Needle Cast

Needle cast begins as tiny yellow spots on new needles in spring, progressing to dark reddish-brown blotches bounded by leaf veins. By late spring, affected needles drop prematurely, leaving branch tips bare and revealing previous years' needle loss. The disease is most severe after prolonged wet springs when moisture levels stay high during needle elongation. On larch and noble fir in Western Washington, yellowing needles in mid-spring are often your first clue.

Needle-cast fungi infect new needles at bud break, so conditions during early spring determine disease severity. Wet conditions during needle elongation are critical for spore germination, making spring irrigation management key. Avoid overhead watering while new foliage is growing, and space trees for good air drainage and circulation. Remove fallen diseased branches from the canopy and ground to reduce spore sources. Thinning lower branches and removing surrounding weeds helps increase air movement around the crown.