CALIFORNIA AGRICULTURAL EXTENSION SERVICE

CIRCULAR 62

APRIL, 1932

Pollination of Deciduous Fruits by Bees

G. L. PHILP and G. H. VANSELL

Cooperative Extension work in Agriculture and Home Economics, College of Agriculture, University of California, and United States Department of Agriculture cooperating. Distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914. B. H. Crocheron, Director, California Agricultural Extension Service.

THE COLLEGE OF AGRICULTURE

UNIVERSITY OF CALIFORNIA

BERKELEY, CALIFORNIA

Digitized by the Internet Archive

in 2011 with funding from

University of California, Davis Libraries

http://www.archive.org/details/pollinationofdec62phil

POLLINATION OF DECIDUOUS FRUITS

BY BEES

G. L. PHILPi and G. H. VANSELL2

INTRODUCTION

Most fruit growers are familiar with investigations and field studies in cross-pollination. Beekeepers, however, are generally as unacquainted with the details of fruit pollination as are the fruit growers with bee problems. This circular attempts to summarize the results of deciduous fruit pollination studies and to point out some bee habits and structures, with special reference to the collection and storage of pollen. Such a paper may perhaps serve as a practical handbook for reference, especially in the field, and facilitate satis- factory pollination arrangements between fruitmen and beekeepers.

The pollination data have been prepared by the first author from material contained in various California Agricultural Experiment Station publications, most of which are now out of print, and sup- plemented with unpublished data from the Division of Pomolgy. The second author has prepared the material on bee habits and structures.

POLLINATION SUMMARY OF DECIDUOUS FRUITS

Among the causes responsible for nonbearing of deciduous fruits are lack of vigor in the tree, presence of injurious insects and diseases, unfavorable weather at blossoming time, winter injury, lack of pollination, and inability of the pollen to fertilize the ovule. This discussion will deal only with pollination as a cause of nonbearing, it being assumed that the orchard is planted in a favorable location and that the trees are kept in normal vigor and free from serious insect and disease troubles.

1 Associate in Pomology.

2 Associate in Entomology ; resigned.

4 California Agricultural Extension Service l^'^- 62

The following' definitions may clarify the discussion :

Pollination^: the transfer of pollen to the stigma; or, in a large sense, the distribution of pollen. Pollination may be accomplished by insects, wind, gravity, water, artificial methods (in experimental work), and birds.

Pollinizer : a plant (tree) used to furnish pollen. The male parent.

Fertilisation: the union of the male germ cell, contained in the pollen grain, with the female germ cell or egg in the ovary.

Fruitful: the term applied to a plant that sets and matures fruit.

Unfruitful or barren: terms describing a plant or variety that is unable to set fruit and mature it.

Fertility: the ability not only to set and mature fruit but to develop viable seed.

Sterility: the inability to set and mature fruit with viable seed.

Self -fruitful: the term applied to a plant that sets and matures fruit with its own pollen.

Self -unfruitful or self -barren: terms describing a plant that is unable to set fruit and mature it with its own pollen.

Inter-fruitful : the term applied to a variety capable of setting and matur- ing fruit when pollinized with a different variety.

Inter-unfruitful or inter-barren: terms describing a variety not capable of setting and maturing fruit when pollinized with a different variety.

The reasons for nonbearing, from a pollination standpoint, are not all known. Some of them, aside from weather conditions, are incompatibility, imperfection or degeneration of sex organs, slow growth of the pollen tube, and premature or delayed pollination.

The fruit grower has a pollination problem with almonds, cherries, plums and prunes, apples, pears, and berries. In general, apricots, peaches, and walnuts set well with their own pollen and hence present no difficulties from this standpoint. The J. H. Hale peach, however, is self -unfruitful and must be interplanted with some other variety. Recent studies indicate that some varieties of walnuts in certain years do not mature the staminate and pistillate flowers at the same time and therefore, under these conditions, cannot pollinate themselves.

With the fruits having a pollination problem, the grower must consider the following factors in selecting the pollinizers : coincidence of bloom, amount of pollen produced, germinability of pollen, com- mercial value of pollinizer, succession in ripening, and regularity of production of the pollinizers used. Varieties which do not blossom at the same time will not cross-pollinate each other.

3 Pollination experiments and investigations include not only the study of the transfer of pollen but also studies of fruit setting associated with pollen transfer and fertilization. In any mention of pollination studies and problems, this broader definition will be intended.

1932]

Pollination of Deciduous Fruits by Bees

Most fruits with showy flowers (fig. 1) require insects to carry the pollen from flower to flower. Bees are the most important insects for this work. The grower should therefore have plenty of bees in the orchard during the blossoming period.

Fig. 1. — Diagram of orange flower in longitudinal section showing location of typical floral parts. The orange blossom has been used rather than the flower of a deciduous fruit because it shows the nectary more conspicuously.

The California Agricultural Experiment Station has conducted pollination experiments with certain fruits. The results may be summarized as follows :

ALMONDS

The following varieties of almonds are self-unfruitful under California conditions and hence should not be planted in blocks of one variety:

Big White Flat	Golden State	King	Nonpareil
California	Harriott	Klondike	Peerless
Drake	I. X. L.	Lewelling	Eeams
Eureka	Jordan	Ne Plus Ultra	Texas

Some varieties of almonds are inter-unfruitful- following :

Nonpareil with I. X. L. Languedoc with Texas

-for example, the

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1932]

Pollination of Deciduous Fruits by Bees

Almonds may be classed as early or late in time of blossoming, as given below. Nonpareil has been given in both lists since it occupies a position about midway.

