Answer: Overwatering can cause bulb and crown rot so it might be worth your while to dig up one of the affected plants. Carefully inspect it for signs of rot. If nothing is mushy replant the lily and cut away the browning leaves. Be sure to water deeply but then allow the top of the soil to dry out between waterings to avoid rot. Overcrowding and competition for sunlight can cause similar symptoms. Each plant should have several inches of free space to encourage good air circulation around and within the plant. Hope this helps you determine just what might be happening with your lilies.
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