These Ribes species are not nearly as popular as they used to be for 2 reasons. In the first place, the fruits must be processed as soon as they are picked. Secondly, most Ribes species have proved susceptible as alternate hosts to the White Pine blister rust disease and there are definite restrictions placed (by Federal Quarantine Acts) against growing them in many states and counties. The home gardener who wants to grow currants (or gooseberries) should first write his State Experiment Station to ascertain whether it is permissible to grow them in his area.
Currants are grown in bush form, in normal garden soil. They are hardy well north of where apple trees are grown. These shrubs take little care. They might be mulched to help with the weed problem. The application of well-rotted manure not only acts as mulch but a fertilizer as well. The application of commercial fertilizers is usually not worth the effort except on very poor soils, but plants in the home garden frequently respond well to addition of nitrogen in the form of a complete fertilizer. They should be spaced about 5 ft. apart. All canes over 3 years old should be removed. Fruits should be used as soon as they are picked, but they can remain on the bush for a week or so in an almost fully ripe condition.
Currants are propagated commercially by hardwood cuttings taken in the fall after the leaves have dropped. The home gardener can easily obtain a few extra bushes merely by layering a few branches.
As for varieties, ‘Red Lake’ is an excellent one for the home garden. ‘Wilder’ produces more heavily and so is preferred for commercial plantings. Fifty percent of the currants grown in the U.S. today are grown in N.Y. ‘White Imperial’ is the best white-fruited variety, and ‘White Grape’ is sometimes listed by nurseries.
The black over-wintering eggs and San Jose scale are killed by dormant sprays of insecticide. Insecticide is effective if thoroughly applied to the curled leaves. Currant borer which tunnels and kills the canes and currant stem girdlers which cause the new canes to break near the tip in early summer are checked by sprays of insecticide when the adults are active, but butting and burning the infested canes is advised. Imported currant worms, the larvae of a sawfly, are voracious caters when the leaves are about full grown. Spray with insecticide but do not use insecticides that may leave harmful residue on the harvested fruit. Plant bugs and San Jose scale may infest currant.
Brown or purplish spots on the leaves indicate infection by currant anthracnose, and fungicide gives good control. Blister rust, which is more important on White Pine, occurs as bright orange spots on Currant leaves in midsummer. Fungicide is advised. Before planting currants, check with local authorities concerning restrictions.
A South African bulbous plant similar to Gladiolus, belonging to the iris Family, is related to Antholyza. Flowers are red and yellow borne in spikes and grown from bulbs planted in the spring.