Introduction;
· stem borer is one of the butterfly types of
insect in rice farming.
· The problem of stem borer occurs in both summer
and spring rice.
· Generally, the high damage or problem of stem
borer is seen in asaar, shrawan, and Bhadra, and this borer is active from
falgun to kartik.
· The damage of the stem borer is normally seen
in the vegetative and panicle initiation to fruit maturity stage.
· The damages of stem borer are like the damages
of rat, neck blast, gundi bug, etc, so it will be difficult to distinguish.
Source:
krishimala
and agropedia
Damages:
· A
stem borer makes the hole in the stem of rice and feeds or eats the inner part
of the stem.
Source:
krishimala
· During
the vegetative phase of rice, the larva of the stem borer makes the hole at the
rice lower portion(stem)Base of rice and eat the inner part, from which we can see
the dried heart( gumbo) or tiller and dead of the heart occur.
Fig:
Dead Heart
Source:
agropedia
· But
during the panicle development of the rice phase, the stem borer makes a hole
in the upper node of the panicle and the stem borer feeds the inner part from
the base of the panicle to the lower part of the stem and it will dry the panic
later. After the maturity of the rice stem borer suspected panicle or fruit
becomes the white or white head.
Fig:
White Head
Source:
agropedia
and apps.lucidcentral.org
· The
inner part of rice transport the nutrient, water from the soil to different
part of rice plant but stem borer feed those inner part so the water and
essential nutrient cant go to the different part of plant and plant will be dry
and then die.
· If
the stem borer damages most of the tiller then the whole rice field plant can
be destroyed.
Source:
agropedia
· Yellow
stem borer damages up to 20 % and damages up to 80% of rice are transplanted
lately.
· White
stem borer found in ghol( Wetland) and if there are more and more white stem
borer the whole rice field can be destroyed.
· Stripped
stem borer is especially found in Asia and it can damage up to 100 %.
· Pinkish
stem borer damge upto 30%
The
main stage of stem borer which damages most is the “ larva Stage”
Alternative host: sugarcane,
different grasses like sama, cyperus etc
Favorable environment:
· Optimum
temperature: 24-29 C
· Humidity:
90-100%
· Larva
can’t emerge from the egg if the temperature is <13 C and RH is <70%
· Remain
pupa stage when the temperature is 15 to 16 C
Stem borer susceptible stage of rice plant:
1. Rice
bed
Source:
irri
2. After
transplanting the rice
Source:
cultivationofcrops
3. Before
the panicle emerging
Source:
jinshan
Types of Stem Borer:
1. Yellow
stem borer: (Scirpophaga incertulas)
· Generally
mostly found in asia of water stagnating field.
Source:
https://agriculturestudy.blogspot.com/2021/02/rice-yellow-stem-borer.html
2. White
stem borer:( Scirpophaga innotata)
· Generally
found in wetland
Source:
ipmimage
and apps.lucidcentral
3. Pink
Stem Borer( Seasamia inferens)
· Found
in upland
Source:
wikipedia and sciencedirect
4. Stripped
stem Borer ( Chilo suppressalis)
· Found
in high hill and unstagnated field
How to know rice is infected by stem borer?
· In
rice farming before the panicle initiation, we can see the dried rice plant in
different areas and spots and if we check them nearly we will see the only
inner part of the stem is dried. If we pull out the infected plant the dry
inner part of the stem will easily detach from the base( Dead Heart).and again if
we see pulling out plant very specifically by tearing the stem, we will see the
larva of stem borer.
· After
the panicle formation and initiation, we will find the non-fruit bearer, white
color panicle, where there will be no fruit filling, development.
· At
the base of the rice stem, we can see small holes.
· Sometimes
we can see the feces of lava of stem borer attached to the stem or inside the
stem.
