Spring flowers and shrubs can be so beautiful — but as Loretta Aaron, one of Oklahoma City's best gardeners, always said in spring: “Do not become complacent. We now have warm days and humid nights, following showers.” Those ingredients can lead to fungal diseases in the garden. Here are Loretta's tips on how to combat diseases on two garden favorites: roses and crape myrtles.
The bane of rose growers is black spot, a disfiguring and damaging disease. If you had the problem last year and your roses went into winter with diseased foliage, you can be sure it will be just a matter of time until you notice the foliage is yellow, with black spots, and is falling to the ground. Your roses may have gone into the winter with healthy foliage; however, you could still have a problem. The fungi are also wind-borne, and we have certainly had wind lately.
If you have not started a preventive program, do so immediately. Control is easier than cure. Apply a fungicide weekly, more often if it rains for days on end. Drench plants thoroughly and even direct the spray material on the soil around the plants to kill spores living in the soil from diseased foliage dropped last fall. A light application of sulfur on the soil around the plants is also beneficial because this is a fungicide, and it will kill the spores. After spring rains cease, days become hot, and humidity drops, it will not be necessary to spray your roses with fungicide as often.
Growth of crape myrtle plants can be rapid when we have continued rain in spring. When that happens, the new growth can be weak due to lack of sunlight. No, the foliage should not be gray. Keep foliage as dry as possible or mildew could become a problem. Move fast between spring showers. Try to spray with a fungicide at least twice weekly. A fungicide such as Benomyl works well. Grow in full sun, and try to give enough space to allow free circulation of air around the plants.
For 21 years, Loretta Aaron, an Oklahoma City gardening expert, was a beloved and well-known gardening columnist for The Oklahoman. Loretta died in 2009. With the permission of Loretta's family, we will reprint some of Loretta's words of gardening wisdom.
Beautiful Things Happening in OKC
Thursday: Making Oklahoma City Beautiful Young Professionals will hold a cooking class with Kamala Gamble. Gamble will use fresh produce from her garden to teach several organic recipes. The class is $20 per person.
May 21: Making Oklahoma City Beautiful Young Professionals will take a boat ride on the Oklahoma River from 6:45 p.m. to 8 p.m. There will be a cash bar and hors d'oeuvres.
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