CITR F..R.U.I IS t; ciencG Series STORAGE ITEM U.B.C. LIBRARY ^tilmif ^Mtlmmhm Atcc$Hxrn 3^. "^v *3^/ 3 iTali ^V. 6fi> 06^ • 6 6 XTbe IRutal Science Series Edited in L. II. liAILEY CITRUS FRUITS E\)t l^ural Science Scries The Soil. King. The Spraying of Plants. Lodeman. Milk AND ITS Products. Wing. Enlarged and Bevised. The Fertility of the Land. Boherts. The Principles of Fruit-growing. Bailey. 20th Edition., Bevised. Bush-fruits. Card. Fertilizers. Voorhees. The Principles of Agriculture. Bailey. 15th Edition, Bevised. Irrigation and Drainage. King. The Farmstead. Boherts. Rural Wealth and Welfare. Fairchild. The Principles of Vegetable-gardening. Bailey. Farm Poultry. Watson. Enlarged and Bevised. The Feeding of Animals. Jordan. The Farmer's Business Handbook. Boherts. The Diseases of Animals. Mayo. The Horse. Boherts. How TO Choose a Farm. Hunt. Forage Crops. Voorhees. Bacteria in Relation to Country Life. Lipman. The Nursery-book. Bailey. Plant-breeding. Bailey and Gilbert. Bevised. The Forcing-book. Bailey. The Pruning-book. Bailey. Fruit-growing in Arid Regions. Baddock and Whipple. Rural Hygiene. Ogden. Dry-farming. Widtsoe. Law for the American Farmer. Green. Farm Boys and Girls. McKeever. The Training and Breaking of Horses. Harper. Sheep-farming in North America. Craig. Cooperation in Agriculture. Bowell. The Farm Woodlot. Cheyney and Wentling. Household Insects. Herrick. Citrus Fruits. Coit, Digitized by the Internet Archive in 2010 with funding from University of British Columbia Library http://www.archive.org/details/citrusfruitsaccOOcoit THE WASHINGTON NAVEL ORANGE CITRUS FRUITS AN ACCOUNT OF THE CITRUS FRUIT INDUSTRY WITH SPECIAL REFERENCE TO CALIFORNIA REQUIREMENTS AND PRACTICES AND SIMILAR CONDITIONS BY J. ELIOT COIT, M.S. A., Ph.D. PROFESSOR OF CITRICULTURE IN THE UNIVERSITY OF CALI- FORNIA AND CITRICULTURIST TO THE UNIVERSITY OF CALIFORNIA AGRICULTURAL EXPERIMENT STATION FORMERLY SUPERINTENDENT IN CHARGE CITRUS EXPERIMENT STATION RIVERSIDE, CALIFORNIA Neto gork THE MACMILLAN COMPANY 1915 All rights reserved Copyright, 1915, By the MACMILLAN COMPANY. Set up and electrotyped. Published April, 1915, NarfajootJ i^rrsg J. S. Cushing Co. — Berwick & Smith Co. Norwood, Mass., U.S.A. PREFACE The citrus industry has now reached a high state of development in both California and Florida. Further- more, it is progressing with rapid strides. Old World practices and precedents have been largely ignored in the development of an industry characteristically Amer- ican in spirit and new in methods. The readiness with which the growers adopt new and better methods is an indication of the virility and youthful vigor of this new industry. The literature has hardly kept pace with the industry and is scattered through a large number of periodicals and reports. On this account, it is largely unavailable to those who need it most. The last comprehensive work published in California was that of Lelong in 1902. This quickly ran out of print and for the last six years lias been rare. The present volume represents an attempt to discuss underlying principles in such a way as to emphasize the importance of certain stable fundamentals upon which the rapidly changing superstructure is built. It has also been the aim to describe the industry as it exists to-day, and bring together in orderly arrange- ment all the information available at this time which is worth while. vi Preface The author has enjoyed the cooperation and assist- ance of many friends. The chapter on History and Development has been read and criticised by J. M. Guinn of Los Angeles. Professors E. J. Wickson, E. B. Babcock, B. A. Etcheverry, W. T. Home, and H. J. Qaayle, together with Messrs. W. S. Reed and E. O. Essig, have kindly read and criti- cised parts of the manuscript. E. G. Dezell of