Pests image: Heterobasidion Irregulare (HRD)


Heterobasidion Root Disease (HRD), formerly known as Fomes Root Rot, or Annosum, is caused by the fungal pathogen Heterobasidion irregulare. HRD causes root rot in conifers (especially pines) which leads to growth loss and mortality. In Eastern Canada and the Northeastern United States, red pines are most susceptible, but other pines and spruces can also become infected. In the Southeastern United States, HRD is particularly damaging in loblolly pine plantations, while in Western North America, HRD causes root or butt rot in several conifer species. The effects of HRD can carry on beyond the current rotation, and can remain in residual stumps and roots for decades in cooler parts of the affected regions, making prime pine sites unsuitable for growing quality pines in the future.

Sign and Symptoms

HRD is most commonly identified when small, irregular-shaped fruiting bodies (resembling popcorn) develop in the duff at the base of dead or dying trees, or shelf-like conks emerge from the stump or snag near the ground.

HRD - Popcorn
HRD Decay root
HRD - Mortality Center
HRD - Shelf-like conks
HRD - Sinker Roots

Red Pine Tree Plantations


Canopy image

HRD can travel through airborne spores landing on newly cut stump surfaces and growing into the wood tissue. Spores are produced when temperatures are greater than 39°F (4°C). The disease can spread from infected stumps to nearby healthy trees, and to seedlings planted after clear felling, via root grafts and root-to-root contact. Lastly, HRD can spread through root systems at a rate of up to two meters per year, depending on the forest site.

Symptoms of HRD include:

  • Thinning crowns, reduced shoot growth, and off-colour foliage (early stages of infection)
  • Windthrown trees, with resin-soaked, white pocket rot progressing to stringy root rot evident on broken roots that failed to support the trees
  • Decline and/or mortality of infected trees (especially pines), often in roughly circular, expanding mortality centers

Rotstop C is a wettable powder that is applied as an aqueous mixture. Blue dye is added to the mixture to better observe treatment coverage. Rotstop C can be applied to the stump during felling when using a mechanized spray system attached to the felling head, or manually after felling, by backpack sprayer. Rotstop C will provide the most effective protection when applied at the time of felling or soon after.

Rotstop formulations have been proven to be very effective in protecting conifer plantations from HRD in Europe for over 30 years. Numerous field studies in Europe and North America and years of operational application have demonstrated very high efficacy (in some studies up to 90% effectiveness) of Phlebiopsis gigantea in preventing HRD.

Benefits of using Rotstop C include:

  • Incorporating Rotstop C into conifer plantation management can maximize productivity by preventing tree growth loss and mortality and provides assurance that conifer assets are protected from HRD.
  • According to peer-reviewed research, Phlebiopsis gigantea poses no risk to living trees or agricultural crops, making Rotstop C an ideal treatment option to help sustain forests for future generations
  • Peer-reviewed research also confirms that Phlebiopsis gigantea naturally decomposes dead wood, aiding in the decay of freshly cut stumps.
Effective Control of Heterobasidion Root Disease (HRD) with Rotstop C

RotStop C is a biological fungicide and is used as a stump treatment to protect freshly cut stumps from Heterobasidion Root Disease (HRD), a serious disease that affects red and white pine plantations.

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Rotstop C

What is Rotstop C?

Rotstop C is a stump treatment used to prevent the introduction and spread of Heterobasidion Root Disease (HRD) in conifer plantations. A biological fungicide, Rotstop C contains spores of the naturally occurring wood decay fungus Phlebiopsis gigantea, which grows into the stump and prevents H...