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Diseases of English (Persian) Walnut
(Juglans regia L.)

S. M. John Mircetich, primary collator; updated by B. L. Teviotdale (last update 7/24/01)

BACTERIAL DISEASES

Crown gall

Agrobacterium tumefaciens (Smith & Townsend 1907) Conn 1942

Deep bark canker

Erwinia rubrifaciens Wilson, Zeitoun, & Fredrickson 1967

Shallow bark canker

Erwinia nigrifluens Wilson, Starr & Berger 1957

Walnut blight

Xanthomonas campestris pv. juglandis (Pierce 1901) Dye (1978)

FUNGAL DISEASES

Anthracnose

Gnomonia leptostyla (Fr.) Ces. et de Not.

    Marssonina juglandis (Lib.) Magn. [anamorph]

Armillaria root rot

Armillaria mellea (Vahl:Fr.) P. Kumm.

Branch wilt

Hendersonula toruloidea Nattrass

Cotton root rot

Phymatotrichopsis omnivora (Duggar) Hennebert

= Phymatotrichum omnivorum Duggar

Cylindrocarpon dieback

Nectria radicicola Gerlach & L. Nilsson

    Cylindrocarpon destructans (Zinssmeister) Scholten
    [anamorph]

= C. radicicola Wollenw.

Downy leaf spot

Microstroma juglandis (Berenger) Sacc.

Melanconium dieback

Melanconis chartusiana Tul.

    Melanconium juglandinum Kunze [anamorph]

Phytophthora crown and root rot

Phytophthora spp.

P. cactorum (Lebert & Cohn) J. Schröt.

P. cinnamomi Rand

P. citricola Sawada

P. citrophthora (R.E. Sm. & E.H. Sm.) Leonian

P. cryptogea Pethybr. & Lafferty

P. drechsleri Tucker

P. megasperma Drechs.

P. nicotinae Breda de Haan var. parasitica (Dastur)
    G.M. Waterhouse

= P. parasitica Dastur

Phytophthora trunk and branch canker

Phytophthora cactorum (Lebert & Cohn) J. Schröt.

P. citricola Sawada

P. citrophthora (R.E. Sm. & E.H. Sm.) Leonian

NEMATODES, PARASITIC

Pin nematode

Paratylenchus spp.

Ring nematode

Mesocriconema xenoplax (Raski) Loof & de Grisse

Root lesion nematode

Pratylenchus vulnus Allen & Jensen

Root knot nematode

Meloidogyne spp.

VIRAL DISEASES

Blackline

genus Nepovirus, Cherry leaf roll virus (CLRV)

Walnut ring spot

genus Nepovirus, Cherry leaf roll virus (CLRV)

MISCELLANEOUS DISEASES AND DISORDERS

Alternaria leaf spot

Alternaria alternata (Fr.:Fr.) Keissl.

Apoplexy

Unknown

Ascochyta ring spot

Ascochyta juglandis Boltshauser

Mesophyll collapse

High temperature and low humidity

Oilless nuts

Unknown

Pistillate flower abscission

Excess pollen

Stem canker

Fusarium solani (Mart.) Sacc.