Cause The fungus Neonectria neomacrospora can cause a canker and dieback on true fir. Host species in the PNW where the pathogen has been detected include native species, such as Abies procera (noble fir), A. grandis (grand fir), A. amabilis (Pacific silver fir), A. lasiocarpa (subalpine fir), A. concolor (white fir), and A. magnifica var. shastensis (Shasta red fir), and introduced crop or landscape species, such as A. alba (European silver fir) A. balsamea (balsam fir), A. balsamea var. phanerolepis (Canaan fir), A. bornmuelleriana (Turkish fir), A. cephalonica (Greek fir), A. fraseri (Fraser fir), A. koreana (Korean fir), A. nordmanniana (Nordmann fir), A. numidiåca (Algerian fir), and A. pinsapo (Spanish fir).
Specific about the life cycle of Neonectria are not known. Research in Scandinavia has shown that this fungus is an active pathogen of true fir and not just a secondary invader of previously-damaged plant tissue. Both landscape and Christmas tree crops have shown damage. Spread of the pathogen is thought to be associated with rain-splashed spores. It is suspected that insect vectors, such as bark beetles, and associations with other problems such as adelgid is possible.
Symptoms Sunken, dead areas (cankers) develop on branches. Branch ends and large portions of the canopy (flagging) to whole trees may die. Resin flow may be noted on damaged trees. Small red sporulation structures (perithecia) may be observed on plant material, particularly on tissue that has been dead for over a year.
Cultural control Regular scouting aids in detecting cankers early.
- Cut out and destroy infected trees in Christmas tree plantations.
- Removing and immediately destroying cankered branches from infected trees in ornamental nurseries or landscapes.
- Isolating susceptible species from other species may help reduce disease spread in the nursery.
Chemical control Although copper-based fungicides have been effective in the laboratory, efficacy of fungicide applications (timing, chemistry, etc.) for Abies in the Pacific Northwest is unknown at this time.
Reference Talgø, V, Thomsen, IM, Nielsen, UB, Brurberg, MB, and Stensvand, A 2011. Neonectria canker on subalpine fir (Abies lasiocarpa) in Denmark. Bioforsk (NO). http://www.bioforsk.no/ikbViewer/Content/100752/Neonectria_VT_v1.1_A3.pdf