doi:10.1038/nindia.2014.162 Published online 27 November 2014
The rolling, fertile hills of the eastern Himalayas are witnessing a steady and expensive casualty to climate change – the slow demise of the aromatic spice large cardamom, owing to severe fungal blight attacks1 and viral diseases. The region’s crop scientists are struggling to find solutions to save its biggest cash crop from being wiped off the face of earth.
Across the eastern Himalayan region spanning India, Nepal and Bhutan, warmer and drier winters – conducive for these diseases – have been killing successive standing crops of large cardamom (Amomum subulatum) over the last decade forcing farmers to switch to less lucrative crops and severely impacting livelihoods and local economies.
In the north-east Indian state of Sikkim, India’s largest producer of large cardamom, yields of the spice have gone down drastically. “From about 26,000 hectares across Sikkim in 2004, the total area under cultivation today has gone down to around 16,500 hectares,” says Sandeep Tambe, commissioner in Sikkim’s rural management and development department.
Farmers, who wait for more than three years for the cardamom crops to bear fruit find it frustrating when the leaf blight caused by the soil-borne fungus Colletotrichum gloeosporioides singes them down. Also, after the disease strikes, the soil is rendered unfit for most crops unless treated.
“My grandfather had a bounty every three years when large cardamom was plucked – the money he made lasted us another 3-4 years till the next crop was ready,” says 25-year-old Passang Yangzee, a farmer in the Perbing village in South Sikkim. Her family has switched over to growing maize, peas and cabbages in rotation to make up for some of the losses. Large cardamom, once a perennial native cash crop, is currently priced at around Rs 1200 a kilogram.
Tambe says in the absence of fool proof scientific interventions, the farmers have been trying hard to find indigenous adaptive solutions to grow the climatically stressed crop. “Practice is ahead of science in this case. Obviously, the markets are playing an important role to salvage this socio-economically important crop. Farmers are finding higher altitude lands to grow large cardamom and experimenting with crop rotation to find solutions.”
In the southern and western districts of Sikkim, he says, cardamom plantations have seen some success in recent times as a mixed crop grown in rotation with other vegetables. Climate resilient crops such as maize, broom grass, turmeric, cabbage, tomato and cherry pepper are being widely cultivated in lands earlier earmarked for large cardamom. India produces about 5000 metric tonnes of cured cardamom annually2 of which Sikkim contributes about 89%. The central agency North Eastern Regional Agricultural Marketing Cooperation (NERAMAC), which operates the only large cardamom auction centre of India at Rangpo in Sikkim, reported a bounced in auctions in 2012-13, after a decade of gloom3.
The Colletotrichum disease strikes around pre-monsoon (April-May). The plants, traditionally grown in the shade of Himalayan Alder trees, become necrotic and die during the rainy season (June-August). A couple of other viral diseases locally called chirkey and furkey also account for yield losses.
“Initially, when the decline in productions started in 2001, we thought it was a mysterious disease,” says entomologist Tilak Gajmer, a project coordinator at the Krishi Vigyan Kendra (KVK), a regional agro-science centre run by the Indian Council for Agricultural Research (ICAR), at Namthang, South Sikkim. ICAR began quantifying the losses and found that production had gone down by half between 2004 and 2008.
The big challenge, Gajmer says, is that scientists have not yet been able to put a finger on the exact cause of the widespread blight attacks. “The same bacteria affects tomatoes and chillies without significant crop damages. For large cardamom, the possible cause of such devastation could be the change in climate bringing in its wake the unique phenomenon of winter droughts as well as senile plantations that retain the infection,” he says.
Tambe says in addition to these problems, the hailstorm frequency in the hills has gone up from 2-3 to 8-10 a year, affecting all cash crops in the eastern Himalayas.
Paramvir Singh Ahuja, leading agriculture scientist and Director General of India’s premier research and development body Council for Scientific and Industrial Research (CSIR) is not surprised at the lack of climate change related insights into the large cardamom debacle. “Climate change related agricultural science needs more funding in India what with the high throughput screening and systems biology solutions that the whole world banks on today. We are only touching the tip of the iceberg in India,” he says.
Ahuja, also the director of the Institute of Himalayan Bioresource Technology in Himachal Pradesh, says there are no quick-fix solutions in sight to bring back the lost glory of the large cardamom. He says the reason behind the severity of the cardamom blight is that the crops had overstayed with the disease in the region, making the soil-borne infection deep seated. “So the best approach would be to look for alternative domains to cultivate large cardamom. Or to initiate research on how to ameliorate the pathogen from the soil and ensure that the planting material is disease free.”
High quality and thorough research on the plant and the blight has been scant and Ahuja says there’s need to immediately fund such research. In the interim, it would be best to treat the affected soil with microbes or solarisation and come back to replant large cardamom on these treated patches 7-8 years later.
“Pushed by climate change, cash crops across Himalayas are finding alternative domains to flourish – for example apples in Himachal Pradesh grow on higher altitudes than before. However, the problem with apples is not as serious as large cardamom since we can work around apples by selecting the right genotypes and treating diseases through early diagnosis,” Ahuja adds.
Since Sikkim is an organic state and does not allow use of chemical pesticides, scientists at the regional research station of the Indian Cardamom Research Institute (ICRI) in the state’s capital Gangtok have proposed using biocontrol agents such as Pseudomonas fluorescens, Bacillus subtilis and Trichoderma harzianum to control diseases affecting large cardamom4. “We did make an exception to the rule and used chemical fungicides on experimental basis but not with much success,” Gajmer says.
Farmers across the region are looking at scientists to find a ‘miracle cure’ that can bring back their most prized crop to the hills. Says Karma Doma Lephca, a panchayat head of the Perbing village, “Our farmers have been applying traditional knowledge and technologies to adapt to the changing climate. But we know that this is a menace that needs rigorous scientific intervention.” Gajmer says scientific teams from Nepal and Bhutan have been studying all the interventions being made in India to figure out how to tackle the diseases in their own crop fields.
1. Saju, K. A. et al. Identity of Colletotrichum infections in large cardamom (Amomum subulatum Roxb.). J. Spices Aromatic Crops 22, 101–103 (2013) Article
2. Large Cardamom – the pride of Sikkim, Indian council of Agricultural Research (ICAR)
3. Large Cardamom is coming back to its bright days again in Sikkim. Economic Times (2012) Article
4. Saju, K. A. et al. In vitro evaluation of biocontrol agents, botanicals and fungicides against Colletotrichum gloeosporioides infecting large cardamom. Plant Dis. Res. 27, 49-53 (2012) Article