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APRICOT
Prunus armenica L., family Rosaceae

Apricots are produced primarily in California. In 1969, 223,000 tons were produced as compared with 3,050 tons in Washington and 4,500 tons in Utah. The estimated value of the total 1969 apricot crop was $33.5 million.

Plant:

In appearance, the apricot tree, fruit, and flower seem to be somewhat intermediate between the plum and the peach. The tree may be larger than a plum tree but spreads like the peach. The flowers are usually white like plum flowers, but they are not borne in clusters. The pit is smooth, somewhat like that of the plum but broader, flatter, and more winged, and intermediate in size between that of the peach and plum (fig. 41). The fruit is peach shaped (Cullinan 1937).

Inflorescence:

The white flower is borne either singly or doubly at a node on very short stems. There are about 30 stamens with one pistil, again like both the plum and the peach (fig. 42). The flowers are attractive to bees for both pollen and nectar. The cultivars of apricots were discussed by Coe (1934) and Hesse (1952).

[gfx] FIGURE 42.- Longitudinal section of 'Royal' apricot flower, x 6.

Pollination Requirements:

The literature on pollination of apricots is meager an not in complete agreement. Cook and Green (1894 reported that the best set of fruit was obtained from bagged flowers, with the next best from flowers in bags with honey bees, and the lowest set in the open. They did not comment on the activity of the bees either in the bags or on the open flowers. Cullinan (1937) stated that the apricot is self-fruitful. He did not indicate whether he meant the flowers would pollinate themselves or that they would set only if pollinated with their own pollen. Jusubov (1957) reported that some cultivars were self-fertile and some were completely self-sterile. Kostina
(1966) also found variation in degrees of fertility between cultivars. When Schultz (1948) bagged flowers on different cultivars, he reported good sets on 'Blenheim', 'Royal', 'Tilton', and 'Wenatchee Moorpark'. Schultz (1948) and Griggs (1970*) identified two self- incompatible cvs., 'Perfection' and 'Riland'. Slate (1970) stated that some cultivars are self-unfruitful. Luce and Morris (1928) stated that visits to blossoms by insects "seem to increase the set of fruit even in larger blocks of a single variety." Corner et al. (1964) reported that half of the Canadian cultivars were self-sterile. Hootman (1935) stated ". . . even self-fertile varieties produce better crops when interplanting is practiced."

The rather meager data indicate that some apricot cultivars must be cross-pollinated and other cultivars are benefited by cross-pollination.

[gfx] FIGURE 41. - Harvesting apricots from fruit-laden tree.

Pollinators:

There seems to be little question as to which pollinating agents are effective on apricots. Jorgensen and Drage (1953) stated that wind is not an effective pollinating agent. Instead, they said that the sticky pollen needs the help of insects to carry it from the stamens to the stigma. Murneek (1937) also concluded that, whether a cultivar is self-sterile or self-fertile, insects are equally necessary for proper pollination and setting of fruit.

The chief pollinators are bees. Stark (1944) stated: "Other insects may be responsible for the pollination of an occasional flower but would not begin to do the job for a commercial crop of fruit."

These observations and statements show that insect pollination is required on self-sterile cultivars and is at least beneficial to the self- fertile cultivars. Honey bees are the primary pollinating agents.

Pollination Recommendations and Practices:

The available literature indicates that the apricot, like the peach and nectarine, depends upon pollinating insects to set a commercial crop on all cultivars. A heavy population of bees may be unnecessary, but they should be distributed throughout the orchard. Thus, since the bees are required but not in large numbers, the recommendation by Corner et al. (1964) of a colony of honey bees per acre would seem adequate, providing the colonies were distributed in small groups in the orchard.

LITERATURE CITED:

COE, E. M.
1934. APRICOT VARIETES. Utah Agr. Expt. Sta. Bul. 251,59 pp.

COOK, A. J., and GREEN, E. C.
1894. SYMPOSIUM ON BEES AND FRUIT-FERTILIZATION, AGAIN. Gleanings Bee Cult. 22: 448-451.

CORNER, J., LAPINS K O.. and ARRAND. J. C.
1964. ORCHARD AND HONEY BEE MANAGEMENT IN PLANNED TREE-FRUIT POLLINATION. Min. Agr., Victoria, British Columbia, Apiary Cir. 14,18 pp.

CULLINAN, E. P.
1937. IMPROVEMENT OF STONE FRUITS. U.S. Dept. Agr. Yearbook 1937: 665-748.

HESSE, C. O.
1952. APRICOT CULTURE IN CALIFORNIA Calif. Agr. Expt. Sta. Cir. 412,58 pp.

HOOTMAN, H. D.
1935. IMPORTANCE OF POLLINATION AND THE HONEY-BEE IN FRUIT YIELDS. Midwest Fruitman 8(9): 3-4,9-10.

JORGENSEN, C., and DRAGE, C. M.
1953. POLLINATION OF COLORADO FRUIT. Colo. Agr. Expt. Sta. and Ext. Serv. Bul. 427-A, 13pp.

JUSUBOV, A. M.
1957. [POLLINATORS FOR NEW APRICOT VARIETIES IN THE CENTRAL BELT.] Sad i Ogorod 2: 47-48. [In Russian.] Plant Breeding Abs. 27(4): 4367, p.721, 1957.

KOSTINA, K. F.
1966. [THE DEGREE OF SELF-FERTILIZATION IN APRICOT VARIETIES AND HYBRIDS OF DIFFERENT ECOLOGICAL-GEOGRAPHICAL GROUPS.] Sel'skokhoz. Biol. 1(3): 352-355. [In Russian, English summary.]

LUCK, W. A., and MORRIS, O. M.
1928. POLLINATION OF DECIDUOUS FRUITS. Wash. Agr. Expt. Sta. Bul. 223,22 pp.

MURNEEK, A. E.
1937. POLLINATION AND FRUIT SETTING. Midwest Fruitman 10(5): 8-9.

SCHULTZ, J. H.
1948. SELF-INCOMPATIBILITY IN APRICOTS. Amer. Soc. Hort. Sci. Proc. 51: 171-174.

SLATE, G. L.
1970. APRICOTS, NECTARINES AND ALMONDS. Horticulture 48(5): 42,47-48.

STARK, A. L.
1944. FRUIT POLLINATION - A PROBLEM IN UTAH. Farm and Home Sci. 5(4): 5-6.