Early	Late
Big White Flat	Lewelling	Dickinson	Nonpareil
California	Ne Plus Ultra	Drake	fleams
Harriott	Nonpareil	Eureka	Sellers
I. X. L.	Peerless	Golden State	Texas
Jordan	Princess	Languedoe
King	Silver Shell
Klondike

The accompanying chart, figure 2, gives the average blossoming dates of certain almond varieties. The date of bloom is dependent upon many factors, such as soil, season, and location.

With the exception of the above-noted cases of inter-unfruitf ulness, any variety in either of the above lists may be used in most instances as a satisfactory pollinizer for any other variety in the same list. Table 1, compiled from the experiments of Tufts and Philp,^ sum- marizes the pollination requirements for almonds. Variety names at the left of the chart indicate the tree, and the names across the top indicate the pollen used. For example, if pollen from the variety Drake were used on a tree of the variety California a good set would result, as indicated by the symbol G in the table.

APPLES

Although this is not a complete list, apple varieties may be segre- gated according to their pollination requirements as follows:

Self-fruitful Baldwin Early Harvest Grimes Golden Oldenburg Wagoner Wealthy

Yellow Newtown Yellow Transparent

Self -unfruitful Arkansas Arkansas Black Delicious Fameuse Gravenstein Mcintosh Northern Spy Khode Island Greening Stark Stayman Twenty Ounce White Pearmain Winesap Winter Banana Yellow Bellflower

Doubtful Ben Davis Esopus Spitzenburg Gano Jonathan Eome Beauty Tompkins King York Imperial

4 Tufts, W. P., and G. L. Philp. Bui. 346:1-35. 1922.

Almond pollination, California Agr. Exp, Sta.

California Agricultural Extension Service

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1932] Pollination of Deciduous Fruits by Bees 9

The varieties in the self -fruitful list will generally produce larger crops when cross-pollinated. Under most conditions, however, com- mercial crops will result when they are planted in solid blocks (self -pollinated).

The varieties in the unfruitful list are unsafe to plant alone and should be interplanted with some other variety for cross-pollination.

The varieties in the doubtful list will in some years, under certain conditions, produce commercial crops. The evidence indicates, how- ever, that better commercial crops will result if provisions for cross- pollination are made.

Few cases of inter-unfruitfulness appear among apple varieties. Winesap, Arkansas, Arkansas Black, and Stayman seem to be inter- unfruitful and should therefore not be planted together. The Arkan- sas, Stayman, and Gravenstein are generally unsatisfactory pollen producers, a fact which makes them undesirable pollinizers for other varieties. Except for the cases indicated above, varieties which blossom together will cross-pollinate each other. The Delicious and Yellow Newtown seem to be the best varieties to, cross-pollinate the Gravenstein.

CHERRrES

All commercial varieties of sweet cherries are self-unfruitful. Tests show that the following are self-unfruitful under California conditions :

Abundance Burbank Mezel

Advance Chapman Napoleon (Royal Ann)

Bing Centennial Pontiac

Black Heart Cleveland Rockport

Black Republican Early Purple Windsor

Black Bigarreau Lambert Wood

Black Tartarian Major Francis

Some varieties of sweet cherry are inter-barren — for example, the following, under certain conditions :

Bing, Lambert and Napoleon with each other Rockport with Advance Early Purple with Rockport

There are, apparently, different strains of certain cherry varieties or else different varieties so similar as to be indistinguishable. This condition exists particularly with Black Tartarian, of which there are at least five strains which vary greatly in their ability to pollinize, especially the Napoleon. More than one strain of Black Republican, from a pollination standpoint, exists.

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No entirely satisfactory pollinizer has as yet been determined for Napoleon. In most cases, however, certain strains of Black Tartarian and Black Republican yield satisfactory results. Findings in Oregon show that the long-stemmed Waterhonse variety is a fairly good pollinizer for Napoleon.

Cherry varieties may be classed as early or late blossoming, as follows :

Early Late

Advance Burbank Bing Pontiac

Black Heart Chapman Lambert Rockport

Black Eepublican Early Purple Napoleon

Black Tartarian

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Fig. 3. — The period of effective bloom of certain cherry varieties, covering a period in nearly all cases of four years. The number of years averaged is shown in a separate column for each variety. (From Bui. 385.)

Black Tartarian and Black Republican generally overlap enough to pollinize most varieties in the second column.

The accompanying chart, figure 3, gives the average period of effective bloom for certain cherry varieties. The term effective hloom indicates the length of time the tree is in conspicuous blossom.

Table 2, compiled from the experiments of Tufts and Philp,^ summarizes the results of cherry pollination. In some cases different results may be secured but in general this information will apply.

5 Tufts, W. P., and G. L. Philp. Pollination of the sweet cherry. Agr. Exp. Sta. Bui. 385:1-28. 1925.

California

1932]

Pollination of Deciduous Fruits by Bees

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TABLE 2

Chart Showing Pollination Compatibilities of Sweet Cherries*

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PEARS

Twenty-six varieties of pears have been tested by the Pomology Division under various California conditions.

