Nutritional Deficiencies of Wheat Nitrogen (N) Phosphorus (P) Potassium (K) Zinc (Zn) Nitrogen (N) Plants are pale gr...
Nutritional
Deficiencies of Wheat
Plants are pale green to yellow
with chlorosis beginning on lower leaves and progressing upwards as the
deficiency intensifies; plants have spindly stems and growth is slow.
P deficient
plants may remain darker green than normal plants and develop purple
discoloration first on the underside and later throughout. Leaf tips may die
back when P deficiency is severe. Plants grow slowly, stems are thin and
shortened and maturity is delayed. P deficient plants also exhibit poor
tillering.
K deficiency is initially
manifested as chlorosis on the older leaves and progresses upwards as the
deficiency intensifies. The leaves eventually become streaked and take on a
scorched appearance along the leaf margins. Chlorotic areas may develop
throughout the leaf. Deficiency symptoms can occur in young leaves of some
fast-maturing high-yielding varieties. Stems of deficient plants are weak and
tend to lodge.
Zinc deficiency in wheat appears
as intervenial chlorosis on the most recently developed leaves; plants are
stunted and produce few tillers; if the deficiency is severe the leaves may
turn white and die. The most characteristic reactions of wheat plants to zinc
deficiency are reductions in plant height and leaf size. These symptoms are
followed by the development of whitish-brown necrotic spots on middle-aged
leaves. As the severity of zinc deficiency intensifies, the necrotic spots
spread on t leaves, and the middle parts of the leaves are often collapsed,
showing a “scorched” appearance.
Source: NIPHM and Directorate
of Plant Protection, Quarantine & Storage
121 ratings and 0
Wheat Pests
Pests of National Significance
Insect and mite pests
- Termite: Odontotermis obesus Rambur, Microtermes obesi
Holmgren (Termitidae: Isoptera)
- Wheat aphid: Sitobian avenae (F.), S. miscanthi Takahashi,
(Aphididae: Hemiptera)
- Army worm/cut worm: Mythimna separata Walker (Noctuidae: Lepidoptera)
- American pod borer: Helicoverpa armigera Hubner (Noctuidae: Lepidoptera)
- Brown mite: Petrobia latens Mull. (Acarina: Tetranychidae)
- Pink stem borer: Sesamia inferens Walker (Noctuidae: Lepidoptera)
- Shootfly: Atherigona naqvii Steyskal and A. oryzae Mall
(Muscidae: Diptera)
Diseases
- Brown rust: Puccinia recondita f. sp. tritici Eriks. &
Henn
- Yellow/Stripe rust: Puccinia striiformis var. striiformis Westend
- Black rust: Puccinia graminis tritici Pers
- Loose smut: Ustilago tritici (Pers.) E. Rostr.
- Karnal bunt: Tilletia indica Mitra
- Powdery mildew: Blumeria graminis (DC.) Speer
- Helminthosporium leaf spot, Helminthosporium spp., Cochliobolus sativus (S.
Ito & Kurib.) Drechsler ex Dastur Cochliobolus sativus
(Helminthosporium sativum) Syn. Bipolaris sorokiniana, Drechslera
sorokiniana
- Foot rot: Pythium graminicolum Subraman and P. arrhenomanes
Drechsler
- Alternaria leaf blight: Alternaria triticina Prasada & Prabhu
- Flag smut: Urocystis agropyri (G. Preuss) J. Schröt.
- Hill bunt: Tilletia tritici (syn. Tilletia caries) Bjerk.
Wint. and T. laevis (syn. T. foetida). Kuhn
- Head Scab/Fusarium head blight: Fusarium graminearum Schwabe, Gibberella zeae
(Schwein.) Petch
Nematodes
- Seed gall Nematode, Anguina
tritici, Tundu or yellow ear rot: Rathaybacter
tritici + Anguina tritici (Tylenchida: Tylenchidae)
- Cereal cyst Nematode, Heterodera avenae (Tylenchida: Heteroderidae:)
- Root knot Nematode, Meloidogyne spp.
Weeds
Broadleaf
- Lambs quarter: Chenopodium spp. L. (Chenopodiaceae)
- Scarlet pimpernel: Anagallis arvensis L. (Primulaceae)
- Sweet clover: Melilotus indica (L.) All. (Fabaceae)
- Fine leaf fumitory: Fumaria parviflora Lam.
