Historic, archived document Do not assume content reflects current scientific knowledge, policies, or practices. Sat ( oe eB d ow 'S. DEPARTMENT OF AGRICULTURE. - BUREAU OF PLANT INDUSTRY—BULLETIN No.6. } B. T, GALLOWAY, Chief of Bureau. THE AVOCADO IN FLORIDA; — ITS PROPAGATION, CULTIVATION, AND MARKETING, — 1 BY _ Pow. ROLES; | PatHonoeist, IN CHARGE oF SuprRopicaL LABORATORY. ) rae y : . ( SS ‘POMOLOGICAL INVESTIGATIONS. Se ae Issuep Jury 7,1904. ¥ bes oe Fal il pales all I i sul us | \\y haw \\ Wars Sa WY SS oss WASHINGTON: GOVERNMENT PRINTING OFFICE. 1904. 5) : ie: th _ BULLETINS OF THE BUREAU OF PLANT INDUSTRY. The Bureau of Plant Industry, w Bich was organized, July 1, 1901, includes ea table Pathological and Physiological Investigations, Botanical Inv estigations and ae > Fix periments, Grass and Forage Plant Investigations, Pomological Investigations, and _ Experimental Gardens and Grounds, all of which were formerly separate Divisions, _ = --andalso Seed.and Plant Toicddaeion and Distribution, the Arlington ie vodac = | : - Farm, Tea Culture Investigations, and Domestic Sugar Investigations. ; Beginning with the date of organization of the Bureau, the several series of bulle- tins of the various Divisions were discontinued, and all are now published as one | - series of the Bureau. A list of the bulletins issued in the present series follows. | _ Attention is directed to the fact that ‘‘the serial, scientific, and technical publica- tions of the United States Department of Agriculture are not for general distribution. All copies not. required for official use are by law turned over to the Superintendent, | of Documents, who is empowered to sell them at cost.’’ All applications for such ~publications should, therefore, be made to the pene of Documents;: GU -ernment Printing Office, Washington, D.C. No. 1. The Relation of Lime and Magnesia to Plant Growth. 1901. Price, 10 cone . Spermatogenesis and Fecundation of Zamia. 1901. Price, 20 cents. - . Macaroni Wheats. 1901. Price, 20 cents. Se . Range Improvement in Arizona. 1902. Price, 10 cents. : ee Seeds and Plants Imported.- Inventory No..9. 1902. Price, 10 cents. A List of American Varieties of Peppers. 1902. - Price, 10 cents. . The Algerian Durum Wheats. 1902. Price, 15 cents. . A Collection of Fungi Prepared for Distribution. 1902.> Price, 10 cents. . The North American Species of Spartina. 1902. Price, 10 cents. . Records of Seed Distribution and Cooperative Exper iments with Grasses and | Forage Plants. 1902. Price, 10 cents. . Johnson Grass. 1902. Price, 10 cents. . Stock Ranges of Northwestern California: Notes on the Grasses and Forage | Plants and Range Conditions. _ 1902. Price, 15 cents. -» 13. Experiments in Range Improvement in Central. Texas. 1902. Price, 10 cents. 14. The Decay of Timber and Methods of Preventing It. 1902. Price, 55 cents. 15. Forage Conditions on the Northern Border of the Great Basin. 1902. -Price, 15 cents. 16. A Preliminary Study of the Germination of the Spores of dace Campes- tris and Other Basidiomycetous Fungi. 1902. Price, 10 cents. - 17. Some Diseases of the Cowpea. 1902. Price, 10 cents. 18. Observations on the Mosaic Disease of Tobaeco. 1902. Price, 15 cents. 19. Kentucky Bluegrass Seed. 1902. Price, 10 cents. ; 20. Manufacture of Semolina and Macaroni. 1902. - Price, 15 cents. 2 21. List of American Varieties of Vegetables. .1903. Price, 35 cents. 22. Injurious Effects of Premature Pollination. 1902. Price, 10 cents. : 23. Berseem: The Great Forage and Soiling Crop of the _ Vater: 1902. Price, 15 cents. C me 24. Unfermented Grape Must. 1902. Prien’ i0 cents. s [Continued on page 3 of cover, ] 1 C2: 00 NI > OT Oo bo pase (om) a hoe PLATE Bureau of Plant Industry, U. S. Dept. of Agriculture. 61, Bul. VIOOSHYQ IWHOD V NO ONIMOYHY ‘G10 SHVSA GE ‘33a, OGVOOAY NVOIMSWY HLNOS-NVIGN| LSAAA U. S. DEPARTMENT OF AGRICULTURE. BUREAU OF PLANT INDUSTRY—BULLETIN No. 61. B. T. GALLOWAY, Chief of Bureau. THE. AVOCADO IN FLORIDA; ITS PROPAGATION, CULTIVATION, AND MARKETING, BY P. H. ROEES, PATHOLOGIST, IN CHARGE OF SUBTROPICAL LABORATORY. POMOLOGICAL INVESTIGATIONS. IssureD JuLy 7, 1904. ae OES SS eet SE I | BT IER TEEN i / ( \s i Oo i i VA = — “on Ww Dee 0 COMMER eed WASHINGTON: GOVERNMENT PRINTING OFFICE. DOA: | \ BUREAU OF PLANT INDUSTRY. BrEveRLY T. GALLoway, Chief. J. E. RocKweEt.u, Editor. POMOLOGICAL INVESTIGATIONS. SCIENTIFIC STAFF. G. B. Bracxerr, Pomologist. WitiiAmM A. Taytor, Pomologist in Charge of Field Investigations. G. Harotp Powe Lt, Pomologist in Charge of Fruit Storage Investigations. H. P. Gown, Assistant Pomologist in Charge of Fruit District Investigations. Sanrorp H. Futon, Assistant Pomologist in Charge of Fruit Storage Investigations, GEORGE C. Husmann, Viticulturist. Pe Ok eA NSM Iie se U. 5S. DeparTMENT OF AGRICULTURE, BurEAU OF PLantT INDUSTRY, OFFICE OF THE CHIEF, Washington, D. C., Apri 7, 1904. Srr: I have the honor to transmit herewith a paper on ‘* The Avocado in Florida; its Propagation, Cultivation, and Marketing,” and respect- fully recommend that it be published as Bulletin No. 61 of the series of the Bureau. This paper was prepared by Prof. P. H. Rolfs, Pathologist in Charge of the Subtropical Laboratory at Miami, Fla., under the direc- tion of Dr. A. F. Woods, Pathologist of this Bureau, but as the subject is pomological rather than pathological, it was submitted to the Pomologist with a view to its publication from his office. The accompanying illustrations are essential to an intelligent under- standing of the text. Respectfully, B. T. GaLLoway, Chief of Bureau. Hon. JAMES WILsoN, Secretary of Agriculture. GO / ee The avocado (Persea gratissima) is one of the most recent fruits to receive intelligent and systematic treatment from American fruit erowers. Though long held in high regard by persons living in southern Florida, the West Indies, and most portions of tropical America, it has not until recently attracted the attention of northern consumers, and is, in fact, at this time an interesting novelty rather than a recognized staple of commerce. This is probably due to the fact that it lacks those characteristics of texture and flavor which are sought for in most dessert