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Needle Cast

Rhabdocline spp. including R

63 host plants

Last updated

Data Coverage 3 of 6 dimensions
Causal Agent
Host Plants
Symptoms
Management
GDD Threshold
Regional Notes

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 cool maritime regions, 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.

Quick Reference

Causal Agent
Rhabdocline spp. including R
Host Plants
63
Favorable Conditions
Conifer needlecast fungi infect newly emerging needles at bud break in spring...

Management

Vulnerability Window

By spring, these spots have expanded and become characteristic dark reddish-brown blotches. | Byther Biology The first symptoms of this fungal infection are many tiny yellow spots on the current

What Triggers Infection

Conifer needlecast fungi infect newly emerging needles at bud break in spring; wet conditions during needle elongation are critical for spore germination (PNW Gardeners Handbook Ch 17).

Cultural Controls

  • On small trees, prune and destroy diseased branches.
  • Avoid overhead watering while new foliage is growing.
  • In Christmas tree plantations, remove and destroy any infected trees.
  • Good air circulation is important for disease prevention.
  • Do not plant in areas with poor air drainage and space trees to provide good air circulation.
  • Remove weeds around trees, thin canopy, and prune lower branches to help reduce humidity around trees.

Host Plants (63)

Abies alba European Silver Fir, Common Silver Fir Abies amabilis Pacific Silver Fir Abies balsamea Balsam Fir Abies concolor White Fir, Colorado Fir Abies delavayi Delavay's Fir Abies grandis Grand Fir Abies koreana Korean Fir Abies lasiocarpa Subalpine Fir Rocky Mountain Fir, Alpine Fir Abies magnifica California Red Fir, Red Fir, Slivertip Fir Abies nordmanniana Nordmann Fir, Caucasian Fir Abies numidica Algerian Fir Abies pindrow West Himalayan Fir, Pindrow Fir Abies pinsapo Spanish Fir, Spanish Pin Fir Abies pinsapo subsp. marocana Moroccan Fir Abies procera Noble Fir Larix decidua European Larch Larix gmelinii Dahurian Larch Larix kaempferi Japanese Larch Larix laricina Tamarack, Eastern Larch, American Larch Larix occidentalis Western Larch, Western Tamarack Larix russica Siberian Larch, Russian Larch Pinus albicaulis Whitebark Pine, Scrub Pine, White Pine Pinus aristata Bristlecone Pine, Rocky Mountain Bristlecone Interior Bristlecone Pinus attenuata Knobcone Pine Pinus banksiana Jack Pine, Scrub Pine, Banksian Pine, Hudson Bay Pine Pinus bungeana Lacebark Pine, Whitebark Pine, Baipi Song Pinus canariensis Canary Island Pine Pinus cembra Swiss Stone Pine Pinus contorta Lodgepole Pine Pinus contorta var. contorta Shore Pine Pinus contorta var. latifolia Rocky Mountain Lodgepole Pine Pinus coulteri Coulter Pine, Bigcone Pine Pinus densiflora Japanese Red Pine Pinus edulis Pinyon Pine, Piñón Pine, Two-needle Pinyon Colorado Pinyon Pinus elliottii Slash Pine, Swamp Pine Pinus flexilis Limber Pine, Rocky Mountain White Pine Pinus halepensis Aleppo Pine, Jerusalem Pine Pinus heldreichii Bosnian Pine, Snakeskin Pine Pinus jeffreyi Jeffrey Pine, Western Yellow Pine, Bull Pine Pinus kwangtungensis Kwangtung Pine, Guangdong Pine Pinus lambertiana Sugar Pine Pinus leucodermis Bosnian Pine Pinus monophylla Singleleaf Pinon Pine, One-leaved Pine Pinus monticola Western White Pine Pinus mugo Mugo Pine Pinus mugo var. pumilio Mugo pine, Dwarf Mugo pine Pinus nigra Austrian Pine Pinus parviflora Japanese White Pine Pinus parvifola Pinus parvifola Pinus pinaster Maritime Pine, Cluster Pine, Turpentine Pine Pinus pinea Italian Stone Pine, Umbrella Pine Pinus ponderosa Ponderosa Pine, Western Yellow Pine Pinus pumila Japanese Stone Pine, Dwarf Siberian Pine Pinus radiata Monterey Pine Pinus resinosa Red Pine Pinus sabiniana Gray Pine, Foothill Pine Pinus strobiformis Southwestern White Pine, Mexican White Pine, Chihuahua White Pine Pinus strobus Eastern White Pine Pinus sylvestris Scots Pine, Scotch Pine Pinus thunbergii Japanese Black Pine Pinus virginiana Virginia Pine, Scrub Pine, Jersey Pine Pinus wallichiana Himalayan Pine, Bhutan Pine Pinus yunnanensis Yunnan Pine