CURRANT
Ribes spp., family SaxifragaceaeBailey (1949*) listed the following species of currants:
[gfx]
fix table below :R. americanum Mill. American black currant R. aureum Pursh. golden (black) currant R. nigrum L. European black currant R. odoratum Wendl. Missouri or buffalo (black) currant R. rubrum L. northern red currant R. sativam common or garden (red or white) currant (Reichenb.) Syme
Red currants are more common in the United States, whereas black currants are produced primarily in Canada, England, and Russia. Shoemaker (1955) stated that production of currants and gooseberry in the United States amounted to about 4 million quarts from about 4,000 acres. The majority of this was currants, of which New York produced about half the total amount. The 1964 U.S. Census of Agriculture showed only about 600 commercial acres of red and golden currants, which produced 2.5 million quarts and valued at about one-half million dollars. Yields of 100 to 400 bushels per acre were obtained.
The fruit, a berry that ripens in late summer, is used primarily in jellies, jam, juice, and canning or is eaten fresh. The fruit may be from I/3 to 2/3 inch in size, oval, soft, and juicy and may contain many seeds.
This crop should not be confused with the dried currants of commerce, which is a seedless grape (Hedrick 1938*).
Plant:
The currant is a stout, woody, usually spineless deciduous shrub, 4 to 7 feet tall unless trimmed to a lower height for ease of fruit harvest. Some of the species are fragrant, but R. nigrum emits a strong unpleasant odor. The fruit (fig. 104) varies in color from black to purple and scarlet with hues and stripes of yellows, greens, and white (Bailey 1914*, v. 2, pp. 603-1200, v. 5, pp. 2423-3041). The plants are native in comparatively cold climates and are the hardiest of fruits from the standpoint of resistance to cold or changing temperatures. They do not thrive in hot or dry climates.
The growing of these crops has been prohibited in some areas because the plant serves as a host for white pine blister rust (Slate 1 933).
Cultivated red currants are set about 5 feet apart in the row; black currants, 6 to 7 feet apart, with the rows 8 to 10 feet apart (Strong 1944).
Inflorescence:
The small flowers of the black and red currants are saucerlike (open-campanulate) and whitish or greenish. The yellow flowers of R. odoratum are tubular, about one-half inch long, with the calyx tube about twice as long as the sepals. Nectar, produced in the base of the flower, and pollen, produced on the half dozen or less anthers (Thayer 1923), are both highly attractive to bees (Pellett 1947*). Zakharov (1958) stated that those cultivars with higher sugar concentration in the nectar were visited more frequently than those with low-sugar concentration. The flowers are in few- to many-flowered racemes, and the minute petals are smaller than the sepals. The extremely short stamens arise on the base of the petals and incline slightly toward the style. Style and stigma are roughly the same length on most species (Thayer 1923); however, at least in some cultivars the stigma extends beyond the anthers (Strong 1944). Apparently, the stigma is receptive about the time pollen becomes available. Some plants are dioecious.
Pollination Requirements:
Fraser (1927), apparently referring to Americangrown species, stated that currants are self-fertile, thus single cultivars could be planted in a block, even though two or more are usually planted together to extend the season. Apparently, he did not distinguish between the receptivity of the plant to its own pollen and the ability of the flower to fertilize itself without the aid of an outside agency. Philp (1933) and Strong (1944) recognized this difference for they stated that currants are self-fruitful but that they require insect application of the pollen to the stigmas. Smith and Bradt (1967*) also stated that some cultivars require transfer of pollen by an outside agency.
Much more research on the black currant (R. nigrum) has been conducted in Europe and Russia than elsewhere. Free (1970*) reviewed the pollination information on this crop, including his own work (Free 1968a). He (Free 1968a) showed that both yield and quality of black currants were improved by cross-pollination by insects. He was supported by Hughes (1966), Glushkov (1958), Williams and Child (1963), and Zakharov (1960a, b). The fruit drop of black currants 7 to 10 days after flowering was associated by Zakharov (1958) with lack of adequate insect pollination. Wellington et al. (1921), according to Free (1970*), associated fruit drop with lack of pollination. Teaotia and Luckwill (1956) concluded that seeds per berry was the main cause for variation in size of fruit and the percentage of drop of the fruit.
Pollinators:
Frequently, when currants bloom, there are few native insects to visit the flowers in numbers sufficient to adequately account for the pollination required in the production of a commercial crop. In general, the honey bee is the only insect present in numbers aufficient to be of economic importance, although at times and in certain locations bumble bees are also of value (Free 1968b). Although, as Free (1970*) indicated, a certain amount of pollen may be transferred from anthers to stigma by swaying of the plant in the wind, in general, insects, specifically bees, are necessary on most cultivars of currants. Free (1968a) showed that selfincompatibility was not a factor in black currants, but transfer is necessary of pollen to the stigma within the flowers of most cultivars. Glushkov (1958) showed that the 'Laxton' black currant set only 2.2 percent of seed (0.08 kg fruit per bush) when isolated from bees but when pollinated by bees it set 46.0 percent of the seed (1.9 kg fruit per bush).