fruits, so that a taste for it must be acquired by most persons. In recent years, however, its usefulness asa salad fruit has gradually been recognized, so that a growing appre- ciation of its value in this regard has led to an increasing demand for it in our larger cities. Until very recently the principal supply for these markets has come from the West Indies, chiefly because of cheaper transportation from those islands than from Florida. The recent extension of railroad facilities to far southern Florida has made possible the safe shipment of this fruit from that section to practically all parts of the country, and interest in its commercial culture there has therefore largely increased. As it provides a wholesome and nutritious food, which, judging from present demand and prices, will afford a profitable crop in loca- tions suitable to its production, its culture on a commercial scale appears worthy of encouragement in Porto Rico, southern Florida, Hawaii, and such locations in California as are practically free from frost during the blossoming season. The greatest need at present appears to be the propagation of pro- ductive varieties of desirable size, form, and quality, ripening at an opportune time—that is, late in autumn or early in winter, when the demand in northern markets at high prices appears to be best. As the bud propagation of this fruit in a commercial! way has but recently commenced, it 1s believed that this publication, which deals largely with that subject, will be of distinct value to those who desire to engage in its production. G. B. BRACKETT, Pomologist. OFFICE OF THE POMOLOGIST, Washington, D. C., March 29, 1904. COM EE NTS. 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Vanletlest memes Sa ce ate nc oe es as Se ee \OISEISE CO) Bad OS SI NAD Ne ee eas Rc Se oS ie Ry ate oar ee aa eras DISCASCRI Sea ee eee eR ORNL Rae 1S eee Mes he SP Sa ae eat diseases. 2 Basse ee re ee Se at lass apt ae REA Rema eChylecao eee eee pM ees se ee MR oe Sige es ea Et Unlibs ISCAS Cas as Heep eany see rere ice a ee Lr ee EXEL OOUSSO yee Rc ic 'S els cm Si es Ee Oe hea a aR wg an RS UUM MNT AAV vy cs a 8 ea PR HC cmt a Ly A ONS a Ne Wescripi clon: Oleplates: 52)... as eee er cia a a ee a 7 Fic. IG PAU SIRI IONS PLATES. Page. ‘Puate I. West Indian-South American avocado tree, thirty-five years old, SLOWING OM AgcOrale One cciaumee ie = eas sere yes ee ee Frontispiece. Il. Fig. 1.—Crown-worked West Indian-South American avocado tree, eighteen months after insertion of bud. Fig. 2.—Top-worked Mexican avocado tree, eighteen months after insertion of bud --- 36 III. West Indian-South American avocado tree in nursery, ueumsig En rel from seed: bed :2: years’ old|4 tect tale ae eee = eee 36 IV. Fruiting branch of West Indian-South American avocado tree, one- tenth natural diameter 22032 5co..-e2 see ee eee ae 36 TEXT FIGURES. 1. Seedling avocado in December from seed planted in September --.--- 16 2. Shield bud) should be avoided and care taken not to use such buds in propagating. Some are likely to occur on any stick. Various methods of budding have been adopted and some forms of grafting have been suggested. The common shield bud (fig. 2) seems to be about as successful as any that have been tried, though the patch bud is also used with a considerable degree of success. ae pe Fig. 2.—Shield Fie. 3.—Seed- _ Fie. 4.—Shield Fie. 5.—Bud stick; a, a, ete., bud cut out ling avocado bud wrapped ‘live’? budsin various stages preparatory stock with with waxed _ of development; }b, b, ete., to insertion. shield bud in- cloth. blind buds which should not serted. be used. GRAFTING. Baltet® recommends four different methods of grafting: (1) Inarch- ing, (2) veneer grafting, (3) cleft grafting, and (4) veneer grafting near the root. In inarching and cleft grafting the top of the stock is fig- ured as having been cut away. In the other two methods the top of the stock is left until the scion has started. Well-matured wood will live for several weeks if kept in a sufficiently moist condition, and will doubtless unite readily with the stock, but it is much more wasteful of scion wood and a more tedious process than budding. aL) Art de Greffer, 7th ed., Paris, 1902, p. 226. TRANSPLANTING. 19 TRANSPLANTING TO THE FIELD. A great deal of the difficulty that has been experienced in trans- planting the avocado is due to the fact that most of the trees have been erown in ‘‘fence corners,” or possibly they have been permitted to erow under the tree where the seed fell, thus producing tall, slender seedlings, with very few branches and long taproots, but not many fibrous roots. A very different result is obtained from trees grown in a nursery (see Pl. III), where, as previously stated, an abundance of fibrous roots and a good bushy top are produced. A tree of this kind transplants without any greater difficulty than is experienced with other orchard trees. One hundred budded trees to an acre are sufficient. If the grower proposes to have a seedling orchard the trees should be set closer— 160 to 200 per acre. This should be done with a view to cutting out the inferior ones when they come to fruiting. Of the large-growing varieties 80 trees to the acre will be found sufficient. If the variety is tall and spindle shaped instead of bushy, a larger number may be planted. | In the Antillean region trees grow during the entire year, so there is no sensible gradation into winter or anything that corresponds to a dormant season, strictly speaking. While fruit trees are usually in a more or less quiescent state during January and February, this con- dition is brought about by a diminution in rainfall rather than as the result of a reduction in temperature. The time to transplant avocados is determined, as in the case of the nursery, by the presence of sufficient moisture, and a suitable moist period will usually occur in Florida during June, July, or August. As the expense of watering during a dry season is much greater than the cost of the tree it is cheaper to set the tree out during a rainy season. A tree should not be transplanted until it has attained a height of about 3 feet in the nursery (see PI. III). In taking up these trees as