Source:
krishimala
and agropedia
Lifecycle of Rice Stem Borer:
Source:
Doadp1.gov.np
Egg:
·
In the case of stem borer, the mating between
male and female butterflies occurs at the night. And 3 days after the mating
female gives the eggs at the time of night on the tip the leaf of rice
·
Female lay the eggs in 2-3 cluster
·
And female gives 50-200eggs per laying.
Source:
Doadp1.gov.np
Larva:
·
After 5-6 days of laying the egg, the larva
emerges from the egg.
·
Larva has a white body and an intense brown
head.
·
After 2-3 hours of larva comes out from the egg,
larvas are beginning to move downward of the plant i.e. to the bases. And
slowly by the spider-like wed rope, they transmit from one plant to another.
·
At the beginning of 2-3 days larva eat leaves
and later they enter into the stem by making holes in the stem nodes and start to
damage the crop. these larvas are damage the
crop by making holes on the stem so these insects or pest is called stem borer.
·
In total 4-6
weeks 5 molting happens and the length of larva increase from 1.5 mm to 20 mm.
Source:
plantwise.org
Pupa:
·
the fully mature larva produces the silk thread
and by these silk thread they make cocoons by rounding them and inside the
cocoon larva will be stable.
·
In the early stage color of the pupa is white
and later slowly it becomes brown.
·
Pupa stage has in total 6-10 days and it can be
up to 1 month depending upon the climate and weather.
Source:
blake
wilson
Adult:
·
Adults are active at the time of night.
·
Adults are come out from the holes of the stem
and it will survive upto 2-3 days after laying eggs.
Source: wikipedia
Source:
doadp1.gov.np
Mechanical method:
·
The cluster of the egg should be collected and
then destroyed
·
Farming method:
·
During cutting the rice plant we should cut it
from the land surface.
·
After cutting the rice the remaining stubbles or
parts of rice should be collected and destroyed by firing or keep them inside
the water for about 3-4 days or we have to do deep plowing the field.
·
If rice seeding the good then we have to transplant
it by cutting their tips.
·
We should apply and growing, early planting,
early harvesting, and a dwarf variety of rice like ( khumal 2, ghaiya 1, ghaiya
2, tarahara 1, radha 4, etc )
·
We should grow stem borer resistance varieties
like IR 20, Taichun 176, Chainung 142, Khumal 4, etc.
·
In irrigated land: 200kg FYM/compost, 7,5 kg
urea, 3 kg DAP, 2,2 Kg MOP per katha.
·
Should use only certified manure and
fertilizers. we should not apply the nitrogen in the field more than recommended
dose because it will make susceptible to
the stem borer.
·
We should app;y the reccomanded dose of nitrogen
fertilizer in 3-4 split dose, it will have more efficiency.
·
If we grow the soybean, in the bund of rice
fields it will repel the different insects and pests.
Source:
doadp1.gov.np
Physical Method:
·
The light trap should use( 5 traps per hacter0
·
Pheromone trap can be use(20 traps per ha)
Source:
doadp1.gov.np
biochemical:
·
After the 3 weeks of the transplanting of rice,
we can spray bacillus thuringeansis at the rate of 3g per liter.
·
We can use neem cake at the rate of 10 kg per
katha
·
Neem-related biochemicals like azadirachtin0.03
EC should spray by making solution at the rate of 3-5 mm per liter.
Chemical Method:
·
We should use the chemical method only when
there is a heavy population of stem borers in the field.
·
Fipronil 0.3 % GR or Cartap Hydro-Chloride 4 % G
chemical at the rate of 1 kg per ropani ( 650 g per katha)
·
Cholrantraniliprole 0.4 % G use in the rate f 500gm per ropani ( 350 g
per katha) Thiamethoxam 25 % WG should apply at the rate of 1 g per 3 liters of
water.
·
Chorantraniliprole 18.5 % SC should make the solution At the rate of 1 mm per 3 liters of water
·
Chloropyriphos 50
% + Cypermethrin 5 % EC should apply and make the solution at the rate of 1.5
ml per liter of water.
· After spraying or apply the chemical in the field the
water of the rice field should not be going out.