The host-pathogen index is a list of ornamental hosts not covered in the Disease Control Outlines and some of the pathogens that attack these hosts. Diseases covered in Key Diseases are noted with an asterisk.
| African Violet (Saintpaulia ionantha) | |
|---|---|
| Bacterial blight | Dickeya (=Erwinia) chrysanthemi |
| Foliar nematode ** | Aphelenchoides ritzemabosi |
| Gray mold * | Botrytis cinerea |
| Phytophthora crown rot * | Phytophthora parasitica |
| Powdery mildew * | Odium spp. |
| Pythium root rot * | Pythium spp. |
| Rhizoctonia stem rot | Rhizoctonia solani |
| Ring spot | physiological (cold water and light) |
| Christmas cactus (Schlumbergera bridgesii) | |
| Crown rot * | Phytophthora parasitica |
| Pythium aphanidermatum | |
| Fusarium rot * | Fusarium oxysporum |
| Gray mold * | Botrytis cinerea |
| Root and stem rot | Rhizoctonia solani |
| Root rot * | Pythium irregulare |
| Stem rot | Phytophthora spp. |
| Stem rot and leaf spot | Bipolaris cactivora |
| Virus | Cactus virus X |
| Candytuft (Iberis amara) | |
| Alternaria leaf spot* | Alternaria brassicae |
| Basal stem rot | Phoma lingam |
| Club root
|
Plasmodiophora brassicae
|
| Downy mildew * | Peronospora parasitica |
| Gray mold * | Botrytis cinerea |
| Phytophthora root rot * | Phytophthora spp. |
| Powdery mildew * | Erysiphe cruciferarum |
| Pythium root rot * | Pythium spp. |
| Root knot nematode ** | Meloidogyne sp. |
| White rust | Albugo candida |
| Cineraria (Senecio cruentus) | |
| Collar rot | Rhizoctonia solani |
| Downy mildew * | Plasmopara halstedii |
| Gray mold * | Botrytis cinerea |
| Impatiens necrotic spot | Impatiens necrotic spot virus |
| Leaf spot* | Alternaria cinerariae |
| Powdery mildew * | Erysiphe cichoracearum
Sphaerotheca fuliginea |
| Root and collar rot * | Phytophthora spp. |
| Root rot * | Pythium ultimum |
| Spotted wilt | Tomato spotted wilt virus |
| Stem rot * | Sclerotinia sclerotiorum |
| *For additional information, see section on Key Diseases. | |
| **For additional information, see section on Nematodes. | |
| Gardenia (Gardenia jasminioides) | |
| Bacterial leaf spot | Xanthomonas campestris pv. maculifoliigardeniae |
| Chlorosis | iron deficiency |
| Petal blight (gray mold) * | Botrytis cinerea |
| Phomopsis canker | Phomopsis gardeniae |
| Root knot nematode ** | Meloidogyne spp. |
| Gerbera (Gerbera jamesonii) | |
| Bacterial leaf spot* | Pseudomonas cichorii |
| Black root rot * | Thielaviopsis basicola |
| Crown and root rot | Rhizoctonia solani |
| Gray mold * | Botrytis cinerea |
| Leaf spots | Alternaria porri |
| Cercospora gerberae | |
| Septoria spp. | |
| Ascochyta gerberae | |
| Phytophthora crown rot * | Phytophthora cryptogea and others |
| Powdery mildew * | Golovinomyces cichoracearum |
| Pythium root rot * | Pythium spp. |
| Sclerotinia crown rot | Sclerotinia sclerotiorum |
| Spotted wilt | Tomato spotted wilt virus |
| Verticillium wilt * | Verticillium dahliae |
| White rust*** | Albugo tragoponis |
| German violet (Exacum affine) | |
| Basal stem rot | Nectria hematocca |
| Gray mold * | Botrytis cinerea |
