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CROP INFORMATION
CROP : RICE (Oryza Sativa)
Rice can be cultivated under a variety
of climatic and soil conditions. Rice cultivation is conditioned
by temperature parameters at the different phases of growth.
The critical mean temperature for flowering and fertilization
ranges from 16 to 200C, whereas, during ripening, the
range is from 18 to 320C. Temperature beyond 350C affects
grain filling. Rice comes up well in different soil types.
For normal growth, a pH range of 5.0-8.0 is suitable.
In general, rice can be grown as transplanted or direct
sown crop during three seasons as shown below depending
on the agroclimatic situations.
View Table 1. Different rice
growing seasons of Kerala
During second crop, for higher yield in photosensitive
high yielding varieties in Palakkad district, where assured
irrigation is available, the crop commencement may be
adjusted in such a way that it flowers only during the
second fortnight of December, facilitating proper integration
with the weather, better utilization of applied fertilizers
and high filling percentage.
View Table
2. Rice varieties suited for different situations
View Table
3. Important characteristics of varieties recommended
for cultivation
Tips on quality seed production in rice
and maintenance of viability of stored seeds
Assure that the seeds for further multiplication are either
from a research station or government farm or recognized
seed producers.
The land used for seed production should be free from
volunteer plants of other varieties grown previously.
To assure genetic purity, a minimum
isolation distance of 3 m from other varieties may be
given in the field. Harvesting for seed purpose can
also be done leaving a border row of 3 m within the
field.
Rogue diseased plants, weeds and off-types
in time.
Line planting facilitates roguing and giving alleyways
of 30 cm after every 3 m planting helps in manuring,
plant protection operations and supervision.
Drain water at least one week before harvesting to assure
that the plants attain equal maturity at harvesting.
Harvest the crop when 80% of the grains in a panicle
are mature (at physiological maturity).
During summer months, assure that the
plants get sufficient water at dough stage till maturity.
Thresh the sheaves on the same day of harvest, as seeds
of heaped sheaves may not perform well.
Dry seeds properly and assure that the
moisture content is not more than 13 per cent.
Avoid excess drying in summer months especially short
duration varieties as it reduces the period of viability.
While drying and storing, avoid contamination from yards
or through baskets or bags.
Seeds may be stored in damp-proof situations for avoiding
absorption of moisture from atmosphere thereby losing
viability early.
Polythene bags of 700 gauge or double gunny bags may
be preferred for storing.
Never stack seed bags in open floors. Store on pallets
or wooden benches. The benches should be 30 cm away
from wall and floor for proper aeration.
Never pile more than eight bags in a stack. This should
be limited to three bags if the seeds require further
drying.
Avoid storing plant protection chemicals, herbicides,
fertilizers etc. in seed store.
Fill up the cracks and crevices of storeroom by cementing
to make it rat proof.
Spray 2% malathion solution in the godown before storing
seeds to check insect pests.
Place pieces of cloth dipped in neem oil between stacked
bags or neem oil cake covered in cloth bags inside seed
bags to ward-off pests.
Test seed germination at monthly intervals if the seeds
are to be stored for more than eight months.
The viability of short duration varieties
can be extended for a further period of 2-3 months at
80% level if the seeds are soaked for four hours in
water and re-dried in shade, back to original weight
at 13% moisture content. Seeds of short duration varieties
like Jyothi and Triveni of virippu crop reach this level
of germination 9-10 months after harvest and that of
mundakan 8-9 months after harvest when stored under
ambient conditions.
Seed rate for Kuttanad may be enhanced from 80-100 kg/ha
to 125 kg/ha, provided excess plants are removed in
order to maintain optimum plant population.
To keep sprouted pokkali seeds viable for two weeks,
sprouted seeds are to be kept in baskets made of plaited
coconut leaves in which koova, banana, karingotta or
teak leaves are used as internal lining material within
the baskets.
Seed rate
Transplanting 60-85 kg/ha
Broadcasting 80-100 kg/ha
Dibbling 80-90 kg/ha
Note: The above seed rates are specified for farmers'
field on the basis of minimum germination of 80%. In
pokkali cultivation, for Vyttila varieties, 100 kg/ha
may be sown on the beds or mounds formed in the field.]
Seed treatment
Dry seed treatment
Dress seeds with the following fungicides on the previous
day of sowing (12 to 16 hours ahead) at dosage given
below:
Pyroquilon (Fongorene 50 WP) 2 g per kg of seed
Carbendazim (Bavistin 50 WP) 2 g per kg of seed
3. Tricyclazole (Beam 75 WP) 2 g per kg of seed
Wet seed treatment
Soak seed for 12 to 16 hours in a solution of any of
the following fungicides and drain to induce germination.
0.2% Fongorene 50 WP 2 g/kg of seed/l of water
0.2% Bavistin 50 WP 2 g/kg of seed/l of water
Treatment with the above fungicides either dry or wet
protects the seedlings from blast disease up to 30 to
60 days after sowing.
The above seed treatment can also be recommended for
giving protection from seedlings blast in endemic areas.
Soak paddy seeds in CuSO4 (0.25%) and ZnSO4 (1%) solution
for 24 hours. Drain and keep for sprouting. For soaking
1 kg of seed, 1 litre of micronutrient solution would
be needed.
Nursery
For transplanting, healthy seedlings have to be raised
in seedbed. Healthy seedlings can cope up better with
the field conditions that affect the growth of young
rice plants. Adopt wet or dry method for raising seedlings.
The choice depends primarily on the availability of
water.