Only the Hardy variety has proved to be self -fruitful under all conditions and during all seasons. Fifteen of these twenty-six varieties tend, under certain conditions, toward self-fruitfulness.

Bartlett pears are, to a certain extent, self-fruitful under valley conditions, and, in most instances, self -barren under foothill conditions.

Winter Nelis showed a tendency toward self-unfruitfulness under all conditions tested.

No cases of inter-barrenness have been found to exist between pear varieties.

A summary of the pollination results secured by Tufts and Philp^ segregates pear varieties into three groups, as shown in table 3.

6 Tufts, W. P., and G. L. Philp. Pear pollination. California Agr. Exp. Sta. Bui. 373:1-36. 1923.

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Those varieties in the doubtful list, although setting satisfactory crops under certain conditions, should for best crops be interplanted with some other variety.

TABLE 3

Summary of Pollination Eesults with Pears

Self-barren	Self-fruitful	Doubtful
Variety	Years tested	Variety	Years tested	Variety	Number years self- fruitful	Number years self- barren
Alencon	2 2 1 1 2 3 1 3	Cornice	4 1 3 3	Angouleme	1 2 5 1 1 2 2 1 1 1 1 1 1 3	1
Bloodgood	Flemish Beauty Hardy		1
B. S. Fox	Bartlett	2
Comet	Howell	Bosc	1
Forelle		Clapp Favorite Clairgeau	1
LeConte	2
Madeline	Col. Wilder	2
Winter Nelis		2
	Easter	2
	Gifford	1
	Glou Morceau Kieffer	1 4
	P. Barry	2
	Seckel	1

Pears have, in most cases, a comparatively short period of bloom. The varieties tested may be divided roughly as early and late blossoming, as follows :

	Early		Late
Alencon	Angouleme	An j ou	Bartlett
Bartlett	Clairgeau	Bloodgood	Bosc
Clapp Favorite	Easter	B. S. Fox	Comice
Dana Hovey	Howell	Comet	Glou Morceau
Forelle	Le Conte	Gifford	Winter Bartlett
Kieffer	P. Barry	Hardy	Winter Nelis
		Seckel	Col. Wilder

The following varieties, tested under California conditions, have proved to be successful poUinizers for the Bartlett :

Angouleme

Anjou

Bosc

Clairgeau

Howell

Hardy

Comice Dana Hovey Easter Forelle Winter Nelis

1932]

Pollination of Deciduous Fruits by Bees

13

PLUMS AND PRUNES

Nearly all Japanese plums are self-unfruitful. Methley, Climax, Beauty, and Santa Rosa are partially self-fruitful. Like the rest, however, these four varieties set much better when interplanted for cross-pollination purposes. The self-barren list of Japanese plums follows :

Abundance	Duarte	Prize
Amador	El Dorado	Satsuma
Apex	Formosa	Sultan
Becky Smith	Gaviota	Upright
Burbank	Kelsey	Wickson
Combination	Los Gatos

The early Japanese varieties, being usually deficient pollen pro- ducers, are unreliable for cross-pollination. The late blossoming varieties are satisfactory pollen producers and may be interplanted safely. The Japanese varieties may be divided as early or late blossoming, as follows :

	Early		Late
Beauty	Kelsey	Abundance		El Dorado
Combination	Satsuma	Amador		Los Gatos
Formosa	Santa Rosa	Apex		Methley
Gaviota	Wickson	Burbank Climax Duarte		Prize Sultan Upright

Formosa and Gaviota are apparently inter-barren, or at least unsafe for planting together. Tragedy is able to pollinate several Japanese varieties but is not pollinated by them. Table 4, by Allen," summarizes the pollination requirements of Japanese plums.

7 Allen, F. W, Plum growing in California. California Ext. Cir. 34:1-65 1929.

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1932]

Pollination of Deciduous Fruits by Bees

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European plums (including prunes) may be classed as self -barren, self -fruitful, or doubtful, as follows:

Self -barren Anita Burton Clyman Diamond

Fellenberg (Italian) Imperial Jefferson President Robe de Sergeant Quackenboss Silver Standard Sultan Tragedy Washington

Self-fruitful California Blue Coates 1418 (Double X) French Giant Sugar Yellow Egg

Doubtful Conquest Grand Duke Pond (Hungarian) Stuart

The doubtful list includes varieties which in some years may pro- duce satisfactory crops with their own pollen but which one should probably not plant without providing for cross-pollination.

There is apparently no inter-unfruitfulness among- Europeon plums. In some years, however, certain varieties do not set satisfac- tory crops. In general, varieties blossoming at the same time will cross-pollinate effectively. Although this is not a complete list, the following varieties may be grouped together according to the time of blossoming:

Early

Clyman Tragedy

Mid-season Burton

Coates 1418 (Double X) Diamond French Grand Duke Imperial Jefferson Eobe de Sergeant Sugar Standard Stuart

Late California Blue Fellenberg (Italian) Giant President

Pond (Hungarian) Quackenboss Silver

Washington Yellow Egg

Table 5, by Allen, ^ summarizes the pollination requirements of ■European plums.