| Root rot * | Pythium ultimum |
| Spotted wilt | Tomato spotted wilt virus |
| Gloxinia (Sinningia speciosa) | |
| Cottony rot and flower blight* | Sclerotinia sclerotiorum |
| Crown rot | Myrothecium roridum |
| Crown rot and tuber rot | Rhizoctonia solani |
| Gray mold * | Botrytis cinerea |
| Ring spot | physiological (cold water and light) |
| Root and crown rot * | Phytophthora cryptogea |
| P. nicotiana | |
| Root rot * | Pythium spp. |
| Southern blight * | Sclerotium rolfsii |
| Spotted wilt | Tomato spotted wilt virus |
| Hydrangea (Hydrangea macrophylla) | |
| Gray mold * | Botrytis cinerea |
| Powdery mildew * | Golovinomyces orontii |
| Rhizoctonia stem rot | Rhizoctonia solani |
| Ringspot | Hydrangea ringspot virus |
| Root knot nematode ** | Meloidogyne spp. |
| Root rot * | Pythium spp. |
| Virescens | Phytoplasma |
| *For additional information, see section on Key Diseases. | |
| **For additional information, see section on Nematodes. | |
| ***Not reported in U.S.A. | |
| Impatiens (Impatiens walleriana) | |
| Bacterial fasciation | Rhodococcus fascians |
| Bacterial leaf spot * | Pseudomonas syringae |
| Black root rot * | Thielaviopsis basicola |
| Brown crown canker | Rhizoctonia solani |
| Crown rot* | Pythium ultimum |
| Rhizoctonia solani | |
| Downy Mildew * | Plasmopara obducens |
| Gray mold * | Botrytis cinerea |
| Impatiens necrotic spot | Impatiens necrotic spot virus |
| Leaf spot | Phyllosticta sp. |
| Root rot * | Pythium sp. |
| Southern blight * | Sclerotium rolfsii |
| Spotted wilt | Tomato spotted wilt virus |
| Verticillium wilt * | Verticillium dahliae |
| Kalanchoe (Kalanchoe blossfeldiana) | |
| Aster yellows * | Aster yellows phytoplasma |
| Edema | Physiological; cause unknown |
| Fasciation | Cercospora sp. |
| Impatiens necrotic spot | Impatiens necrotic spot virus |
| Kalanchoe mosaic | Kalanchoe mosaic virus |
| Leaf and stem blight | Botrytis cinerea * |
| Leaf spots | Stemphylium spp. |
| Powdery mildew * | Sphaerotheca fuliginea |
| Root and crown rot * | Phytophthora spp. |
| Spotted wilt | Tomato spotted wilt virus |
| Stem rot | Myrothecium roridum |
| Lilac (Syringa vulgaris and S. persica) | |
| Armillaria root rot* | Armillaria mellea |
| Bacterial blight* * | Pseudomonas syringae pv. syringae |
| Crown gall * | Agrobacterium tumefaciens |
| Gray mold * | Botrytis cinerea |
| Leaf blotch | Heterosporium syringae |
| Phytophthora blight | Phytophthora spp. |
| Phytophthora root rot* * | Phytophthora spp. |
| Powdery mildew * | Microsphaera penicillata |
| Shoot blight* | Sclerotinia sclerotiorum |
| Lilies (Lilium spp.) | |
| Cottony rot and petal blight* | Sclerotinia sclerotiorum |
| Foliar nematode * | Aphelenchoides spp. |
| Gray mold* | Botrytis spp. |
| Leaf spots* | Cercospora, Heterosporium, and Ramularia spp. |
| Root knot nematode * | Meloidogyne spp. |
| Rust * | Uromyces spp. |
| Scale rots | Colletotrichum spp. |
| Lisianthus (Eustoma grandiflora) | |
| Foliar nematode ** | Aphelenchoides spp. |
| Gray mold* | Botrytis cinerea |
| Leaf spot * | Cercospora eustomae |
| Powdery mildew* | Leveillula taurica |
