Leaf spot, drought, frost damage and environmental conditions are some reasons laurel leaves turn brown. Laurel is affected by leaf spot, causing yellowing and browning of the leaf tissue and irregular blotches, lesions and spots. New plants are most susceptible to drought damage, while frost harms the plant at any stage of growth. Well-drained soil with a pH level over 6 and a sunny location are necessary for best development.
Treat leaf spot by raking up and removing dropped leaves to prevent the fungus from spreading. Mix 2 teaspoons of fungicide powder containing benomyl with 1 gallon of water, and apply evenly over the foliage every two weeks in the spring.
Water plants weekly during a drought. The soil should be saturated 12 to 18 inches deep. Mulch around the base of the plant to hold in moisture.
Laurel should only be planted in U.S. Department of Agriculture zones 4 through 9. If the plant is harmed by an unexpected cold snap, prune out dead or dying branches to reduce the possibility of attracting pests and diseases.
If mountain laurels are located in an area with clay soil, plant them in a raised bed to improve drainage. Plant near other trees to create a canopy of dappled shade.