New Zealand Journal of Forestry (2014) 58(4): 22–25
©New Zealand Institute of Forestry

Professional Paper
Forecasting sapstain after windthrow in pine plantations

Ian Hood ^*,1, Mark Kimberley ² and James McCarthy <sup>3

1</sup> Scion, Rotorua
² Scion, Rotorua
³ Scion, Christchurch
^*Corresponding author.

Abstract: Data on sapstain incidence, previously collected at different locations throughout New Zealand during a simulated windthrow project, were compared with weather records covering the same period. This was undertaken to see if daily online fire weather data may be used to anticipate the progress of sapstain within fallen Pinus radiata stems after storms. The variable Drought Code, selected as the most appropriate fire weather index, was found not to be an effective predictor of sapstain. This was probably because sapstain fungi and fire risk variables are influenced by different biological and physical parameters. However it was established that sapstain is not likely to become significant until daily mean temperatures exceed 21°C. Appreciable sapstain, affecting 10 per cent of disc cross-sectional area, is therefore unlikely to develop anywhere in New Zealand during winter. Once this daily temperature is exceeded significant sapstain generally develops within one to two months. Faster or slower development may sometimes occur though, apparently influenced by stem moisture content, with higher moisture content delaying development.
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