On the dead stems small, black fruiting pustules are produced and visible with a hand lens. Pruning and removing infected canes back to healthy wood when the bark is dry is a key strategy for control. It is also helpful to maximize plant vigor by following sound cultural practices which include fertilizing, pruning, and watering. White pine blister rust, Cronartium ribicola. All species and varieties of currants are susceptible to one stage of the rust causing white pine blister rust.
Symptoms appear as flat bright orange spots on the leaves in midsummer.
Red currants are not very susceptible but black currants are very susceptible. Although this rust is of minor importance on currants, the fact that they are an alternate host for the white pine blister rust, probably the most serious disease of white pine, gives added importance to this disease on currants. Although Connecticut no longer prohibits growing currants, many other New England states still limit their growth. These include Titanic, Consort, and Crusader. Chemical control is not effective.