Hughes (1966) showed a significant increase in black currant production from the presence of bees, and Zakharov (1960a) concluded that the heavy fruit drop 7 to 10 days after the end of blooming is because of a lack of adequate pollination by honey bees. Pollination by bees was always more effective than hand pollination (Zakharov 1960b). Schanderl (1956) obtained 10.9 to 17.3 times as much fruit from open bee-visited plants of R. nigrum as from those covered with a gauze screen cage, even though this species is considered self-fertile.
Although information is far from complete on the pollination of currants, it indicates that some cultivars require insect transfer of pollen within the cultivar. Most cultivars are materially benefitted by an adequate supply of pollinating honey bees or related bees, which can cause fruit to set and to be larger.
Pollination Recommendations and Practices:
Only Skrebtsova (1959) has studied the relation of insect populations to set of currants. He found that with 0.5 to 0.7 colonies per hectare, only 53 to 59 percent of the fruit set; with three colonies per hectare, the set of black currants was 88.3 percent. An increase to nine colonies per hectare, increased bee visitation but not seed set, primarily because the plants could not support additional fruit due to lack of fertility.
The demand for supplemental pollination of our crop of currants would not be great under any conceivable need; however, the evidence indicates that if maximum production is desired, maximum insect pollination should be provided. If local pollinators are insufficient, they should be supplemented with colonies of honey bees placed in or adjacent to the plantings.
LITERATURE CITED:
FRASER, S.
1927. AMERICAN FRUITS. 892 pp. Orange-Judd Publishing Co., New York.FREE, J. B.
1968a. THE POLLINATION OF BLACK CURRANTS. Jour. Hort. Sci. 43: 69-73.____ 1968b. THE FORAGING BEHAVIOR OF HONEYBEES (APIS MELLIFERA) AND BUMBLEBEES (BOMBUS spp.) ON BLACKCURRANTS (RIBES NIGRUM), RASPBERRIES (RUBUS IDAEUS) AND STRAWBERRIES (FRAGARIA X ANANASSA) FLOWERS. Jour. Appl. Ecol. 5: 157 - 168.
GLUSHKOV, N. M.
1958. PROBLEMS OF BEEKEEPING IN THE USSR IN RELATION TO POLLINATION. Bee World 39: 81-92.HUGHES, H. M.
1966. INVESTIGATIONS ON THE POLLINATION OF BLACK CURRANT, VAR. 'BALDWIN'. Exp. Hort. 14: 13 - 17.PHIL(I)P, G. L. (sic.)
1933. BRIEF SUMMARY OF CALIFORNIA POLLINATION STUDIES. In Iowa State Apiarist Rpt. 1932: 39-43.SCHANDERL, H.
1956. [EXPERIMENTS ON THE EFFECTS OF HONEYBEES ON THE YIELD OF CULTIVATED VARIETIES OF RIBES NIGRUM.] Gartenbauwiss., Munchen, n.s. 3(3): 284-291. [In German.] AA- 96/58.SHOEMAKER, J. S.
1955. SMALL-FRUIT CULTURE. Ed. 3, 447 pp. McGraw-Hill Book Co., Inc., New York and Toronto.SKREBTSOVA, N. D.
1959. [BEES INCREASE THE CROP OF BLACK CURRANTS.] PchelovodstVo 36(5): 25 - 28. [In Russian.] Abstract in Biol. Abs. 35(3): 25411, p. 2234, 1960. AA-357/60.SLATE, G. L.
1933. RED CURRANTS AND GOOSEBERRIES. N.Y. (Geneva) Agr. Expt. Sta. Cir. 112, 11 pp.STRONG, W. J.
1914. CURRANTS AND GOOSEBERRIES. Ontario Dept. Agr. Bul. 440: 1 - 13.TEAOTIA, S. S., and LUCKWILL, L. C.
1956. FRUIT DROP IN BLACK CURRANTS: FACTORS AFFECTING 'RUNNING OFF'. Bristol Univ., Agr. and Hort. Res. Sta. Ann. Rpt. (1955) 64: 64- 74.THAYER, P.
1923. THE RED AND WHITE CURRANTS. Ohio Agr. Expt. Sta. Bul. 371, pp. 307 - 394.WELLINGTON, R. [A.], HATTON, R. G., and AMOS, J. M.
1921. THE 'RUNNING OFF' OF BLACK CURRANTS. Jour. Pomol. 2: 160 - 198.WILLIAMS. R. R., and CHILD. R. D.
1963. SOME PRELIMINARY OBSERVATIONS ON THE DEVELOPMENT OF SELF- AND CROSS-POLLINATED FLOWERS OF BLACK CURRANTS. Bristol Univ., Agr. and Hort. Res. Sta. Ann. Rpt. (1962): 59-64.ZAKHAROV, G. A.
1958. [BEES IN THE POLLINATION OF BLACK CURRANTS AND GOOSEBERRIES.] PchelovodstVo 35(5): 29 - 33. [In Russian.] AA-179/60.____ 1960a. [ABOUT THE VISITATION OF BLACK CURRANTS BY BEES.] PchelovodstVo 37(5): 39 - 40. [In Russian.] AA-944/63.
____ 1960b. [THE ROLE OF SUPPLEMENTAL POLLINATION WITH FOREIGN POLLEN IN INCREASING THE YIELD OF BLACK CURRANTS.] Agrobiologiya 3(123): 461-462. [In Russian. ] AA-449/63.
