ROOT DISEASES

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OVERVIEW OF
ROOT DISEASES Reading Text Chapter 12.
Reserve. Allen et al. 1996. pages 2-25.
Hadfield et al. 1986. Root diseases in Oregon
and Washington conifers. USDA Forest
Service,State and Private Forestry, Forest Pest
Management, Portland, OR R6-FPM-250-86.
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1. Important root diseases in the Pacific
Northwest
Most important Laminated root rot Armillaria root
disease Annosus root and butt rot Black stain
root disease Phytophthora root disease Others Schw
einitzii root and butt rot (Velvet top
fungus) Tomentosus root and butt rot Rhizina root
disease Yellow root rot
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a. Laminated root rot caused by Phellinus weirii
(primary hosts - Douglas-fir, mountain hemlock,
western hemlock) b. Armillaria root rot caused by
Armillaria ostoyae - previously known as
Armillaria mellea (all conifers, especially
Douglas-fir and ponderosa pine)
c Annosus root and butt rot caused by
Heterobasidion annosum - previously known as
Fomes annosus (primary hosts - western hemlock,
true firs, ponderosa pine) d. Black stain root
diseases caused by Leptographium wageneri
previously known as Verticicladiella wagnerii
(primary hosts Douglas-fir and pines)
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e. Phytophthora lateralis (primary host Port
Orford Cedar) f. Other root rot organisms i.
Phaeolus schweintizii (primary host - older
Douglas-fir) ii. Inonotus tomentosus (primary
hosts - Engelmann spruce, true firs, ponderosa,
lodgepole pines) iii. Rhizina undulata (primary
host Douglas-fir seedlings iv. Perenniporia
subacida (primary hosts - western hemlock,
Douglas-fir, mountain hemlock, lodgepole pine,
larch, grand fir, western redcedar)
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2. TYPES OF ROOT
DISEASES 1. Structural root diseases- decay of
large woody roots caused by Basidiomycete
fungi Laminated root rot caused by
Phellinus weirii Armillaria root disease
caused by Armillaria ostoyae and other
Armillaria species Annosus root and butt
rot caused by Heterobasidion annosum 2. Feeder
root diseases organisms enter through fine
roots caused by Oomycetes
Phytophthora root disease P. lateralis, P.
cinnamomi Rhizina undulata root disease
(Ascomycete) 3. Vascular root diseases
organisms are usually vectored by insects
caused by Ascomycete/Deuteromycete fungi
Black stain root disease Leptographium wageneri
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3. Symptoms and signs of the five most important
root diseases - See Text Table 12.2.
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4. Root pathogen complexes and rootdisease/bark
beetle interactions - see Text Table 12.3.
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