Christmas trees from Europe and Japan are rescuing their brethren in the US from a fungal enemy.
A soil fungus, Phytophthora cincinnamomi, threatens to decimate plantations of Fraser fir in North Carolina. The state supplies six million of these luxuriant trees to US homes.
鈥淚n a recent survey, six to eight per cent of Fraser fir stands were affected, and Phytophthera seems to be spreading,鈥� says Eric Hinesley, professor of horticultural science at the University of North Carolina at Rayleigh. 鈥淚t鈥檚 not going to cripple the industry, but once we have it in a field, there鈥檚 no way to get rid of it,鈥� he says.
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To counter the threat, Hinesley and his colleagues, John Frampton and Michael Benson, have sought help from foreign Christmas trees which appear more resistant to the fungus. They鈥檙e also trying to identify strains of Fraser fir with natural resistance.
Tough trees
Hardiest of all the relatives Hinesley screened was the momi fir from Japan. The Nordmann fir, the most popular tree in Europe, was next most resistant, along with its near relative, the Turkish fir. Next, Hinesley grafted the roots of these resistant varieties onto Fraser fir trees.
鈥淚t means we have a Fraser fir, but on top of a root system of a different species resistant to the fungus,鈥� says Hinesley. He planted the grafted trees earlier this year.
To find Fraser firs that are naturally resistant to the fungus, Frampton exposed hundreds of seedlings to the fungus. Most died, but around two per cent survived, suggesting they might have resistance that can be cross-bred into elite trees.
Frampton also visited abandoned plantations and found a few stragglers that might be resistant. 鈥淎ll the trees had gone except one or two,鈥� says Hinesley. 鈥淛ohn has taken cuttings and rooted them, and is evaluating them to see if they鈥檙e resistant.鈥�
