The Q&A Archives: gladiolus leaves turning brown

Question: I have two flower beds that I planted gladiolus bulbs in, one of the beds the leaves are turning brown on most of the plants, could you please tell me why this might be happening, the plants with the problem are on the south side of my house and recieves at least 6 hours of direct sun a day, could I be watering to much or not enough. Thanks, Sandra

Answer: It may be that your glads are infested with thrips. These tiny insects feed by sucking liquids out of the tissues. Affected leaves shrivel and dry up. Female thrips can lay up to 200 eggs and only 2-4 weeks are required for them to reach maturity, so there can be as many as 5-6 generations in a single growing season. Unfortunately, once the thrips are in the flowers, it's very hard to control them. In greenhouse situations, high humidity leads to increased thrips mortality because it fosters a fungus that attacks the insects. You can try keeping your soil more moist than usual to kill the pupating stage in the soil. You can purchase predatory mites, lady beetles and lacewings and release them, as they all feed on thrips. Beneficial nematodes also feed on the pupae in the soil. Next spring you can try to prevent their presence with reflective mulch of aluminum foil. Studies show that the reflected light confuses the thrips that migrate from surrounding areas, and prevent them from landing on plants which the foil surrounds. I wish you the best of luck!

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