The Grecian laurel, from which we get culinary bay leaves, is a slow-growing evergreen tree that eventually reaches 12 m (40 feet) tall. Pests and specific cultural issues negatively affect bay trees.
Nutrient deficiencies in bay trees cause foliage distortion and discolouration. Common deficiencies are iron and nitrogen. Nutrient deficiencies are usually caused by conditions that prevent a tree from taking up minerals such as waterlogged soil, root disease and nematodes. Eliminate these problems and test soil before feeding to determine which minerals to apply.
Overfertilising and excessive pesticide use can lead to bay leaf tip and margin burn and branch dieback. Use care with pesticides, ensure adequate drainage and avoid overfeeding.
Watch for scale and thrips on bay trees. Thrips are tiny winged insects that feed on new leaves, causing scarring, distortion and defoliation. Scale insects are brown or black bumps on leaves that cause wilting, yellowing and leaf drop. Treat both pests with horticultural oil.
Water management problems
Improper watering and insufficient drainage cause discoloured and wilted leaves, defoliation and susceptibility to root rot in bay trees. Water when the first 7.5 to 10 cm (3 to 4 inches) of soil is dry and avoid wetting the trunk.