The first "willow catkins forecast"! You read that right, it's here again

Spring is here

The flowers are in full bloom in Beijing's parks

I wonder if you have gone out to enjoy the flowers?

Recently, the topic #Park20MinuteEffect#

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Studies have shown

Spend a little time outdoors every day

Can make people feel happier

Even if you don't exercise

Just go to the park for 20 minutes every day

It can also make people feel better

Image source: Spring is in the air at Youxianshan Pavilion in Zizhuyuan Park, Beijing Municipal Parks Administration Center

Image source: Beijing News

However, for friends in Beijing

Spring also means bad news:

The season of flying catkins is here again!

The Beijing Municipal Bureau of Landscape and Forestry and the Beijing Meteorological Bureau released this year's first "Willow Catkins Forecast" - the first peak is from April 12 to April 18, the second peak is from late April to early May, and the third peak is in mid-May, with the worst weather from 10 am to 4 pm every day .

Image source: Old Summer Palace Ruins Park

I believe that everyone is troubled by it every year. When you walk on the road, the floating catkins will not only cover your face, but also make it difficult to breathe, your nose itchy, and you want to sneeze, which will cause allergies.

0 1What are these flying catkins? Why are there so many of them?

The catkins in Beijing mainly come from poplars and willows that are scattered throughout most of the green belts in the city. Every spring, they enter the breeding season and begin to spread seeds desperately. Poplars and willows are not specific plants, but a type of tree. In Beijing, the main trees planted are Populus tomentosa and Salix matsudana . Generally speaking, poplar catkins fly first, followed by willow catkins .

Populus tomentosa Source: Beijing Forestry University

Willow tree image source: Beijing Forestry University

Flying catkins look like a white, fluffy mass, but they actually contain seeds from poplars and willows. If you dig them carefully, you will find that the white hairs contain small seeds. These white hairs are just to help poplars and willows spread their seeds. With these flying catkins, their seeds can fly farther with the wind, spreading life to even farther places .

These trees are fast-growing, drought-resistant, and highly resistant to adversity. They are widely planted in northern China and can bring large areas of green shade in a short period of time . Unfortunately, people did not expect that the catkins of poplars and willows would have such a big impact at first.

02 So, is it possible to prevent willow trees from producing catkins?

If you go to Chaoyang Park recently, you can see some symbols painted on the trees on both sides of the road. These are marked as female trees. In fact, not all poplar and willow trees are the "masterminds" behind the flying catkins. Only female trees have flying catkins .

Image source: Beijing Chaoyang Park

In spring, male and female trees mate and reproduce. After the flowers on the female trees receive pollen from the male trees and are fertilized, they develop into fruits. The fruits contain seeds that have developed from embryo sacs and are surrounded by a bunch of fluff. As the fruits and seeds mature, the fruits split open, and the white fluff carries the seeds and floats around with the help of the wind.

Image source: Copyright Library

Now people have also found some ways to prevent and solve the problem of flying catkins:

The simplest and most brutal way is to replace them! Can we replace these trees with trees that do not produce fluff? Or replace all the female poplar and willow trees with male trees. However, replacing trees is a huge project. Not only must we consider the number of existing trees, but also the replacement trees will not be able to achieve the original greening and shading effects in the short term.

What about "sex change" or "sterilization"? For example, sex change surgery for willows is to cut off the crown of the female tree and graft young male branches. However, sex change surgery for poplars is as risky as that for humans, and requires constant maintenance and high costs.

In addition, this purpose can also be achieved by using drugs, which are divided into "external application" and "oral administration" .

For poplar and willow trees, "external application" is to spray inflorescence thinning agents to make the female inflorescence fall off early before the catkins fly. However, the thinning effect of this thinning agent is only 70%, and the spraying process may cause air pollution, affecting some other broad-leaved plants that sprout early, causing their leaves to be damaged and deformed.

"Oral administration" is to inject them with catkin inhibitors . This can inhibit the differentiation of female flowers. Inject them between 45 days before and 50 days after the poplar and willow trees start to fly catkins each year, which can ensure that the flower buds turn into leaf buds in the second year and the catkins disappear. However, this method also has disadvantages - one injection only works for one year, and injections are required every year. Once there are too many poplars and willows, human and financial resources are limited, and it is impossible to guarantee that all of them can be controlled.

03 The harm of flying catkins is not just allergies

For those who are caught in the flying catkins, the pain is simply indescribable! When going out, they want to cover themselves tightly with masks and glasses. For people who are prone to allergies, these floating catkins are more likely to cause skin allergies, and in severe cases, they can also stimulate respiratory diseases such as asthma and chronic bronchitis .

In addition, flying catkins are also a major safety hazard. If they fly into car water tanks, computers and various mechanical instruments, they will affect their normal operation; if they fly onto the road, they will affect the sight of pedestrians and drivers, causing traffic safety hazards. What's more frightening is that flying catkins are flammable. If they accumulate in large quantities and accidentally come into contact with fire sources such as cigarette butts, they can easily cause fires .

Image source: China Fire

04 Resist the attack of flying catkins, and run away if you can’t defeat them!

In fact, willow catkins themselves are not allergens . While flying, willow catkins will adhere to dust, pollen, bacteria and many other substances that may cause allergies, and then attach to our skin or be inhaled, causing allergies.

In the face of flying catkins, sensitive people should stay indoors as much as possible during the day . Even if you want to do outdoor activities, you should do it when there are fewer catkins, such as in the morning and at night. The symptoms will be greatly alleviated after rainfall. For indoor ventilation, close the screen windows, pay attention to indoor hygiene, wet sweep, and turn on the air purifier when necessary.

People with sensitive skin should wear masks for protection when going out. When using masks, they should follow the instructions for use. When wearing them, they must completely cover the nose, mouth and chin, and keep the mask close to the face. The better the airtightness, the better the protective effect. In order to prevent flying catkins from entering the eyes, you should wear a gauze scarf, goggles, glasses, etc. when going out.

People with skin allergies should try to avoid contact with flying catkins, otherwise the skin will itch unbearably, or even become red, swollen and inflamed. When going out, you should "wrap yourself up", wear a hat, long clothes and long pants, and try to avoid direct contact between your skin and flying catkins.

If the skin is stained with catkins, it should be removed in time, preferably with warm water, which can help prevent allergies or relieve allergic symptoms. When the skin has allergic symptoms, do not scratch it. Gently patting, cold compressing, and applying anti-itching medicine can relieve the symptoms .

END

Audit experts:

Li Chen, Senior Engineer, Beijing Meteorological Service Center

Liu Qian, Senior Engineer, Beijing Academy of Landscape Architecture

Editor: Dong Xiaoxian

Thanks to Beijing Meteorological Society and Beijing Municipal Bureau of Landscape and Greening for their support