish stripes across
the body. The larvae are active
during night for 20-25 days. They
pupate in a earthen cocoon and papal
period is for 10-15 days.
Symptoms of damage
 In nursery the larvae cut the plant at
base and feed on the fallen plants. In
the main field they feed on leaves by
climbing the plants leaving behind
midrib. If the population is heavy they
from field to field causing heavy
amount of loss in such cases the field
appears as if it is grazed by cattle’s.
Paddy grass hopper, (Acrididae;Orthoptera)
Hieroglyphus banian : larger in
size (3.75cm.) green with three
transverse dark lines on the
prothorax and poses bluish green
hind tibia. It attacks rice
sugarcane and other millets.
Oxya chinensis : is smaller,
about 2.5 cm long, green with
longitudinal brown streak on
either side of the thorax.
This attack rice and grasses
• The nymphs and adults feed on leaves
leaving the midrib and stalks.
• They also nibble the florets and base of
panicle causing white ears. Usually they
have one brood in a year.
• The hopper hatch in June-July from the
eggs laid in sandy soil in batches of 30-40
along the bund sides in the previous seasons
(Oct-Nov).
• The *nymphs feed on grasses of bunds after
hatching and move to main crop when crop
is planted.
Oriental mole cricket
Gryllotalpa orientalis Burmeister
Orthoptera: Gryllotalpidae
Adults and nymphs
have enlarged and
spade-like front legs
Nature and symptoms of damage
 Adults and nymphs
feed on sown seeds
and roots.
 Young plants can die
from root loss
producing bare spots
and missing plant
stand in the field
ON LEAF
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Blast
Brown spot
Downy mildew
Narrow brown leaf spot
Leaf smut
Stack burn disease :
Leaf Scald
:
:
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:
:
:
• Eye spot
:
• Rust
:
:
Pyricularia oryzae
Heliminthosporium oryzae
Sclerophthora macrospora
Cercospora oryzae
Entyloma oryzae
Alternaria padwickii
Gerlachia oryzae
(Rhynchosporium oryzae)
Helminthosporium
gigantea
Uromyces coronatus
Puccinia graminis oryzae
ON STEM & LEAF SHEATH
• Stem rot
• Bakane disease :
:
• Sheath blight
• Sheath rot
:
• Myrothecium blotch
:
Sclerotium oryzae
Fusarium moniliforme
Gibberella fujikuroi
:
Rhizoctonia solani
:
Thanatophorus
cucumeris
Sarocladium oryzae
:
Myrothecium
verrucaria
GRAIN
• False smut / Green smut :Ustilaginoidea
virens
Claviceps oryzae
• Kernal smut
:Tilletia barclayana
• Udbatta
: Balansia oryzae
(Ephilis oryzae)
• Grain discoloration :Curvularia spp.
Blast
Well known disease
Widely distributed & destructive.
Blast is also called as Rice fever disease in China,
Japan, and Brusone in Italy.
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 %..
Loss due to blast (%) = Y= 0.69 X + 2.8
Where X
= % panicle affected
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
Leaf blast of Paddy- Pyricularia oryzae
Nodal Blast
NECK BLAST
STEM BORER
Reasons:
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Susceptibility inversely related to soil moisture
Silicification of epidermis is more by low 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.
Dew period shortest near water surface and longer
near top of rice canopy.
Weeds as hosts : Panicum repens, Leersia
hexandra & Brachiaria mutica
Resistance : ↑ Silica content
↓ N2 application ↑ R
Oxidation of polyphenols
↑ Peroxidase
↓ Catalase activity
Resistance genotype – TKM – 1,ADT – 25, Tetep,
Tadukan, Peta, IR – 8, 36
INTAN & IR 64 ---Earlier Resistance Now Susceptible
Yield loss Estimation
a) Yield in Epidemic & non epidemic area.
b) Resistant & susceptible genotype
c) Protected & unprotected by fungicide
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
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.
Sheath blight of Rice – Coticium sasaki
Stem rot : Sclerotium oryzae
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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.
Stem rot - Leptosphaeria salvinii
False smut / Green smut Ustilaginoidea
virens
First report from Tirunelveli in Tamil Nadu in
1878.
• More prevalent in seasons favorable for good
growth and high yields
• The farmers consider its incidence as an omen
of God Harvest.
Symptoms
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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.
Colour changes when it is exposed by
breaking of membrane.
False smut - Claviceps oryzae
(Ustilaginoidea virens)
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.
Bacterial leaf blight of paddy
Xanthomonas campestris pv. oryzae.
• In Fukuoka -1884.
Earlier physiology origin / Acidic soil.
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.
Post typhoon disease or Rain borne disease
Loss
Loss is 20 – 30 % in Japan
In India 6 – 60 %.
The higher loss in India.
Stage of crop affected
Symptoms
• 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.
Bacterial leaf streak Xanthomonas oryzicola oryzicola
• Another symptom is yellowing of leaves
mainly tip leaves
• 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.
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
of leaves.
→
through roots at transplanting or chaffing
• 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.)
Weeds/wild host
Leersia hexandra, L. sayanuka, Leptochloa chinensis,
Cyperus rotundus
Forecasting :
– Growing S & R in field and forecast regularly.
– By climatic conditions. : Flood, rain, sunshine,
wind & temp.
1. By Bacterial population.
2. Take samples from leaf & analyse.
3. By phage.
Resistance : Resistance is related to
Number of water pore or hydathodes.
• Hardness of leaves.
• Short narrow leaves with less horizontal spread
• Susceptible have high concentration of free amino
acids but less concentration of reducing sugars &
poly phenol.
• AiKoKu – soto – sango – kei & Nakashin 120 are
resistant genes to all three groups of bacteria.
• Resistant varieties → IR 20, IR 22, IR-8, TKM – 6,
Lead rice from Burma.
THANK
YOU
Narrow brown leaf spot- Cercospora oryzae
Sheath rot - Acrcylindrium oryzae
Narrow brown leaf spot- Cercospora oryzae
Sheath rot - Acrcylindrium oryzae