I have had for several years a thriving japonica kerria with round double yellow flowers in the spring.
Recently the entire bush got leaf spot disease and almost all branches are leafless.
What should I do?
Many thanks for your advice.
Don’t panic. Although leaf spot may have defoliated your japonica kerria, the defoliation should not cause the death of a healthy shrub.
If you want to try and control for leaf spot, for next year, make sure that you rake and destroy all old leaves under or near your shrub. Do not compost them. Prune away any dead growth, as the healthier your shrub is the more it will be able to resist the infection. As well, to try and prevent an occurrance, next spring you can spray with neem oil or a sulpher based fungicide. The spraying should be done by several applications. The first should be early in the spring just before the leaves unfold. The second one to two weeks later. A third application can be made, especially if there is a wet rainy spring.