No more free ‘beer’ from Delhi Univ neem tree, thanks to rising temperature

The euphoria is over as suddenly as it began five months ago. The oozing of the ‘beer-like’ liquid from a neem tree on Delhi University’s north campus stopped a few days ago, leaving tipplers high and dry.

Scientists of the university’s environment department believe that the rising mercury, which has touched almost 40 degrees Celsius, might have taken a toll on the nature’s free bar. Though they are now testing the sap, it may take up to three months to know what it actually was.

“As the tree started secreting the liquid sometime in November when the chill was setting in and it stopped earlier this month, we think that the rising temperature has something to do with it. Tests are going on,” said David Kothamasi, assistant professor at Centre for Environmental Management of Degraded Ecosystems (CEMDE) of Delhi University.

HT had earlier reported that a neem tree aged more than 50 years and located near the university stadium was secreting at least 10 litres of a fermented white-coloured liquid since November 2016. The beer-like aroma spread as far as 10 feet — sometimes even more.

“It was an unusual phenomenon. It is for the first time that we have witnessed something of this sort in Delhi,” said CR Babu, professor emeritus at CEMDE.

“The liquid had the smell of toddy (natural alcoholic sap of palm) and tasted somewhat bitter. People from the campus and outside were collecting it in buckets and bottles to drink. They said it was intoxicating,” said Vikrant Goswami, a scientific assistant at CEMDE.

Scientists are now trying to find out what caused the tree to secrete the intoxicating liquid. Even though their initial hypothesis is that a microbe could be behind the phenomenon, they are exploring other angles such as genetic mutation.

“We collected samples from the tree. Based on our initial hypothesis, we are first trying to isolate the microbe to see if it was because of some microbial activity that the tree secreted the liquid,” said Babu.

Scientists working on the liquid said that once they manage to isolate the microbe they would simulate the exact environmental conditions – temperature and relative humidity among others – in the lab to ferment a fresh sap sample to see if the microbe has the same effect.

“Only then we would be able to say for sure what forced the tree to secrete the fermented sap. But it might take another three months at least to come out with the results,” said Kothamasi in Delhi.