| Root knot nematode ** | Meloidogyne spp. |
| Root and stem rot | Fusarium avenaceum, Phytophthora, Pythium, and Rhizoctonia spp. |
| Viruses | Tomato spotted wilt virus, Impatiens necrotic spot virus |
| Pouch Flower (Calceolaria x herbeohybrida) | |
| Cottony rot * | Sclerotinia sclerotiorum |
| Gray mold * | Botrytis cinerea |
| Root and crown rot * | Phytophthora spp. |
| Root rot * | Pythium spp. |
| Spotted wilt | Tomato spotted wilt virus |
| Stem rot | Myrothecium sp. |
| Verticillium wilt * | Verticillium dahliae |
| Primula (Primula x polyantha) | |
| Crown rot | Rhizoctonia solani |
| Fasciation | Physiological; cause unknown |
| Gray mold * | Botrytis cinerea |
| Leaf spot | Ramularia primulae |
| Root rot * | Pythium spp. |
| Spotted wilt | Tomato spotted wilt virus |
| Protea (Protea, Banksia, Leucospermum, and other spp.) | |
| Canker | Botryosphaeria spp. |
| Gray mold * | Botrytis cinerea |
| Leaf spots | Colletotrichum spp., Mycosphaerella spp. |
| Root and crown rot * | Phytophthora spp., Rhizoctonia solani |
| Root knot nematode * | Meloidogyne spp. |
| Verticillium wilt * | Verticillium dahliae |
| Queen Anne's Lace (Daucus carota) | |
| Aster yellows * | Aster yellows phytoplasma |
| Bacterial blight* | Xanthomonas campestris pv. carotae |
| Black root rot | Alternaria radicina |
| Early blight* | Cercospora carotae |
| Leaf blight* | Alternaria dauci |
| Powdery mildew* | Erysiphe heraclei |
| Root and stem rot | Fusarium spp. |
| Root, crown, and stem rots * | Phytophthora, Pythium, and Rhizoctonia spp. |
| Southern blight* | Sclerotium rolfsii |
| Tuber rot | Rhizopus spp. |
| Viruses | Celery mosaic virus, Carrot motley dwarf virus |
| Ranunculus (Ranunculus spp.) | |
| Aster yellows * | Aster yellows phytoplasma |
| Bacterial blight* | Xanthomonas campestris pv. carotae |
| Cottony rot* | Sclerotinia sclerotiorum |
| Downy mildew* | Peronospora spp. |
| Gray mold* | Botrytis cinerea |
| Leaf spots* | Ramularia spp. |
| Powdery mildew * | Erysiphe polygoni |
| Root rots* | Pythium spp., Rhizoctonia solani |
| Rust * | Puccinia spp. |
| Smut | Entyloma spp. |
| Southern blight* | Sclerotium rolfsii |
| Viruses | Tomato spotted wilt virus, Ranunculus mosaic virus |
| Stephanotis (Stephanotis floribunda) | |
| Crown rot | Rhizoctonia solani |
| Gray mold * | Botrytis cinerea |
| Powdery mildew * | Oidium sp. |
| Stem dieback | Glomerella cingulata |
| Virus | Impatiens necrotic spot virus, Tomato spotted wilt virus |
| Sunflower (Helianthus sp.) | |
| Aster yellows * | Aster yellows phytoplasma |
| Charcoal rot | Macrophomina phaseolina |
| Cottony rot * | Sclerotinia sclerotiorum |
| Downy mildew * | Plasmopara halstedii |
| Gray mold * | Botrytis cinerea |
| Head rot | Rhizopus oryzae |
| Leaf spots* | Alternaria, Cercospora, and Septoria spp. |
| Powdery mildew * | Golovinomyces cichoracearum |
| Root and stem rot * | Phytophthora sp. |
| Rust * | Coleosporium, Puccinia, and Uromyces spp. |
| Smut | Entyloma calendulae |
| Southern wilt * | Sclerotium rolfsii |
| * For additional information see section on Key Diseases. | |
Text Updated: 11/20