many of the smaller roots should be secured as possible. The roots should be kept moist and the tree well watered when set out. The top should be cut back to some extent, but enough foliage left to shade the stem. If the tree is not suffi- ciently provided with leaves an artificial shade can be made by the use of palmetto fans. TOP-WORKING TREES. Bearing trees may be top-worked (see PI. II, fig. 2), but it is neces- sary to insert buds on vigorously-growing sprouts to succeed. If there are no sprouts with bright green bark, they may be induced to grow by cutting back the branches and thus stimulating some of the 20 THE AVOCADO IN FLORIDA. latent buds, or by cutting the trees off near the ground and then wait- ing for sprouts to start from the crown. Several of these sprouts are then budded and the most vigorous of those that have taken are per- mitted to grow (see PI. I, fig. 1). CULTIVATION. When the trees are set in the field a considerable quantity of mulch should be placed about them; this prevents the soil from becoming hot about the roots and from drying out. In Florida it is better to plant some field crops, such as cowpeas or - velvet beans, or to sow beggar weed in a young orchard. During the winter, crops of vegetables may be grown in the orchard with advan- tage to the trees. The ‘‘middles” may be planted to pineapples, since the pineapple fertilizer will produce a good growth of avocado; but there is the disadvantage that these plants will dry out the soil severely during a drought. During dry weather cultivation should be frequent and thorough, but not deep;°3 inches of soil mulch is sufficient to conserve capillary moisture. During the rainy season cultivation may be suspended entirely and the middles planted to some cover crop, as indicated above. FERTILIZERS. In selecting fertilizers a formula should be chosen in which the ammonia is from an organic source, such as dried blood or cotton- seed meal, in preference to sulphate of ammonia or nitrate of soda. Sulphate of potash will be a safe form to employ as a source of potash. It should be used in liberal quantities to insure good firm leaves and wood, and also to prevent the dropping of the fruit. Phosphoric acid, so far as experiments teach, may be supplied from any source that is ordinarily used. If the trees be planted about poultry yards, or fowls are allowed to roost in the trees, potash will be all the fertilizer needed, but this should be used liberally to keep the trees healthy and free from insect attacks. Such trees when not fertilized with potash are usually attacked by insect pests, but as a rule are exempt from Gloeosporium. : When commercial fertilizers are to be applied, the ordinary ‘fruit and vine” fertilizer, with the ammonia from an organic source, may be used. The quantity required will vary according to the concentra- tion of the particular brand, the character of the soil in which the trees are growing, and the age of the trees. Fifteen pounds per tree per year of fertilizer prepared according to the following formula will be found good for growing trees four or five years old: Ammonia, 5 per cent; potash, 6 per cent; phosphoric acid, 6 per cent. SUPERIORITY OF BUDDED TREES. yall As the trees grow older and begin to fruit heavily, increase the percentage of potash and phosphoric acid. Apply the fertilizer in two or three doses during the growing season. The time of applying must be determined by the particular orchard under consideration; ordinarily an application should not be made during December or Jan- uary, as it would be likely to force an early spring growth or even cause a vigorous winter growth, which should be avoided. If the trees be put into a dormant or semidormant condition during December and January, they will make a strong spring growth and produce a heavy crop of bloom. If the bloom is retarded as long as possible the blooming period will be shortened, and consequently the fruit will mature more nearly at one time, thus doing away with the necessity of making several pickings from the same tree. Trees that have been neglected do not prove productive unless they happen to be standing on some place where a large quantity of organic matter has accumulated. Trees on abandoned homesteads located in the piney woods scon become unproductive and require two or three years’ nursing to bring them back to good growth and bearing. It usually pays better to start in with good, fresh trees from the nursery than to attempt to ‘‘ bring out” an abandoned orchard. SUPERIORITY OF BUDDED TREES. The earlier productiveness of orchards composed of budded and grafted trees has been repeatedly demonstrated with most of the tree fruits that are grown under cultivation. While occasional seedling trees of most species bear at as early an age as the ordinary budded or erafted tree of the same species, the trees in a seedling orchard usually vary greatly in this particular, and on the average come into bearing much later than budded or grafted orchards of varieties of the same types of fruits grown under similar conditions. While many factors are concerned in producing this result, the greatest advantage of budding and grafting is that varieties of known precocity and productiveness, as well as other desirable characteristics, can be per- petuated with httle variation, while the seedling orchard contains indi. viduals differing widely in some or all of these important particulars Seedling avocados usually do not fruit until they are four or more years old, and they are usually six years old before bearing a crop. There are exceptions to this, but the number of seedlings that bear a good crop before they are six years old will not amount to 10 per cent. VARIATION OF FRUIT FROM SEEDLING TREES. The systematic work of propagating and cultivating avocados is just beginning. The fruit being of American origin, it has come into cul- tivation rather recently, and has not had the benefit of centuries of BY THE AVOCADO IN FLORIDA. selection and propagation, as is the case with many other orchard fruits. Throughout Central America and the West Indies it grows in a native state, and only half-hearted attempts are made to put it into