Spreading "Oak Wilt" Damage-Expectations for New Research for Early Detection-January 13, 19:59
A tree with a lot of wood chips and numerous holes.
The damage of "Oak wilt", in which trees such as Quercus crispula die, is spreading all over the country.
Last year, it occurred in 42 prefectures, and the amount of damage reached 192,000 cubic meters.
Not only does oak wilt kill trees, but it is also feared that people and private houses may be at risk because the trees may break easily due to rain or wind and fall from the roots.
There is no waiting for measures to stop the damage, and new research has begun to detect oak wilt efficiently and quickly.
(Kofu Broadcasting Station reporter Kasei Shimizu)
"Oak wilt" spreading nationwide
"Oak wilt" is an infectious disease that occurs in trees such as Quercus crispula and Quercus serrata.
The cause is a pathogen called "Oak fungus" transmitted by the insect "Platypus quercivorus" with a body length of about 5 mm. When infected, the function of sucking up water from trees is hindered and it withers.
Since the 1980s, it has expanded mainly on the Sea of Japan side, and recently the damage has been increasing nationwide.
Last year, it occurred in 42 prefectures, and the amount of damage reached 192,000 cubic meters.
If the dead tree is left unattended, hundreds of Platypus quercivorus will occur the following year and another tree in the vicinity will die, and the dead tree will easily break due to rain or wind and fall from the root. In some cases, there are concerns that people and private houses may be at risk.
Damage spreading in Yamanakako village surrounded by forest
Yamanashi Prefecture, where forests occupy 80% of the prefecture's area.
About two years ago, oak wilt was first found in three villages and towns.
Currently, the damage has spread to 15 cities, towns and villages, and it has become a serious problem.
The most damaging of these is Yamanakako Village, which is located at the foot of Mt. Fuji and is visited by many tourists for its abundant nature.
Last year, the oak wilt confirmed in the forest of the village was about 3000 cubic meters, which is the highest in the prefecture.
When converted to a tree of a general size, it is equivalent to 4600 trees.
Furthermore, 600 cubic meters and about 1000 dead oak wilt trees were found in people's living areas such as kindergartens and private house premises, and it was found that the risk of damage to people and private houses is increasing.
Village staff
"There are many oak wilt trees in Yamanakako village relatively close to the houses. If you do not accurately understand the damage caused by the withering of oak wilt and take measures, the villagers may be at risk, so early on. Must correspond to "
Damage investigation is a persevering task
The village staff visited a temple in the village on this day.
When I was informed that there was a dead tree, I found that the Quercus crispula tree planted near the building and grave was dead.
The chief priest of the temple
"I learned about the oak wilt in the news, and when I saw the tree in the temple, it was dead. I don't know when it died, but I think it died in a blink of an eye."
In the village, we are conducting a survey using a dedicated app for tablet devices.
When the staff finds a dead oak wilt, they record the position with the app, enter about 10 items such as the type and thickness of the tree, whether the building is nearby and whether there is an electric wire, and send it.
These data are displayed on the online map in three different colors according to the degree of withering of the tree, and it is a mechanism to know at a glance whether it is dangerous, such as the distribution of oak wilt and whether it is near a house. ..
Although this method can be used to accurately grasp the damage, staff members must visit the site and check the condition of each tree one by one.
Only five people have been assigned by the village this year.
I went to the site every day while doing normal work, but it did not finish even after 3 months, and the investigation was discontinued.
Village staff
"The survey was completed in about 80% of the total. In winter, the leaves had fallen and it took time to judge whether it was a healthy tree or a dead oak wilt.
Also, the damage was more extensive than I had imagined, and I had to give up the investigation halfway.
"
Utilizing "drone" and "AI"
Is there a way to efficiently grasp the damage while the manpower is limited?
Assistant Professor Naoko Miura of the University of Tokyo is considering countermeasures after receiving consultation from the village about the withering of Japanese oak wilt.
Mr. Miura is currently researching a new mechanism that utilizes drones and AI = artificial intelligence.
Assistant Professor Naoko Miura
"I am conducting research with the aim of creating a system that can automatically determine the damage caused by oak wilt by collecting various data."
Mr. Miura first photographed the forest from the sky using a drone and collected data such as the position and images of trees.
Then, the collected tree images were divided into three types, "healthy oak wilt", "oak wilt", and "other trees", and AI was trained.
AI has read 85,000 images so far.
By reading a large number of images, AI learns the characteristics of oak wilt, and it has become possible to distinguish whether oak wilt or not with a probability of 99% or more.
It is still in the testing stage, but when completed, it will be possible for people to find dead oak wilt trees from the images of the forest taken with the drone without having to check the trees one by one.
Assistant Professor Miura
"Currently, investigators are still visually judging whether or not oak wilt has died in mountains, but if this method can be used, it will be possible to grasp the damage situation of a wide range of forests at once. Yes, and if you combine it with road and housing data, I think it will be possible to automatically extract trees that are particularly dangerous. "
Furthermore, by accumulating such data on oak wilt every year, it will be possible to find trees that are likely to die in the future and to predict damage in the next year.
Assistant Professor Miura
"I think it will be very useful for improving the efficiency of the Japanese oak wilt survey, so I would like to create a system that can be used not only in Yamanakako Village but throughout the country."
Village staff
"If we can leave difficult surveys such as mountains to drones, we staff can concentrate on surveying around houses, exterminating bugs, and cutting dangerous trees, so we can conduct surveys more efficiently. I hope that doing so will prevent the damage from spreading. "
"Oak wilt" is spreading damage not only in Yamanashi prefecture but also in the whole country.
Mr. Miura's research using drones and AI is currently supported by NEDO = New Energy and Industrial Technology Development Organization, saying that it will lead to the development of innovative technology that accurately grasps the damage caused by oak wilt and stops the expansion. , Research for practical use is underway in cooperation with private companies.
Kofu Broadcasting Station reporter
Kasei Shimizu Joined the
2020
prefectural police, and after working for the Yugun, is currently in charge of prefectural and Kofu municipal administration.