| Disease |
Symptoms |
Pathogen/Cause |
Management |
| Aster Yellows |
Leaves yellow. Abnormal branching occurs. Yellowed,
leaf-like tissue forms instead of flower parts. |
Phytoplasm |
Destroy infected plants. Maintain good leafhopper
control. Destroy any similarly affected weeds in the vicinity. |
| Botrytis Blight |
Brown specks form on petals. The entire flower
browns and dies. |
Botrytis cinerea |
Avoid sprinkler irrigation. Apply chlorothalonil,
mancozeb, or iprodione. |
| Fusarium Wilt |
Young seedlings are killed. Older plants are
stunted and have yellowing and wilting up one side of the plant.
Water-conducting tissue in the stems browns. |
Fusarium oxysporum |
Use potting soil that has been treated to eliminate
pathogens. Or, use soil less potting mix. |
| Leaf Spots |
Spots form on leaves. Leaves yellow, wilt, and
die. Usually lower leaves are affected first and symptoms progress
upward. |
Alternaria,
Ascochyta, Cercospora,
Septoria |
Avoid sprinkler irrigation. Apply chlorothalonil,
azoxystrobin, myclobutanil, mancozeb, iprodione, or thiophanate
methyl + mancozeb. |
| Powdery Mildew |
White, felty growth develops on the surface of
leaves. Leaves wither and die. |
Erysiphe cichoracearum |
Apply Ampelomyces,
mancozeb, myclobutanil, paraffinic oil, triforine, azoxystrobin,
triadimefon, or thiophanate methyl + mancozeb. |
| Pythium Root Rot |
Plants wilt and die. Roots are bown and limp. |
Pythium spp. |
Use pasteurized soil. Apply propamocarb to protect
healthy plants. |
| Rust |
Reddish-orange masses of spores form on the underside
of leaves. Severely affected leaves yellow and die. On the alternate
host--pines--blisters of spores form on needles in the spring. |
Coleosporium solidaginis |
No control is recommended. |
