After destroying the corn crops of African countries
three years ago, the Fall Armyworm has made a foray into many states of India and
if not identified and controlled in time, shall cause immense harm in the
future.
Fall Armyworm has been detected in the corn crops of
Karnataka, Tamil Nadu, Bastar district of Chhattisgarh followed by Uttar Pradesh’s
Kannauj and Sitapur districts. Farmer Nand Kishore of Barbata Zalimpur village in
Sitapur, Uttar Pradesh has sown corn in his one-acre farm. He said: “I have
grown corn for many years, but this time it has been infested by a newer type
of pest that I know nothing about. It is fast destroying the crop.”
Prior to this, the Fall Armyworm had been detected
by the scientists of the Regional Central Integrated Pest Management Centre,
Lucknow during their surveying and monitoring of corn crops in Kannauj district.
The Indian Corn
Research Institute, Ludhiana’s scientist Dr Mukesh Chaudhary informed: “Since
past few months, this pest is sighted in many states of the country affecting
the corn crop from South India’s Karnataka and Tamil Nadu, thereafter Chhattisgarh,
West Bengal, Mizoram, Uttar Pradesh and more recently in Bihar where the
farmers are yet to be made aware of this pest.”
He added: “Presently we have sighted it in Punjab
too—it covers a distance of up to 100kms in a night. If sighted in a farm and
left chemically uncontrolled, it travels hundred kilometers further. An adult
pest produces 1,000 eggs at one go and even if 10 survive, they would further
produce 10,000 eggs.”
This has even affected crop production. Regarding this, he said: “It also has affected the
production, this time farmers in South India have sown less corn as it seems to
be the pest favoured crop. In the absence of the corn crop, the pest will move on to
the sugarcane crop. Even in the absence of sugarcane, it will thrive on jawor,
bajra etc. Corn being its primary target, it can harm over 190 different types
of crops.”
The ill-effects of this pest were first noticed in
Karnataka’s Shivamoga on May 18, 2018. Thereafter, the Fall Armyworm was reported
in dangerous level in the fields of
Tamil Nadu, Andhra Pradesh, Telangana, Maharashtra, Madhya Pradesh, Odisha, West
Bengal, Gujarat, Chhattisgarh, Kerala, Rajasthan, Jharkhand, Mizoram, Manipur,
Nagaland, Tripura, Meghalaya, Arunachal Pradesh and Sikkim.
Krishi Vigyan Kendra’s crop protection
Scientist, Dr Daya Srivastava informed, “This pest is known as ‘Fall Armyworm’,
it was first sighted in May 2018 upon the corn crops of Shivamoga district in
Karnataka. Thereafter it has rapidly spread across Tamil Nadu, Maharashtra,
Andhra Pradesh and even Mizoram. Uttar Pradesh cultivates sugarcane and corn in
a large scale so now the pest’s presence in the state is an extremely grave
issue.”
It is primarily a corn-based
pest. If the corn crop is not available then it attacks jowar. If both aren’t
available then it feeds upon other crops such as sugarcane, rice, wheat, ragi
and even fodder grass. It also causes harm to cotton and vegetables. Fall
Armyworm adult moths are rapid flyers which can fly over 100kms in search of
host crops.
What is fall armyworm?
Fall
armyworm (FAW), a destructive pest native to the Americas, recently invaded India
and presently causing economic damage in maize.
Which crops in danger?
It is primarily a pest of maize. If maize is not
available it will look for sorghum. If both are not available, it will attack
other crops belonging to poaceae, the family of grasses, such as sugarcane,
rice, wheat, ragi, fodder grasses etc. It may attack cotton and vegetables as
well, which is not reported yet.
How to recognize if FAW has arrived in your
field?
The adult moth is a strong flier. It can fly over 100
km in search of host plants. Pheromone traps specific to FAW will attract male
moths. Male moth has two characteristic markings — a fawn-coloured spot
towards the center and a white patch at the apical margin of the forewing. Forewing
of the female is dull with faint markings.
How to ascertain the larva feeding your crop
is FAW?
Larvae of many species of Armyworm belong to
the genus Mythimna and Spodoptera look the same for a layman and cause similar
symptoms in maize.
FAW larvae appear in shades of green, olive, tan
and grey with four black spots in each abdominal segment and has three creamy
yellow lines running down its back.
It is easily identified from any other armyworm
species by its tail end, where the black spots are bigger and arranged in a square pattern on abdominal segment 8 and trapezoid on segment 9. The head has
a predominant white, inverted Y-shaped suture between eyes.
What are the symptoms of FAW damage in maize
and what are the management measures to be taken with the progression of symptoms?
A symptom-based treatment is very much essential
in FAW management because of two reasons — the stage of symptom progression
indicate the stage of larval growth, and the stage of larval growth decides the
choice of pesticide/ control measure.
(1) Elongated papery windows
Start observing the maize crop from the seedling
stage. If elongated papery windows of all sizes are seen spread all over the
leaves in a few adjacent plants the crop might have been infested with FAW.
This symptom is caused by 1″ and 2™ instar FAW larvae which feed by scrapping
on the leaf surface. Early identification of this symptom is a must for effective
management of FAW.
What measure to be taken at this stage?
It is easy to manage the larvae at this stage with
botanical and microbial pesticides. The choices are:
(1) 5% Neem Seed Kernel emulsion (NSKE) or
azadirachtin 1500ppm @ 5ml/I water.
(2) Bacillus thuringiensis variety kurstaki
formulations (Dipel 8 l @ 2ml/I of water or Delfin 5WG @ 2g /l water).
(3) Entomopathogenic fungi Metarhiziumanisopliae
(1 x 108 cfu/g) @ 5g/l and /or Nomuraearileyi rice grain formulation (1 x 108
cfu/g) @ 3 g/l water.
However, when the infestation is more than 10% in
the field, it is better to resort to chemical pesticides which are recommended
below for the bigger larvae. Apart from pesticide sprays, put some sand/soil
alone or mixed with lime/ash (9:1) into the plant whorl when the whorl is well-formed to withstand its weight. This will directly harm larvae and increase the
effectiveness of pesticides sprayed, especially by acting as a reserve for
microbial pesticides.
2. Ragged-edged holes:
Once the larva enter 3rd instar, its feeding
cause ragged-edged round to oblong holes on leaves. The size of holes increases
with growth of larvae.What measure to be taken at this stage?
Damage at this stage needs the application of
chemical pesticides. The choices are,
Emamectin benzoate 5 SG @ 0.4 g/l
Spinosad 45 SC @ 0.3 ml/l
Chlorantraniliprole 18.5 SC @ 0.4 ml/I
3. Extensive leaf damage:
Once the larva enters 5th instar, it feeds
voraciously, losing larger areas of leaves. Sixth instar larva extensively
defoliates the leaves and produce large amount of faecal matter.
What measure to be taken at this stage?
Pesticides sprays fail to control 5th and 6th
instar larvae. Only effective measure at this stage is poison baiting. Mix 10
kg rice bran and 2 kg jaggery in 2-3 liters of water and
keep the mixture for 24 hours to ferment. Add 100g Thiodicarb 75% WP and roll
into balls of 0.5- 1 cm diameter just half an hour before application in the
field. Add some sand while rolling if the balls are too sticky. The bait should
be applied into the whorl of the plant in the evening. The above mixture is
sufficient to cover one acre.