cultivation. So far as the writer is aware, no orchard of any consid- erable size exists outside of Florida. In Cuba, Jamaica, Porto Rico, and the Bahamas a few seedling trees are growing around nearly every settler’s place. The owner plants the seed and takes his chances as to the character and fruitfulness of the tree. Under these conditions a considerable quantity of fruit is being grown and marketed, but the product is of an exceedingly variable nature. The two following illus- trations prove the truth of this statement. DESCRIPTION OF VARIATIONS. Mr. G. L. Macdonald, of Cocoanutgrove, Fla., related his expe- rience to the writer. In preparing for his orchard Mr. Macdonald selected the seed from a tree that bore fruit of exceptionally fine quality and in large quantity. At the time the selection was made it was generally believed that avocados came true to seed. The parent tree produces pear-shaped avocados of large size, fine flavor, and purple color, ripening late. The seedling orchard from this tree has now come into bearing and produces fruit of variable size and shape; good, bad, and indifferent flavor; the color varying from green through yellow to purple; and the fruits ripening at different times in the season. The following census, taken near Buenavista, Fla., in an orchard of about an acre in extent, shows how little foundation there is for the belief that the avocado trees are unusually fruitful and that the tree comes ‘true to seed.” The impression that the tree is unusually fruitful doubtless originated from the fact that occasional trees bear a heavy crop (see PI. III), causing the observer to overlook the dozens of trees that have less than ten fruits each or possibly none at all. The unfruitfulness and the variability of the product is not more than - should be expected from an orchard of seedlings. This orchard contains 160 trees, 110 of which are five or more years of age and of a size to permit the smallest to bear 50 fruits, weigh- ing from a pound to one and one-half pounds each. This number of trees produced 1,161 fruits in 1903, a year during which the avocado crop was unusually heavy. This gave an average of approximately 10 fruits to the tree. Forty-seven trees bore no fruit at all; 41 trees bore from 1 to 12 fruits; 22 bore a crop of more than 12 fruits, 9 of these latter trees bearing 595 fruits, or slightly over half the crop. The four most prolific trees bore 385 fruits—that is, one-twelfth of the trees produced one-third of the fruit, or, stating the matter in percentages, 43 per cent of the trees produced no fruit; 37 per cent MARKETING. NS} produced 1 to 12 fruits each; 20 per cent produced over 12 fruits each. | | Considering only the prolific trees, we find that 8 per cent of the trees produced 66 per cent and that 8 per cent produced 33 per cent of the fruit. The nine trees that produced at least a fair crop were of medium size, while the largest and most vigorous trees in every instance bore less than a fair crop. , The trees referred to above were from specially selected seed, so that it may safely be assumed that they were up to the standard for seedling orchards of the same type that have received fair attention and are of the same age. Some of the trees that were without fruit this year had a fair crop last year, indicating a tendency on the part of the avocado to fruit in alternate years. The most fruitful trees are only moderately vigorous and of a bushy growth. Of the 68 trees that have fruited in the orchard mentioned there are only 2 which combine good qualities in such a way as to be of special merit. Some trees that bear tine fruits are not prolific; others ripen their fruit at an inopportune time of the year, while still others bear a fair crop at the right time but the fruit is inferior in ‘quality. (See nes. 6,7, A; 8, and 9.) If a census of all the seedling orchards were taken, it is not probable that the general results would be very different, but this is just what should be expected in propagating from seed a species that is so variable as the avocado. MARKETING. PICKING. The time of ripening of the avocado extends in Florida from the middle of July to December. As now grown, the fruits of a tree do not as a rule mature uniformly, so that in most cases two or more pickings have to be made. The variation in this respect is so much an individual characteristic that the peculiarities of each tree in the case of a seedling orchard, and of each variety if budded, will have to be ascertained by test. The fruit must be removed from the tree while it is still very firm if it is to be shipped to a distant market. For local consumption the crop may be permitted to remain on the tree until a few fruits have fallen. . In picking, the avocado should be broken off so as to leave a portion of the stem attached to the fruit. If a particular variety does not break properly, an orange clipper or the ordinary pruning shears may be used. If the stem be pulled out of the fruit, as occurs in ‘‘ drops,” there is a strong probability that some of the fruit will be lost from ripe rot in transit, or by softening in the hands of the dealer. 94 ; THE AVOCADO IN FLORIDA. GRADING AND SIZING. With the avocado, as with all other fancy fruits, it is necessary to exercise care to have all the specimens in a crate of uniform shape and Be Fie. 6.—Longitudinal sections of round avocados, West Indian-South Ameriean varieties (about one- half naturai diameter): A, seed filling the cavity; B, fruit from another tree of better quality, but seed loose in the cavity. ‘on, ie TANS Ges, A. Fie. 7.—Longitudinal sections of oblong avocados, West Indian-South American varieties (about one- half natural diameter): A, small seed, loose in large cavity; B, large seed, loose in the cavity. size. (See figs. 6, 7,8,and 9.) A few small ones ina crate of otherwise large fruits will cause a greater loss to the seller than would have been PAOKING. 