Managing Apple Scab
Scab is one of the most devastating diseases of ornamental crabapples and apples. If early spring weather conditions are optimum (warm and moist), hawthorn and mountain ash may also be seriously affected.
Fungicide sprays will effectively control apple scab if applied in spring. Treatments should be applied at seven to ten day intervals from bud break until two weeks after petal falI. It is also advised to improve tree vitality by appropriate fertilisation, mulching and watering as needed. If scab is already present at the time of treatment, greater benefits are generally observed the following year.
Later, in autumn, we advise that you remove fallen leaves and any mummified fruit to reduce the inoculum potential. During winter, pruning is recommended. A Bartlett Arborist can clean and/or lightly thin the crown to improve circulation of air.
Keep in mind that some varieties of crabapple have demonstrated resistance to apple scab. When selecting new plantings, resistant varieties that have the desired aesthetic foliage, fruit, and flower characteristics, should be used.