Wet method
The wet method can be adopted in areas where water is
available as in the second crop season. Seedlings raised
by the wet bed method can be harvested one week earlier.
The seedbed should be prepared in advance, so that the
pre-germinated seeds can be sown in time. As far as
possible, fertile lands with irrigation and drainage
facilities should be selected for raising the nurseries.
Such lands should be suitably located to receive full
sunlight. The following are the steps in raising wet
nursery.
Plough and harrow the fields two or three times until
the soil is thoroughly puddled and levelled. Prepare
raised beds 5 to 10 cm high 1 to 1.5 m wide and of convenient
length with drainage channels between the beds. The
total seedbed area should be 1000 m2 for each hectare
of the field to be transplanted.
Apply compost or cattle manure @ 1 kg per m2 of the
nursery bed and mix well with the soil at the time of
preparation of the field.
Treat the seeds by wet method. Drain and incubate in
warm moist place for sprouting. Never allow the seeds
to dry up. Moisten them occasionally. Sow germinated
seeds on the third day. Delay will result in poor seedling
stand.
Irrigation may be commenced on the 5th day after sowing
and continued up to the 7th, to a depth of about 5 cm.
After this period, irrigate the seedbed continuously
to a depth of about 5 cm in order to control weeds.
Drain occasionally to encourage production of vigorous
seedlings with short roots. Flooding the soil with too
much water for long periods produces tall and weak seedlings,
which do not readily recover during transplanting.
If symptoms of nitrogen deficiency are observed, broadcast
urea at the rate of 1 kg for 100 m2 as top dressing
about 10 days prior to pulling out of seedlings, depending
upon the duration of variety.
Dry method
This method is practised in areas where sufficient water
is not available and the time of planting is uncertain.
During first crop season, wherever transplanting is
done depending upon receipt of rainfall, it is safer
to adopt this method since growth of the seedlings can
be controlled.
Plough the nursery area to a fine tilth.
Prepare raised beds of 1 to 1.5 m width, 15 cm in height
and of convenient length. Apply compost or cattle manure
at the rate of 1 kg/m2 of the nursery bed and mix well
with the soil at the time of preparation of the field.
Sow the seeds treated as described under dry seed treatment
method, evenly over the bed and cover with fine sand
/ soil.
Water the nursery as and when required depending upon
the receipt of rains.
Note: Rice seedlings from solarised nursery beds showed
high initial growth, early maturity and resistance to
leaf blast disease (ad hoc recommendation).
Age of seedlings
Seedlings are ready to be pulled out when they attain
the stage of 4-5 leaves, about 18 days after sowing
in the case of short duration varieties and 20-25 days
after sowing in the case of medium duration varieties.
Under ill drained conditions, the long duration varieties
like Pankaj, Jagannath and IR5 may be planted 30 days
after sowing. Seedlings more than 30 days old when transplanted
in the field recover slower than younger seedlings,
especially, if they suffer stem and root injury. However,
during the virippu season, age of seedlings can go up
to 35 days in case of medium duration varieties and
25 days for short duration varieties. If the seedlings
are over aged, plant at a closer spacing with 3 or 4
seedlings per hill and apply extra dose of nitrogen
@ 5 kg/ha as basal dressing.
Irrigate seedbeds a day before pulling out the seedlings
to soften the soil and to facilitate washing of roots.
Pull out one or a few seedlings at a time to reduce
damage. Wash off mud and soil from the roots carefully
and tie the seedlings into bundles of convenient size
for transplanting.
Pruning of the top portion and root
is not recommended as it inflicts wounds through which
disease causing organisms may subsequently enter.
Preparation of land
General
Plough the field thoroughly to incorporate the weeds
and straw into the soil. Ensure a smooth, level field
for transplanting the seedlings. It would be better
to transplant 10-15 days after incorporating organic
manure. Before transplanting or sowing, apply manures
and fertilizers at the rates specified for the region
and varieties as indicated in Table 4. Apply fertilizers
on the drained soil at the time of final ploughing and
levelling and thoroughly mix into the soil.
Kuttanad
Drain out standing water from the main field. Plough
the field thoroughly to incorporate the weeds in the
field. Ensure a smooth and levelled field. Maintain
a thin film of water to facilitate sowing so that the
germinated seeds do not get covered with clayey soil,
which affects seedling establishment.
Kole
For the first crop in Kole, after the cessation of the
heavy monsoon, dewatering is effected by petti and para
or centrifugal pump and rarely by chakkram. Land is
ploughed thoroughly and transplanting is done.
For the second crop, land is prepared thoroughly and
direct sowing of sprouted seeds or transplanting is
done.
Onattukara
With the onset of pre-monsoon showers, land is ploughed
thoroughly. Dibbling of unsprouted seeds behind the
country plough is the common practice.
Pokkali
By April, the bunds are being strengthened and sluices
repaired for regulating water level. Fields are then
drained during low tide and the sluices are closed.
When the soil in the field becomes dry, mounds of 1
m base and 0.5 m height are formed. This facilitates
the washing down of the dissolved salts from the surface
of the mounds, which are ultimately removed from the
field by tidal action. The mounds act as elevated in
situ nursery and protect the seedlings from flash floods.
A special method is adopted for sprouting the seeds.
The seeds are tightly packed in baskets made of plaited
coconut leaves, the inside of which is lined by banana
or teak leaves. These baskets are then immersed in fresh
water ponds for 12 to 15 hours. They are then taken
out and stored in shade. The radicle just sprouts and
remains quiescent under this condition for more than
30 days. When the soil and weather conditions become
favourable for sowing, the baskets containing the seeds
are re-soaked for 3 to 6 hours before sowing. The mounds
in the field are then raked and top levelled. The sprouted
seeds are sown on the top of mounds, which act as an
in situ nursery. When the seedlings reach a height of
40-45 cm (in 30-35 days), the mounds are cut into pieces
with a few seedlings, which are uniformly spread in
the field.
