Needle blight in fir8/7/2023 ![]() ![]() In B.C., Dothistroma needle blight has had greatest impact in the ICH zone and in this zone the best management practice is to avoid planting lodgepole pine as there are numerous non-host commercial tree species options. Where lodgepole pine has been planted and failed due to the disease, management efforts have focused on determining whether or not sufficient non-host natural regeneration is present. Ascospores are thought to be more robust and capable of longer distance dispersal than conidia but are less common, and are typically only released for a month in early summer. The life cycle of Dothistroma generally requires one to two years to be completed but the latent period between infection and subsequent sporulation is quite variable depending on temperature, rainfall, host species and provenance. Weaver).ĭothistroma infects needles of all ages, causing pre-mature leaf mortality and reduced photosynthetic capacity. Dothistroma spreads primarily by means of splash-dispersed asexual conidia which may be released and germinate any time temperatures are above 5⁰C and moisture is available. Although the fungus can sporulate and germinate over a wide range of conditions, a combination of temperatures between 15 and 20⁰C with extended periods of moisture is optimal for infection. When the red banding is not present distinct black spherical fruiting bodies emerging from hinged ruptures in the needle epidermis can provide a means of visual identification of this foliar pathogen.ĭistinctive red bands on straw coloured lodgepole pine foliage (right) with more recently attacked needles on the left (Photo: D. These infected needles will be straw coloured and may have visible dark red bands. Woods).Ĭharacteristic foliar signs are most clear in the spring when needles that were affected the previous year are still attached and before new growth occurs. Needles that have been killed one to two years earlier are best for positive identification. Severely attacked lodgepole pine stand showing heavy defoliation in the lower crown (Photo: A. DescriptionĬrowns of affected trees tend to be thin and tufted in appearance. The lower crown is often most severely affected and from a distance damaged stands appear as though they have been burned by a low intensity wildfire. and as the climate warms it is expected that its northern range will expand. Occasionally individual trees show marked resistance to the disease.Dothistroma has been reported throughout most of the range of lodgepole pine in B.C. ![]() Epidemic infection years occur in cycles and depend on climatic conditions during the infection period. The symptoms caused by these organisms are similar, however, so precise identification is seldom important. The most common in British Columbia is R. Other informationĭouglas-fir needle blight is caused by a number of species and subspecies of the genus Rhabdocline. Christmas tree plantations can be severely damaged. The impact of the disease therefore is greatest on small trees because of their smaller total number of needles large trees usually undergo only light defoliation and sustain little damage. Repeated severe infection almost completely defoliates trees, leaving only the current year's needles. Western Canada Damage, symptoms and biology ![]()
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