Spots on Irises - Knowledgebase Question

nashville, Te
Question by jvs7829
April 10, 2009
My mother-in-law's irises are looking bad this year and not blooming. She's very concerned. They've been fine for years. They've got brown spots on them that look like mold or a fungus this year. She's worried that she over watered them using drip water from a sink that was leaking. What can we do to save them?

Answer from NGA
April 10, 2009


Sounds like a standard fungal disease and irises are prone to them if they are overcrowded or leaf debris is not cleared from the garden at the end of the growing season. The fungus that's attacking your plants overwinters on dead leaves and other plant remains, so be sure to clean the iris bed up and remove any plant debris. Spores are produced in spring and infect leaves, especially if the weather is warm and wet. To help prevent infection, and the spread of infection, give your plants enough space between so the leaves are not touching one another. You can apply a garden fungicide such as lime-sulfur to the leaves if you notice spots beginning this spring. Don't spray until the leaves are 6-8 inches high. You may have to spray every 10-14 days if the weather remains warm and wet. In August, after flowering has finished, dig and divide the clumps, then replant so that there's adequate air circulation around each plant. I don't think the recycled water had anything to do with the problem, so encourage your Mother-in-law to use that drip water from her sink - as long as it is clean and has no residue from dish detergent. Best wishes with the iris bed!

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