How can I effectively remove a white stain from my fence?

To effectively remove a white stain from your fence, you can try using a mixture of warm water and mild detergent to gently scrub the affected area. If that doesn't work, you can also try using a mixture of equal parts vinegar and water or a commercial stain remover specifically designed for outdoor surfaces. Be sure to test any solution on a small, inconspicuous area of the fence first to ensure it doesn't cause damage.