Invasive Species Compendium

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Abstract

Root and butt rot of Pinus luchuensis caused by Heterobasidion insulare and its nutrient physiology.

Abstract

Heterobasidion insulare was first observed on dead butt and root of Pinus luchuensis at Shihding, Taipei County in 1995. Later, it was commonly found on plantations of P. luchuensis in northern Taiwan. The white mycelial mat was found between the bark and wood of decayed butts and roots. Seedlings of 4 pine species, P. luchuensis, P. thunbergii, P. morrisonicola [P. parviflora], and P. taiwanensis as well as Taiwania cryptomerioides, were inoculated with H. insulare grown on pine twig fragments or sawdust medium. After 7 weeks, some of the inoculated seedlings of P. luchuensis and P. thunbergii had died, and the fungus was reisolated from the diseased pines. The other 3 tree species remained healthy during the inoculation experiments. This is the first report of H. insulare in Taiwan. The mycelial growth occurred in a temperature range of from 12 to 32°C, and the optimum temperature was 24°C. The optimum pH for mycelium growth of the fungus was at 4.9-6.0, and the best pH was at 5.2. Pectin, glucose, galactose, and mannitol were good carbon sources for mycelial growth. Optimum concentrations of glucose for mycelial growth were at 40-80 g/litre, while increasing glucose concentrations inhibited growth, and it stopped at a concentration of 240 g/litre. Ammonium chloride and calcium nitrate were the best inorganic nitrogen sources for mycelial growth. Most amino acids were favourable to mycelial growth, while tyrosine and cysteine were not favourable. The optimum nitrogen normalities of ammonium chloride for mycelial growth were at 0.01-0.02 N, whereas mycelial growth was in proportion to the concentration of asparatic acid in the range of 0.0-0.2 N of nitrogen. Thiamin-HC1 one of the 9 vitamins tested, had the greatest enhancing effect on mycelial growth. Moreover, pantothenic acid, ascorbic acid, and inositol also enhanced growth of mycelium.