8 Allen, F. W. Plum growing in California. California Ext. Cir. 34 : 1-65. 1929.

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California Agricultural Extension Service

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1932] Pollination of Deciduous Fruits by Bees 17

ARRANGEMENT OF POLLINIZERS

In planting" an orchard where poUinizers are required, one should, if possible, have every sixth and preferably every fourth row a pollin- izing" variety. For convenience in harvesting it is best to plant two, four, or six rows of one kind, then two of the pollinizing variety, and repeat. In some instances it is desirable to have a minimum number of pollinizers. Under these circumstances, one tree to eight, planted as every third tree in every third row, is recommended. This arrange- ment places a pollinizer next to every tree of the main variety in the orchard.

Certain conditions may make it advisable to graft a pollinizer into every tree to insure satisfactory cross-pollination. Such an arrangement will, of course, tend toward confusion in harvesting ; when the pollination problem is serious, however, the grower can afford to forget the commercial value of the fruit on the pollinizing branch.

The suggestion given above is primarily for the orchardist whose mature trees, because of the planting of self or inter-barren varieties, have failed to fruit. During the years when one is waiting for the trees grafted over to pollinizing varieties to come into bearing, some relief may be obtained by cutting off branches of pollinizing varieties, placing the cut ends into vessels of water, and distributing them throughout the orchard during the blossom period. Such branches will live for several days and continue to bloom, forming pollen for the bees to transfer to the unfruitful varietv.

THE HONEYBEE AS A POLLEN DISTRIBUTOR

The intimate relationship between bee life and plants is well known to students of nature. Certain bees require pollen and nectar for sustaining life; the pollen, in the case of the hive bee, is fed, along with other substances, to the larval forms; while nectar is converted to honey primarily for adult food. In many cases, the plants require the pollen from other varieties of the species for the setting of fruit and seed. Nectar, a weak sugar solution, attracts many insects ; and its presence in close proximity to the stamens better assures visitation by the living pollen carriers. The bee wholly depends for existence upon the plant products — pollen and nectar ; while, on the other hand, many plants would fail in productivity^ except for the presence of insects suitable for effecting cross-pollination.

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POLLEN MANIPULATION BY THE BEE

The structures over the body of the worker bee are admirably designed for the efficient collection and transportation of pollen. In the first place, the whole body is densely clothed with hairs (fig. 4),

Fig. 4. — The body of the hive bee is completely covered with hair, in which the pollen grains become entangled. The bee, before it starts its return flight to the hive, combs the grains into the pollen basket. See figure 7.

which are barbed in such a way that pollen grains of varying size (figs. 5 and 6) cling to them. The legs, too, bear pollen-manipulating devices : each front leg, for example, has a notch of the proper diame- ter for stripping the antennae clean ; the middle and hind legs have spines, spoon-shaped depressions (called pollen baskets), hair combers, etc.

The bee partially cleans its body of pollen grains by means of the combs and other structures. A large ball of pollen is finally formed in the pollen basket, on the outside of each rear tibia (fig. 7), from which it is removed after being carried to the hive. Many pollen grains remain scattered over the bee's body, even after combing, and it is believed that it is this pollen which effects cross-pollination. The labor and time expended in collecting a load of pollen are con-

1932]

Pollination of Deciduous Fruits by Bees

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Fig. 5. — Photograph of femur from a bee 's leg, showing hairs with pollen grains from some plant. This field bee was caught entering the hive, as it returned from a collecting trip. These grains come in contact with the viscid surface of the stigma as the bee pushes into the blossom for nectar or pollen, and bring about cross-pollination. Also see figure 6.

Fig. 6. — Diagrammatic sketches showing arrangement of barbs on the hairs of bees. The pollen grains cling on the hair between these barbs. The irregular spacing of barbs on the hair shaft is an adaptation suited to picking up pollen grains of varying size and shape. See also figures 5 and 8.

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Fig. 7. — Hind legs of hive bee with large mass of pollen in the pollen basket upon the outside of the tibia. Note the combs on the first tarsal segment. The parts of the leg are the coxa (a), the trochanter (b), the femur (c), the tibia (d), and the five tarsal segments (e).

1932]

Pollination of Deciduous Fruits by Bees

21

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a b ll^ ^

A

^ # ^^P

W*^

«!

Fig. 8. — Photographs of pollen grains, indicating comparative size and shape: (a) cherry, (b) almond, (c) hollyhock, (d) olive, and (e) date palm. Magnifica- tion of all, X 250. Also see figures 5 and 6.

22 California Agricultural Extension Service [CiR- 62

siderable: often a bee spends an hour in workings over the anthers of the blossoms (fig*. 1) before returning to the hive. The different kinds of pollen (fig. 8) are stored in the cells of the comb until needed for feeding the bee larvae. Pollens from different plant species are of various color (white, yellow^, brow^n, blue, red, etc.), a fact which facilitates their identification in the comb cells.