(Fumariaceae)
- Corn spurry: Spergula arvensis L. (Caryophyllaceae)
- Field bindweed: Convolvulus arvensis L. (Convolvulaceae)
- Onion weed: Asphodelus tenuifolius Cav. (Liliaceae)
- Swine cress: Coronopus didymus (L.) Sm. (Brassicaceae)
- Jangali Palak: Rumex dentatus L. (Polygonaceae)
- Yellow pea: Lathyrus aphaca L. (Fabaceae)
- Thistle weed: Cirsium arvense (L.) Scop. Asteraceae
Grasses
- Wild oat: Avena ludoviciana (L.) Nees. (Poaceae)
- Canary grass: Phalaris minor Retz. (Poaceae)
- Bluegrass: Poa annua L. (Poaceae) 4.16 Rye grass: Lolium
spp. (Poaceae)
Sedge
- Purple nut sedge, Cyperus
rotundus L. Cyperaceae
Rodent pests
- Lesser bandicoot: Bandicota bengalensis(Gray)(throughout India)
- Black Rat: Rattus rattus L.
- Field mouse: Mus booduga (Gray) (throughout India)
- Soft furred field rat, Millardia meltada (Gray) (throughout India)
- Indian Gerbil, Tatera indica (Hardwicke) (throughout India)
Insect pests
- Wheat thrips: Anaphothrips favicinctus, Haplothrips tritici
(Kurdjumov) (Thripidae: Thysanoptera)
- Ghujhia Weevil: Tanymecus indicus Faust (Curculionidae:
Coleoptera) (Uttar Pradesh)
Disease
- Seedling blight: Rhizoctonia solani Kuhn and Fusarium sp. (Himachal Pradesh, Punjab, Tamil Nadu)
To know
the IPM practices for Wheat, click here.
Source: NIPHM and Directorate
of Plant
Protection, Quarantine & Storage
149 ratings and
Wheat: Crop Stage-wise
IPM
|
Management |
Activity |
Pre-sowing*
|
|
|
Common cultural practices: |
|
|
Nutrients |
• At the time of field preparation, apply FYM @ 4.0
t/ acre 2-3 week before sowing or vermicompost @ 2.0 t/acre at one week
before sowing. |
|
Weeds |
Cultural control: |
|
Soil and seed borne pathogens, Nematodes, Termites,
Resting stage of insects |
Cultural control: |
Sowing/Seedling*
|
|
|
Wheat is a Rabi crop that is grown in the winter
season. Sowing of wheat takes place in October to December and harvesting is
done during the months of February and May. The wheat crop needs cool winters
and hot summers, which is why the fertile plains of the Indo-Gangetic region
are the most conducive for growing it. Though well-drained loams and clayey
loams are considered the ideal soil for wheat, good crops of wheat have also
been raised on sandy loams and black soils of the peninsula region. India is
broadly divided into 5 wheat zones based on agro-climatic conditions |
|
|
1. The North-Western Plains Zone: This
is the most important zone and comprises the plains of the States of Punjab,
Haryana, Jammu, Rajasthan and western Uttar Pradesh. The wheat here is
planted in late October - November and the harvesting usually begins by
middle of April. |
|
|
2. The North Eastern Plains Zone: This
zone consists of eastern Uttar Pradesh, Bihar, West Bengal, Assam, Odisha,
Manipur, Tripura, Meghalaya, Nagaland, Mizoram, Arunachal Pradesh and Sikkim.
