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Business News/ Industry / Fingernail-sized pest poses most serious threat to tomato crop

Fingernail-sized pest poses most serious threat to tomato crop

Not only does this threat point to growing rural distress, but also flags the new class of risks that Indian farmers are being exposed to as they switch to commercial farming

The tomato leafminer (Tuta absoluta) originated in Latin America. Photo: Hemant Mishra/MintPremium
The tomato leafminer (Tuta absoluta) originated in Latin America. Photo: Hemant Mishra/Mint

New Delhi/Bengaluru/Mumbai: Thousands of tomato farmers are destroying their crops across some of the biggest tomato-producing states in India. The reason: they are desperate to kill off a fingernail-sized pest called the tomato leafminer or tomato leaf moth that is infesting farms in Maharashtra, Karnataka, Andhra Pradesh, Gujarat and Tamil Nadu.

Together, these five states account for more than half the tomatoes produced in India. Experts believe that the pest, classified as the most serious threat to tomato production worldwide, is expected to spread further to other tomato-growing states in the country.

Infested and damaged crops, say farmers, have been rooted out from the field and buried in nearby fields to prevent further infestation from the pest.

Not only does this threat point to growing rural distress, it, more importantly, flags the new class of risks that Indian farmers are being exposed to as they switch to commercial farming, tempted by its lucrative prospects.

Earnings from commercial farming can be three-four times that of investment. But the risks are unlike what Indian farmers have been used to so far—like the threat of a failed monsoon. These challenges become harder to confront in the absence of safety nets and adequate testing facilities for new pests.

The tomato pest, known as Tuta absoluta, originated in Latin America.

As Indians’ consumption habits change in tandem with economic growth, horticulture has emerged as among the fastest growing segments of Indian agriculture. In fact, horticulture production (268.9 million tonnes, or mt) surpassed foodgrain output (257 mt) for the first time in 2012-13. In the case of tomato, production has grown two-and-a-half times to 18.7 mt in 2013-14 from 7.4 mt in 2001-02.

Tuta absoluta

It all started in October 2014 when scientists at a Pune research station under the Indian Council of Agricultural Research (ICAR) observed an unknown pest in their tomato trial fields. A team of taxonomists and entomologists from the Indian Agricultural Research Institute (IARI), Delhi, and ICAR, Pune, conducted surveys in nine tomato-growing districts near Pune and found the pest infestation in all. Specimens were taken to Delhi, and after DNA bar-coding, it was confirmed that the tiny moth-like pest was indeed the South American Tuta absoluta (tomato leafminer).

A nationwide alert was issued by ICAR in January this year for the pest, known to be responsible for 80-100% of yield and fruit quality losses under greenhouse and field conditions. The pest skeletalises the leaves of the plant, and feeds on stems and buds, leaving line-like bore marks on the fruit.

Santosh Shelar, a farmer from Yedgaon village in Junnar Taluka of Pune district, was expecting a harvest of around 2,000kg of tomato from his one-acre plot. After the infestation, he will be happy if he manages to grow 25-30% of the amount. “I used all kinds of pesticides to control this Nag Ali (leafminer), but nothing seems to be working. And now, as advised by officials from the agriculture department, I am destroying my entire tomato plantation so that the disease doesn’t spread to other crops and other plots on my farm."

A senior official from the state government’s agricultural department, who did not want to be named, said: “A team of scientists from the central government visited to see the conditions in Pune district and we are waiting for their report, but so far we have not received any recommendation. So, meanwhile, we are advising them to completely destroy plants in their farms to ensure it doesn’t spread to other crops and we are also suggesting some pest management measures which we hope will help them to ensure it doesn’t attack the next time around."

Like Shelar, thousands of farmers from Pune, Nashik, Ahmednagar, Satara and Sangli districts—part of what is called the vegetable belt of Maharashtra—are trying to deal with the pest.

In Kolar district, about 70km from Bengaluru, many tomato farmers seem to be unaware of the presence of Tuta, even after their tomato fields started showing signs of crop damage in February this year.

Fifty-eight-year-old Shinapa (who goes by only one name), who grows tomatoes, carrots and potatoes in Ammerahalli village of Kolar district, said the tomato crop he had sown earlier this year on half an acre of land is mostly infested with the pest. Shinapa said he was unaware of the existence of the pest till neighbouring farmers reported their crops too had been completely destroyed. That was two weeks ago. So far, one-fifth of his tomato crop has been ruined by Tuta.

