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| Photo Credit: ©2002 Dolezal Publishing/John M. Rickard |
| Mosaic virus is an incurable plant disease. Remove infected plants from the garden and dispose of them in household waste or burn them. Avoid composting. | It’s easy to blame plant loss on pests, but it’s not always insects that destroy a garden. Viruses and fungal problems can be just as damaging – and sometimes worse. Here’s a look at some common disease symptoms you may notice on your plants, as well as possible causes and remedies.
Symptom: Black, tan or red spots on leaves. Leaves yellow and drop. Black cankers on stems, with a general wilt of branch tips.
Cause: Anthracnose, a fungal disease that occurs in late spring and summer, typically after humid conditions.
Remedies: Remove infected leaves and branch tips. Collect and destroy infected fallen leaves. Thin excessive growth to promote air circulation. Spray with bordeaux mixture – a copper sulfate and lime-based fungicide. Symptom: Leaves are mottled with black spots, then eventually yellow and die. Powdery
black or brown dusting on foliage and blossoms. Leaves may drop.
Cause: Black spot and/or leaf spot – fungal diseases found on many plants. Both spread by spores blown onto moist plant leaves. Common in shady, crowded plantings.
Remedies: Space plantings to allow good air circulation. Remove shading foliage. Apply water at base of plant. Strip and destroy infected leaves. Spray with bordeaux mixture – a copper sulfate and lime-based fungicide. Symptom: Flowers wilt, and foliage tips curl, yellow and die. Oozing cankers form at base of shoots with main stem. Affected foliage may have a strong odor.
Cause: Blight and scab, several bacterial diseases caused when soil containing bacteria is splashed onto cut and bruised foliage or is carried to flowers by pollinating insects.
Remedies: Remove and dispose of affected plants. Apply water at base of remaining plants. Install floating row covers and pollinate by hand. Rotate plantings annually to new beds. Spray with bordeaux mixture – a copper sulfate and lime-based fungicide. Symptom: Flowers and foliage collapse under a heavy fuzz of brown or gray fungal spores.
Cause: Botrytis rot, also known as gray mold.
Remedies: Remove affected blossoms, foliage or entire plant. Space plants for more air circulation. Reduce nitrogen fertilizer. Symptom: Gray scabs form on the blossom ends of maturing tomatoes and peppers.
Cause: Blossom-end rot, a developmental and cultural disorder rather than bacterial or fungal infection caused by stress and mineral deficiency.
Remedies: Strip affected fruit from plants. Fertilize with a 5-10-10 formula and mulch soil surface with organic compost. Water deeply and regularly. Shade affected plants from hot midday sun.
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