Higher temperatures and prolonged dry spells are leading to increased pest attacks, disease outbreaks and lower yields in sugarcane; organic farming could be the best way to cope
Jaikumar Gouda of Khavatakoppa village in Belgaum district of Karnataka is a worried man. Just 10 to 15 years ago, he used to harvest 80 to 90 tonnes of sugarcane per acre, which has now slumped to 40. Variable rainfall, prolonged dry spells and frequent droughts influenced by climate change are affecting the lives of Gouda and other sugarcane farmers in Karnataka and Maharashtra in western India.
The erratic monsoon in 2018 characterised by long dry spells, followed by short spells of heavy rainfall, has affected sugarcane cultivation in Belgaum, Bagalkot, Mandya, Bijapur and Haveri districts of Karnataka and Kolhapur, Ahmednagar, Pune, Sangli and Satara districts of Maharashtra.
“During drought years, sugarcane area and production are going down drastically. Now it has become a routine feature in the tropical climatic zones of coastal Karnataka and Maharashtra,” says Sanjay Patil, Sugarcane Breeder and Principal Scientist and Head, Agriculture Research Station (ARS), Sankeshwar, Karnataka. “During the drought years to maintain the sugarcane crop is quite tough in a situation where groundwater is depleting extensively.”
“Scarcity of rainfall lessens the nitrogen, which is an essential nutrient that affects ecosystem productivity. Dry spells had increased the rust disease in sugarcane. If the rainfall is optimum, infestations are less. Pest and fertilisation has increased, but sugarcane yield has come down,” said Gouda.
Sugarcane is grown extensively in India and provides a livelihood to thousands of farmers, particularly in northern and western India. The South Asian nation is the second-largest sugarcane producer in the world after Brazil. The biggest producer of sugarcane is the state of Uttar Pradesh, followed by Maharashtra and Karnataka. It requires large amounts of water to cultivate and frequent droughts in Maharashtra and Karnataka in recent years has led to widespread farm distress.
Climate Change at play
Prolonged summer, erratic rainfall and shortening of winter season in Belgaum and Kolhapur have drastically reduced sugar production from cane, experts and farmers say. “Incidence of diseases like rust, leaf spots, pokka boeng, smut etc. has also increased,” says Ningapappa R. Giddoli, a sugarcane farmer of Yadagud village in Karnataka.
Pests like white grubs and aphid thrive due to dry spells and rising temperatures. The white grub pest attack was widespread in 2018 due to unusual rainfall.
“Due to erratic rainfall and continued dry spell in June- July, there is infestation of white grubs. These pests remain in the ground and surface during the dry periods. The grubs that feed on the roots of cane plants can only be eradicated by pulling out the crop. Everything has to be replanted, which adds to the stress of sugarcane farmers already dealing with meagre harvests. Cane stalks started wilting despite timely irrigation since August. When we tried to find out the reason, we found white grubs were eating the shoots,” farmer Mahesh Chougala of Khavatakoppa village said. “Many desperate farmers have burnt land patches hit by white grubs, but the pest attack continues.”
“We tried to kill the grubs by spraying kerosene, salt and various pesticides, but couldn’t as the worms reside nearly a foot below the ground. In June to July, white grub worms remain small enough to be killed with pesticides, but they are now fully grown and survive underground even after different pesticides are applied,” said Bane Namdeo V. Tukaram of Herwad village in Kolhapur district in Maharashtra.
Purnima, Assistant Professor at Dharwad Agriculture University in Karnataka, believes that climate change, along with indiscriminate use of pesticides, could well be the reason for the surge in pest attacks. The infestation happens at two levels and it affects the growth of sugarcane, says Purnima, who uses only one name.
“Elevated carbon dioxide increases the levels of simple sugars in leaves and lowers their nitrogen content. This increased the damage caused by many insects, which consumed more leaves to meet their metabolic requirements of nitrogen. Thus, pest attacks were more severe. Due to higher temperatures as a result of global warming more pests survived the winter,” says agronomist Maruti N. Malawadi of Krishi Vigyan Kedra (KVK – agricultural science centre) in Tukkanatti, Karnataka.
“Rising carbon dioxide emissions with increase in temperature might prove to be lethal” to sugarcane, says Sunil S Noli, agronomist at an agricultural research station in Sankeshwar, Karnataka. “Photosynthetic efficiency, water efficiency and yield efficiency will be reduced. With low availability of water, the stress is higher. Even after four months, sugarcane yields will be minimal. Winter is shrinking and slow growth during winter will affect sucrose accumulation in sugarcane. High CO2 levels due to climate change have drastically reduced essential nutrients in sugarcane, affecting its yield.”
Rust disease in sugarcane
Climate change has increased the incidence of rust disease in sugarcane, experts say. It causes wilting, some leaf tip death and has accelerated death of leaves. Jaikumar Durgammavar, a sugarcane farmer, shows his 10-acre field and says, “Fluctuation in temperature has caused rust. Fungicide was sprayed but there is no control over the rust.”
Showing the rust, Dattaray Jondhale, a sugarcane farmer of Herwad village in Kolhapur district of Maharashtra, explains, “Rust in the sugarcane plant is becoming severe. Numerous lesions occur on individual leaves giving it brown or rusty appearance. These lesions result in premature death of the leaf. In such cases, the number of live leaves per plant is seriously reduced, while in very susceptible varieties there may be fewer stalks and reduced diameter and length of the stalks. Rust is more severe in the young stages of plant; it usually declines with increasing crop age. A mild winter like the one we are experiencing this year will likely allow rust to survive and re-emerge as a problem.”
Need for organic farming
“Sugarcane cultivators need to practise organic farming at a large scale,” says agronomist Maruti N. Malawadi. “Sufficient quantities of organic manure and compost need to be applied in the water-scarce land plots. Soil and water conservation measures should be the topmost priority. Drip irrigation during dry spells is important. If there is excess of water and nitrogenous fertilisers, then sugarcane crop will become susceptible to pest and disease. Proper quantity of water through drip irrigation and recommended dose of nitrogenous fertilisers will give a good yield.”
“To withstand climate change, we need to practise organic farming in sugarcane cultivation,” agrees Ganpat Rao Appasaheb Patil, Chairman of farmers’ collective Sridatt Shetkari Sahkari Sakhar Karkhana Ltd, Shirol, Kolhapur. “Our cooperative has adopted organic farming. We have supplied 6,000 quintals of organic sugar in the market (this year). To produce organic sugar, organically grown sugarcane is a prerequisite.”