Concentrate spraying of apple trees

Abstract

SUMMARYFollowing earlier indications of the importance of the quantity of lime‐sulphur concentrate applied per acre (dosage) in the control of apple scab and powdery mildew, further intensive paint‐gun experiments were designed to clarify basic dosage/volume relationships. They established that control depends primarily on the dosage and not merely on the volume of spray applied, but the volume was in some circumstances a critical factor in spray damage.Incidental data showed the influence of lime‐sulphur dosage also on the population of fruit tree red spider mite and on infestations of sawfly. There was evidence that the incidence of fruit russet and poor skin finish is sometimes related to impaired foliage.Gravity flow and droplet‐size of spray together increased with increasing dilution of lime‐sulphur, and thus influenced spray distribution on the foliage when a range of dilutions was applied at fixed volume/acre.