Thursday, 13 August, 2020

Menace Of Fall Armyworm


Maheshwor Acharya


Agriculture has the biggest share in Nepal’s economy. Among 5.4 million households, 3.8 million rely on agriculture as their means of livelihood. But an average Nepali farmer is engaged in agriculture on his own. These farmers are generating jobs for themselves and producing food for their family and the community. Majority of them do not have access to government-aided technical support, nor do they have access to agricultural technicians.
Farming in Nepal is a tedious task in itself while every now and then agriculture sector suffers from this and that problem, like seasonal germs and pests. In the present time, maize cultivation is being invaded by American fall armyworm.

Pest Threats
The Nepali maize farm is always facing threats of pests like sting borer, grey leaf spot, corn stalk, corn smut and so on. These pests have been creating havoc in maize cultivation for a long time besides other armyworms. But, this particular American fall armyworm (FAW), is a new one, that mostly targets maize in the context of Nepal.
It was first noticed 0n 9th of May last year, in the maize field in Gaidakot of Nawalparasi. However, a group of scientists reported that it had entered Nepal via Jhapa and Sindhuli, three months prior to that.
But, the authorized body to identify pests and recommend preventive measures, Nepal Agriculture Research Centre (NARC), was confused in the initial stage, to ascertain if it was FAW. Even the then Agricultural Minister, Chakrapani Khanal accepted that the government failed in its task to identify the invasive worm on time. Somehow, the maize season passed by and the focus shifted to the main crop of the country, rice, which was razed by another kind of pest.

What is FAW?
The FAW, that targets maize in Nepal, falls in the family of butterfly. Its scientific name is Spodoptera frugiperda. The adult moths of this worm are highly migratory in the Americas, capable of travelling up to 1,500–2,000 km per year in search of warmer climate. It can travel 500 km in a single season to find sites to lay eggs. The main crops it destroys are maize, rice, wheat, sugarcane and 80 plus other plants, including vegetables crops.
The armyworm mostly feeds on leaves at night, but under certain circumstances, also feeds on the seed stem, resulting in head loss. Moths emerge in the spring, mate, and lay eggs in masses on the host plant. The larvae feed for about four weeks but do most of their damage between 14 to 21 days.
This FAW is native to tropical and sub-tropical regions of the Americas. In early 2016, it was reported in the rainforest zones of Central and Western Africa, on its first voyage beyond its native domain, where it destroyed significant amount of maize leading the continent to face food crisis.

Invasive Worm
According to the data published by the Ministry of Agriculture in the fiscal year 2018/19, the total area of land where maize is planted is 954 thousand hectares. And, the total production is 2.5 million metric tons. Though the production had marginally increased by nearly 2 percent than the previous year, the total area of maize cultivation had shrunk by nearly 3 percent.
After rice and wheat, maize is the top third food grain product of the country. Most of the hilly regions rely on maize. Experts believe that this invasive worm has reached in almost all the parts where maize is farmed though it is reported in 46 districts so far. As the country is fighting the crisis of COVID-19, the FAW is rising as a pandemic in the field of maize cultivation. It is making the situation even worse when the country is already heading towards food insecurity and dearth of food scenario.
The national centre of maize research, National Maize Research Programme in Rampur, Chitwan, is doing its best to find a proper solution to eradicate FAW from the field. The centre is yet to reach a conclusion which would be applicable to the farmers all around. On the basis of their study up to now and their pervious researches they have prescribed some measures which could be followed to prevent the worm doing any damage.
The preliminary study has showed that if the maize plot comes under the attack of this worm, it may diminish the production from 60 to 80 percent. So, the management measures should be applied sooner than later to secure the production. The small farmers should rely on integrated pest management (IPM), while the commercial farmers may opt for pesticide along with the biological remedies.

To prevent the FAW from entering the plot there are several methods suggested by the experts. In case of FAW, all the methods should be applied including the biological method and use of pesticide.
It is easier to manage the FAW in the initial stage that is when the butterfly is seen flying around immediately warlike measures should be taken to prevent it from laying eggs on the plant. Butterfly trap is recommended for it.
Experts suggest planting 'Nepair' (Pennisetum purpureum) grass at the edge of the plot which would attract FAW. It is liked by the FAW and it would lay eggs on its leaves rather than the maize plant leaves. And in the maize plot 'Desmodium' (Desmodium intortum), a grass with multiple benefits, should be planted that would push the FAW out of the field as its smell repels the worm, while it boosts up the nutrients in the soil.
Similarly, crops of beans family (Simi, Bodi, etc) along with the maize plants are recommended. Yet another biodiversity method suggested is to build bird nests by the side of the maize field. The birds prey on flies and spread of worm would be limited.
These methods would not achieve hundred percent results and some flies would lay eggs at the front and back side of the maize plant leaves. It is better to destroy them before they hatch, by spraying contact poisons, and if the larva gets older, there are other pesticides to apply. The scientists in Rampur have suggested 4 types of pest controllers, for different stages of the larvae of FAW. The prescribed pesticides are i) Spinosad 45% SC, ii) Spinetoram 11.7% SC, iii) Chlorantraniliprole 18.5%SC and iv) Emamectin benzoate 5% SG. They should be applied in the plants in different times, under the guidance of technicians.
Similarly, the plot should be monitored frequently. Leaves should be minutely checked to find out if there are eggs of worm or not. As the FAW is highly adaptable and has high travel capacity it is really a challenge to control it from invading the fields.
Successful method in Africa and researchers in Chitwan indicate that controlling the worm is easier in the initial stage. As 46 districts across the country are already affected by the FAW, prompt action is needed.
It is clear that the mid-hill small farmers would be badly affected by the FAW. So, it is high time for farmers and agro-vets, under the shadow of COVID-19, to combat the FAW. The task force formed by Agricultural Ministry to tackle FAW needs to move faster to tackle the situation. Otherwise, immediate economic loss because of the crop damage might led to social unrest that would create havoc in the society.

(Acharya is freelance journalist) 

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