SOME COLLECTING HABITS OF BEES OF VALUE IN FRUIT POLLINATION

Bees, whether collecting pollen or nectar, usually visit on a par- ticular trip but one species of plant. Where blossoms are scarce, the bee may be forced to collect from more than one species; but such is not the case during fruit blossoming. Some species of plants are definitely preferred to others. The time of day influences availability of both nectar and pollen, so that activity shifts from one plant to another : for example, filaree, in the orchards, is very attrac- tive during the early morning; but most of the blossoms close by 10 o'clock on sunny days. Apparently some of the fruits secrete nectar most freely during the night ; bees quickly harvest this in the morning and then shift to some other plant. During certain seasons, for example, this change from prunes to mustard is particularly noticeable. Very often pear blossoms are less attractive than others which are open at the same time. Bees like apple blossoms particularly : they will sometimes leave pear for cherry and cherry for apple. In certain areas, at least, bees visit pear blossoms for pollen only, ignoring the nectar which is plainly visible. Some recent work indicates a vari- ation in sugar concentration for various nectars, which may explain the periodic preference shown by bees for certain flowers.

SPRAYING DETRIMENTAL TO BEES

The problem of spray poisoning is often acute for bees near orchards where arsenic or nicotine is used on the plants. Not only are the nectar and pollen of trees contaminated, but those of the covercrop as well. In addition, bees drink up dew from leaves and thus may secure a fatal dosage of poison, so that one cannot entirely eliminate this source of loss even by properly timed spraying-. Wherever cover- crops occur in orchards, the spray poison problem is particularly serious. Beekeepers and fruit growers must, in short, cooperate if loss of bees is to be reduced to a minimum; and the beekeeper should receive timely warning to move out before spraying operations begin.

1932]

Pollination of Deciduous Fruits by Bees

23

SET OF FRUIT NOT DEPENDENT UPON BEES ALONE

The need for more insects to bring about cross-pollination in areas of fruit concentration is well recognized by scientific workers and many orchardists. One must emphasize the fact that a supply of pol- linating insects alone is not sufficient to cause a commercial set of fruit, but that other factors, such as favorable weather and suitable varieties properly planted, are also important. The fact that hive bees are efficient pollen distributors which can be placed where and when wanted, needs only to be mentioned.

^^^•••••»

Fig. 9. — A bee comb illustrating the large area occupied by brood during fruit blossoming time; five to ten combs are necessary. Both sealed (a) and unsealed brood cells (b) as well as honey (upper left) may be seen. During periods of low temperature, as often occur during fruit blossoming time, all the bees in a weak colony may be needed in the hive to keep up the temperature for brood; therefore, it is only in the case of strong colonies that there are bees available for field work.

BEEKEEPING A SPECIALTY

The fruit-grower is usually too busy with orchard problems to become an efficient beekeeper. Bees require considerable attention throughout the year if they are to be strong in numbers at the end of winter. Only strong colonies will prove of much value during early spring, when a large number of bees are required in the hive to main- tain the brood nest temperature at 95° F (fig. 9). Generally, the most

24 California Agricultural Extension Service [C^R- 62

feasible plan for securing pollinating insects is to rent bees from highly skilled beekeepers. The importance of an early agreement must be stressed, because many cases of bee shortage are annually reported too late for correction.

NUMBER OF BEES REQUIRED FOR POLLINATION

The usual recommendations call for one colony of bees to the acre of fruit to be pollinated. The condition of the weather so affects results, however, that often more bees would justify their cost, while at other times even the prescribed number probably exceeds actual re- quirements. According to one beekeeper at Oroville, a section near him has 10,000 acres of prunes and 3,000 acres of pears with a bee population of only 1,000 colonies (1930). This number of bees must certainly be inadequate for best results, particularly when the general insect population, because of weather conditions or other cause, is low. Table 6 shows the acreage of fruits (exclusive of grapes) and the reg- istered number of colonies of bees in the counties of California. The colony figures are primarly from the State Department of Agriculture registration list for 1929.

TABLE 6

List of California Counties with Fruit Acreage and Number of Bee Colonies

Bearing fruit Colonies of County acreage* hees

Alameda 7,708 2,944

Alpine 1 2

Amador 970 48

Butte 21,864 8,449

Calaveras 507 224

Colusa 3,687 6,322

Contra Costa 12,417 3,321

Del Norte 4 71

Eldorado 5,374 662

Fresno 43,911 16,875

Glenn 8,497 5,931

Humboldt 1,665 1,531

Imperial ..- 4,930 19,639

Inyo 1,102 3,640

Kern 8,470 11,142

Kings 13,191 5,911

* These figures do not include grapes.

1932] Pollination of Deciduous Fruits by Bees 25

TABLE 6— Continued

Bearing fruit Colonies of

County acreage* bees

Lake 7,141 120

Lassen 185 981

Los Angeles 71,567 38,389

Madera 9,079 2,010

Marin 633 443

Mariposa 263 67

Mendocino 5,295 1,068

Merced 20,485 8,188

Modoc 434 1,114

Mono 74 100

Monterey 8,823 4,546

Napa 14,528 1,217

Nevada 2,349 199

Orange 49,159 15,742

Placer 30,910 311

Plumas 34 47

Eiverside 39,835 22,585

Sacramento 24,399 5,864

San Benito 15,532 404

San Bernardino 74,055 39,830

San Diego 12,379 30,279

San Francisco 67

San Joaquin 21,308 13,573

San Luis Obispo 5,826 3,438

San Mateo 1,843 188

Santa Barbara 3,197 4,846

Santa Clara 102,617 3,275

Santa Cruz 18,775 538

Shasta 2,173 4,510

Sierra 19 118

Siskiyou 364 1,256

Solano 24,062 2,139

Sonoma 42,994 2,157

Stanislaus 31,343 8,200

Sutter 45,329 4,846

Tehama 8,228 4,728

Trinity 26 163

Tulare 76,377 11,446

Tuolumne 2,071 408

Ventura 11,900 14,873

Yolo - 15,078 3,511

Yuba 9,663 1,031

* These figures do not include grapes.

