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"No Cure for Impatiens Necrotic Spot Virus" Q. I have never had this problem before but my impatiens are dying or something. The leaves are turning yellow and have black spots. We know they are getting enough water as we water and have fertilized regularly. So what's going on? Thank you. A. I also bought impatiens transplants at the same place you did this spring so I know exactly what problem you brought home. The problem is called impatiens necrotic spot virus, or INSV for short. In recent years INSV has become a very serious and widespread disease of greenhouse flower crops including, but not limited to, impatiens, New Guinea impatiens, ageratum, amaranthus, amaryllis, anemone, baby's breath, begonia, calceolaria, calendula, calla lily, campanula, China aster, chrysanthemum, cineraria, coleus, columbine, coreopsis, cosmos, cyclamen, dahlia, delphinium, exacum, forget-me-not, gaillardia, geranium, gladiolus, gloxinia, hydrangea, lobelia, marigold, nasturtium, peony, petunia, phlox, poppy, primrose, ranunculus, salvia, sinningia, snapdragon, stock, tiger lily, verbena, zinnia, and over 300 others. INSV also affects certain vegetables like broad bean, cauliflower, celery, eggplant, lettuce, pea, pepper, potato, snap bean, spinach, and tomato. INSV is a serious problem facing the floriculture industry. As you know, when you buy your plants they look fine, but later on they start looking bad and showing symptoms of the disease. INSV can look different on different plants. Symptoms you may see include necrotic (brown, dead) ring spots on the leaves, yellow circular spots on the leaves, stems may have black or brown discoloration, stunted plants, flower color breaking, leaf veins may be brown, death of the tip growth, wilting, collapse of the entire plant, leaves may have yellow line patterns in them, or there may be mosaic, variegated patterns of light and dark green in the leaves. Years ago when I first identified this disease on plants I had bought I was told it comes in on the seed. Tiny, nearly invisible insects known as thrip spread INSV from plant to plant. Researchers say the virus may also be spread throughout the greenhouse industry by the movement of infected plants or cuttings. Unfortunately, once the plants are infected there is no cure. The best thing to do now is to remove and throw out in the trash any infected plants and to control the thrips before they can spread the virus to other plants in your garden. I use Neem Oil to control thrips. Made from the seeds of the Neem tree that grows in India, this amazing all-natural spray is an insecticide, fungicide, and miticide all in one. It can be used on all plants including roses, perennials, annuals, trees, shrubs, flowers, fruits, vegetables, and house plants. It controls all stages of insects (adult, larvae, and egg). It acts as a growth regulator, antifeedant, repellent, and contact killer of many common and hard-to-control insect pests, including thrip. Click here to read more about Neem Oil and order it from Pernell Gerver's Online Store.
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