Koottumundakan
In this system of rice cultivation, a mixture of seeds
of a non-photosensitive (virippu) variety and a photosensitive
(mundakan) variety of rice in the proportion 70:30 (w/w)
is sown during virippu season. This system is practiced
in areas where sowing / planting of mundakan crop is
not possible due to excess water in the field. Hence,
mixture of the two varieties is sown in the first crop
season (April-May). The first crop variety will be ready
for harvest in August-September and the second crop
variety can be harvested in December-January. No cultivation
is practised after the harvest of first crop season
variety. But both organic and inorganic manures are
applied and incorporated. Though the yield will be less
than that of the two independent crops, this type of
cultivation is taken up in view of the special circumstances
prevailing in such areas.
Transplanting
Transplant seedlings of appropriate age for the variety
@ 2-3 seedling per hill in rows, at spacing as shown
in Table 5. Leave wider row of 30 cm after every 3 m
to facilitate spraying and other cultural operations.
Transplant seedlings at a depth of 3-4 cm
View Table 4.
Spacing for rice transplantation
View Table 5.Cropping pattern
/ system
Hints for reducing cost of cultivation
1. Grow a green manure crop like daincha in April-May
in areas where the virippu crop is usually transplanted.
Application of organic manures @ 10 t/ha will help to
reduce the fertilizer level by 50%.
2. If azolla is available, this may be applied instead
of green leaf or FYM at 5t/ha.
3. Puddle and level the field thoroughly. This will help
to reduce the cost of weed control and also the loss of
water and nutrients through percolation.
4. Maintain optimum plant density per unit area, i.e.,
50 hills/m2 for mid duration varieties and 67 hills/m2
for early duration varieties.
5. Plant the seedlings shallow (3-4.5 cm), as shallow
planting increases the tillering of seedlings.
6. Control the weeds during the vegetative phase itself.
One weeding thoroughly on the 30th day after sowing is
ideal. Use herbicides for weed control, wherever it is
cheaper than hand weeding.
7. Under good management practices (vide item 1-6) reduce
the dose of fertilizer N to half the present recommended
level. Apply the fertilizer when the plant is able to
make the best use of it, at tillering and seven days before
panicle initiation.
8. When the field preparation and planting are done on
rainy seasons, postpone the application of the basal dose
of nitrogen to the early tillering stage (10 days after
planting).
9. When the amount of available N is limited, apply it
7 days before panicle initiation. This is the best time
for top dressing N.
10. Adopt agronomic practices for increasing fertilizer
use efficiency such as: (a) Incorporating ammoniacal N
in the reduced zone in the soil (b) Incubating urea with
moist soil (1:6) for 24 hours (c) Blending urea with neem
cake.
11. Choose fertilizer materials, which are cheaper, e.g.
urea is cheaper than ammonium sulphate; rock phosphate
is cheaper than superphosphate.
12. Apply phosphatic and potash fertilizers once in two
seasons in areas where there is no marked response for
these nutrients.
13. Adopt timely control measures against insect pests
and diseases based on surveillance.
14. Harvest the crop at optimum moisture content in order
to avoid loss due to shedding and also for improving the
recovery of rice.
Integrated pest management (IPM) in rice
The indiscriminate use of pesticides for pest control
has led to disturbances in natural ecosystem leading to
resurgence of pests, secondary pests outbreak, toxic hazards
and residues besides environmental pollution. This has
led to major emphasis on integrated pest management and
gained greater momentum. Integrated pest management programmes
promote favourable, ecological, economic and sociological
outcome, which is accomplished by the best mix of pest
control tactics. The use of appropriate scouting tactics,
proper diagnosis of pest, the use of economic thresholds
and conservation of naturally occurring biocontrol agents
are fundamental components of a sound Integrated pest
management programme. The use of chemicals is restricted.
It is used only if it is absolutely essential based on
surveillance. The important components in the IPM are
the use of tolerant/resistant varieties, regulating planting
density, adjusting the time of planting / sowing, group
farming practices, cultural management of pests, integrated
nutrient management, removal of weeds, use of botanical
pesticides and preservation of natural enemies. For the
preservation of natural enemies, collect the egg masses
of pests in perforated polythene bags and keep them in
the field so that the parasites that emerge can establish
in the field effectively.
View Table6 .categories
of irrigation schedule for rice
Manuring
Organic manuring
Apply organic manure in the form of farmyard manure or
compost or green leaf @ of 5 t/ha and incorporate into
the soil while ploughing. The entire quantity of phosphatic
fertilizers may be applied along with the organic manures.
Use of biofertilizers is recommended
Cowpea may be raised as an intercrop in dry seeded low
land (semi-dry) rice by sowing 12.5 kg seed/ha along with
rice to serve as a source of green manure. When the rice
field gets submerged with the onset of southwest monsoon,
cowpea at the age of about six weeks and at active vegetative
stage decays and gets self-incorporated in the soil adding
substantial quantity of green manure. Such a system of
concurrent growing of cowpea also reduces weed pressure
in semi-dry rice.
Fertilizer application
The rates of N, P2O5 and K2O recommended as fertilizers
are given in Table 7 and stages of application in Table
8.
