More knowledge of nature can tackle disease in trees
Sowing mixes of species to replicate the natural world may solve the issue
Published 12/04/2011 | 05:00
We are all familiar with potato blight or Phytophthora infestans, the disease that caused the great famine of the mid-1800s. Most of us would also be aware of Sudden Oak Death, which caused serious damage to oak in the US and some further limited damage in Europe.
Phytophthora diseases are very much in the news right now because of the infection of one lone Sitka spruce following the recent outbreaks of Phytophthora ramorum (P.ramorum) in Japanese larch.
Extensive surveys have been undertaken by our Forest Service since 2003 and while P.ramorum had been detected in woodland on wild rhododendron, there had been no instances of it attacking commercial tree species. However, in July last year it was discovered in Japanese larch and also in a few stands of Noble fir, beech and Spanish chestnut that were growing close to the infected larch.
When I saw a photograph of the lone, infected Sitka spruce, which was found growing under a canopy of diseased rhododendron, it reminded me of someone sitting in a doctor's waiting room surrounded by flu victims coughing their lungs out. In that situation it is hard to imagine how one could escape infection.
As I write, no further evidence of P.ramorum has been found in Sitka and the area in question is in strict quarantine.
But we must remain on our guard and the Forest Service is recommending vigilance and asking that woodland owners report any suspicious signs of disease.
My guess is that, in time, many more species will be added to the already extensive list of trees and shrubs that are vulnerable to Phytophthora attacks and maybe fresh, and, as yet, unknown pathogens will emerge to cause further damage in our woodland.
We will just have to learn to live with them as we have with all other blights and diseases, and cope with outbreaks while continuing to add to our store of knowledge of what is required to grow strong, healthy trees.