26 California Agricultural Extension Service [<^R- 62

PLACING THE BEES IN THE ORCHARD

Bees are moved into orchards of this state almost entirely by motor truck or trailer. The actual move is usually made during- the night. The entrances of the hives are as a rule closed, before moving, with some screening device or cloth material. During hot weather a moving-screen, in place of the hive cover, is essential for ventilation.

The recommendation of one hive to the acre does not mean that one hive should be located on each acre. Under normal conditions it is seldom that bees are left in orchards in groups under ten colonies. The manipulation of single colonies is too difficult, particularly after rains ; also the increased time and labor required for removal of scat- tered colonies adds to the expense. Sunshine, wind, temperature, rain, and other factors outside of the hive affect the flight of bees; therefore, general recommendations cannot be given relative to the proper placement of the colonies in the orchard. If the weather is fair and warm, during fruit-blossom time, bees can undoubtedly fly far enough to cover 100 acres or more of fruit from one location ; on the other hand, during a cold wet season flight is very limited. The absence of fruit or nuts, except within a few rows distant from the bee location, is occasionally reported following a particularly bad spring.

Under average conditions bees in groups of 10 to 20 colonies, for as many acres surrounding them, have been found very satisfactory both to the fruit grower and the beekeeper. Accessible situations along roadways in the orchards should be chosen, because of mud as well as the difficulty of driving the trucks among the trees at night.

The bee population as is evident in the table is strikingly low, in comparison with the fruit acreage, for several of the important fruit counties in northern California, notably Eldorado, Napa, and Nevada. Some beemen regularly move bees into these fruit areas on a rental basis. A factor partly responsible for this low resident bee population is the presence of the detrimental California buckeye tree. The lack of a major honey plant also greatly reduces the possibility of profit- able beekeeping. Undoubtedly the intensive insecticidal spraying operations practiced in many deciduous fruit areas play a part too in further reducing the number of bees.

To the southward, on the other hand, the number of colonies of bees increases greatly in proportion to the fruit acreage requiring pol- lination. In the upper end of the San Joaquin Valley, for example, at the present time, bees are rarely rented to the fruit grower for pol-

1932] Pollination of Deciduous Fruits by Bees 27

lination purposes. Beemen are, in fact, very desirous of locating near deciduous fruit orchards to enable their colonies to build up early in preparation for the orange honey flow during April. Tulare County alone has some 33,000 acres of citrus fruits.

COST OF RENTING BEES

The rental price paid by the fruit grower for bees in orchards depends upon several factors : for example, necessary moving distance, condition of roads, local rainfall, and supply of bees, coupled with demand. In a given area, like the Santa Clara Valley, rental possi- bilities change with time: during the World War, for example, with the accompanying high price of prunes, many bees were moved in from the vicinity of Modesto at $5.00 to $7.00 per colony for the blos- soming period. Now but few bees are taken in — mostly for cherry orchards, at $2.00 to $2.50 rental. The beekeepers, in fact, find it dif- ficult to surmount the barriers set up by the sentiment of pear growers concerning blight. The present rental demand for bees in California comes largely from almond and plum growers, though the cherry, apple, and foothill pear growers also rent a good many colonies.

The earlier in the fall a fruit grower can place his order for bees, the greater the chance for satisfactory accommodation, because after the orchard becomes muddy, moving is difficult. Experience has taught beekeepers the unprofitableness of renting colonies at current prices when expensive moving problems arise. The average rental price at present is perhaps $2.00. The fruit growers should insist on good, strong colonies, for these are by far the most efficient in pollination.

AGRICULTURAL EXTENSION SERVICE CIRCULARS

No. 3. 5.

9. 10. 11. 12. 13. 14.

15. 16.

17.

21. 22. 23. 25. 26. 29.

30.

31.

32. 33.

Feedine: Beef Cattle in California.

Lettuce. (Series on California Crops and Prices.)

Suggestions on Grapefruit Culture in Imperial Valley.

Rabbit Raising.

The Home Preparation of Fruit Candy.

Cauliflower Production.

"Wool Production in California.

The Manufacture of Monterey Cheese.

Selection and Care of Electrical Equip- ment Used in Dairy Manufacturing.

Pork Production in California.

Irrigation of Orchards by Contour Fur- rows.

Liver Fluke and Stomach Worm of Sheep.

Bovine Tuberculosis.

Thinning Sugar Beets.

Strawberry Culture in California.

Bush Fruit Culture in California.

The Home Vegetable Garden.

Control of Pocket Gophers and Moles in California.

Elements of Grape Growing in Cali- fornia.

Pow^dery Mildew of the Grape and Its Control in California.

What to do About Bovine Tuberculosis.

Rearing Dairy Heifers Free from Tuber- culosis and Abortion Disease.

No.

34. Plum Growing in California,

35. Alfalfa Production.

36. Beekeeping for the Beginner in Cali-

fornia.

