Woodland owners who have co-operated with the Forestry Commission’s Phytophthora ramorum control programme have been thanked for helping to achieve a slowdown in the spread of the disease in England.
The Forestry Commission has published an update on its 2014 programme of aerial surveys for Ramorum disease in larch woodland. At the completion of the flying programme, a significantly smaller total area of concern was identified than that recorded in the previous two years.
A total of 135 hectares of larch woodland were marked for follow-up ground inspection, compared with 254ha in 2013. Subsequently, as a result of ground inspection, it is estimated that Statutory Plant Health Notices will be issued on around 250ha of woodland, compared to 800ha in 2013 (and about 500ha in each of the previous two years).
And the Commission says this slowdown is partly due to the public-spirited co-operation of affected woodland owners with statutory requirements to fell infected trees to slow the spread of the disease.
Andrew Smith, Head of Sustainable Forest Management for Forestry Commission England, said,
“After a worrying few years when Ramorum disease spread rapidly through larch woodland in some areas, it will come as a great relief to the forestry sector to know that its spread slowed significantly in England this year.
“Clearly the weather played a role, but we are confident that affected woodland owners’ public-spirited co-operation with our control programme has also made a significant contribution to slowing the spread. Without their co-operation in felling infected trees before they can produce the spores which spread the disease, there is no doubt that we would be facing a significantly greater problem now, with all the implications that would have for woodland and heathland ecosystems, the timber trade, and the trade in other economically important plants which are susceptible to P. ramorum infection.
“We wish to thank those woodland owners for their understanding and support when faced with the difficult situation of being required to fell valuable trees before their time.
“However, we must not become complacent. All of us in the sector must remain vigilant and ready to act quickly if we are to achieve our long-term goal of reducing the incidence of Ramorum disease to a level where it can be controlled as part of every-day forest management. Part of this slowdown can be attributed to the drier weather we had in 2013 and 2014 compared with 2012, and we must anticipate future periods when the weather at critical times of the year will again be conducive to spread of the disease.”
The report shows that most trees detected with symptoms for the first time were close to known existing areas of infected larch or rhododendron. Most of the small number of wholly new areas of infection have generally been attributable to infected rhododendron as the likely source of infection.
The surveys also found some localised death and dieback of sweet chestnut trees in South-West England due to P. ramorum infection, and these are also being required to be felled for disease control purposes, because sweet chestnut is a sporulating (spore-producing) host plant.
Low-level damage has also been observed on non-sporulating host species, including Douglas fir, Noble fir and western hemlock, on sites where infected larch had previously been felled, “demonstrating P. ramorum's potential to persist on sites where large amounts of inoculum (infective spores) have been generated”.
The full report is available on the Forestry Commission website.