Mumbai: After all, why does BMC paint tree trunks in white, red?

Passing under the shade of trees on a hot sunny day, you might have sometimes wondered why the base of these trees are painted in white and red. So, the answer to your query is that the paint practice is a traditional safeguard against fungal diseases and potential pest attacks.

And for a fun fact, the method of painting the base of tree trunks with thin coat of white lime (calcium hydroxide) and red geru (sinopia or red ochre powder) didn’t just grab your eyeballs but it also attracted the kind attention of Malaysia's Kedah state Sultan Tunku Sallehuddin when he visited the city in early 2021.

Stressing on the need for garnering global attention to this very own Indian tree painting method, BMC’s garden department superintendent, Jeetendra Pardeshi, said, “As a part of our urban tree management programme, applying a thin coat of white lime (calcium hydroxide) and red geru (sinopia or red ochre powder) at the base of tree trunks is a traditional practice used across Mumbai. Thin paints prepared from white lime and red geru mixed with water are applied on the trunk in bands one above another, starting from the ground level up to about 1.5 m height.”

The alternate white and red bands are approximately 30 cm to 40 cm wide. Lime (calcium hydroxide) is alkaline, whereas geru (red ochre powder or sinopia) is acidic in nature and rich in iron oxide. This combination helps to protect trees from fungal diseases and potential pest attacks, he explained.

He further said as Mumbai is home to more than 200 tree species owing to the city’s tropical climatic conditions. “As per our latest Tree Inventory/ Census, carried out by the Tree Authority using GIS-GPS technology, there are approximately 2.9 million trees in Mumbai. With such rich tree diversity and such a large tree population, we also have to manage multiple challenges in terms of tree health, safety, and the overall management and preservation of our urban trees,” he said.

“We aim to promote such traditional tree care practices in India, and we hope that its importance and relevance are understood by private tree owners and other local authorities dealing with the protection and preservation of trees," he added.

City arborist, Vaibhav Raje, welcomed the initiative saying, “I think it's a good initiative of painting the trees with lime and geru and it should be done for all matured trees of our city.” However, simply painting tree trunks with fabric colours might affect a living tree and its natural processes but painting dead tree trunks to enhance its beauty can be done, he underlined.

Oh yes, the fun fact remained, so the story goes further; after Sultan was intrigued by the peculiar tree painting, he instructed the Malaysian Consul General in Mumbai, Zainal Azlan Mohd Nadzir, to study it.



Benefits of the white lime and red geru paint:

1. The paint provides protection from fungal and other microbial infestation

2. It stops insects like stem borers as they kill the tree by tunnelling the trunk

3. The colour contrast also makes it easier to spot cell sap oozing

4. It deters unnecessary felling without proper permission from authority

5. The paint works as a reflector during nights hence improving road safety