View Table7 . Fertilizer recommendation
for rice, kg/ha
View Table8 . stages of fertiliser
application in rice
For modan cultivation (upland crop) and direct seeded
crop in wet lands, apply nitrogen in three equal split
doses, first as basal dressing, second at tillering stage
(three weeks after seeding) and the third at panicle initiation
stage (about thirty days before flowering). Apply the
full dose of P2O5 at the time of land preparation as basal
dressing. Apply K2O either in a single dose as basal or
in two split doses half as basal and half at the panicle
initiation stage.
In Kuttanad region, wherever wet broadcasting (direct
seeding) is adopted, give the first basal application
of the N at the time of letting in water after drying
the field. Water-soluble phosphorus can be recommended
for application in two split doses in Kuttanad region,
as basal and at maximum tillering stage.
The general principle to be followed is that in light
soils as well as in soils with high leaching, N may be
applied in three or four split doses according to the
duration of the variety.
For typical Onattukara region, where soil is sandy loam
and with iron toxicity problem, apply 5 tonnes of organic
matter and 67.5 kg K2O/ha.
During the first crop season, when basal application of
N is not possible due to incessant rains, basal dose can
be shifted to 15 days after transplanting.
A fertilizer doze of 60:30:30 kg/ha is recommended in
the second crop season for photo-insensitive variety Dhanya
under Onattukara conditions.
For dry sown Mahsuri, the fertilizer dose of 50:25:25
kg/ha N:P2O5:K2O is sufficient. Nitrogen dose may be given
in three equal splits at basal and 45 and 85 days after
sowing.
In coarse sandy loam soils with high
percolation as in Onattukara region, N and K2O fertilizers
may be applied in five equal splits given at planting,
15th, 38th 53rd and 70th day for medium duration varieties.
These periods coincide with the stages of early tillering,
neck node differentiation, early reduction division
and heading stages respectively in the case of medium
duration varieties.
For Thiruvananthapuram and Malappuram districts, P2O5
application is essential for increasing rice yields.
Rock phosphate may be substituted for superphosphate.
In Onattukara region, continuous application of N in
the form of fertilizer without P2O5 and K2O shows deleterious
effects. Basal dose of N may be postponed to initial
tillering phase of rice crop, especially during the
rainy season. Nitrogen top dressing at the initial tillering,
mid-tillering and panicle initiation favours maximum
rice production. Split application of K2O, 50% basal,
25% at tillering and 25% at panicle initiation stage
is recommended for this region.
In Pokkali (acid saline) areas, apply entire quantity
of fertilizers (N:P2O5:K2O) at the rate of 20:40:0 kg/ha
at the time of dismantling of mounds.
(Note: Not applicable to Kaipad areas)
Specific dose of fertilizer for Koottumundakan system
A fertilizer dose of N:P2O5:K2O 20:10:10 kg/ha for the
first crop and 30:15:15 kg/ha for the second crop is
recommended for high yield in Koottumundakan system.
N and K2O may be applied in two equal parts for the
first crop, one as basal and other at panicle initiation
stage. P2O5 may be applied fully as basal. The fertilizer
for second crop may be applied as a single dose immediately
after the harvest of the first crop (ad hoc recommendation)
Fertilizers (N:P2O5:K2O) @ 40:20:20 kg/ha for virippu
and 20:10:10 kg/ha for the photosensitive mundakan crop
are recommended as economic dose for the northern region
under koottumundakan practice.
Methods of fertilizer application
For pre-planting application, apply the fertilizers
at the final ploughing. In areas where availability
of water is assured, temporarily draining the field
one day prior to application and re-flooding after twelve
hours is recommended for top dressing of fertilizer.
For increasing the efficiency of urea for top dressing,
mix urea with six times its weight of slightly moist
soil and apply to the field 24-28 hours after mixing.
Oil seed cakes such as punna and neem cakes can also
be mixed with urea (1 part of oil cake + 5 parts of
urea by weight) for increasing fertilizer efficiency.
This method is particularly useful for basal application
of N. Under special conditions of drought and waterlogging,
apply N as foliar spray. Urea may be applied as a low
volume spray at 15% concentration using power sprayer
or at 5% concentration using a high volume sprayer,
the quantity applied in one application being limited
to 15 kg/ha.
Whenever carbofuran application is needed at around
20 days after planting, it would be advantageous to
mix 10 kg N in the form of urea. Carbofuran should be
used @ 0.75 kg ai/ha.
When zinc deficiency is noticed, apply zinc sulphate
@ 20 kg/ha. Early stages of zinc deficiency are evidenced
by interveinal chlorosis, bleaching of midribs and light
yellow colouration of the leaf. Older leaves develop
brown rusty spots and are extremely brittle. Zinc sulphate
and potash should not be applied on the same day.
Split application of water-soluble phosphatic fertilizers
in two equal splits as basal and at maximum tillering
stage is effective in giving higher grain and straw
yield than the full dose as basal dressing under certain
situations.
Application of chemical fertilizers can be dispensed
with for Vyttila-1 and Vyttila-2 in pokkali rice fields.
When the soil has less than 10 ppm of
calcium chloride extractable sulphur or 15 ppm of phosphate
extractable sulphur, substitute urea with ammonium phosphate
sulphate to correct sulphur deficiency. For medium duration
rice grown in brown hydromorphic soils ammonium phosphate
sulphate may be used to supply 25 kg sulphur per hectare
to protect the crop from sulphur deficiency (ad hoc
recommendations)
Liming
In general, addition of lime is absolutely necessary
when the pH is lower than 5.5 and it is advisable when
pH varies between 5.5 and 6.5
For direct seeded crops during the first season, apply
lime @ 600 kg/ha in two split doses, the first dose
of 350 kg/ha as basal dressing at the time of first
ploughing and the second dose of 250 kg/ha as top dressing
about one month after sowing.
