On the front line
When the plant pathogen Phytophthora ramorum strikes, it can do so with a vengeance. One Devon woodland owner found himself having to adapt quickly to a changing situation as ramorum disease of larch, caused by this fungus-like organism, spread through his woods.
Robert White knows a thing or two about woodlands. Not only has the Devon forester spent his working life managing other people’s woodlands, his passion for forestry continued into semi-retirement. In 1999 Robert purchased 140 hectares of commercial woodland which supplies timber to South West England. Yet even this seasoned woodsman was shocked to see the speed and scale of the destruction wrought by the virulent plant disease caused by Phytophthora ramorum (P. ramorum).
“I had read about the Phytophthora ramorum pathogen and how it had spread from rhododendron to larch, but didn’t really think much about it because I had had no first-hand experience,” says Robert. “Although it was found on rhododendron in 2005, its spread to larch was first spotted only in 2009.
“It was in 2010 that I first saw the devastation in larch that ramorum disease can cause. I was a judge in the Devon County Show Plantation competition, and visited the Forestry Commission’s Plym Forest, which had been ravaged by the disease. It was shocking to see.”
Less than two months later, Robert found himself facing this destructive disease in his own woodland, which is partially situated in Dartmoor National Park.
“In April 2010 I saw four trees in two different areas of the wood which had gone brown and looked a bit odd. I contacted the Forestry Commission, who carried out various tests and confirmed that the Japanese larch was infected with P. ramorum.
“It was the news I didn’t want to hear. As a forester you spend your time looking after trees, and it was terrible to face the prospect of felling them long before maturity because of a disease.”
That summer the Forestry Commission issued Robert with a Statutory Plant Health Notice (SPHN), which required him to fell all trees which exhibited any of the symptoms of the disease. At that time, such ‘sanitation’ felling involved cutting down only those trees which were visibly infected following a weekly survey.
“With a steeply sided wood, it was fairly easy to spot signs of the disease, and with two full-time employees we could respond quickly,” says Robert. “By the end of the summer of 2010 I had felled more than 500 trees, and I thought the number of symptomatic trees was reducing.”
Unfortunately this was not the case. During the autumn months Robert could see that infection was spreading, and it was clear that felling only the trees with visible symptoms was not working. A more robust solution was needed. From this point onwards the minimum SPHN requirement became the felling of all sporulating (spore-producing) hosts within 100 metres of the known or suspected point of infection. (‘Hosts’ are tree and plant species capable of being infected by P. ramorum.) As a result, and in conjunction with the Forestry Commission, it was decided that all the Japanese larch within the woodland should be felled.
Parts of the woods were fairly inaccessible, so to meet the time requirement, Robert felled the trees before coming back later to extract them so they could be sold as timber.
“By the end of June 2011 some 7000 trees had been felled, with about 4000 tonnes of larch lying in the wood to be extracted,” said Robert. “This had a big financial impact: not only were the trees immature and hence less valuable, but the timber itself was also reduced considerably in value. This was due both to the costs of the biosecurity measures which were put in place to prevent the disease-causing spores from the felled trees being transmitted to uninfected trees, and to the extra volume of larch coming on to the market and affecting prices,” he says.
Although the financial support the Forestry Commission was able to give was limited, Robert appreciated the approach its staff took to the problems he faced.
“They didn’t just issue me with a Plant Health Notice and leave me to get on with it,” he says. “They were sympathetic as well as being pragmatic. They are, after all, foresters, and could see the devastating impact of this disease.”
To support woodland owners affected by ramorum disease, Forestry Commission England introduced a replanting grant specifically for sites affected by it. Robert was pleased that the Commission listened to woodland owners when it came to deciding which species could be included within the grant.
“I am pleased to say they haven’t just restricted the financial assistance to broadleaf trees, but have also included conifers, because they play such an important role in commercial forestry,” he says, adding: “Following Forestry Commission advice, I have restocked with four different species of conifers so I don’t get caught out again with a single species. In addition I have also replanted with some mixed broadleaf species.”
Robert was one of the first private woodland owners in the United Kingdom to deal with ramorum disease, and needed to adjust his approach as it developed.
“Back in 2010 we were very much in the early stages of the disease, and both I and the Forestry Commission were on a steep learning curve as how best to deal with this pathogen,” he recalls.
“When I first purchased the woodlands my intention was to manage them with a minimum of clear felling and restocking, but nature has a habit of disrupting plans. In the end I had no choice but to completely clear large areas of the wood. It wasn’t pleasant, but I had to adapt to the changing situation. I could see from early on that burying your head in the sand is not an option. You have to act quickly when you spot any signs of the disease.”
Over the past couple of years the challenges have been immense for Robert, but he has tried to stay as positive as possible despite the financial and emotional impact of ramorum disease.
“We have ended up with some lovely views which we didn’t have before,” he points out. “It also gave me a chance to look at new ways of managing the woodlands which, again, I wouldn’t have done had I not been forced to.”
NOTE: Since 2010 the Forestry Commission in England, Wales and Scotland has introduced support to help woodland owners affected by P. ramorum with the costs of:
- engaging qualified agents to act for owners to fell and market infected larch trees;
- clearing infected young larch under 26 years old; and
- restocking (replanting) cleared sites.
Reporting suspected cases
Suspected cases of ramorum disease can be reported to the following:
- England - email@example.com, or tel. 0117 372 1070;
- Scotland - firstname.lastname@example.org; tel. 0131 445 2176;
- Wales - email@example.com; tel. 0300 068 0300.