As if our magnificent trees didn’t have enough problems, they’re now being threatened by our emails.
When they’re not being assailed by some foreign bug or moth, there’s often a council official looking for an excuse to cut them down.
Now researchers say radiation from wi-fi networks that enable our burgeoning online communications may be their latest enemy.
Research in Holland showed that trees that were planted in close proximity to a wireless router suffered from damaged bark and dying leaves.
The alarming study will raise fears that Wi-Fi radiation may also be having an effect on the human body and will lend weight to parents and teachers who have campaigned to stop wireless routers being installed in schools.
The city of Alphen aan den Rijn, in the West of the country, ordered the study five years ago after officials found unexplained abnormalities on trees which they did not believe had been caused by any known viral infection.
The researchers took 20 ash trees and exposed them to various kinds of radiation for three months.
The trees were exposed to six sources of radiation with frequencies ranging from 2412 to 2472 MHz and a power of 100 mW at a distance of just 20 inches.
Trees placed closest to the Wi-Fi radio developed a ‘lead-like shine’ on their leaves that was caused by the dying of the upper and lower epidermis.
This would eventually result in the death of parts of the leaves, the study found.
Researchers also discovered that Wi-Fi radiation could slow the growth of corn cobs.
In the Netherlands, about 70 per cent of all trees in urban areas show the same symptoms, compared with only 10 per cent five years ago, the study found. Trees in densely forested areas are not affected.
The scientists behind the research, which has not yet been published, said that further studies were needed to confirm whether it was Wi-Fi radiation that was to blame for the trees’ condition.
And the Dutch health agency has issued a statement which reads: ‘The researcher from Wageningen University indicates that these are initial results and that they have not been confirmed in a repeat survey.
‘He warns strongly that there are no far-reaching conclusions from its results. Based on the information now available it cannot be concluded that the WiFi radio signals leads to damage to trees or other plants.’
Other scientists have expressed scepticism at the study’s preliminary results.
Dr Michael Clark, from the Health Protection Agency, said: 'This work has not been published in science journals so we don’t have any details of the study.
'We therefore have to treat the claims with some scepticism and strictly HPA only deals with public health.
'Nevertheless we note that last year there were claims in news media and on websites that WiFi and mobile phone signals were affecting bee colonies.
'Published scientific studies have shown that fungal and viral infections are the most likely causes of bee colony decline.
Marvin Ziskin, a professor of radiology and medical physics at Temple University in the U.S. said: 'Stuff like this has been around a long time . . . there's nothing new about Wi-Fi emissions. Scientifically there's no evidence to support that these signals are a cause for concern.’
The study is to be the subject of a conference in Holland in February next year.
In 2007 a BBC Panorama documentary found that radiation levels from Wi-Fi in one school was up to three times the level of mobile phone mast radiation.
The readings were 600 times below the government's safety limits but sparked a furious discussion about whether Wi-Fi networks should be installed in schools.
The chairman of the Health Protection Agency called for a review of Wi-Fi in public places in the wake of the programme. A report on the findings is expected next year.