Since rice is harvested later in this area, wheat can be sown only in late
November or early December. Harvesting is done by March - April. |
|
|
3. The Central Zone: This
zone consists of Madhya Pradesh, Gujarat, southeastern Rajasthan and the
Bundelkhand area of Uttar Pradesh. Almost 75 per cent of the wheat cultivated
here depends on rain for irrigation. The best quality Durum wheat is produced
in this zone. |
|
|
4. The Peninsular Zone: The
peninsular zone consists of the southern States of Maharashtra, Andhra
Pradesh, Karnataka, and Tamil Nadu. Sowing is usually completed by early
November and harvesting begins in the second half of February. Wheat is
produced the earliest in this zone. |
|
|
5. The Northern Hill Zone: This
zone includes the hilly areas of Kashmir, Himachal Pradesh, Uttar Pradesh,
West Bengal, Assam and Sikkim. Wheat is sown in October and harvested in
May-June. The crop remains dormant in the cold months of November to March
and starts growing as the temperature rises in April. |
|
|
For good and uniform germination, the wheat crop
requires a well pulverised but compact seedbed. The wheat seeds should be
healthy and have a good germination capacity. Make sure the seeds for sowing
don't contain any seeds of weeds. Experts suggest the use of certified seeds
obtained from a reliable seed agency. Seeds need to be planted on time to
conserve moisture for a good crop. |
|
|
Nutrients |
• Seed treatment should be done with Azotobactor
culture @ 200 g/acre. |
|
Weeds |
• Hand weeding |
|
Soil and seed borne pathogens, Nematodes, Resting
stage of insects |
Cultural control: |
|
Termites |
Cultural control: |
Vegetative
|
|
|
Common cultural practices: |
|
|
Nutrients |
• Apply 1/3 of N as top dressing with 1st
irrigation and remaining 1/3rd N with second irrigation. |
|
Weeds |
Chemical control: |
|
Aphids |
Cultural control: |
|
Pink borer, (leaf eating caterpillar) |
Cultural control: |
|
Shoot fly |
Cultural control: |
|
Brown mite |
Cultural control: |
|
Army worm/Cutworm |
Cultural control: |
|
Ghujhia Weevil**, Wheat bug, Wheat thrips** |
• Follow common practices for cultural and biological
control. |
|
Leaf rust, Stem rust and Yellow rust. |
Cultural control: |
|
Powdery mildew |
Cultural control: |
|
Foliar blight, Seedling blight**, Leaf spot, Leaf
blight |
Cultural control: |
Ear head stage
|
|
|
Nutrients |
• Foliar application of deficient micronutrient
should be done as when the symptoms are observed. |
|
Weeds |
• Remove left over weeds to check the weed seed
spread. |
|
Helicoverpa American pod borer), armyworm, |
Cultural control: |
|
Kernal bunt |
Cultural control: |
|
Loose smut, Hill bunt and Head scab, Flag smut |
Cultural control: |
|
Note: The
chemical dosages and spray fluid volumes are based on high volume sprayer. |
|
Source: NIPHM and Directorate
of Plant Protection, Quarantine & Storage
119 ratings
Wheat: Diseases and
Symptoms
- Powdery mildew
- Loose smut
- Brown rust
- Stripe rust /Yellow rust
- Black rust
- Flag smut
- Hill bunt or Stinking smut
- Karnal bunt
- Leaf blight
- Foot rot
- Head scab/ Fusarium leaf blotch (Snow
Mold)
- Helminthosporium leaf blotch (Spot
Blotch)
- Seedling blight
- IPM for Wheat
Powdery mildew
Disease symptoms
- Powdery mildew can easily be
diagnosed by the white, powdery patches that form on the upper surface of
leaves and stem.
- Greyish white powdery growth
appears on the leaf, sheath, stem and floral parts.
- Powdery growth later become
black lesion and cause drying of leaves and other parts.
Survival and spread
- Fungus remains in high hills
during summers in infected plant debris as dormant mycelium and asci.
Primary spread is by the asciospores and secondary spread through airborne
conidia.
Favourable conditions
- The disease infects plants
during periods of high humidity (not necessarily rain) and cool to
moderate temperatures (20-21°C).
Loose smut
Disease symptoms
- It is a seed borne disease;
infection occurs during Loose Smut flowering through wind-borne spores.
- The infection remains dormant
inside the otherwise healthy looking seed but the plants grown from such
seeds bear infected inflorescence.
- At this time, infected heads
emerge earlier than normal heads. The entire inflorescence is commonly
affected and appears as a mass of olive-black spores, initially covered by
a thin gray membrane.
- Once the membrane ruptures, the
head appears powdery.
Survival and spread
- The disease is internally seed
borne, where pathogen infects the embryo in the seed.
- Primary infection occurs by
sowing infected seeds.
Favourable conditions
- Infection is favored by cool,
humid conditions during flowering period of the host plant.
Brown rust
Disease symptoms
- The most common site for
symptoms is on upper leaf blades, however, sheaths, glumes and awns may occasionally
become infected and exhibit symptoms.
- The pustules are circular or
slightly elliptical, smaller than those of stem rust, usually do not
coalesce, and contain masses of orange to orange-brown Urediospores.
Survival and spread
- Pathogen over-summers in low
and mid altitudes of Himalayas and Nilgiris. Primary infections develop
from wind deposited urediospores in eastern Indo-gangetic plains in middle
of January where it multiplies and moves westwards by March
- Alternate host is Thalictrum
sp.
Favourable conditions
- Temperatures of 20-25° C with
free moisture (rain or dew) cause epidemics. Severe infection causes upto
30 percent yield losses.
