Answer: It's difficult to know exactly what the problem is because you didn't identify the shrubs or tell us about the care they have been receiving. Are the leaves turning brown all over, or just some of the leaves? Did it start at the top and move down, or at the bottom and move up? Did you inspect the leaves for insects. If so, what did you find? Malathion is a powerful insecticide but it won't fix diseased plants. Maybe your plant has a disease and that's why the malathion had no effect.
Send us another question with as many details as possible and we'll try to diagnose the problem with your shrubs.
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