25 occasioned by rejecting the small ones. Fruits that average more than fifty to a tomato crate are not desirable for sending to distant markets. While the demand has been so strong that almost any avocado in sound condition would sell, too great emphasis can not be placed upon the necessity for packing each crate with fruit of uniform size, Shape, and color. While the market has no pronounced demand for any particular form, those of a decided pear shape (see fig. 8), of even size, and of which about three dozen can be packed in a tomato crate, bring the highest price. A. Be Fic. 8. —Longitudinal sections of pear-shaped avocados, West Indian-South American varieties (about one- “half natural diameter): A, very large seed, loose in the cay ity; B, large seed, loose in the cavity. PACKING. For shipping purposes the market at present demands a tomato crate or an eggplant crate. In the course of a few years a ee package of dimensions best adapted to this particular fruit will, doubt, be adopted. Neither the tomato crate nor the eggplant ae is perfect from the growers’ point of view. The larger package brings such a quantity of fruit into one compartment that some of the lower ones are likely to be bruised in transit. If some of the avocados hap- pen to become soft on the way, the appearance of the remainder will be much injured and the selling value of the entire crate will be greatly reduced. The tomato crate is much better in these respects, but it is not entirely satisfactory, because only the round fruits pack well in it. 26 THE AVOCADO IN FLORIDA. When the ideal crate shall be adopted it will probably be similar in shape to the boxes used for California pears. Before packing, the individual avocado should be wrapped in some substantial and attractive paper. This will add materially to the car- rying quality and to the selling price of the fruit. Enough fruit should be put into the crate so that it will be packed firmly, to pre- vent any possibility of shaking on the way to market. It is not always Se A. Fic. 9.—Longitudinal sections of bottle-necked avocados (about one-half natural diameter): A, West Ici an count American yariety, with very large cavity; B, Mexican variety, with seed filling possible to properly fill the crates now used, and it sometimes becomes necessary to fill up the vacant space with excelsior. In large crates and with well-matured fruit a considerable quantity of excelsior must be used to make sure that the fruit will not be bruised. The produc- tion of avocados in the United States is so limited and the demand thus far is so much greater than the supply that comparatively little care has been necessary to secure good prices, provided the fruit reached the market in sound condition. THE FRUIT. ON THE FRUIT. The avocado varies greatly as to size, shape, color, texture, and com- position, while the trees also present distinct differences. In size, the fruits vary from those no larger than a hen’s egg to specimens which weigh 3 pounds. (See fig. 7, A, and fig. 9, B.) As to shape, there are four recognized types, although all possible gradations occur. The so- called round. fruit (see fig. 6) is not strictly spherical, being flattened at the distal end or at both ends. The oblong fruit (see fig. 7) may be of various lengths, but the diameter is always greatest from the stem to the distal end. The pear-shaped (see fig. 8) and bottle-necked varieties (see fig. 9) are sufficiently described by their names. The color of a ripe avocado varies from a dark purple, like that of a ripe eggplant, to scarlet, yellow, and grass-green. As a rule, the fruit is not of one color over all of its surface; the purple or scarlet fruits are usually lighter and the green fruit tinged with yellow at the distal end. All combinations of the sizes, colors, and shapes men- tioned are found. — THE EDIBLE PORTION. The edible portion of the fruit, called the meat, in desirable varie- ties is a smooth, rich substance, with the texture of cream cheese. Some inferior fruits are decidedly watery and oily in appearance, while others are comparatively dry. : The following analyses were made by Charles D. Woods and L. D. Merrill.“ The pulp of three fruits was. taken for an analysis. Grams. | Percent. MGibIe pOrbome =. = aes ey ee ate ed 762.2 71.09 SRG i Ee eo i ee ee el ares 201.4 19.71 SiciTieele eae ge ee te, ee ee tn ei ee 94.0 9.20 AONE Me ce oo RA se aaa oe a NEN Se eee 1,021.6} 100.00 a Thirty-six ounces. It was found that 1 pound of the edible portion contained the fol- lowing weights of nutrients: Pound. NAVE NAST ain rm ae Ole ain kee Bin nig a Saino a I gE nan ae ye Roe 0. 811 OFT ES ie ss teen meee aera Oe en EL PAP ee. kok Bas a) . 010 FEA aetna emis ie ee oma natn ee Gna Ae oe See he ey Peed aod 5 OY, @2rbolnycdrates ie! a 3s ee reer Aes oe er ee Ee . 068 JRF) Gs Se hyo eM ee i eg ae 8 Oe ACI Ee cn ea Pac . 009 The fuel value is estimated at 1,758 calories- per pound of edible portion. @Maine Agr. Exp. Sta. Bul. 75, July, 1901, p. 111. 28 THE AVOCADO IN FLORIDA. In color of meat the fruits of different varieties vary. Immediately under the epidermis it is green, sometimes for only a fraction of an inch; in other varieties it may be green three-quarters of the way | through the meat, the remainder being either whitish or yellowish, or the green color may extend almost to the seed. Some of the finest varieties have a cream-colored meat. In texture some avocados have rather watery meat, with a number of strings running through it, and are decidedly inferior to fruit with firm meat and no strings. SEED AND SEED CAVITY. The variations in the seed cavity are of importance from a commer- cial standpoint. In some fruits the seed is lodged firmly in the meat; in others it occupies only a fraction of the cavity (compare figs. 6, 7, 8, and 9), and variations occur anywhere between these extremes. Obviously, the best shipping fruit is that with a seed cavity so small that the seed can not be shaken about, since in handling the fruit in transit the seed in a large cavity so bruises the meat as to cause rapid deterioration. This point should be borne in mind in selecting varie- ties for propagation. In the shape and size of the seed marked variation occurs. The shape does not necessarily conform to that of the fruit, while the size may vary from one-half the bulk of the fruit down to one-tenth or even less. (Compare figs. 6, 7,8,and 9.) One tree that bears seedless fruit has been