Host Plants - Westcott's Plant Disease - page 637

R OT , Root. Aphanomyces cladogamus, NJ, VA;
Phymatotrichum

B ACTERIAL Hairy Root. Agrobacterium

omnivorum, TX; rhizogenes, IA.

L EAF S POT . Cylindrosporium filipendulae, IA,
OR, WA, WI.
N EMATODE , Root Knot. Meloidogyne spp., FL,
MS; M. hapla.
P OWDERY M ILDEW . Microsphaera alni, CT;
Podosphaera oxyacanthae, widespread;
Sphaerotheca macularis, TX.
R OT , Root. Phymatotrichum omnivorum, AZ,
TX.

Pyrenochaeta terrestris, IA; Olpidium

brassicae.
R OT , Root, Crown; Wilt. Fusarium solani;
F. oxysporum f. sp. spinaciae, general;
Phytophthora sp., AZ, IN, NJ, NY;
P. cryptogea, CA; P. megasperma, CA,
NC; Sclerotinia sclerotiorum, GA, NY.
R UST . Puccinia aristidae (0, I), AZ, CA, CO, OR,
WA; II, III on grasses.
S MUT , Leaf. Entyloma ellisii, NJ, WA.
V IRUS . Cucumber Mosaic (Spinach Blight);
Spinach Yellow Dwarf; Beet Curly Top;
Beet Ring Mottle; Beet Pseudo Yellows;
Tomato Spotted Wilt; Lettuce Mosaic,
NY; Lettuce Speckles Mottle, CA; Spinach
Latent; Potato Leaf Roll, Pacific Northwest;
Spinach Severe Curly Top, AZ; Impatiens
Necrotic Spot, CA; Bean Yellow Vein, CA;
Curtoviruses, AZ; Tobacco Rattle, CA.
W HITE R UST . Albugo occidentalis, AR, OK, TX.
W ILT . Verticillium sp., NY.
Downy mildew is the outstanding spinach dis-
ease, with all varieties susceptible in some degree
because of physiologic races, although Dixie Mar-
ket, Savoy Supreme, and others are considered resis-
tant. To reduce blight, use virus-tolerant varieties.

Spondias (Mombin)

N EMATODE , Root Knot. Meloidogyne sp., FL.
S POT A NTHRACNOSE ; Mombin Scab. Sphaceloma
spondiadis, FL.

Spruce (Picea)

B LIGHT , Brown Felt. Herpotrichia nigra, MT,
Northern Rocky Mts., Pacific Northwest;
Neopeckia coulteri.
B LIGHT , Needle. Sirula macrospora, ND;
Stigmina lautii, NC.
B LIGHT , Seedling Smother. Thelephora
terrestris, ID, MN, OH; seedling, Rosellinia
herpotrichioides, WA.
B LIGHT , Shoot. Sirococcus strobilinus, KS, NC,
WI; Phomopsis occulta, WI.
B LIGHT , Snow. Phacidium infestans, New
England states; Botrytis cinerea, NJ;
Lophophacidium hyperboreum, MN.
B LIGHT , Twig. Ascochyta piniperda,ME,NC.
B ROOMING . Rhizosphaera kalkhoffii, Central
Rocky Mts.
C ANKER ,

Spiraea (Native Hardhack,
Meadowsweet)

B LIGHT , Seedling; Stem Girdle. Thelephora
terrestris, ID.
C ANKER . Cryptodiaporthe macounii, NY.
L EAF S POT . Cercospora rubigo, CA, KS,
OR, WI; Cylindrosporium spp., ID, NY;
Phloeospora salicifoliae, NY to KS, TX, WA.
P OWDERY M ILDEW . Podosphaera oxyacanthae,
widespread; Sphaerotheca macularis, CT,
MI, NY, PA.

Bark. Aleurodiscus amorphus,

widespread.
C ANKER ;TwigBlight.Cytospora kunzei ( Valsa
kunzei var. piceae ),NewEnglandtoNJ,IL,
MN.
D AMPING -O FF . Cylindrocladium scoparium,MI,
NJ; Phytophthora cinnamomi,MD,NY,VA;
P. cactorum, NY, VA; Pythium ultimum,

Spirea, Oriental Flowering (Spiraea)

B ACTERIAL Fire Blight. Erwinia amylovora, MD,
NJ, NC, VA.