Heterobasidion Root Disease Interactive Guide
Result
HRD is present in the stand.
Learn more in Chapter 4 of the HRD guidelines.
Recommendation
If harvesting occurs from April 1–November 30, preventive stump treatment on pine and spruce is recommended if more than 50% of the stand is pine and/or spruce. The minimum tree size for treatment is merchantable size. No treatment is required from December 1–March 31. Harvesting without preventive stump treatment can be considered April 1–November 30 under certain conditions listed as Exceptions or Modifications.
Exceptions/Modifications
Chapter 4 (HRD is present in your stand), Exception 3, may be utilized and you may choose not to apply the preventative stump treatment. Exception 3 states that HRD is widespread in the stand. Stump treatment will help prevent new infestations but will not stop the movement of H. irregulare through root systems that are already colonized. Expect some additional infection through root contact and root infection. If stumps are not treated at the time of harvest, there may be additional stump infection following deposition of windborne spores.
Exceptions are considered relatively common and are straightforward to apply. No detailed justification is needed to apply the Exceptions. However, a short explanation of which Exception was used should be included in the timber sale documentation.
Things to consider
If you choose to harvest during April 1–November 30 without stump treatment, consider the potential impact to the stand and subsequently to adjacent stands if HRD were to develop in the stand. It is important to note that there are no treatments to eradicate the pathogen after it infests a stand.
Background information
Factors affecting disease incidence & severity (Chapter 5.5)