Stripe rust /Yellow rust
Disease symptoms
- Mainly occur on leaves than the
leaf sheaths and stem. Bright yellow pustules (Uredia) appear on leaves at
early stage of crop and pustules are arranged in linear rows as stripes.
- The stripes are yellow to
orange yellow. The teliospores are also arranged in long stripes and are
dull black in colour.
- The pustules of stripe rust,
which, contain yellow to orange-yellow urediospores, usually form narrow
stripes on the leaves.
- Pustules also can be found on
leaf sheaths, necks, and glumes.
Survival and spread
- The inoculum survives in the
form of uredospores /teliospores in the northern hills during off season
on self sown crop or volunteer hosts, which provide an excellent source of
inoculums and primary spread occur through uredospores from hills
Favourable conditions
- Disease is prominent when temperature
is 10-20°C and high humidity.
Black rust
Disease symptoms
- Symptoms are produced on almost
all aerial parts of the wheat plant but are most common on stem, leaf
sheaths and upper and lower leaf surfaces.
- Pustules (containing masses of
urediospores) are dark reddish brown - occur on both sides of the leaves,
on the stems, and on the spikes.
- Pustules are usually separate
and scattered, heavy infections -coalesce.
- Prior to pustule formation,
"flecks" may appear. Before the spore masses break
through the epidermis, the infection sites feel rough to the touch.
- As the spore masses break
through, the surface tissues take on a ragged and torn appearance.
Survival and spread:
- Both survive on stubbles and
volunteer crops, alternate host: Berberis spp. and primary spread occur
through uredospores from southern hills
Favourable conditions
- Moisture and temperature above
20° C favours the development of disease.
Flag smut
Disease symptoms
- Symptoms can be seen on stem,
clum and leaves from late seedling stage to maturity.
- The seedling infection leads to
twisting and drooping of leaves followed by withering.
- Grey to grayish black sori
occurs on leaf blade and sheath. The sorus contains black powdery mass of
spores.
Survival and spread
- The disease is seed and soil
borne. Smut spores are viable for more than 10 years.
- Primary infection occurs by
sowing infected seeds or by resting spores present in the soil.
Favourable conditions
- Temperature of 18-24°C.
- Relative humidity 65% and
above.
Hill bunt or Stinking smut
Disease symptoms
- The fungus attacks seedling of
8-10 days old and become systemic and grows along the tip of shoot.
- At the time of flowering hyphae
concentrate in the inflorescence and spikelets and transforming the ovary
into smut sorus of dark green color with masses of chlamydospores.
- The diseased plants mature
earlier and all the spikelets are affected.
Survival and spread
- The pathogen survives in seeds
and sowing such seeds are source of primary infection.
Favourable conditions
- Temperature of 18-20°C.
- High soil moisture.
Karnal bunt
Disease symptoms
- Symptoms of Karnal bunt are
often difficult to distinguish in the field due to the fact that incidence
of infected kernels on a given head is low.
- There may be some spreading of
the glumes due to sorus production but it is not as extensive as that
observed with common bunt.
- Symptoms are most readily
detected on seed after harvest.
Survival and spread
- The disease is seeds borne and
sowing of infected seeds is the source of primary infection.
Fabourable conditions
- Temperature of 18-20°C.
- High soil moisture.
Leaf blight
Disease symptoms
- Reddish brown oval spots appear
on young seedlings with bright yellow margin. In severe cases, several
spots coalesce to cause drying of leaves.
- It is a complex disease, having
association of A. triticina, B. sorokiniana and A. alternate.
Survival and spread
- Primary spread is by externally
seed-borne and soil borne conidia. Secondary spread by air-borne conidia.
Favourable conditions
- Temperature of 25°C and high
relative humidity.
Foot rot
Disease symptoms
- The disease mainly occurs in seedlings
and roots and rootlets become brown in colour.
- Seedlings become pale green and
have stunted growth.
- Fungus produces sporangia and
zoospores and oospores.
Survival and spread
- The disease is soil borne,
pathogens survives in soil.
- Primary spread occurs through
soil and irrigation water.
Favourable conditions
- Wet weather and high rainfall.
Head scab/ Fusarium leaf blotch (Snow Mold)
Disease symptoms
Leaf blotch
- The blotching caused by this
organism becomes evident on leaves at about late-joint to early-boot
growth stage.
- Young lesions occur as oval to
elliptical, greyish green mottled areas, usually located where the leaf
bends. The lesions enlarge rapidly, developing into large,
"eyespot" blotches with bleached or light grey centers; the
leaves tend to split or shred, beginning at the centers of the lesions.
