QuestionsHow to growTrees and ShrubsPests and DiseasesBay Tree 0 Vote Up Vote Down Aisling O\’Leary asked 16 years ago I have a Bay Tree in a large container. It has been doing well until the last month. It has now got little brown scaly lumps under the leaves and a lot of the inner leaves near the trunk have turned yellow. Do you know what is causing this? 1 Answers 0 Vote Up Vote Down Gerry Daly Staff answered 7 years ago This is scale insect and you need to spray with an insecticide, thoroughly, and do not use the leaves for cooking for a while.