For transplanted crop, apply lime @ 600 kg/ha in two
split doses, 350 kg/ha as basal dressing and 250 kg/ha
as top dressing about one month after transplanting.
For Pokkali areas, apply lime @ 1000 kg/ha, 50% at the
time of preparation of mounds and the rest at the time
of dismantling the mounds.
A time lag of one week should be given between application
of lime and fertilizers. For top dressing, lime may
be applied one week prior to the application of fertilizers.
Water management
Maintain water level at about 1.5 cm during transplanting.
Thereafter increase it gradually to about 5 cm until
maximum tillering stage. Drain water 13 days before
harvest.
[Note: In areas where water for irrigation is assured
and where acidity is high, draining and reflooding every
15 days are recommended. In flood prone areas, aged
seedlings of Mahsuri or other varieties recommended
for waterlogged conditions may be planted. The planting
may be preponed or postponed to avoid synchronization
of the critical stages of maximum tillering or heading
with the usual flood period in the tract.]
During the mundakan crop season, water level of 5 cm
need not be maintained continuously after the cessation
of northeast monsoon. Five centimetre irrigation once
in 6 days will be quite adequate for project areas where
water is assured.
For summer rice (in situation where the ground water
level is shallow, i.e., within 1 m from the surface),
5 cm irrigation two days after disappearance of ponded
water is sufficient instead of 5 cm continuous submergence
throughout the crop period.
Irrigation schedule for rice under limited water resources
For summer rice under limited resources of water, phasic
stress irrigation can be practised to the advantage
of saving substantial quantity of irrigation water without
any significant reduction in yield. About 20-30% more
area can be irrigated with the same water resources
by adopting any of the following phasic stress irrigation
schedules (Table 7). Depending up on the schedule, water
saving ranges from 24-36% of the requirement for 5 cm
continuous submergence throughout the crop growth. Grain
yield reduction in the above practice is only 0.1% to
1.6%.
Weeds and their control
Common weeds in rice fields of Kerala are:
Grasses: Oryza rufipogon (varinellu), Echinochloa
crusgalli (kavada), E. colona (kavada), E. stagnina (kavada),
Saccolepis interrupta (polla), Isachne miliacea (chovverippullu,
naringa).
Sedges: Cyperus iria, (manjakora,
chengoal), C. difformis (thalekkattan), Fimbristylis
miliacea (mungai)
Broad leaved weeds: Monochoria vaginalis (neelolppalam),
Ludwigia perennis (neergrampu), Limnocharis flava (nagappola),
Ammania baccifera (nellicheera)
Ferns: Salvinia molesta (African payal), Marsilea
quadrifolia (naalilakodian), Azolla pinnata (azola)
Algae: Chara spp. (chandi), Spirogyra
spp. (payal)
Control
Keep the rice fields free from weeds
up to 45 days either by hand weeding or by use of herbicides.
The recommendation for use of herbicides in different
systems of rice culture are given below:
A. Dry seeded rice [upland and lowland (semi-dry)
rice]
Spray any of the following pre-emergent herbicides:
Thiobencarb @ 1.5 kg ai/ha, butachlor @ 1.25 kg ai/ha,
oxyfluorfen @ 0.15 kg ai/ha, pendimethalin @ 1.50 kg
ai/ha, pretilachlor @ 0.75 kg ai/ha on the same day
of seeding or within six days of seeding.
B. Wet seeded rice (direct seeding with sprouted
seeds under puddled conditions)
Spray any of the following herbicides:
Butachlor @ 1.25 kg ai/ha or thiobencarb @ 1.00 kg ai/ha
6-9 days after sowing;
(b) Pretilachlor + safener (sofit) @ 0.45 kg ai/ha 3-5
days after sowing.. Give a follow up application of
2,4-D @ 0.8 kg ai/ha at 20 days after sowing.
To control Echinochloa sp. spray cyhalofop butyl @ 0.08
kg ai/ha at 15-18 days after sowing.
In certain areas like Kuttanad, wild rice has become
a menace in recent years. If effective water control
is possible, the following agronomic practices can successfully
control the infestation of wild rice.
Coat dry seeds with 20% calcium peroxide using 4% PVA
solution as an adhesive and then broadcast in the field
with 10-15 cm column of standing water. (b) Maintain
the water level for 10-12 days to prevent germination
of wild rice. (c) Drain the field and apply N and K
fertilizer as per recommendation for rapid growth of
the rice seedlings. (d) Where yeranda (common teal)
is a problem, bird scaring should be arranged till the
water is drained.
C. Transplanted rice
Apply any of the following herbicides at 0-6 days after
transplanting.
Thiobencarb @ 1 kg ai/ha, pendimethalin @ 1.5 kg ai/ha,
butachlor @1.25 kg ai/ha, anilofos @ 0.4 kg ai/ha.
Where broad-leaved weeds and sedges are predominant,
apply 2,4-D @ 1.0 kg ai/ha at 25 days after transplanting.
Wherever the fields are level and water management could
be effectively done, 2,4-D can be mixed with 10 kg urea/ha
and broadcast on 20 DAS/DAT. This would save the spraying
charges.
Control of Salvinia molesta (African payal)
Trampling salvinia in situ in the wet lands a week before
transplanting will control the weed and add to soil
fertility. For chemical control of salvinia, spray paraquat
@ 0.75 kg ai/ha. Herbicides should be applied only in
areas where protected drinking water supply is available.
