Nutrition

Also refer to "Nutrient Management" in this guide for more information .

Soil Analysis

Specific soil test-based fertilizer recommendations have not been developed for currants and gooseberries. In the absence of other information, refer to the P and K recommendations for raspberries and strawberries in this guide. Conduct a soil analysis every three or four years to monitor changes in pH, P, K, Ca and Mg.

Leaf Analysis

Leaf analysis can be a useful method to determine nutrient needs; however standard tissue levels have not been established for currants and gooseberries. Leaf analysis may also be used if a nutrient deficiency is suspected. For the best interpretation, take leaf samples at the same stage of plant development (e.g. mid-harvest or late-harvest) each year and monitor year-to-year trends in nutrient status. For routine leaf analysis, collect the most recent fully expanded leaves from the current season’s growth. Select about 5 leaves from 10 plants distributed at random through the field. If leaf analysis is to be used to diagnose a problem, take separate samples from good and poor growth areas for comparison. Leaves must be free of soil, pesticide and irrigation water residue. Air dry them in an open paper bag or take them directly to a lab.

Fertilizer

Currants and gooseberries require soil applications of nitrogen and other nutrients to maintain adequate vigour. The rate and type of fertilizer will depend on the soil type and fertility, plant age, plant spacing, leaf tissue levels and the observed vigour and productivity of the plants.

Unless using a slow release fertilizer, nitrogen should be applied in split applications — the first at bud break and the second in early June. Slow release fertilizers are applied once, usually in early spring. Follow the manufacturers’ directions for blends and application rates to avoid late season nitrogen release.

There is no local research information on which to base fertilizer recommendations. A general recommendation is to apply a complete fertilizer to supply yearly rates of 50 to 75 kg/ha (20 to 30 kg/acre) of nitrogen and rates of phosphorus and potash according to initial soil test results. Adjust fertilizer rates over the years according to leaf testing results and observations of plant vigour.

Minor Elements

Magnesium may be low in many soils in BC. Magnesium oxide (MgO) at 2 to 8% in the basic fertilizer is usually enough to take care of the plant’s needs. Correct deficiencies during the growing season by applying a spray containing 1 kg of magnesium sulphate (Epsom salts) in 100 L of water. Spray to thoroughly wet the bushes and spray under cool, slow drying conditions.

Iron (Fe), boron (B), zinc (Zn) and copper (Cu) are other minor elements that can be deficient. Foliar sprays to supply minor nutrients can be applied when the bushes are well leafed out but not during bloom. Apply during slow drying conditions in enough water to wet the bushes. See Table 12 in "Nutrient Management" section for materials and rates. Some minor elements can also be applied to the soil to overcome deficiencies. Custom fertilizer blends are available which supply various minor nutrients.

Pruning

Annual pruning is necessary to maintain vigour and encourage new, productive fruiting wood. Pruning is best done during the dormant period from mid December to early March.

Black Currants

Black currants produce the highest quantities of the best quality fruit on one-year-old wood. They should be pruned heavily every year to remove older non-productive wood and encourage strong new growth. Weak growth and spreading, horizontal branches should also be removed. In some situations, the cost of hand pruning can be prohibitive. Pruning can be mechanized using specialized mechanical harvester attachments. Another optional cost-saving practice is to renovate (mow to the ground) a part of the field every fourth year.

Red currants/Gooseberries

Unlike black currants, red currants and gooseberries produce fruit on two-year-old wood and on spurs which form on three-year-old wood. Prune to remove weak, low and diseased wood, encourage an open shape with fruiting spurs well distributed through the bush and to remove old, poorly producing wood. Red currants and gooseberries can also be trained to a cordon (permanent leg) system to allow easier harvesting and tighter spacing.