Head Scab
- The fungus also can cause head
scab.
- Symptoms of Fusarium head
blight include tan or light brown lesions encompassing one or more
spikelets. Some diseased spikelets may have a dark brown discoloration at
the base and an orange fungal mass along the lower portion of the glume.
- Grain from plants infected by
Fusarium head blight is often shriveled and has a white chalky appearance.
- Some kernels may have a pink
discoloration.
- Infected florets (especially
the outer glumes) become slightly darkened and oily in appearance.
Survival and spread
- The disease is soil borne and
inoculums of fungi survive in soil. Spores are produced on crop debris
left on or near the soil surface. These spores are transmitted to leaves
by the wind or by splashing rain.
Favourable conditions
- Disease development is favored
by cool, moist weather.
Disease symptoms
- Lesions caused by this disease
are elongated to oval in shape and are generally a dark brown color.
- As lesions mature, the centers
often turn a light brown to tan color, surrounded by an irregular dark
brown ring (21 on leaf; 22 on spike).
- Primary infections tend to be
on the lower leaves, beginning as chlorotic flecks or spots. These
infection sites enlarge, turn dark brown, and often coalesce. When the
disease is severe, affected leaves or leaf sheaths may die prematurely.
Survival and spread
- The Disease is seed as well as
soil borne and inoculums present in the seeds and soil are the source of
primary infection.
Favourable conditions
- Disease is prevalent in more
humid and higher rainfall areas.
Disease symptoms
This
symptom is seen when ears become infected during the early flowering
stages. Later infections may result in infection of the grain but without obvious
bleaching of the ears.- Fusarium lesions often begin in
the leaf sheath at the stem base where crown roots split the leaf sheath
when emerging. This infection can then spread up the leaf sheath causing
long dark brown streaks at the stem base
- The ear blight phase of the
disease can cause yield loss but is most important as it can result in
mycotoxin production in the grain.
Survival and spread
- The most important source of
Fusarium for wheat crops is the seed but the fungus can also survive on
debris in the soil
Favourable conditions
- Relatively high soil moisture
and soil temperature are favourable for the infection.
To know
the IPM practices for Wheat, click here.
Source: NIPHM, Directorate
of Plant
Protection, Quarantine & Storage
144 ratings and
Wheat: Insect, Mites
and Nematode Pests Management
- Termites
- American pod borer
- Aphids
- Brown mite
- Army worm/cut worm
- Shoot fly
- Wheat thrips
- Pink stem borer
- Ghujhia weevil
- Root-knot nematode
- Molya nematode / cyst nematode
- Wheat-gall nematode
- IPM for Wheat
Termites
Biology
- Egg: Dull, kidney shaped and hatches in 30-90 days.
- Nymph: Moult 8-9 times and are full grown in 6-12
months.
- Adult: Creamy coloured tiny insects resembling ants with
dark coloured head.
Damage symptoms
Termites damage the crop soon after sowing and
sometimes near maturity. They feed on roots, stem of growing plants, even
dead tissues of plant feeding on cellulose. The damaged plants dry up
completely and are easily pulled out. The plants damaged at later stages
give rise to white ears. Infestation is heavy under unirrigated conditions
and in the fields where un-decomposed farm yard manure is applied before
sowing.
American pod borer
Biology
It is a
polyphagous, infesting gram, lablab, safflower, chillies, groundnut, tobacco,
cotton etc.
Egg: The
spherical, yellowish eggs are laid singly on tender parts and buds of
plants. The egg period lasts for 2-4 days.- Larva: Caterpillars are of varying colour, initially
brown and later turn greenish with darker broken lines along the side of
the body.
- The larval period lasts for
18-25 days. Body covered with radiating hairs. When full grown, they
measure 3.7 to 5 cm in length. The full grown caterpillar pupates in the
soil in an earthen cell and emerges in 16-21 days.
- Pupa: Pupation takes place inside the soil, pupal stage
lasts 7-15 days.
- Adult: Moth is stout, medium sized with brownish/greyish
forewings with a dark cross band near outer margin and dark spots near
costal margins, with a wing expanse of 3.7cm.
Damage symptoms
- Young larva feeds on the leaves
for some time and then attacks earheads. Internal tissues are eaten
severely and completely hollowed out. While feeding the caterpillar thrust
its head inside leaving the rest of the body outside.
- Fed leaves awns and earheads.