Precaution while using herbicides
Apply herbicides at the recommended dose and time.
Drain the field before herbicide application.
Re-flood after 48 hours to prevent further weed germination
when post emergent herbicides are used. For pre-emergent
herbicides, wait for a week before re-flooding the field.
Use herbicide nozzle (flood jet / flood fan) for herbicide
application.
Move at uniform speed when applying herbicides.
Spray without gaps and overlapping.
(7) Use 300-400 litres of water per hectare for spraying
the herbicide.
Adopt control measures only if the pest
/ disease population exceeds the economic threshold levels
which are given in Table 12.
Pests
Rice stem borer (Scirpophaga incertulas)
Symptoms
In the vegetative phase, the central
shoot dies off turning yellow in colour (dead heart).
In the ear bearing stage, the ear head appears completely
chaffy and white in colour (white ear head). Both come
out easily when pulled up and show indication of feeding
injuries at the base.
Control
1. Collect egg masses from the nursery
plants and observe for parasitisation.
2. Cultivate tolerant varieties like IR-20 in endemic
areas.
3. In areas where stem borer occurs as a serious pest
in all seasons, apply any one of the following insecticides
first 15-20 days after transplantation and then at the
boot leaf stage keeping minimum water level: Fenthion,
quinalphos (spray or granules), fenitrothion, monocrotophos,
carbofuran (granule), carbaryl.
4. Use sex pheromone for the control of rice stem borer
as detailed in Table 9.
Note: (1) The population should be estimated on the
basis of careful and regular surveillance. (2) When
natural enemies of brown plant hopper, green leaf hopper,
stem borers and leaf folders are present, application
of chemical measures can be delayed or dispensed with.
View Table
9 : Sex pheromone used for the control of rice yellow
stem borer (ad hoc recommendation)
Gall midge (Orseolia oryzae)
Symptoms
Presence of silver shoot in the place
of central leaf is the prominent symptom. The symptom
appears from the nursery to the flowering stage. However,
in very young seedling the silver shoots are not always
expressed. Instead, a swelling at the basal portion
and excess tillering are often noticed.
Control
1. Use tolerant varieties like Pavithra,
Panchami and Uma
2. Avoid late transplantation during
the first crop season.
3. Careful monitoring of the crop seasons
in the month of July during additional crop season and
October during puncha season.
4. Use optimum seed rate of 100 kg/ha
5. Destruction of collateral host like
wild rice Cynodon dactylon, Ischaemum aristatum, Echinochloa
spp. and Isachne sp.
6. Dipping germinated seed in 0.2% chlorpyrifos
solution for 3 hours before sowing give protection up
to 30 days.
7. In transplanted crop the root of
seedlings may be dipped in 0.02% chlorpyrifos suspension
for 12 hours prior to planting.
8. The nursery treatment has to be followed
by main field treatment, 10-15 days after transplantation
using anyone of the following insecticides: quinalphos,
phorate, carbaryl, carbofuran.
9. In areas where the pest is of regular occurrence,
apply granules of phorate 10G (1.5 kg ai/ha), carbofuran
3G (0.5 kg ai/ha), quinalphos (1.5 kg ai/ha) or chlorpyrifos
10G (0.5 kg ai/ha) within 10 days after sowing. The
granules should be broadcast in 2-3 cm of water and
the field should be impounded for at least 4 days.
Rice bug (Leptocorisa acuta)
Symptoms
Look for the presence of bug in the
field during the early ear bearing stage. Due to de-sapping,
grains show brownish discoloured patches on the husk.
Control
1. Strict vigilance is necessary at
milky stage.
2. Keep the field and bunds free of weeds and grasses.
3. Avoid overlapping cultivation in an Ela.
4. When the bug is seen in large numbers apply one of
the following insecticides: Malathion, carbaryl, formothion,
methyl parathion.
Note: Since the occurrence of the bug coincides with
the flowering stage, application of the insecticide
may be done either before 9 a.m. or after 3 p.m. so
that fertilization of the flowers is not adversely affected.
Leaf folder (Cnaphalocrocis medinalis)
Symptoms
The leaves of the plant are seen folded,
rolled and often webbed together with white patches
on them indicating the areas fed by caterpillar. When
such folded leaves are opened up, larvae can be seen.
Shaded conditions and application of excess nitrogen
are conducive for leaf folder attack
Control
1. Open up the leaf folds with the help
of a thorny twig.
2. Apply one of the following insecticides in the field
where the symptoms of attack are manifested: quinalphos,
carbaryl, monocrotophos, methyl parathion, fenitrothion,
fenthion, phosalone, phenthoate (EC/AF formulations)
triazophos or acephate.
Note: - In the initial stages restrict spraying to infested
patches only. The field may be sprayed completely in
case the infestation occurs uniformly.
Brown plant hopper (Nilaparvata lugens)
Symptoms
Yellowish circular patches appear here
and there in field. The plants in these areas dry up
very soon (hopper burn) and the yellowing and drying
extend rapidly. Examine the plants as soon as the yellowing
appears. Presence of the hoppers at the base of the
plants confirms the infestation. Very close planting
leads to enhanced attack.
Control
1. Use resistant varieties such as Jyothi,
Bharathi, Aiswarya, Kanakom, Nila etc. for cultivation.
2. Apply one of the following insecticides
as soon as the yellowing symptom is observed, covering
the infested patches and the areas surrounding the patches:
Carbaryl, quinalphos, fenthion, carbofuran, monocrotophos,
phosalone and imidacloprid. While spraying and dusting,
care has to be taken to see that the insecticides reach
the base of the plants.
