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Sirococcus blight is a disease caused by the fungus Sirococcus tsugae. It is mainly associated with cedars (Cedrus atlantica and C. deodara) but has also been recorded on hemlocks (Tsuga spp.). Samples from trees affected by Sirococcus blight were first received by Forest Research in late 2013 and by 911±¬ÁÏ Gardening Advice in June 2016.

S. tsugae causes shoot tip blight, characterised by a pinkish needle discolouration, first visible from spring but later turning a browner colour, which can be seen from a distance. It is important to be aware that other factors can cause foliage discolouration and dieback in aerial parts of trees.

If you suspect a case of Sirococcus blight, please report it via .

You may see the following symptoms;

• Pink to brown needle discolouration
• Shoot tip dieback, often affecting several shoots on the same tree
• Partial needle shedding
• Cankers on branches. These are not immediately obvious – look for changes in bark
  Bark is the outermost layer of woody plants (trees, shrubs and woody climbers). It is several cells thick and provides protection against physical damage, disease and environmental stresses. Bark comes in a wide variety of colours and patterns, and these can help gardeners when identifying plants. The fissures and crevices of bark on older plants also creates valuable habitat for many garden creatures as well as lichens and small plants. colour (green shades to red/purple) and a reduction in branch diameter. The cankers may be accompanied by resin exudation
• Brown lesions in the sap
  Sap is a fluid that circulates through a plant's vascular system, in a similar way to blood moving through our veins. Phloem sap carries the sugars produced in the leaves by photosynthesis down to roots and other storage organs, as well as carrying minerals and hormones. Xylem sap is watery and transports nutrients absorbed by the roots upwards to the rest of the plant. Some plants leak sap from wounds or pruning cuts, and this is known as bleeding. conducting ( phloem
  Part of a plant's vascular system (internal plumbing) responsible for transporting sugars and other products of photosynthesis from leaves to the rest of the plant. ) tissue
• Small fungal fruiting bodies can be found on dead needles and on the surface of cankers from summer onwards

Non-chemical control

There are currently no effective control measures for Sirococcus blight. Good tool hygiene may reduce the spread of the disease on an affected tree. However, the conidia (asexual spores) of the fungus are dispersed by rain splash, with strong winds likely to disperse them over longer distances.

It is, however, reported that trees infected with Sirococcus blight can live for many years and that it is unlikely that infected trees will need to be felled unless there is a risk of structural failure. If necessary, seek professional advice from a qualified tree surgeon or arborist .

Chemical control

There are no fungicides available to home gardeners with specific recommendations for use against Sirococcus tsugae.

Sirococcus tsugae is an asexually reproducing fungus. It survives in infected dead plant material, being found in needles, stems and plant litter beneath affected trees. It produces spherical fruiting structures with apical openings (pycnidia); inside these the conidia (asexual non-motile spores) develop. Infection occurs when the conidia are released from the fruiting bodies and splash or are dispersed by wind.

Young shoots are particularly susceptible with most new infections occurring in spring and early summer when there is also a higher abundance of viable conidia.