Natural enemies of american pod borer
- Parasitoids: Tricogramma chilonis, Tetrastichus spp., Chelonus
spp., Telenomus spp. (egg) Bracon spp., Ichneumon promissorius, Netelia
product, Chrysoperla zatrowii sillemi, Carcelia spp., Ovomermis albicans,
a nematode, Chaetopthalmus, Campoletis chloridae (larval), Lissopimpla
excels, Ichneumon promissorius (pupal)
- Predators: Coccinellids, King crow, Braconid wasp, green
lacewing, dragon fly, spider, robber fly, reduviid, praying mantis, red
ants.
Aphids
Biology
- Eggs: Eggs are dirty white in colour and laid along the
veins of leaves.
- Nymphs: There are four nymphal stages (instars). The general
appearance of each stage is similar except for increase in size during
subsequent instars. The first, second, third and fourth nymphal stages
last 1-2, 2, 2, and 3 days respectfully. The nymphs and the females look
alike, except that the latter are larger. It breeds at a fast rate during
cold weather and reaches the height of its population in February-March
when the ears are ripening.
- Adults: Aphids are small, soft-bodied, pearl-shaped insects
that have a pair of cornicles (wax-secreting tubes) projecting out from
the fifth or sixth abdominal segment. Aphids are green colour. Both
apterous (wingless) and alatae (winged) forms pass through 4-5 nymphal
instars in their development and the nymphal period ranges from 5-7 days.
Both the forms mate within a day or two after the final moult and start
reproducing young ones. The apterous forms produce significantly more
number of young ones than alatae but their life-period is shorter than
that of alatae.
- In the field generally
viviparous apterous forms are observed in large number.
Damage symptoms
- Like other aphids, the nymphs
and adults suck the sap from plants, particularly from their ears. They
appear on young leaves or ears in large numbers during the cold and cloudy
weather.
- The damage is particularly
severe in years of cloudy weather. A heavily manured, well-irrigated and
succulent crop will harbour the pest for a longer period and suffer
greater damage.
Natural enemies of aphid
- Parasiotids: Aphidius spp., Aphelinus spp. etc.
- Predators: Syrphid fly, lacewing, minute pirate bug damsel
bug and ladybird beetle, praying mantis, predatory thrips, rove beetle
etc.
Brown mite
Biology
Eggs: Hyaline,
globular laid in mass. Eggs are generally laid beneath clods and are
either active i.e. red in colour and not visible to the naked eye or
dormant i.e. white eggs.- Clearly visible on the
underside of clods
- Nymphs: Yellowish in colour
- Adults: The mites are very small measuring about 0.5 mm
in length, metallic brown to black with pale yellow legs and their
forelegs are distinctively longer than the other three pair of legs.
Damage symptoms
- They feed on leaves by sucking
sap by inserting two needle like stylets into the leaf there by
withdrawing nutrients from the plants.
- Affected leaves become whitish
and under severe conditions become reddish brown and bronzy
- Leaves wither and dry
Natural enemies of mite
- Predators: Oligota spp., Anthrocnodax occidentalis,
Feltiella minuta etc., Green lacewings (Mallada basalis and Chrysoperla
zatrowii sillemi), lady bugs.
- Predatory mite: Amblyseius alstoniae, Phytoseiulus persimilis.
Predatory coccinellid beetle – Stethorus punctillum.
Army worm/cut worm
Biology
- Eggs: Eggs are laid in cluster, consisting of
approximately 500 eggs
- Larvae: The younge caterpillars hatch from the eggs in
4-5 days. After hatching the caterpillars starts feeding on the leaves of
the seedlings. The caterpillars are fully grown in about 15 days and
measures 3-5 cm in length. Larvae usually have 6 instars (very seldom 7 instars),
reaching 40 mm in length at older age. Larva with 2 wide black-brown and
one intermediate light dorsal stripe, with black-brown lateral stripe
along spiracle line; spiracles brown with black rim.
- Pupae: Larvae pupate in soil at depths to 2 cm, under lumps
of ground or under tussocks. Pupal phase lasts 13-21 days. Pupae are
yellowish-brown, shiny. Body length is about 15-20 mm. It has a cremaster
on last segment bearing 2 bent and crossed spines and 4 thin hooked setae.
- Adults: Adult is brownish white in colour. Forewings are
grayish-yellow, with dark-gray or reddish-yellow tint. Round and reniform
spots are light or yellowish with indistinct edges; reniform spot with
white point at lower margin. External wing margin blackened obliquely from
top backward, with dark stroke and with a row of dark points. Hind wings
are gray, with dark external margin. Antennae are thread-like.