discovered in Florida. Since the formation of seeds is the greatest tax on the energies of the plant, it is important for the grower to produce fruits with as small seeds as possible; these the buyer will also prefer, as to him the seed is of no value. SHAPE OF THE TREE. The manner of growth of avocado trees differs exceedingly. Some trees grow with a slender shape, like the Lombardy poplar; others spread out in the form of an American elm, while the greater number take on the compact shape of a fruit-bearing tree, making an outline somewhat similar to that of a haycock. (Compare Pls. I, H, and IIL.) This last mentioned form is, of course, the most desirable of the dif- erent shapes. It gives the tree a chance to withstand gales, and per- mits the fruit to sway on slender branches, thus keeping it from being blown off during storms. FORMS AND VARIETIES. The species (Persea gratissima Girtn., or what is popularly known as avocado, is well defined from the other species of the genus, but inside of the species as at present understood it is exceedingly vari- able. Some attempt has been made to separate this species into vari- eties, but so little has yet been done in the way of perpetuating FORMS AND VARIETIES. 29 particular sorts by bud propagation that varieties in the pomological sense have not yet found a place in literature. La Sagra® gives the following classification, based upon the characters of the fruit: The aguacate is, without doubt, one of the most valuable iruit trees of South America. The fruit is in form of a large pear, without any depression at the head. The skin is a yellowish green ora pale violet color, and smooth. The substance of the fruit, when well matured, is nearly white and has a soft, oily consistency and a slightly sweet taste, somewhat sugary. It is eaten in its natural state and also seasoned in various manners, nearly always with a little salt. The animals devour it eagerly. The tree blossoms in April and the fruit matures in July and nema, The varie: ties which are cultivated in Cuba are— 1. The violet color, which is nearly round in shape. 2. The large green, round, with the inside yellowish and having the consistency of bread. 3. The large yellow, similar to a large pear. 4. The long green. The maturity of the fruit is known when the seed which it contains become loosened from the substance of the fruit and rattles when it is shaken. ? In order to obtain good trees one must sow the seed in the place where it will remain permanent, in holes of 3 feet in dimension in every direction, which are filled with good soil. These trees ordinarily bear fruit from the fifth year and live to about. their eightieth year. They are planted in form of beautiful groves and walks about the dwellings of the inhabitants, and as their growth is very vigorous they soon take strength from neighboring trees. Their flowers yield a very agreeable perfume. Compare the description of plates, page 36, and figs. 6, 7, 8, and 9 with the above description. Meissner’ recognizes several botanical varieties based upon the shape and size of the leaves. _ Vulgaris has leaves ‘‘3-4 poll” by 1% poll;” Oblonga, ‘*4-9 poll” by ‘* $-2 poll;” Macrophylla, ‘ 6-9 poll” by *° 34-44 poll.” THE MEXICAN AVOCADO. There is a small-fruited form of avocado which was introduced in 1893 from Mexico (see fig. 9, B) in the form of seeds by the Divi- sion of Pomology of the Department of Agriculture, to which no ref- erence 1s made in the literature examined, and no specimens of this form were found in the herbaria visited. It is regarded in Mexico as more frost resistant than the common form found in Florida and the West Indies, but is not considered as valuable as the larger fruited varieties where the latter may be grown successfully. Its fruit is pear-shaped, or bottle-necked, about the size of a hen’s egg, usually of a dull blackish or bluish color. The skin of the fruit is thin and leathery. The seed is small, conical, usually about an inch in diameter. “Translation from Historia Fisica de Cuba (is49); Vol XI p. 186. » Correct for some varieties only.—P. H. R. ¢Martius, Flora Brasiliensis, Vol. V, pt. 2, fase. 41, p. 159. 30 THE AVOCADO IN FLORIDA. The tree is a less vigorous grower, and the branches are inclined to be slender. The leaves are borne on a slender petiole about half as long as the blade, which is thin and elliptical in shape. The flowers are borne in an open panicle on long slender pedicels and the fruit ripens earlier than the West Indian—South American form. Another striking peculiarity of this form is that the first pair of scale-like leaves produced have, while those of the West Indian—South American form do not have, a distinct petiole and blade. (See fig. 1.) This form has been grown successfully in California, where it is becoming popular. Figure 9, B, is from a specimen kindly furnished by Mr. W. Chappelow, Monrovia, Cal., from a tree grown from seed of the first importation from Mexico by the Department of Agriculture. THE WEST INDIAN-SOUTH AMERICAN AVOCADO. The fruit of the West Indian—South American avocado is large, varying in weight from a quarter of a pound to 3 pounds. The shape is as variable as the size, varying from oblate spheroidal to almost banana shaped. (See figs. 6, 7,8, and fig. 9, A.) The color of the fruit is purple, scarlet, yellow, and green. The rind is usually thick and brittle. The seed is often very large, sometimes making up one-half the weight of the fruit; the shape of the fruit variable—spheroidal to conical. The tree is of vigorous growth, reaching a height of 20 to 30 feet, and sometimes is even taller; the branches are thick and brittle. The leaves are borne on a short, thick petiole, less than one-fourth the length of the blade, which is thick, elliptical, and from 4 to 10 inches long. The lower surface of young leaves is covered with a pubescence. Flowers in open panicle are borne ona short peduncle. The fruit is borne on a thick pedicel, and ripens from the middle of July to Decem- ber. A few trees retain their fruits until January, and even up to March. In the native habitats the species seem to run to distinct forms, as is indicated from the botanical literature and