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Diseases in the Flower Garden

Written by Kayla Harless, People’s Garden Intern

Today, Dr. Karen Rane presented a workshop in the People’s Garden about diseases of the flower garden. As a plant pathologist and diagnostician, she provided us with lots of fascinating insight. Dr. David Clement, a fellow plant pathologist, joined her in instructing the workshop.

There are several factors that contribute to the chances of your flower garden becoming infected. An easy way to remember these three things is the disease triangle. The three points on the triangle, or risk factors, are having a susceptible host, providing a favorable environment for diseases, and the presence of a pathogen.

Fortunately, a lot can be done to avoid having the disease triangle present in your garden. Choosing resistant cultivars is one important step, simply research the different cultivars that are resistant and select those when buying plants. Some species are more susceptible to disease than others. While buying plants, examine them thoroughly to make sure you aren’t bringing home a pathogen. Check not only the leaves, but also the roots to make sure they are white and healthy. If they are stringy and brown, that means trouble. Using drip irrigation, or watering in the early morning so that the plants can have a chance to dry is another advantage, considering most pathogens thrive only in wet environments. Over-fertilizing your plants is something to avoid, for example, if a plant has too much nitrogen, it can become stringy and weak and more susceptible to disease. Additionally, garden clean-up at the end of the season can rid the garden of potentially infected leaves that a pathogen could over-winter in your garden.

Lastly, Dr. Rane brought many samples of flowers and plants that were infected with varying types of diseases: fungi, viruses, bacteria, leaf spots, and root diseases. Most of these can be prevented by practicing the measures discussed earlier, but some are exceptions. For example, powdery mildew lives and thrives on the surface of leaves that are not wet, unlike most. Southern blight is another disease worth mentioning, as it is very resistant to measures to rid it from the garden, and the best way to be rid of it once it has taken root is overhaul and replace the soil.

If you have specific questions about problems in your own flower garden, extension services and land-grant universities often have researchers and laboratories on-hand and can provide lots of specific information about relevant plant problems in your area.

Dr. Karen Rane brought samples of plants with various diseases, here she showed the workshop attendees a Vinca with a bright yellow leaf spot.

Dr. Karen Rane brought samples of plants with various diseases, here she showed the workshop attendees a Vinca with a bright yellow leaf spot.

Southern Blight, a fatal plant disease in the roots, can be recognized by very small tan spots on the roots that resemble birdseed.

Southern Blight, a fatal plant disease in the roots, can be recognized by very small tan spots on the roots that resemble birdseed.



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