Damage symptoms
- The primary symptom is
defoliation of the plant. Larvae feed on leaves, chewing from the edges to
the midrib, or on the heads of cereal plants.
- Heavy infestations can be very
destructive; larvae may climb the plant and sever the neck just below the
head. Some species may be found feeding at the soil surface, others
underground feeding on roots, and still others feeding inside the stem.
- The armyworm feeds during dawn
and dusk period as it is shy of sun light.
Parasitoids
and Predators: Same as Helicoverpa armigera
Shoot fly
Biology
- Eggs: The eggs hatch in 1 - 3 days and the maggots
which are yellow in colour migrate to the dorsal surface of the leaf,
enter the space between the leaf sheath and the axis and make a clean cut
at the base of the leaf. The growing point of the plant dies and decays on
which the maggots feed.
- Larvae: The larval period lasts for 6 - 10 days.
- Pupae: Pupation takes place inside the stem itself and
the adults emerge in about a week.
- Adults: The adult is a small dark fly. It deposits
whitish eggs singly on the central surface of the leaves. Each female fly
is capable of laying 30 eggs during its life time. Life cycle occupies 17
- 20 days.
Damage symptoms
- The maggots bore into the shoot
of young plants, a week after germination to about one month and as a
result the central shoot dries up resulting in „dead hearts‟. If it is a
little later the mother plant may produce side tillers. But the tillers
also may be attacked. The infestation often goes as high as 60%.
Wheat thrips
Biology
- Eggs: Embryonic development lasts 9-10 days.
- Nymphs: There are 2 instars; nymphal development lasts
23-27 days. The young nymph feeds on the lemmae and then penetrates the
flower which may become sterile due to the nymph's feeding damage. When
the grain has reached the milky-ripe stage, the nymph moves into the
furrow of the grain and attacks the pericarp. Once it has completed its
development, the nymph vacates the lemmae and falls to the ground.
'Pupation': there are 3 stages, 1 'pre-pupal' and 2 'pupal', lasting only
a few days.
- Adults: Adults are very small, brown or black insects with
a tapering, segmented abdomen, elongated and fast moving measuring 2 mm in
length with four narrow fringed wings and live for about 10-12days.
Damage symptoms
- They are usually infecting the
sheath of the flag leaf, feeding on the stem. However, leaves, stems, and
heads may be attacked. Adults and nymphs both can cause damage and, if
present in large numbers, may cause the tissue on which they are feeding
to take on a silver coloration.
Natural enemies of wheat thrips
- Parasitoids: Thripobius semiluteus
- Predators: Franklino thrips, predatory mite, hoverfly.
Pink stem borer
Biology
Eggs: Round
pearl like yellowish eggs ranging 80-300 are layed in 2-3 longitudinal
rows usually within the sheaths of bottom leaves of young plant of two to
three weeks old. As the time for hatching approaches, eggs become brown or
shy grey.- Larvae: Newly hatched larvae remain in group behind the
leaf sheath and begin chewing on the stem and epidermal layer of the
sheath. Full grown larvae are stout smooth about 25 to 30 mm in length
purplish pink on the dorsal side and white on ventral side.
- Pupae: Pupa is dark brown in colour.
- Adults: The adult moth is straw-coloured with white
wings. Life cycle is completed in 6-7 weeks with 4-5 generations in a
year.
Damage symptoms
- Severe damage causes the stem
to break. Severely infected plants due to stunting may appear to have some
times the cob and tassel at one place. Whorl feeding of larvae results in
rows of oblong holes in unfolding leaves unlike round shot holes produced
by Chilo partellus.
- Later they bore in to central
shoot resulting in the drying up of the growing point and formation of “dead
heart” in young plant as a result of larval feeding sometimes the
bottom internodes show circular ring like cuts. At ear head stage “white
ears” are produced.
Natural enemies of pink borer
- Parasitoids: Apanteles,Tetrastichus, Telenomus, Trichogramma
japonicum ,T chilonis, Bracon etc.
- Predators: Spiders, drynids, water bugs, mirid bugs, damsel
flies, dragonflies, meadow grasshoppers, staphylinid beetles, carabids,
coccinellids etc.
Ghujhia weevil
Biology
- Eggs: Insect mate frequently and lay 6-76 eggs in 5-11
installments in the soil under clods or in crevices in the ground. The egg
period is 6-7 weeks.
- Larvae: Young grubs enter the soil. Grub period is 10-18
days.
- Pupae: Larvae pupate in earthen chambers at a depth of
15-60 cm. The pupal stage lasts 7-9 weeks.