3. Drain away water from the field and keep it in that
conditions until the pest population dwindle.
4. In Kuttanad tract, early planting of paddy in September-October
is advisable, wherever possible.
Rice case worm (Nymphula depunctalis)
Symptoms
Leaves of plants are eaten by the caterpillars,
which remain within small cylindrical cases and are
seen hanging on the leaves. It occurs in ill drained
fields. The cases may be seen floating on water also.
Control
1. Drain away the water from the fields.
2. If infestation is severe, apply carbaryl dust or
spray.
Rice swarming caterpillar (Spodoptera mauritia)
Symptoms
It appears in the field sporadically
and cyclically in large swarms and feed on crops gregariously.
The nursery and early stages of the crop are attacked
leaving the plant as mere stumps.
Control
Apply carbaryl, trichlorphon,
fenthion or methyl parathion as soon as the caterpillars
are noticed.
Rice hispa (Dicladispa armigera
Symptoms
The adults feed on the green tissues
of the leaves and the feeding scars appear as short
white lines on the leaf surface. The grubs mine the
leaves causing formation of white blotches. Early stages
of the crop are more susceptible.
Control
Spray any contact insecticide.
Rice thrips (Stenchaetothrips biformis)
Symptoms
The crop is highly susceptible in the nursery stage
for the first 23-25 days after transplanting/sowing.
The tips of leaves get rolled longitudinally into needle
like outgrowths and turn whitish. In severe cases, the
lower leaves also turn yellowish. The infestation may
be rated as mild, if there is less than three needle
like leaves and as severe, if there are more than three
outgrowths with the lower leaves also showing chlorosis
and scorching.
Control
In severe infestations, apply carbaryl 50% WP 1.25 kg
ai/ha + DDVP 100% EC/AF 250 ml/ha or dimethoate or quinalphos
or phenthoate (EC/AF formulation).
Whorl maggots (Hydrellia philippina)
Infestation is common in the nurseries and in the main
fields up to six weeks after transplantation. Yellowish
patches and streaks are seen along the margins of leaves,
which may become deformed.
Control: Apply phorate 10G @
1.5 kg ai/ha, if infestation is severe.
Leaf hoppers (Nephotettix spp.)
Symptoms
General yellowing of the leaves is seen,
if the attack is severe. When the plants are disturbed,
the jassids are seen jumping out.
Control
Apply carbaryl, quinalphos, monocrotophos,
fenthion or fenitrothion, if needed.
Rice mealy bug (Brevennia rehi)
Symptoms
Weak yellowish stunted plants are seen
in patches. White waxy fluff is seen in leaf sheaths.
Control
Apply dimethoate at 0.05%
Rice root nematode (Hirschmanniella oryzae)
Symptoms
Infests paddy roots and make them partially hollow.
Feeding adversely affects absorption of water and nutrients.
Plants show stunted growth in patches. Tiller production
is affected.
Control
Treat the nursery with carbofuran @ 0.75 kg ai/ha and
dip the roots of seedlings in 0.2% dimethoate for six
hours before transplanting in tracts were nematode attack
is detected.
Rice cyst nematode (Heterodera oryzicola)
The cyst nematode occurs in various proportions in certain
areas of the State. The symptoms of infestation include
leaf chlorosis, stunting and reduction in the number
of leaves, earhead length etc. In seriously affected
patches, yield is substantially reduced.
Control
Soak paddy seeds in 0.02% solution of
carbofuran for six hours. Wherever possible, dip paddy
seedlings in 0.02% solution of carbofuran for six hours
before planting.
Note: This recommendation is to be adopted in areas
where the nematodes occur at very heavy population causing
severe damage. The suggested measures are to be adopted
only if the measures are warranted on the basis of soil
and root sample assay for nematode population levels.
View Table
10. Insecticide guide for rice pest control
Note:
1. Sub-lethal concentration of insecticides
may lead to pest resurgence.
2. Granular application is recommended
only up to the booting stage.
3. Spot application method should be
resorted to wherever possible
4. Use 200, 300 and 500 l/ha of spray
fluid at 10, 25, 45 DAT or 30, 45, 60 DAS respectively
for high volume spray equipment.
5. When low volume spray equipment is
used the spray fluid can be limited to 90, 120, 180
l/ha, but the quantity of insecticide should remain
the same as used in high volume spray 200, 300 and 500
l/ha respectively.
6. Waiting periods for quinalphos, fenthion
and mercaptothion are 7, 7 and 3 days respectively.
7. In regions where BPH is a regular
pest avoid the application of the following insecticides
due to the chances of resurgence: Methyl parathion,
fenitrothion, deltamethrin, carbaryl, fenthion and quinalphos.
Diseases
A. Diseases affecting leaf blade
1. Symptoms appear as distinct leaf spots
a. Blast (Pyricularia oryzae): Appear as distinct large
indefinite spindle shaped spots with grey centre and brown
margin.
b. Brown spot (Helminthosporium oryzae): Spots small,
definite and may be oval or oblong, with light brown,
or straw coloured center and dark reddish brown margin.
c. Narrow brown leaf spot (Cercospora oryzae): Numerous,
linearly arranged small and narrow spots on leaf with
light brown or darker margin.
