Q. Last year, my gladiolus got a blight. They would get about 2 feet high and then turn yellow and start to die. Some of them did bloom, but blossoms were small with blotches. Is this a ground problem or a plant disease? What is the treatment? – Clyde Dawson, Urbana, Ind.
A. Several diseases can attack gladiolus leaves. It’s most important to remove and destroy diseased plants. Plant glads in locations with good drainage and air circulation. Take a sample of the infected plant to your local county Extension office for diagnosis. A fungus can be sprayed or dusted with the appropriate fungicide to keep the symptoms at bay, but a virus cannot be controlled chemically. It’s important to know what you’re dealing with before you try to fix the problem with herbicides.
Viruses are spread by aphids, so keeping the aphid population under control can reduce its spread. Regularly spray the foliage with water to knock down aphid populations or spray with an insecticide containing diazinon. Always read and follow label directions.
Q. I have had a problem with my white radishes for the past several years. When they are half-matured, they start turning black and are inedible. Can you give me an answer to this? – Roy Meyers, Kokomo, Ind.
A. Your radishes are afflicted with a fungus that is most severe on white radishes, especially ‘White Icicle.’ It’s most damaging in warm, wet soils. Throw away all infected roots, and keep the garden clean of all plant debris after harvest. Rotate the location of radishes so they are not planted in the same spot for 3 or 4 years. Avoid over watering and grow in well-drained soil. You may also choose to dust seeds with a fungicide containing captan or thiram before planting.
Q. I forgot that my weeping peach tree was tied to a stake for a year or so. When I untied it, I discovered that it had a serious sap problem. The leaves do not look healthy in the summer, although I have watered it. Any suggestions? – Pat Ritter, Bloomfield, Ind.
A. There are several possibilities. Bacterial canker causes sunken lesions on the trunk or branches. A thick sap oozes from them, and the diseased branches need to be pruned from the tree. In the fall, spray with a fruit spray containing basic copper sulfate to partially control the canker.
The sap that you see could also be caused by peachtree borers, which bore into the trunk and lower crotches of the tree. Again, a thick, gummy sap oozes from the holes, although you may see sawdust around the holes in this instance, and leaves may be wilted. Spray the trunk and lower branches with lindane or kill individual borers by inserting a wire into the holes. This spring, prevent borers by spraying the trunk and branches with liquid sevin in late May or early June.
Keep the tree healthy with proper fertilization, watering and a multipurpose fruit spray, carefully following label directions and scheduling.
Q. I’ve tried to find the full address of the Seed Savers Exchange for several years. Could you please help me? – Judith Clubb, Indianapolis, Ind.
A. The Seed Savers Exchange is a nonprofit, tax-exempt organization that works toward saving heirloom garden seeds from extinction, with an emphasis on varieties brought to North America by immigrant gardeners and farmers. You can reach SSE at 3076 N. Winn Road, Decorah, IA 52101, phone (319) 382-5990, or find them on the World Wide Web at http://seedsavers.org.