The male, female and pollen behind J&K order to chop ‘Covid-19’ trees

Covid-19 is a new infection and not enough is known about it, but experts don't think the pollen of Russian poplars spreads the virus.

Representational photo of Russian poplars in Kashmir | ANI

Bengaluru: Environmental experts are worried that the Jammu & Kashmir administration’s order to lop or fell lakhs of female Russian poplar trees in Kashmir could severely impact the local ecosystem as well as hurt the union territory’s economy.

The J&K administration gave the order over fears that pollen from the trees could act as carriers of the SARS-CoV-2 virus, which has caused the Covid-19 pandemic.

There remains confusion over two issues — whether the 40-feet high trees are to be felled or just their branches cut (lopped off), and whether the pollen transmits the virus.

However, it is fact that the large-scale cutting of the trees will have a drastic effect on the region.

Not pollen, but ‘cotton hair’

The J&K government has specifically targeted female poplars, reportedly for pollen shedding. But pollen is produced by male flowers and then fertilises with the female stigma on a female plant. Female plants do not produce pollen at all — they are the sperm-equivalent of the plant world.

Once released by flowers from a male tree, the pollen is carried by the wind until it gets captured by female flowers for fertilisation. If anything, typically, female plants are actively allergy-combating as they remove pollen from the air.

However, female plants do produce seeds after fertilisation, which then need to be dispersed.

The Russian poplars shed seeds coated with cotton-like tufts of seed hair, which have the potential to cause allergies, explained Arun K. Shanker, Principal Scientist (Plant Physiology), Central Research Institute for Dryland Agriculture (ICAR), Hyderabad.

“The seeds are often released in great quantities, and the fluffy seed hairs assist in wind dispersal. This fluffy cotton can have the potential to cause allergy and respiratory problems,” he explained.

These tufts are what give the poplar its common name, cottonwood. A single tree can release up to almost 50 million seeds in its lifetime.

This is what has concerned the government. In its order, the office of the district magistrate of Anantnag mentions that the “pollen enveloped in cotton” not only floats in the air while attached to the seed, but does so after landing on a surface. “Thus there is a potential risk of it becoming the carrier of virus,” it says.

Poplars could complicate our problems. Public must comply, in their own interests. pic.twitter.com/P5NWgjIQVu

— Syed Yasir (@yasirsyedx) April 3, 2020

As a result, the order explicitly states: “It is hereby ordered that all female Russian poplar trees be axed within a week positively.”

While there is no evidence to support the theory that Covid-19 transmission occurs through pollen or airborne plant matter, lopping off branches might potentially help lessen the burden on hospitals by reducing the occurrence of allergies. A low probability of allergies would also mean higher immunity among humans.

Chances of viral transmission?

No part of the poplar tree or any other plant can transmit virus in the air, from what we understand.

“There can be a potential problem when this allergy can act in tandem and can exacerbate the conditions caused by the Covid-19 disease, (but) these cotton tufts as such cannot be a source of the virus,” said Shanker.

Others agree.

“There have been reports of bees getting infected by pollen visited by other infected bees,” said Parul Tripathi, a geneticist with a Singapore-based research company. “But Populus deltoides is wind pollinated. Hence the chance of pollen getting contaminated by a virus or harbouring it is very low.”

It is also highly unlikely that the fluffy tufts could land on a person, pick up the virus through cough droplets, and then cause an infection when it lands on someone else, she added.

However, considering everything about this virus is new, scientists do not rule out anything with 100 per cent certainty. Despite the very low chances of Covid-19 being transmitted through pollen or airborne plant matter, there hasn’t been a consensus about the mechanisms of virus dispersion due to insufficient research. Given the low probability of contracting Covid-19 from pollen, it doesn’t warrant actionable concern.

“We know the SARS-CoV-2 virus can survive in the environment for 4-6 hours in the form of aerosols,” explained Shweta Chelluboina, molecular virologist at Interactive Research School for Health Affairs working on Hepatitis E virus.

“Theoretically, we must not ignore potentially moist aerosols or salivary secretions that merge with the pollen and survive for longer periods leading to disease progression. And pollen is known to be a carrier of plant or insect viruses. However, there is no evidence of human viruses being transmitted through pollen or such seeds,” she said.

North America, which has the world’s highest number of coronavirus cases, has a lot of poplars, but the trees seem to have played no significant role in affecting the spread of the disease there. Similarly, several cities all over the world are infamous for their pollen allergies, but have seen no correlation with the spread of the disease.

“Covid-19 virus is spread primarily through droplets from infected persons. Pollen from any tree being the carrier to spread infection of a human disease, is unlikely to be a high probability event,” said some members of the Indian Scientists’ Response to Covid-19 (ISRC), in a collective statement to ThePrint.

The ISRC is a collective of scientists that works on combating scientific misinformation on Covid-19.

“Pollen is a known allergen for some people. As you are aware, severity of Covid-19 depends on whether an individual has other coexisting conditions, that can make it harder for their immune system to fight a new pathogen… Therefore, it is advisable for those who have pollen allergies (most people do not) to avoid exposure, and follow lockdown,” the scientists said.

All about poplars

The Russian poplar trees (Populus deltoides) were introduced in Kashmir in the early 1980s under the Social Forestry Project, with support from the World Bank. They are not native to India or Russia, but instead come from North America. They are known locally as ‘Russi Frass’ and provide timber for pencil and plywood manufacturers. They are an integral part of the Kashmiri landscape today, and experts believe there might be over 1.5 crores of Russian poplars in the state.

These poplars grow much faster than their cousins or even other species, growing nearly 10 m each year for about 25 years. They have the potential to live for up to 400 years, but survive typically for about 100 years. They are also quite large and thick. The world’s largest recorded cottonwood tree is the Frimley Park tree located in Hastings, New Zealand. It measures 42 m tall, 34 m wide and 10.2 m in girth. It was planted in the 1870s.

The poplars are dioecious, meaning they reproduce sexually, with different trees for male and female plants. The flowers look similar and bloom in drooping catkins or flower clusters.

Poplars play an important role in the ecosystem of river banks or ‘riparian’ ecosystems. They contribute to absorbing heavy metals from the soil, and can help rehabilitate fragile ecosystems, combat desertification, and aid in restoring forests.

“Trees are an important part of the ecosystem (and) difficult to replace quickly if cut down,” said the ISRC scientists. “It is highly inadvisable to cut down trees in the fear that pollen may transmit novel coronavirus to humans; of which presently there is no evidence,” they added.

(This is an updated version of the article)