- Adults: Weevils are earthen grey and measure about 6.8 mm
in length and 2.4 mm in width. Their fore wings are oblong and hind wings
are more or less triangular, but they cannot fly. The pest is active from
June to December and undergoes larval or pupal diapause during rest of the
year in the soil.
Damage symptoms
- Only adults feed on leaves and
tender shoots of the host plants. They cut the germinating seedlings at
the ground level. Often the crop is resown. The damage is particularly
serious during October-November when the rabi crops are germinating.
Root-knot nematode
Biology
Most
species of plant parasitic nematodes have a relatively simple life cycle
consisting of the egg, four larval stages and the adult male and female.- Development of the first stage
larvae occurs within the egg where the first molt occurs.
- Second stage larvae hatch from
eggs to find and infect plant roots or in some cases foliar tissues.
- Under suitable environmental
conditions, the eggs hatch and new larvae emerge to complete the life
cycle within 4 to 8 weeks depending on temperature.
- Nematode development is
generally most rapid within an optimal soil temperature range of 70 to
80°F.
Damage symptoms
- Infected plants in patches in
the field
- Formation of galls on host root
system is the primary symptom
- Roots branch profusely starting
from the gall tissue causing a „beard root‟ symptom
- Infected roots become knobby
and knotty
- In severely infected plants the
root system is reduced and the rootlets are almost completely absent. The
roots are seriously hampered in their function of uptake and transport of
water and nutrients
- Plants wilt during the hot part
of day, especially under dry conditions and are often stunted
- Nematode infection predisposes
plants to fungal and bacterial root pathogens
Survival and spread
- Primary: Egg masses in infected plant debris and soil or
collateral and other hosts like Solonaceous, Malvaceous and Leguminaceous
plants act as sources of inoculums.
- Secondary: Autonomous second stage juveniles that may also
be water dispersed.
Favourable conditions
- Loamy light soils.
Molya nematode / cyst nematode
Biology
- This nematode passes
unfavourable season in the form of cysts, mostly in the soil. A cyst
consists of the dead body of a female containing a large number of eggs.
- When the conditions are
favourable, eggs hatch within the cysts and the larvae are set free into
the soil in the second stage of growth.
- The larvae may invade any
underground part of a susceptible plant but most of them enter it at or
near the root tips.
- After moving a short distance
through the cortex, they assume a position, more or less parallel to the
main axis of the root, with the head away from the tip.
- Male has capability to
metamorphosis, increase in girth 1/5th of its length. The female does not
undergo such metamorphosis, but after the second and third moultings it
continues to increase in girth until it becomes ovate. It then undergoes
the fourth or final moulting and emerges as a full grown adult.
- After mating, the eggs mature
inside the body of the female and it dies, the body being converted into a
cyst.
Damage symptoms
- Attacked plants remain stunted
and give a shriveled unhealthy appearance.
- Presence of nematodes
stimulates the formation of branched rootlets.
- The main root remains short or
bunchy, bearing small galls. In case of severe infestation, the seedlings
may fail to come out of the soil.
- The plants that escape the
early damage produce short stalks and ears, yielding a poor harvest.
Wheat-gall nematode
Biology
- Seed galls are dispersed along
with seed during planting and harvest. In moist soil, seed galls release
thousands of larvae.
- Wet weather favors larval
movement and the infestation process.
- The nematode invades the crown
and basal stem area, finally penetrating floral primordia. There they
mature and produce large numbers of eggs.
- Seed galls develop in
undifferentiated floral tissues.
- In the developing galls, the
larvae mature into males and females, as the case may be. A single gall at
this stage may contain 40 females and an equal number of males.
- They mate within the gall and
the gravid females lay a large number of eggs. The young larvae on
emerging from the eggs develop up to the second stage and then become
dormant. They remain in that state in the dry galls till the next sowing
season. There is only one generation in a year
Damage symptoms
- Basal swelling of stem.
- Crinkling, twisting and diverge
leaves.
- Stunted growth and increased
tillering
- Diverge nature of spikes.
- Reduce ear head.
- Presence of damaged grain
(cockels) Tundu : (A. tritici + Rathaybacter tritici)
- Yellow slimy ooze on ear head.
- At later stage production of
blight yellow bacterial mass on the abortive ear.
- Complete destruction of ear
head.
IPM for Wheat
To know
the IPM practices for Wheat, click here.
Source: NIPHM and Directorate
of Plant Protection, Quarantine & Storage
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