Hyderabad: Tens of thousands of neem trees in Telangana are under attack. From a fungus that is invisible to the human eye, but one that leaves the trees with an appearance of some wayward arsonist’s failed attempt to torch them.
This is the third year in a row that the fungal infection is running through the neem trees in the state, with alarm bells ringing over their future.
While the trees are not dying, the attack by the fungus Phomopsis azadirachtae is enough to affect the tree’s ability to produce its prized fruit, in many cases reducing its ability to flower. The extract from neem seeds are used in pharmaceuticals manufacture, while neem oil is used as an insect repellent.
“This is an enigmatic tree,” said Dr Jagdeesh Bathula, an assistant professor of plant pathology at the Forest College and Research Institute at Mulugu in Siddipet district.
“This is a tree that shows antibacterial, antifungal, insecticidal and other versatile biological activities. More than 150 compounds have been isolated from different parts of this tree. India is the leading exporter of neem and neem products. However, this doesn’t make the neem exception from the attack of pests and diseases. Many bacteria and fungi are known to infect neem,” he said.
Dr Bathula told Deccan Chronicle that in the past few years, neem has been under increasing threat from what he called a destructive disease known as ‘twig blight’ and ‘dieback’ in which woody plants experience progressive death of twigs, branches, shoots, or roots, starting at the tips.
There are many solutions being bandied about including advice on how fungicides can be sprayed.
“But this is dangerous as these chemicals can affect other plants around the tree. Each tree is an individual. Each tree needs to be treated just as a doctor treats an individual human patient,” he said. “We also need an enumeration of neem trees.”
According to Dr Bathula, affected and fully grown trees need an arborist’s attention who can guide in pruning operations to remove diseased twigs and burnt to stop further spread during next season.
How Neem Twig Blight came to Telangana
> First reported from new forests of Dehra Dun in the 1980s.
> In early 2000s, noticed in Tamil Nadu, and then in Karnataka.
> From Karnataka it invaded neighboring Rayalaseema region of Andhra Pradesh.
> From Rayalaseema, it entered Gadwal region of Telangana, from where it spread to Mahabubnagar, Ranga Reddy, Nalgonda, Siddipet and Warangal districts.
Symptoms
> Twigs on terminal branches, disease progresses backwards to the stems, chokes fluid movement resulting in death of twigs and stems.
> Infection causes leaves to turn yellow, in severe cases to brown, ending up in the entire canopy drying up
> Mostly seen August-December. Symptoms start with the onset of the rainy season.
