Leaf Blight affects Heirloom Carrots and occurs in seven states in the U.S. These states include Arizona, Indiana, Iowa, Michigan, New York, Oregon, and Wisconsin. Leaf blight starts out with spots on seedling leaves that start out yellow white and in time they turn brown and look water soaked.
The prevent leaf blight in heirloom carrots, try the following preventive solutions. Try a hot water seed treatment; out the seeds in 126°F water for 25 minutes. This will kill the leaf blight bacteria on the carrot seeds. Make sure all of your heirloom carrot seed is disease free. Remove and destroy all heirloom carrot tops at harvest time to help keep the bacteria from wintering over. Remember to rotate all you heirloom carrot as well as other heirloom crops on a 3 year basis.