37. Home and Farm Preparation of Pickles. 3». Alfalfa Varieties and Seed SuRply.

40. Frost Protection in California Orchards.

41. Prune Culture in California.

42. Peach Culture in California.

43. The California Avocado Industry.

44. Bang's Disease (Infectious Abortion).

45. Zinc Chloride Treatment for Pear Blight

Cankers.

46. Clierrv Culture in California.

47. Equipment for the Bulk Handling of

Grain.

48. The Manufacture of Cottage Cheese.

49. Sheep Production in California. 51. Apricot Growing in California.

53. Home Floriculture in California.

54. The Control of Weeds.

55. Growing and Handling Sweet Potatoes

in California.

56. Girdling Grape Vines.

57. Commercial Fertilizers and Soil Fertility

in California.

58. Turkey Raising in California.

59. The 1932 Agricultural Outlook for Cali-

fornia.

STATION PUBLICATIONS AVAILABLE FOE FREE DISTKIBUTION

BULLETINS

No. No.

253. Irrigation and Soil Conditions in the 433.

Sierra Nevada Foothills, California. 263. Size Grades for Ripe Olives.

279. Irrigation of Rice in California. 435.

283. The Olive Insects of California. 310. Plum Pollination.

331. Phylloxera-Resistant Stocks. 439.

343. Cheese Pests and Their Control.

348. Pruning Young Olive Trees.

349. A Study of Sidedraft and Tractor

Hitches.

357. A Self-Mixing Dusting Machine for 440.

Applying Dry Insecticides and Fun- gicides.

361. Preliminary Yield Tables for Second- 445.

Growth Redwood.

364. Fungicidal Dusts for the Control of 446.

Bunt. 447.

369. Comparison of Woods for Butter Boxes.

370. Factors Influencing the Development 448.

of Internal Browning of the Yellow Newtown Apple. 449.

3 71. The Relative Cost of Yarding Small

and Large Timber. 450.

373. Pear Pollination.

374. A Survey of Orchard Practices in the

Citrus Industry of Southern Call- 452.

fornia. 454.

379. Walnut Culture in California. 386. Pruning Bearing Deciduous Fruit 455.

Trees. 389. Berseem or Egyptian Clover. 456.

392. Fruit Juice Concentrates.

393. Cron Sequences at Davis. 458.

394. I. Cereal Hay Production in California.

II. Feeding Trials with Cereal Hays. 459.

395. Bark Diseases of Citrus Trees in Cali-

fornia. 462.

396. The Mat Bean. Phaseolus Aconitifolius. 464. 404. The Dehydration of Prunes.

406. Stationary Snray Plants in California. 465.

407. Yield. Stand, and Volume Tables for 466.

White Fir in the California Pine

Region. 467.

408. Alternaria Rot of Lemons. 468.

409. The Digestibility of Certain Fruit By-

products as Determined for Rumi- 469.

nants. Part I. Dried Orange Pulp 470.

and Raisin Pulp.

410. Factors Influencing the Quality of Fresh 471.

Asparagus After It is Harvested.

416. Culture of the Oriental Persimmon in 472.

California. 473.

417. Poultry Feeding: Principles and Prac-

tice^ 474.

418. A Study of Various Rations for Fin-

ishing Range Calves as Baby Beeves.

419. Economic Aspects of the Cantaloupe 475.

Industry. 476.

420. Rice and Rice By-Products as Feeds 477.

for Fattening Swine.

421. Beef Cattle Feeding Trials, 1921-24. 479. 423. Apricots (Series on California Crops

and Prices).

425. Apple Growing in California. 480.

426. Apple Pollination Studies in California.

427. The Value of Orange Pulp for Milk 481.

Production.

428. The Relation of Maturity of California 482.

Plums to Shipping and Dessert 483.

Quality. 484.

431. Raisin By-Products and Bean Screen-

ings as Feeds for Fattening Lambs. 485.

432. Some Economic Problems Involved in 487.

the Pooling of Fruit.

Power Requirements of Electrically Driven Dairy Manufacturing Equip- ment.

The Problem of Securing Closer Rela- tionship between Agricultural Devel- opment and Irrigation Construction.

The Digestibility of Certain Fruit By- Products as Determined for Rumi- nants. Part II, Dried Pineapple Pulp, Dried Lemon Pulp, and Dried Olive Pulp.

The Feeding Value of Raisins and Dairy By-Products for Growing and Fattening Swine.

Economic Aspects of the Apple In- dustry.

The Asparagus Industry in California.

A Method of Determining the Clean Weights of Individual Fleeces of Wool.

Farmers' Purchase Agreement for Deep Well Pvimps.

Economic Aspects of the Watermelon Industry.

Irrigation Investigations with Field Crops at Davis, and at Delhi, Cali- fornia, 1909-1925.

Economic Aspects of the Pear Industry.

Rice Experiments in Sacramento Val- ley, 1922-1927.

Reclamation of the Fresno Type of Black-Alkali Soil.

Yield. Stand and Volume Tables for Red Fir in California.

Factors Influencing Percentage Calf Crop in Range Herds.

Economic Aspects of the Fresh Plum Industry.

Prune Supply and Price Situation.

Drainage in the Sacramento Valley Rice Fields.

