Host Plants - Westcott's Plant Disease - page 606

Stunt. Waterlogged soil.
P OWDERY M ILDEW . Oidium sp., CA.
R OT , Crown and Stem. Phytophthora nicotianae
var. parasitica, FL.
R OT , Root. Chalaropsis thielaviopsis, IL;
Clitocybe tabescens, FL; Phymatotrichum
omnivorum, AZ, TX; Rhizoctonia solani,
FL, IL, NJ, TX; Thielaviopsis basicola, seri-
ous, common; Pythium aphanidermatum,
PA; P. irregulare, PA; P. ultimum, PA.
R OT , Stem; Wilt. Fusarium sp., FL, NJ; Pythium
debaryanum, OK; P. perniciosum, root rot,
CA;

P OWDERY M ILDEW . Phyllatinia gutata, WA, MI.
R UST . Pileolaria brevipes, AZ; Pileolaria

effuca, AZ.
S TEMS . Discosia rhoina, CO, IL, NJ; Discosia
toxica, CO, IL, NJ; Botrydiplodia compressa
f. toxicodendrum,NY.
T RUNKS andW OOD . Bjerkandera adusa,MD,WV;
Daedaleopsis confragosa,NC;Dendrophora
albobadia,GA;Perenniporia medulla-panis,
MI; Phellinus gilvus,MD;Schizophyllum
commune, VA; Trameres hirsute,MD;
Trameres versicolor, MD, ND; Dothidea
puccinoides, GA; Diaporthe spiculosa,IL,
MA, NJ, NY; Hainesia lythri,WI;Hypoxylon
rubiginosum,GA;Rhytidhysteron rufulum,
GA.

P. ultimum; Phytophthora sp., NJ;

Sclerotinia sclerotiorum, WA;

Amphobotrys ricini, basal, LA.
R UST . Uromyces euphorbiae (0, I, II, III), OK, TX.
S POT ANTHRACNOSE ; Poinsettia Scab. Sphaceloma
poinsettiae, FL.
V IRUS . Poinsettia Mosaic, WI.
Keep soil acid, pH 4.8 to 5, to reduce trouble
with Thielaviopsis. Rhizoctonia is prevalent at
high temperatures, Pythium at

Poison Oak (Toxicodendron
diversilobum, West Coast and
Toxicodendron pubescens, East Coast)

low. Steaming

soil is safer than using chemicals. B LIGHT , Leaves. Cristulariella moricola, GA;

Colletogloenon

rhois, NJ; Phyllosticta

toxica, IA, IL, MS, SC, WV.
B LIGHT , Stems. Diaporthe peckii, NJ;
Botryodiplodia compressa f.
toxicodendron, NY; Dothiorella radicans,
CO, IL, NJ; Dothiorella rhoina, CO, IL, NJ;
Dothiorella toxica, CO, IL, NJ.
L EAF S POT . Stigmina pallid, CO, ID, TX;
Discosia artocreas, MS; Gloeosporium
toxicodendri, eastern states, KS, MS, MT,
OK; Phyllosticta rhoicola, MS, NY, TX,
WA, WV; Phyllosticta toxicodendri, SC;
Septoria rhoina, ID, Tubakia dryina, IL.
P OWDERY M ILDEW . Phyllactinia guttata, WA.
R OT , Decline. Hypoxylon rubiginosum, GA;
Valsa ceratosperma, GA; Pileolaria effusa,
AZ, CO; Stereum hirsutum, NC.
R OT ,

Poison Hemlock (Conium)

V IRUS . Alfalfa Mosaic, WA; Clover Yellow
Vein, WA; Apium Virus Y,WA.

Poison Ivy (Rhus
radicans ¼ Toxicodendron radicans)

B LIGHT , Twigs. Botryopheria obtusa.
C ANKER , Limbs and Trunk. Valsa ceratosperma,
GA.
L EAF S POT . Alternaria sp. WV; Cercospora sp.,
FL; Stigmina pallida, CO, TX;
Colletotrichum sp., CA; Discosia artocress,
MS; Gleosporium toxicotrichum, eastern
states, KS, MS, MT, OK; Phoma Sp., NC;
Phyllosticta rhoicola, MS, NY, TX, WA,
WV; Phyllosticta toxicodendri, SC;
Phyllosticta sp., WI; Septoria rhoina, ID;
Tubakia dryina, IL.
O N L EAVES . Cristulariella moricola, AL, GA;
Collectogloem rhois, NJ.

Limb. Diaporthe spiculosa, IL;

Rhytidhysteron rufulum, GA.
R OT , Root. Dasyscyphus corticalis, WA.
R OT , Trunk. Bjerkanderea adusta, MD, WV.
R OT , Wood. Dendrophora albobadia, GA;
Perenniporia medulla commune, MI;
Schizophyllum commune, VA; Trametes
versicolor, MD, NC.