Banyan moth plague: Four ancient trees suffering from "tree cancer" are trapped by insect pests

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Written by: Lao Minyi

2021-05-30 00:00

Last update date: 2021-05-30 00:00

This year, the number of banyan trees affected by the larvae of the vermillion moth has increased. According to the maintenance records of the tree management department, there are 23 ancient and famous trees, which has doubled compared with last year. Four of them have suffered from "tree cancer". Brown root disease.

The Kam Tin Tree House, described by the government as a "local treasure", is one of them. It was once voted as the "King of Trees". Since last year, this century-old tree has also faded because most of its leaves have been eaten by moths. Light.

A former arborist from the Leisure and Cultural Services Department lamented that the first wave of moth plagues in Hong Kong this year has been lost, and the owls that have reproduced in tree houses in previous years have also disappeared. With dead wood, the "tree king" no longer has the beauty.

[Extended reading]

Banyan moth plagues | Vermillion moths broke out again in the New Territories banyan trees were attacked and bald, affecting 23 ancient trees

Banyan moth plagues | Tree trunks wrapped in straw mats, linen bags and insect catching experts promote the removal of insect pupae to prevent large outbreaks

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According to the number of the 23 ancient trees affected by the vermillion moth larvae provided by the Development Bureau, more than 70% of the ancient and famous trees affected by the disaster are located in the North District. Of these, 12 trees were only found to be affected by moths this year, and there are also 4 trees. The affected old tree also suffers from brown root disease commonly known as "tree cancer". The most famous one is the Kam Tin Tree House in the Shui Mei Village Playground.

The Kam Tin Tree House is made up of a huge banyan tree over 100 years old surrounding a stone house. The aerial roots of the banyan next to the stone house come into contact with the soil layer and grow into new trunks to support the huge canopy. A parasol covers the earth.

▼The "Tree King" Jintian Tree House that has changed from prosperity to decline▼

Kam Tin Tree House is under attack from inside and outside

Once stationed in the New Territories North Trees Section of the Leisure and Cultural Services Department, Yuan Dacheng, a former senior recreational assistant, witnessed the decline of the tree king, from the evergreen natural "parasol" to only branches.

He recalled that Kam Tin Tree House was bald twice last year. The tree canopy density fell by 60% in September and fell by at least 10% in November. Even if it recovered roughly at the beginning of this year, it became severely bald again this month.

After suffering from "tree cancer", the tree king's vitality has been slightly reduced. In the past, the vermillion moth was only a minor pest of the banyan tree, but last year there were too many, and the affected "patients" became weaker, like a secondary injury.

Looking up, the tree canopy was originally dense enough to barely see the blue sky. Looking at it again this month is like opening the skylight. The criss-cross branches are clearly visible, and only a few green leaves are left on the lower horizontal branches.

During the reporter's observation at the tree house last Friday (28th), more than ten low-flying adults of Vermillion Moth were found at the bottom of the tree, and some of them were mating on the leaves of nearby weeds.

Yuan Dacheng estimates that larvae will hatch again in late June at the earliest. He is worried that the baldness of the big tree will reappear in July, "it will be difficult to recover this summer."

Yuan Dacheng believes that the authorities should first clean up the weeds near the tree house so that the larvae cannot colonize and pupate and form cocoons. At the same time, they must grasp the breathing period between pests, irrigate and fertilize appropriately, and regularly apply medicine for treatment. Otherwise, "it is like being sick." Constantly taking antibiotics is useless."

Arborist: The first wave of this year has been lost

Retiring from the front line three years ago, Yuan Dacheng continued to monitor the health of banyan trees and formed a tree ecology concern organization "Starting with Love Banyan Trees" with like-minded people.

A survey of banyan trees at the beginning of the year found that among the 15 routes in Yuen Long, Tin Shui Wai, Tuen Mun and Sheung Shui, a total of 2,147 banyan trees, nearly half of the banyan trees were severely damaged by insects.

Yuan lamented that the government’s incomplete prevention and control work has made the pest infestation worse this year. "(The authorities) have no sense of crisis and no responsibility, especially the old and famous trees. Now there is only a dry brown area, which has failed to improve the heat island effect. Trees are also difficult to protect themselves. Nowadays, it is often said that "herd immunity" is used. If only one person is immunized in the end, what is the use? The pest problem should be solved together."

Yuan believes that the first wave of pests in Hong Kong this year has been lost, and he is worried that the next wave will be more serious and will further spread the moth plague. He described the moth plague in Kam Tin that has been more devastated than Tian Shui Wai, where the vermillion moth was first discovered.

He also said that the vermillion moth can fly for a short period of time, and it also has the opportunity to use the engineering vehicle that frequently enters and exits the housing estate to enter Kowloon and Hong Kong Island in a "hitcar". He hopes that the authorities will conduct "insect monitoring" and formulate scientific prevention and control measures. "Heart and Liver" to deal with pests.

▼The change of Kam Tin Tree House in half a year▼

▼The larva of Vermillion Moth ▼

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Tree Conservation, Tree Management, Tree Management Office, Brown Root Disease of Old Trees