botanical specimens named by authorities on the subject. These forms do not come true to seed when brought into cultivation, owing probably to the fact that the trees are put under special new conditions, and that trees from a large number of varieties are planted near to each other, making cross- pollination almost certain. It is not surprising, therefore, that we find large-fruited and small-fruited trees; yellow, green, scarlet, and purple colored fruit; small, medium-sized, and large leaves; good, bad, and indifferent qualities, all coming from selected fruits from a single tree, as indicated from observations cited on a former page. It is really only what should be expected when viewed from a plant breeder’s standpoint. FORMS AND VARIETIES. al THE IDEAL AVOCADO. The tree should be of small or medium size. So long as the supply is limited and the fruit brings fancy prices, the cest of gathering from the tall-growing trees is no serious obstacle, but much fruit is lost from a tall tree as a result of high winds, which are common in the Antillean region during the ripening season. The fruit should weigh about a pound to a pound and a half. This is large enough for persons with an ordinary liking for this fruit, while those who are extraordinarily fond of it can call for two fruits. Pear-shaped (see fig. 8) or oblong varieties (see fig. 7) should be pre- ferred, as they can be packed readily and transported without much danger of being bruised in transit. The seed should not be loose in the cavity, as the shaking of it in transit pounds the meat into an unsightly mush. The color of the fruit should be either yellow or scarlet. The fruits that ripen green are considered by the novice as having been picked when too immature, and those that ripen brown or purple look as if they were in the first stages of decay. A very late variety would undoubtedly be the most desirable, since it would ripen at a time when all the West Indian and Mexican avocados were gone, and most of the northern fruits were out of the market. USES OF THE FRUIT. According to Patrick Brown,” horses, cows, cats, dog's, as well as all sorts of birds, feed on this fruit. Much has been written regarding the manner of serving this salad fruit, but only one or two essential additions have been made in the last two hundred years. No matter how daintily it may be prepared one can scarcely relish it more than when, tramping through the forests, he happens upon a tree with a few fruits fully matured. The traveler is likely to be seated at once, enjoy his fruit without salt, sugar, or other condiments, and forever after he will remember the deliciousness of that particular fruit, which if eaten with any or all condiments at the most carefully appointed table would not have made as strong an impression on his memory. An avocado should not be used until the meat cuts smoothly with a teaspoon and is about the consistency of well-frozen ice cream. No one should attempt to eat the fruit after it has softened; a rancid avocado may well be compared to rancid butter. The simplest way of using this fruit is as already stated. One merely halves the fruit, removes the seed, and dips out the meat with a teaspoon, or to the plain fruit a bit of salt may be added. Some people use pepper in addition. The number of ways in which the «Civil and Natural History of Jamaica, London, 1789, p. 214. 32 THE AVOCADO IN. FLORIDA. avocado may be served is as varied as the possible salad combinations. One should not, however, deluge this rich fruit with oil nor overpower with condiments its mild, nutty flavor. Salt, pepper, and vinegar are often used; if to this enough sugar be added to take off the sharpness _of the vinegar, it will be an improvement. Lime juice or lemon juice may be substituted for the vinegar with advantage. The avocado is sometimes served as a dessert with sugar and sherry. Another distinct method of using this fruit is to remove the meat from the skin, add the condiments desired, and then stir the whole into the form of a salad and serve either alone or on lettuce leaves. Some chefs cut the meat into small cubes of about a half or one-third of an inch in size and serve it with condiments, as in minced salad. The use of the avocado as an ingredient of lobster or other shellfish salad is said to have become quite general in localities where the fruit ean be obtained, as it gives the salad a pleasing nutty after flavor not otherwise secured. Another use is in mixed pickles. For this purpose the fruit should be selected before it has become soft, yet after it is no longer hard and brittle. The fruit is pared, the seed taken out, and the meat cut into pieces not over a half inch thick. This is then prepared in the usual manner for cucumber pickles, ete. DISEASES. LEAF DISEASE. While the avocado has recently been introduced into cultivation, it has some severe diseases, which, however, can be handled without much difficulty if taken in time.. One of the most prominent and common diseases noticed is due toa Gleosporium, probably an unde- scribed species. This almost invariably attacks the leaf at the tip, and gradually works back from this point into the blade. By the time the leaf has become two-thirds or three-quarters diseased, it usually falls off, and in this way the fungus may defoliate the entire tree. Remedy.—Spraying with Bordeaux mixture® should be begun on the first appearance of the trouble. If spraying is delayed until the tree has been partially defoliated, success will be attained with much greater difficulty. «Bordeaux mixture may be prepared by dissolving 6 pounds of bluestone in 25 gallons of water. This may be done readily by piacing the bluestone in a feed sack and suspending it near the surface of the water. Slake 6 pounds of lime with just enough water to coverit. When this has been thoroughly slaked, dilute with 25 gal- lonsof water. Strain the slaked lime into the tank of the spraying machine through coarse sacking, to remove all particles which might clog the spraying machine. Pour the dissolved bluestone into the lime water, stirring vigorously for two or three min- utes. Apply at once. SUMMARY. Bie) FRUIT DISEASE. Apparently the same fungus which causes the disease of the leaves attacks the fruit in various stages of development. If the disease becomes prevalent while the fruit is small, it will shed off until the tree is quite fruitless. If the disease attacks the more mature fruit, it is able to remain on the tree until nearly ripe, but the fungus pro- duces a brown spot, and finally the skin cracks. Remedy.