| Disease (causal agent) |
Symptoms |
Survival of pathogen and effect of environment |
Comments on control |
Black root rot
(Thielaviopsis basicola) |
Poor top growth. Black lesions on roots and root rot. Seedlings may be killed. |
Fungus is soilborne. Favored by cool, wet soils and any condition that weakens the plant. |
Avoid fields previously planted in legumes. Avoid overirrigation and overfertilization. Plant on raised beds. |
Powdery mildew
(Erysiphe polygoni) |
White powdery growth on surface of
leaves and stems. Older infected leaves yellow and wither. Growth of heavily infected plants is diminished. |
Favored by moderate temperatures.
Spores (conidia) are produced in great abundance and they are airborne.
Moisture is not necessary for germination and infection and is actually detrimental to the fungus. |
Several powdery mildew fungicides
are effective if applied in a regular preventative program commencing with
the first signs of the fungus. Check product label for registration. more info * |
Ramularia leaf spot
(Ramularia deusta) |
Large, irregular or circular tan
spots without definite margins. Lower leaves are first affected. Infected leaves often drop. |
Fungus is specific to sweet pea and survives in sweet pea refuse. Favored by wet conditions. |
Rotate with other crops for 2
years. A fungicide may be necessary in some severe cases. Avoid overhead irrigation. |
Seed decay
(Pythium spp. and other fungi) |
Seeds rot in soil. Seedlings do not emerge. |
Favored by wet soil and poor aeration. |
Provide better drainage. Grow on raised beds. |
| |
| Virus or viruslike disease |
Symptoms |
Host range and natural spread |
Comments on control |
Enation mosaic
(Pea enation mosaic virus) |
Leaves contain scattered
translucent areas ("windows"). Foliage may be crumbled and stunted. There may be "windows" in the flowers. |
Virus is spread by aphids. Host plants include many legumes. |
Control nearby weeds, especially legumes. Control aphids. |
Mosaic
(Pea mosaic virus) |
Mottling and chlorosis of the
foliage. Dark green areas interspersed with yellow‑green portions of leaves. Flowers have "broken" colors. |
Virus is spread by aphids. Host plants include many legumes. |
Control nearby weeds, especially legumes. Control aphids. |
Spotted wilt
(Tomato spotted wilt virus) |
Reddish brown streaks on stems.
Leaves with circular spots that are yellow at first and later turn brown. Plant may die. |
Spread by thrips. Virus has a wide
host range, including many weeds. Juvenile thrips (nymphs) acquire the virus and transmit it as adults. |
Control nearby weeds including grasses. Control thrips. |
| Sweet peas are also susceptible to
Ascochyta blight (Ascochyta lathyri), bacterial streak (Erwinia herbicola), fasciation (Rhodococcus fascians), Pythium root rot * (Pythium spp.), cottony rot * (Sclerotinia sclerotiorum), downy mildew * (Peronospora trifoliorum), and damping-off * (Rhizoctonia solani,
Fusarium spp., and Pythium spp.) |
| * For additional information, see section on Key Diseases. |
![[UC Peer Reviewed]](/IMAGES/logo-ucpeerreviewed.jpg){kind=logo}
![[Precautions]](/IMAGES/btn-precautions_bul.gif)