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NEW DELHI: Paving the way for native plants by eradicating an invasive weed, Lantana camara, which is believed to have infested 30% of Delhi’s ridge, conservationists and the Forestry Department have started using the ‘cut rootstock method’ to control further ecological degradation at Asola Bhatti Wildlife Sanctuary.

The species is spreading over much of Asola, depriving the forest of its natural native vegetation. So, as one official said, the focus is on eliminating invasive species using this method to clear the way for native shrubs. Another official said that while the past practice was either to uproot the weed using digging machines or to cut it down, the methods failed because the species native to South America would resurrect. The “cut rootstock method”, however, takes a scientific approach and by rendering the growth dormant through a hormonal imbalance, it ensures that the lantana does not sprout.
The practice is to uproot the weed manually and cut its roots below the ground by a margin of 6 to 7 inches. The process also involves holding the uprooted plant upside down to kill it and manually uprooting the smaller lantana seedlings, as well as the larger weed. Once the species is cleared, it allows native shrubs and vines to spread, which have often found themselves underdeveloped or struggling to grow naturally near the invasive species. “We have already removed it from over 50 acres in the area. It is a manual method that uses only shovels or a crowbar and does not require any automated machinery. We hope that by the end of this year, there will be no lantana left in Asola,” said Mandeep Mittal, Divisional Forest Conservator, South Delhi.
According to experts, the problem with lantana is that it suppresses native shrubs. “We previously removed lantanas using this method as part of a pilot project and then surveyed larger areas of forest to collect data on the extent and density of the infestation. We followed basic principles like starting the retreat from high density areas as well as starting up the slopes and down to the valleys. After that, the removal of adult clumps is carefully done using the cut rootstock method,” said Sohail Madan, deputy director of the Bombay Natural History Society (BNHS). He added that by uprooting the lantana, they also saw that several native species were already there, but could not grow.
According to Professor Emeritus CR Babu, who together with his team at the Center for the Environment and Degraded Ecosystems developed the ‘cut rootstock method’, the ‘aggressive invasive species’ has already done enough damage. He pointed out that there are more than 20 such birds in India that eat lantana seeds and hence propagate the species.
“Lantana produces several volatile chemicals, which prevent any insects from coming to eat on the plant, so there are no pests on this plant except the pests of the country of origin. Cut the branches or stem n “is not a solution because once the branch is left on the ground, it germinates. Even if you burn the weed in summer, the plant will germinate with the first rain,” said Babu. Explaining the new method, which is now used in several parts of the country, including Corbett National Park, Babu said lantana has a shallow root system.”In the cut rootstock method, when we cut the stem at the meristem, lift it up and turn it over the plant, it leads to a hormonal imbalance so that no new roots sprout and the plant dries out. Dry wood can be used as firewood. This is the only effective and cheap way to go,” said Babu.