Complete underleaf spray coverage is essential for good control of several pest problems in strawberries. Two-spotted mites (Tetranychus urticae), for example, tend to build up on the undersides of the lowest leaves. Diseases such as common leafspot (Ramularia tulasnii) and powdery mildew (Sphaerotheca humuli) infect the underleaf and can develop into important sources of disease.