| 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 diseases |
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. |
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