| Disease (causal agent) |
Symptoms |
Survival of pathogen and effect of environment |
Comments on control |
Anthracnose
(Colletotrichum gloeosporioide) |
Plants wilt and become mildly chlorotic. Crown tissues decay and
plant may die. In initial stages, roots are not affected. The fungus also
causes leaf, stem, and flower spots, but this phase of the disease is not
common in California. `Gold Coast' is highly susceptible; blue and white cultivars are more tolerant. |
The fungus survives on infected plants and debris. The disease is
favored by wet weather and overhead irrigation. Spores are spread by splashing water. |
Avoid overhead irrigation. Protect plants with chlorothalonil or copper. Chlorothalonil may cause blackening of flowers. |
Cercospora leaf spot
(Cercospora insulana) |
Small, dull red lesions that enlarge up to 0.67 inch (15 mm) and become tan and membranous in the center with reddish borders. |
Spores are airborne. Disease is favored by warm, moist conditions and condensed water on foliage. |
Avoid overhead irrigation. Protect foliage with chlorothalonil. |
Downy mildew
(Peronospora statices) |
Bluish gray sporulation occurs on undersides of leaves. On upper
surface of leaves, infections appear as light green areas that turn yellow,
then coalesce, and eventually the leaf dies. In California it is currently
found on cultivars in the "Misty" series; in Europe it occurs on
many Limonium species. |
Unlike powdery mildew fungi, this fungus requires very wet
conditions to flourish. Favored by cool temperature. High relative humidity
(90% or greater) and free moisture required for spores to germinate and
infect plants. Spores require a minimum of 8 hours of wetness before infection occurs. |
In greenhouse, provide good air circulation and keep relative
humidity below 85%. Avoid wetting foliage, using drip instead of overhead
irrigation if possible. Remove infected plants immediately. Protect foliage with fungicides if necessary.* |
Gray mold
(Botrytis cinerea) |
Rot of leaves, stems, and flowers. Rot may enter crowns and kill
plants. Woolly gray fungus sporulation develops on decayed tissues. Flower
stubs remaining after flower harvest are particularly susceptible. The fungus also may kill seedlings. |
Fungus has a wide host range and develops on dead plant parts.
Spores are airborne. The disease is prevalent in California in cool (below 77°F) rainy weather. |
Clean up plant debris. Incorporate crop residue into soil as soon
after harvest as feasible. Avoid overhead irrigation especially when flowers
are present. Protect plants with iprodione or fenhexamid. more info * |
Verticillium wilt
(Verticillium dahliae) |
Plants are stunted. Lower leaves yellow, wilt, and dry. |
The fungus, which has a wide host range, survives in soil as microsclerotia. |
Fumigate soil with methyl bromide to chloropicrin combination. Heat,
fumigate, or solarize soil used in production of transplants. more info * |
| |
| Virus or viruslike disease |
Symptoms |
Host range and natural spread |
Comments on control |
Aster yellows
(Phytoplasma) |
Stunted growth, multiple production of short stalks, malformation
and bunching of young leaves. Leaves on more mature plants are reddened in
the basal rosette. Flowers are abnormal: reduced size, abnormal shape and color (frequently green), and may fail to open. |
Phytoplasma are transmitted by leafhoppers. |
Control insects. Destroy infected plants. |
Mosaic
(Turnip mosaic virus) |
Plants are stunted and have a mosaic pattern of light and dark green in leaves. Plants infected when young often die. Leaves may be distorted. |
Virus is transmitted by several different aphids and is common in many weedy plants in the mustard family (Cruciferae). |
Control nearby cruciferous weeds. Control aphids. |
| Statice is also susceptible to powdery
mildew * (Erysiphe polygoni), rust * (Uromyces spp.), bacterial crown rot (Pseudomonas spp.), southern blight * (Sclerotium rolfsii), Broad
bean wilt virus, Cucumber mosaic
virus, Statice virus Y, Tobacco rattle virus, Tomato bushy stunt virus, and root knot nematode** (Meloidogyne spp.). |
| * For additional information, see section on Key Diseases. |
| ** For additional information, see section on Nematodes. |
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