The Sapstain Danger Index (SDI) is a model that is used to indicate sites in the New Zealand forest where felled logs are more prone to sapstain, specifically it should indicate how soon after felling of a log should it be treated for sapstain. The validation of SDI has the goal to identify whether the SDI can be used to predict sapstain development and to eventually minimise loss of value of logs by sapstain by altering harvesting operations. The SDI monitors temperature, rainfall, relative humidity and considers seasonal periods to calculate the time taken until a felled log should be treated for sapstain. The current SDI does not directly monitor the infection of logs by sapstain fungi. This study to validate SDI addresses this latter point by monitoring the direct infection of logs by sapstain fungi. This study to validate SDI has monitored the direct infection of logs by sapstain fungi at 5 sites in Central North Island New Zealand, over a period of two years. It has also calculated the SDI at those 5 sites. This study has shown that at 4 of the 5 sites there is a correlation between the SDI and the number of days until direct sapstain infection. At the other monitored site the SDI values did not correlate with the number of days until sapstain infection. Therefore, this study has concluded that the SDI can be used to predict the direct infection of felled logs at some sites. However, there are other variables not considered in the SDI that affects the direct infection of logs with sapstain.

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