Bengaluru

Invisible killer threatens India’s sandalwood forests

Warning signs: Experts warn that the disease has the potential to wipe out the entire population of the tree.  

India’s sandalwood trees, the country’s pride — particularly of Karnataka — are facing a serious threat with the return of the destructive Sandalwood Spike Disease (SSD).

The infection has resurfaced in the aromatic tree’s natural habitats in Karnataka and Kerala.

According to a study by scientists R. Sundararaj and R. Raja Rishi of the Bengaluru-based Institute of Wood Science & Technology (IWST), the natural population of sandalwood in Marayoor of Kerala and various reserve forests in Karnataka, including MM Hills, are heavily infected with SSD for which there is no cure as of now. Presently, there is no option but to cut down and remove the infected tree to prevent the spread of the disease, caused by phytoplasma — bacterial parasites of plant tissues — which are transmitted by insect vectors.

With between 1 and 5% of sandalwood trees lost every year due to the disease, scientists warn that it could wipe out the entire natural population if measures are not taken to prevent its spread. Also, they fear that any delay in arresting the trend may result in the disease spreading to cultivated sandalwood trees.

SSD has been one of the major causes for the decline in sandalwood production in the country for over a century. The disease was first reported in Kodagu in 1899. More than a million sandalwood trees were removed in the Kodagu and Mysuru region between 1903 and 1916, prompting the Maharaja of Mysuru to announce a reward in 1907 of ₹10,000 for anyone finding a remedy. Later 98,734 trees were extracted during 1917-1925 in Salem also due to SSD.

Such was the impact of this disease in Karnataka that the growing stock had been reduced to 25% of its initial level between 1980 and 2000. The devastating impact in natural habitats resulted in sandalwood being classified as “vulnerable” by the International Union for Conservation of Nature in 1998.

Presently, the natural populations of sandalwood are available in Marayoor in Kerala and some patches of reserve forests and adjoining areas in Karnataka — both these stands are now heavily infected with SSD.

The present rapid spread of the infection is largely due to restrictions on green felling in forests, which has allowed vectors to spread the disease to healthy trees, says the IWST study.

Dr. Sundararaj observes that presently it is very difficult to identify the symptoms of SSD. “It can be noticed only when the tree gets completely affected,” he says.

In an effort to combat the killer disease, the IWST will join hands with the Pune-based National Centre for Cell Sciences for a three-year study, initiated by the Union Ministry of Ayush with a financial allocation of ₹50 lakh.

The study will try to identity the vectors that transmit SSD and also identify alternative plant hosts, their ecological and epidemiological mapping besides examining optimisation of non-chemical methods of pest-management.

It is significant to note that the price of Indian sandalwood and its oil has risen significantly since 1995 at a rate of 20% annually mainly due to depletion in production.

While the production of heartwood has decreased from 4,000 tonnes in 1930s to a mere 300 tonnes now, the prices correspondingly have risen from ₹12,000 to ₹29,500 per kg now.

India has been the traditional leader of sandalwood oil production for perfumery and pharmaceuticals. As early as 1792, Tippu Sultan had declared it a ‘Royal Tree’ of Mysuru. The much-loved and much-valued tree now faces a threat to its existence from SSD.

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Printable version | Oct 22, 2020 3:49:51 PM | https://www.thehindu.com/news/cities/bangalore/invisible-killer-threatens-indias-sandalwood-forests/article32709703.ece

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