| Disease |
Symptoms |
Pathogen/Cause |
Management |
| Anthracnose and Crown Rot |
Young plants wilt, yellow, and die. Tan to brown
spots with yellow halos develop on flower stalks, wings, and
flower parts. These enlarge, become reddish brown to brown or
black on some cultivars. |
Colletotrichum gloeosporiodes |
Apply chlorothalonil to protect healthy plants. |
| Bacterial Rot |
Yellow and dead leaves are found among healthy
basal rosette leaves. Symptoms sometimes develop only on one
side of the midvein. Veins may be red. Crowns and entire plant
die. Rotting crowns smell foul. |
Pseudomonas |
Plant disease-free seedlings. |
| Botrytis Blight |
Leaves on seedlings die and become covered with
gray mold. Flowers discolor and collapse. When dried, infected
flowers fall out of the head. Entire flower stalk may yellow
and die. |
Botrytis cinerea |
Purchase decorticated seed that has been treated
with hot water and fungicide. Avoid overhead irrigation. Water
early in the day so that leaf surfaces dry. Space rows and maintain
good weed control to insure adequate air circulation. To protect
healthy plants, thoroughly cover plants with chlorothalonil,
mancozeb, or iprodione. |
| Cercospora Blight |
Small reddish spots form on leaves and flower
stalks. Spots become brown and the entire leaf dies. |
Cercospora insulana |
Protect seedlings as well as older plants by
applying chlorothalonil or mancozeb before infection occurs. |
| Red Leaf |
Leaves redden. |
Cold weather or virus infection |
Cold weather-injured plants recover. Virus-infected
plants do not recover and should be destroyed. |
| Rhizoctonia Crown Rot |
Gray spots develop on leaves near the soil. The
crown and entire plant die. |
Rhizoctonia solani |
To protect healthy plants, apply PCNB or etridiazole
+ thiophanate methyl. |
| Seedling Blight |
Seedlings are killed. |
Alternaria,
Botrytis, Stemphylium,
Fusarium, Cercospora,
and Colletotrichum |
Produce seedlings from decorticated, hot water
and fungicide-treated seeds. |
| Virus |
Depending upon virus involved, stunting, deformed
leaves, mosaic, red leaves, red or yellow line patterns and
ring spots may develop. |
Broadbean wilt, cucumber mosaic, statice Y, tobacco
rattle, tomato bushy stunt or turnip mosaic virus |
Destroy infected plants. Maintain good aphid
control to delay virus spread. Wash hands and disinfect tools
thoroughly after handling infected plants to prevent mechanical
spread. |
| Yellows |
Small leaves, yellowing, stunting, and excessive
branching occur. Mature plant leaves may redden. Flowers may
fail to open, be reduced in size, or have abnormal color and
shape. |
Phytoplasm |
Destroy infected plants. Maintain good leafhopper
control to delay spread. |
