Workers cut higher willow branches in the hope of reducing catkins. Photo: Legal Mirror

By Zhu Yifeng and Zhang Shufang

Forestry authorities have launched their annual offensive against the pesky catkin menace associated with Beijing's blooming willow and poplar trees.

Early May every year, the entire city sinks under tons of snowy-looking tree blossom, creating air pollution and health concerns for people with respiratory problems.

The fluff invasion especially upsets people with allergies and diseases like asthma, said Xu Jia, director of the science and technology department at the Municipal Bureau of Landscape and Forestry.

Xu announced the Bureau is adopting a two-pronged approach to tackle the fuzzy contagion: chemical injections and tree sex changes

Only 'female' willow trees produce catkins. Thus garden workers will cut down higher willow branches and try to splice male branches. This one-sex policy leaves most trees golden and catkin-free, Xu said.

"Each willow just needs to change branches once and the tree will never produce the stuff anymore for his entire life," he said.

Poplar tree branches receive annual jabs to inhibit their catkin-growing ability. After the injection, a poplar produces fewer catkins the next year.

Since 2003, a systematic policy of discrimination has targeted female poplars and willow trees near schools, residential areas and certain industrial areas that rely on precision instruments.

Forestry departments in the past tried to control catkins by spraying chemicals on the branches.

"However, the old method might pollute the environment and harm human health," Xu said.

A total 550 willow trees have had their branches swapped since 2007 and about 10,000 trees have been injected. "Changing the sex of the female species of willows costs more than injections," Xu said.

Besides the damage to health, catkins of female poplar and willow trees can even disrupt traffic due to reduced visibility, said Che Shaochen, director of the Botany Conservation Office of Beijing Munici-pal Bureau of Landscape and Forestry.

The cotton-ball-like clusters are highly inflammable, according to the Beijing Times.