Curly Top Symptoms of the Sugar Beet.

The Continuous Can Washer for Dairy Plants.

Oat Varieties in California.

Sterilization of Dairy Utensils with Humidified Hot Air.

The Solar Heater.

Maturity Standards for Harvesting Bartlett Pears for Eastern Shipment.

The Use of Sulfur Dioxide in Shipping Grapes.

Adobe Construction.

Economic Aspects of the Sheep In- dustry.

Factors Affecting the Cost of Tractor Logging in the California Pine Region.

Walnut Supply and Price Situation.

Poultry Houses and Equipment.

Improved Methods of Harvesting Grain Sorghum.

I. Irrigation Experiments with Peaches in California. II. Canning Quality of Irrigated Peaches.

The Use, Value, and Cost of Credit in Agriculture.

Utilization of Wild Oat Hay for Fat- tening Yearling Steers.

Substitutes for Wooden Breakpins.

Utilization of Surplus Prunes.

The Effects of Desiccating Winds on Citrus Trees.

Drying Cut Fruits.

Asparagus (Series on California Crops and Prices).

BULLETINS— (Corjfinwerf)

No.

488.

489.

490.

491.

492. 493. 494. 495.

496.

497.

498. 499. 500. 501. 502.

503.

504.

Cherries (Series on California Crops and Prices).

Irrigation Water Requirement Studies of Citrus and Avocado Trees in San Diego County, California, 1926 and 1927.

Olive Thinning^ and Other Means of Increasing Size of Olives.

Yield. Stand, and Volume Tables for Douglas Fir in California.

Berry Thinning of Grapes.

Fruit Markets in Eastern Asia.

Infectious Bronchitis in Fow^ls.

Milk Cooling on California Dairy Farms.

Precooling of Fresh Fruits and Tem- peratures of Refrigerator Cars and Warehouse Rooms.

A Study of the Shipment of Frei^h Fruits and Vegetables to the Far East.

Pickling Green Olives.

Air Cleaners for Motor Vehicles.

Dehydration of Grapes.

Marketing California Apples.

Wheat (Series on California Crops and Prices).

St. Johnswort on Range Lands of California.

Economic Problems of California Agri- culture. (A Report to the Governor of California.)

No.

505. The Snowy Tree Cricket and Other

Insects Injurious to Raspberries.

506. Fruit Spoilage Disease of Figs.

507. Cantaloupe Powdery Mildew in the

Imperial Valley.

508. The Swelling of Canned Prunes.

509. The Biological Control of Mealybugs

Attacking Citrus.

510. Olives (Series on California Crops

and Prices).

511. Diseases of Grain and Their Control.

512. Barley (Series on California Crops

and Prices).

513. An Economic Survey of the Los

Angeles Milk Market.

514. Dairy Products (Series on California

Crops and Prices). 515^ The European Brown Snail in Cali- fornia.

516. Operations of the Poultry Producers

of Southern California, Inc.

517. Nectar and Pollen Plants of California.

518. The Garden Centipede.

519. Pruning and Thinning Experiments

with Grapes.

520. A Survey of Infectious Laryngotrache-

itis of Fowls.

521. Alfalfa (Series on California Crops

and Prices).

CIRCULARS

No.

115. Grafting Vinifera Vineyards.

178. The Packing of Apples in California.

212. Salvaging Rain-Damaged Prunes.

230. Testing Milk. Cream, and Skim Milk

for Butterfat. 232. Harvesting and Handling California

Cherries for Eastern Shipment.

239. Harvesting and Handling Apricots and

Plums for Eastern Shipment.

240. Harvesting and Handling California

Pears for Eastern Shipment.

241. Harvesting and Handling California

Peaches for Eastern Shipment.

244. Central Wire Bracing for Fruit Trees.

245. Vine Pruning Systems.

248. Some Common Errors in Vine Pruning

and Their Remedies.

249. Replacing Missing Vines. 253. Vineyard Plans.

257. The Small-Seeded Horse Bean (Vicia

faba var. minor).

258. Thinning Deciduous Fruits.

259. Pear By-Products.

261. Sewing Grain Sacks.

262. Cabbage Production in California. 265. Plant Disease and Pest Control.

269. An Orchard Brush Burner.

270. A Farm Septic Tank.

No.

279. The Preparation and Refining of Olive

Oil in Southern Europe. 282, Prevention of Insect Attack on Stored

Grain. 288. Phylloxera Resistant Vineyards. 290. The Tangier Pea. 292. Alkali Soils.

294. Propagation of Deciduous Fruits. 296, Control of the California Ground

Squirrel. 301. Buckeye Poisoning of the Honey Bee.

304. Drainage on the Farm.

305. Liming the Soil.

307. American Foulbrood and Its Control.

308. Cantaloupe Production in California. 310. The Operation ef the Bacteriological

Laboratory for Dairy Plants.

316. Electrical Statistics for California

Farms.

317. Fertilizer Problems and Analysis of

Soils in California.

318. Termites and Termite Damage.

319. Pasteurizing Milk for Calf Feeding.

320. Preservation of gruits and Vegetables

by Freezing Storage.

321. Treatment of Lime-induced Chlorosis

with Iron Salts.

322. An Infectious Brain Disease of Horses

and Mules (Encephalomyelitis).

16m-4,'32