Swiss Needle Cast

Fungal disease caused by the fungus Nothophaeocryptopus gaeumannii (aka: Phaeocryptopus gaumannii)
Impacts Douglas-fir
Growth and symptom development is favored by wet environmental conditions
Needles become discolored (blotchy yellow or completely yellow) and then brown from the tips before dropping prematurely
Older needles are more susceptible than younger ones, so infected trees may be bare except for the new growth
Small, black reproductive structures of the fungus can be seen in two bands on the underside of the infected needles (hand lens!)
Infected needles cannot be cured so treatments will only prevent additional infections

Inspect stock being planted
Remove severely infected tree prior to crop bud break (30%+ infected)
Prune infected branches during DRY weather, disinfect pruning tools between cuts
Avoid overhead irrigation
Promote air circulation
Mulch to moderate soil temperature
Fertilize to support tree’s natural defenses (not too much N though!)
Reduce plant stress

Contact fungicides:
- Chlorothalonil [M05]
- Mancozeb [M03]
- Coppers [M01]
Systemic/Translaminar fungicides:
- Propiconazole [3]
- Azoxystrobin [11]
- Thiophanate-methyl [1]
- Combination products
Considerations:
- First application in the spring when candles half-elongated / ½”
- Second application 2-3 weeks later (unless high pressure/wet, then 10-14d later)
- Continue applications every 2-4 weeks (total of 3-5 sprays)
- Total # of applications depend on history of disease severity
- Cover needles thoroughly for effective treatment
- Canopy penetration is critical
- Must follow allowable Ai/acre

Swiss Needle Cast​