Because Tuta’s symptoms are similar to those caused by other pests that regularly attack tomato crops, Shinapa used routine pesticides, but found they had no effect. “Instead, it multiplied very fast," he added. Tuta is notorious for acquiring immunity against pesticides and proliferating despite being sprayed heavily by chemicals.

Shinapa spends about 80,000 every season on his tomato crop, earning 3-4 lakh in a good harvest season that lasts three-four months. This year, however, he has already overspent his budget acquiring pesticides and is now facing the prospect of a poor harvest.

From South America to India

Tuta absoluta, which not only affects tomatoes but also others from the solanaceous family of vegetables such as potatoes, eggplant and capsicum, became one of the most virulent pests in South America in the 1960s. Later, it was detected in Spain in 2006, and since then has rapidly spread to other European countries, infested North African and Mediterranean countries including Bahrain, Iraq, Israel, Jordan, Turkey, Yemen, Syria and even Japan. It was found in Iran in late 2010, and it is suspected that the pest has infested crops in Pakistan, too.

“Insects have no boundaries; they can travel from one country to another as wind currents can easily carry them. Unpublished data on the populations found in India seems to indicate that they are the same as the ones in Spain," said D.K. Nagaraju, assistant director, Plant Quarantine Station, Bengaluru.

According to Nagaraju, the pest could not have come in through commercial imports. “During exports from other countries, tomatoes are put in trays and wrapped in a plastic sheets, (so there is) remote chance of it spreading through plastic sheets," he said. Nagaraju explained that internal audits were carried regarding plant material and there is no official commercial import of plant material or seedlings.

“Where it might be coming from is wind drafts from countries sharing a border with India," he suggested. While Pakistan, Nepal and Bangladesh do not have official reports of Tuta, experts say there are unconfirmed reports of the presence of the pest in these countries.

“Domestically, the biggest problem is the movement of farmers carrying plant material such as plantings and seedlings from one part of the country to another, and the vehicular movement cannot be controlled," said Nagaraju.​

Search for natural enemies

There are 28 pesticides recommended for tomatoes in India, but none of them work on Tuta. India, however, is conducting surveys on which pesticides are being used against Tuta in other countries.

“This is a new invasive pest. So there is no label claim for a pesticide against Tuta absoluta in India. At the agricultural ministry, we are trying to recommend some of these (those used abroad) pesticides in India on a temporary basis for two years. So for two years, we can generate data and see the effect of the pesticide and then approval for label claim can be given," said S.N. Sushil, plant protection advisor, ministry of agriculture.

Label claims for all pesticides and insecticides used across the country are approved by the Central Insecticides Board and Registration Committee.

As a result, scientists are looking at biological agents to control the Tuta invasion.

In Bengaluru, at the National Bureau of Agriculturally Important Insects (NBAII), under the ministry of agriculture, scientists are busy devising sturdy low-cost and chemical-free methods to manage the pest.

A lab, spread over two floors, is being used to breed “natural enemies" to help fight Tuta, with some success. Trichogramma, natural endoparasitoids that breed on eggs and paralyse them before they are hatched, are being bred in tubes before being released in fields. Their eggs—black in colour and a millimetre or two in size—are being put on small stickers that can be stuck on the leaves of the damaged tomato crops.

“We are breeding the culture here and sending it to 22 institutes across the country which can further breed the Trichogamma and disseminate it locally to farmers," said Abraham Verghese, director at NBAII.

The biggest challenge for now is to educate farmers, who remain unaware of the presence of the pest in their fields. The institute, along with various other local horticultural departments, is tapping village panchayats and local farmers’ bodies to disseminate information about Tuta symptoms and prevention in local languages.

Invasion of alien pests has become a growing problem in India in recent years in tandem with the increased global trade in agriculture. Some of the recent exotic entries in the farmlands of India are the papaya mealybug, coconut mite and serpentine leafminer.

“Lack of required infrastructure and skilled human resources coupled with porous borders and lack of public awareness on quarantine pests have resulted in the entry of many plant pests which are causing devastating damage," said N. Sathyanarayana and K. Satyagopal, from the National Institute of Plant Health Management, in a 2013 paper published in the journal, Pest Management in Horticultural Ecosystems.

There are testing stations run by ICAR across the country and quarantine stations, too.

The experience of tomato farmers is a reminder of the fact that while the Indian farmer has been quick to take to the commercial opportunities opened up by horticulture, the absence of an institutional safety net has left them vulnerable to the downsides of an entirely new class of risks.

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Updated: 30 Apr 2015, 05:41 PM IST
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