2. Symptoms appear as lesion, not distinct spots
a. Sheath blight (Rhizoctonia solani): Greenish grey irregular
lesions with dark line on margins, lesions large and develop
indefinitely on older plants.
b. Stackburn (Alternaria padwickii): Large oval or circular
dark brown, lesions with narrow distinct margins.
c. Leaf scald (Rhynchosporium oryzae): Lesions olive with
reddish brown margin and with typical zonations with dark
coloured wavy lines. Usually start at the tip and extend
downwards. Sometimes arise at the margin and advance inside.
Never start at centre.
d. Bacterial blight (Xanthomonas oryzae pv. oryzae): Leaves
with undulated yellowish white or golden yellow marginal
necrosis, drying of leaves back from tip and curling,
leaving mid rib intact are the major symptoms.
e. Bacterial leaf streak (Xanthomonas oryzae pv oryzicola):
Leaves with fine narrow brownish yellow translucent interveinal
line joining to form large dirty white patches.
B. Diseases affecting stem and sheath
a. Blast (P. oryzae): The symptoms appear on the stem
one or two nodes just below the panicle as greyish black
or dark lesions. The grains are mostly half filled or
unfilled.
b. Sheath blight (R. solani): Greenish grey or dark edged
whitish lesions appear on the sheath. Lesions are oval,
oblong or irregular and necrotic. Small white or brown
globular sclerotial bodies loosely attached to the surface
are also seen.
c. Foot rot (Fusarium moniliformae): Drying of leaves
and leaf sheath, discolouration of lower nodes and adventitious
roots are the major symptoms. Pink bloom on the sheath
above water level is also seen. Sometimes plants are taller
than the normal.
d. Sheath rot (Sarocladium oryzae): Oblong or irregular
lesions with brown margins and grey centre or greyish
brown appears throughout on the leaf sheath, especially
on the sheath covering the panicles. The panicles remain
within the sheath or only partially emerge with whitish
powdery fungal growth inside the rotten sheath.
C. Diseases affecting the entire plant
a. Bacterial blight: Transplanted seedling showing bluish
colouration within curled central leaf. Plants completely
rot, starting from the outer leaves. If these plants are
cut and immersed in water bacterial ooze appear at the
cut ends.
b. Foot rot: Plants turn pale yellowish green, thin, abnormally
elongated or rot in patches in the field.
Virus diseases: General stunting, abnormal tillering,
discolouration and death of affected parts.
1. Tungro: Brownish yellow discolouration, severe to mild
stunting and reduced tillering of plants are the usual
symptoms. Leaves tested with iodine show black or dark
brown colour.
2. Yellow dwarf: Leaves yellowish green usually with rusty
spots, pronounced stunting and excessive tillering with
slight curling of leaves.
3. Grassy stunt: Leaves pale green with rusty spots or
blotches, severe stunting, excessive tillering and erect
habit with grassy appearance.
4. Ragged stunt: Stunting, ragged appearance of leaves,
leaf edges are serrated and twisting of the leaf tips,
nodal branching, vein swelling, incomplete panicle emergence
and infested grains are the symptoms. The vector of this
disease is brown plant hopper.
D. Diseases affecting the grains
a. Blast: Grains partially chaffy and brittle or unfilled.
Panicles show white appearance.
b. Brown spot: Dark brown or black, oval or oblong spots
on the glumes or whole surface of the grain turning black
and velvety.
c. Stackburn: Pale brown to whitish
spots with dark brown margin bearing black dots in the
centre
d. False smut (Ustilaginoidea virens): Grains completely
replaced by large spherical yellowish or orange body,
which changes to powdery mass later.
e. Udbatta (Ephelis oryzae): Whole panicle transformed
in to a cylindrical rod covered with white mycelium.
View Table
11. Guide on control of rice diseases
Note:
1. Spray fresh cowdung extract for the
control of bacterial blight. Dissolve 20 g cowdung in
one litre of water; allow to settle and sieve. Use supernatant
liquid.
2. Application of bleaching powder @
5 kg/ha in the irrigation water is recommended for checking
the spread of bacterial leaf blight particularly in
the kresek stage.
3. Before application of antibiotics
for control of bacterial blight, identify the disease
by observing the bacterial ooze.
4. Ediphenphos may be applied by high
volume sprayers only. For control of sheath blight and
sheath rot the following prophylactic measures may be
adopted:
(a) Apply neem cake-coated urea as recommended under
fertilizer application.
(b) Apply 50% more potash than normal recommended dosage
in split application.
(c) Control weeds as suggested under weed control.
5. For control of sheath rot, spray
the fungicides at the time of panicle emergence.
6. Application of carbofuran granules
@ 1 kg ai/ha on the 25th day after planting is advised
to control sheath blight and sheath rot and to keep
down the population of rice nematode.
7. Spraying of any fungicide, preferably
dithiocarbamate before the heading stage of the crop
may be followed for the control of false smut and leaf
scald diseases. Wherever control measures are adopted
for sheath blight and sheath rot diseases, separate
treatments are not needed for the control of leaf scald
and false smut. Use 500 liters water for high volume
spraying and 200 liters water for low volume spraying.
It is advisable to use chemical on a rotational basis
than using the same product continuously.
View Table 12. Economic threshold
levels (ETLs)
View Table 13. Common natural
enemies of insect pests found in rice ecosystem
Effective and eco-friendly pest management
in wet land rice ecosystem
1. Cultivate tolerant varieties
2. Monitor the field at least at weekly intervals
3. Pest and natural enemy population should be monitored
for deciding about spraying schedule.
4. Spraying should be avoided during the reproductive
phase.
5. Spot application of insecticide may be adopted in
heavily infested pockets to control further spread of
the pest and to conserve the existing natural enemy
population in rice ecosystem.
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