—The same remedy should be used as for the leaf fungus. SUMMARY. Avocados do not come true to seed. Orchards of seedling trees can not be relied upon to produce good crops. Budding is practicable and it is the most desirable way of propa- gating. i Crown-working is preferable to top-working. Budded trees grown in a nursery should be used in planting an orchard. ? All the fruit shipped to market in a crate should be of the same size, of the same shape, and of one color. Preferences for color are as follows: Yellow, scarlet, green, brown. Pear-shaped fruits and oblong shapes are preferred. Round are less desirable than bottle-necked fruits. The varieties which ripen during December, or later, sell for the highest prices. The large percentage of fat contained in this fruit makes it especially desirable, since it is much more agreeable to some people than the fat obtained from an anima! source. 29619—No. 61—04——3 iE A ait DESCRIPTION OF PLATES. Puiate I. Frontispiece—West Indian-South American avocado tree, about 35 years old, growing on a coral breccia reef. Produces fruits of fine quality. Ripens purple. é Piate Il. Fig. 1.—Crown-worked avocado tree eighteen months aiter insertion of bud. The bud was placed in a sprout that had started from a stump of a tree the summer before. West Indian-South American variety. About 8 feet tall. Fig. 2.—Top-worked tree eighteen months after insertion of bud, which was placed ina green sprout. The tree was approximately of the same age and vigor as the one shown in Plate II, figure 1. Mexican variety. About 12 feet tall. Compare the general mode of growth, arrangement of leaves, etc., with the tree shown in Plate II, figure 1. Puate Ill. Nursery tree two years old, transplanted from seed bed, West Indian— South American variety. A good, vigorous stock for budding. About 4 feet tall. : Pirate LY. Fruiting branch of West Indian-South American variety, showing the manner in which the fruit is borne upon the branches. The photograph from which this illustration was made was taken from the inside of the tree to bring out the peculiar mode of attachment. This branch may be considered as earry- ing a very heavy crop. Fruits about one-tenth natural diameter, ripening green. 36 O PLATE Il. Bul. 61, Bureau of Plant Industry, U. S. Dept. of Agriculture. FIG. 1.—CROWN-WORKED WEST INDIAN-SOUTH AMERICAN AVOCADO TREE, EIGHTEEN MONTHS AFTER INSERTION OF BUD. Fia. 2 TOP WOR KED MEXICAN AVOCADO TREE, MONTHS AFTER INSERTION OF BUD. Ela HTEEN Bul. 61, Bureau of Plant Industry, U. S. Dept. of Agriculture. PLATE III. WEST INDIAN-SOUTH AMERICAN AVOCADO TREE IN NURSERY, 2 YEARS OLD, 4 FEET TALL. f ty pe ee | PLATE IV. Bul. 61, Bureau of Plant Industry, U, S. Dept. of Agriculture. FRUITING BRANCH OF WEST INDIAN-SOUTH AMERICAN AVOCADO TREE (ONE-TENTH NATURAL SIZE.) “No. D5. vu hx - [Continued from page 2 of cover. ] Miscellaneous eee ‘The Seeds ‘af Rescue Grass and Chess. TE: Saragolla : Wheat. IIT. Plant Introduction Notes from South Africa. IV. Congres- - sional Seed and Plant Distribution Circulars, 1902-1903. 1903. Price, 15 cents. ; Sa : Spanish ‘Almonds. 1902. Price, 15.cents. . Letters on Agriculture in the West Indies, pale, and the Orient. _ 1902. - Price, 15 cents. . The Mango in Porto Rico. 1903. Price, 15 cents. . The Effect of Black Rot on Turnips. 1903. Price, 15 cents. . Budding the Pecan. 1902. Price, 10 cents. : . Cultivated Forage Crops of the Northwestern States.. 1902. Price, 10 cents. — . A Disease of the White Ash Caused by Polyporus Te ne 1903. Price, 10 cents. . North American Species of Leptochloa. 1903. Price, 15 cents, . Silkworm Food Plants. 1903. Price, 15 cents. . Recent Foreign Explorations, as Bearing on the Agricultural Development oY the Southern States. 1903. Price, 15 cents. . The ‘ Bluing”’ and the ‘‘Red Rot”’ of the Western Yellow Pine, with Spe- =e cial Reference to the Black Hills Forest Reserve. 1903. Price, 30 cents. . Formation of the Spores in the Sporangia of Rhizopus Nigricans and of ‘ Phycomyces Nitens. 1903. Price, 15 cents. . Forage Conditions and Problems in Eastern Washington, Hastorn ee ete. 1903. Price, 15 cents. . The Propagation of the Easter Lily from Seed. 1903. Price, 10 cone : . Cold Storage, with Special Reference to the Pear and Peach. 1903. Price, 15 cents. . The Commercial Grading of Corn. 19038.. Price, 10 ae . Three New Plant Introductions from Japan. Price, 10 cents. . Japanese Bamboos. 1903. Price, 10 cents. . The Bitter Rot of Apples. 1903. Price, 15 cents: a5 ib . The Physiological Role of Mineral Nutrients in Plants. Price, 5 cents. . The Propagation of Tropical Fruit Trees and Other Plants. Price, 10 cents. - . The Description of Wheat Varieties. 1903. Price, 10 cents. . The Apple in Cold Storage. 1903. Price, 15 cents. CAD . The Culture of the Central American Rubber Tree. 19038. Price, 25 cents. . Wild Rice: Its Uses and Propagation. 1903. Price, 10 cents. if . Miscellaneous Papers: Part I. The Wilt Disease of Tobacco.and its Control. _ 1903.,, Price, 5 cents. Part II. The Work of the Community Demonstra- tion Farm at Terrell, Tex. 1904. Price, 5 cents. Part. III: Fruit Trees Frozen in 1904. 1904. Price, 5 cents. . Wither-Tip and Other Diseases of Citrous Trees and Fruits Caused by Colletotrichum Gloeosporioides. 1904: Price, 15 cents, . The Date Palm and its Utilization i in the Southwestern States. 1904. Price, 20 eents.- os . Persian Gulf Dates. 1903. Price, 10 cents. . The Dry Rot of Potatoes Due to Fusarium Oxysporum. 1904. Price, 10 cents. - Nomenclature of the Apple. | [In press. ] - Methods Used for Controlling and Bee aaa Sand Dunes. 1904. Price, 10 - cents. . The Vitality and Germination of Seeds. 1904. Price, 10 cents. . Pasture, Meadow, and Forage Crops in Nebraska. 1904. -. Price, 10:cents. - A Soft Rot of the Calla Lily. [In press. ]