the California Fruit Growers' Exchange read the chap- ter on Marketing. I am indebted to my co-worker, I. J. Condit, for contributing parts of the chapters on insects and fumigation. For cordial cooperation in taking the atmometer records reported on in Chapter XII, I am under obligation to W. M. Mertz of the Citrus Experiment Station. Some historical and other data Uwsed in Chapter 'XIV on "Frosts and Orchard Heating " lias been taken from the excellent graduat- ing thesis of Carl Nichols. For the use of certain illustrations I am indebted as follows: to Carl Nichols for Nos. 10, 14, 15, 64, 65, and 86; to W. I. Jones for Nos. 57 and 58; to the Roeding & Wood Nursery Company for Nos. 110, 111, & 110 ; to L. H. Moore for Nos. 113 and 120 ; to Professor H. S. . Fawcett for No. 128 ; to professor H. J. Quayle for Nos. 139, 141, 142, 143, 144, 145, and 147; and to Professor C. W. Wood worth for No. 151. J. ELIOT COIT. Berkeley, California, February 17, 1915. CONTENTS CHAPTER I PAGES History and Development ...... 1-24 First planting of orange seeds in California, 1 — first . commercial orchard, 2 — other pioneer plantings, 3 — early citrus fairs, 5 — the panic of 1884-1886, 6 — the cottony cushion scale, organization of cooperative marketing, 8 — California citrus shipments, 9 — other factors which have made for progress, 10 — history of the Washington Navel orange, 13 — the citrus industry in Arizona and Sonora, 23 CHAPTER II Geography and Climatology of California . . . 25-39 Classification of citrus areas, 26 — southern coast, 28 — interior valley, 80 — northern coast, 31 — the frost hazard, 33 — atmospheric humidity, 34 — winds, 36 — sunlight, 38 CHAPTER 111 Botany, Gross Structure, and Habits or Growth . 40-64 Classification, 42 — conspectus, 43 — structure of the citrus plant, 45 — roots, 45 — wood, 46 — leaves, 49 — thorns, 51 — flowers, 52 — pollination and seed forma- tion, 55 — polyembryony, 59 — structure and composi- tion of the fruit, (50 — seasons of blossoming and harvest, 63 — longevity, 64 vii viii Contents CHAPTER IV PAGES Varieties 65-83 Seedling trees no longer planted, 65 — the struggle be- tween many varieties, 65 — the survivors few in num- ber, 66 — the orange, description of varieties, 66 — the lemon, description of varieties, 72 — the pomelo, description of varieties, 75 — the mandarin, descrip- tion of varieties, 78 — the Swingle- Webber hybrids, description of varieties, 79 — the citron, 80 — the shad- dock, 81 — the lime, 81 — the kuraquat, 83 — the sweet lemon, 83 — the trifoliata, 83 CHAPTER V The Citrus Nursery ........ 84-105 The seed-bed, 84 — source and cost of seed, 86 — preparation and planting of seed-bed, 87 — eradication of scale from nursery trees, 90 — planting seed-bed stock, 91 — propagation, 92 — cutting bud- wood, 93 — storing bud-wood, 94 — time of budding, 95 — method of bud- ding, 95 — training the nursery tree, 100 — balling and shipping, 102 CHAPTER VI HoRTTrULTURAL INSPECTION AND QUARANTINE SERVICE . 106-113 The California State Commission of Horticulture, 106 — inspection of interstate shipments, 107 — quarantine orders, 109 — State Fruit Growers' Conventions, 109 — the County Commissioners of Horticulture, 1 10 — duties of county commissioners, 110 — compulsory fumigation, 110 — the necessity for inspection. 111 CHAPTER VII Improvement ok Citrus Fruits by Breeding . . . 114-131 Hybridization, 115 — structure of citrus flower, 1 15 — cross-pollination, 116 — improvements most needed, 118 Conienis ix — vecjetativo mutations or bud-sports, 118 — kinds of variations, 110 — fluctuations, 115) — mutations, 120 — sectorial chimeras or mixed plants, 121 — performance records needed, 124 — record of West Highland (irove, 126 — selection of bud-wood, 128 — pedigreed stock, l.'JO CHAPTER VIII Ji;i)GixG Citrus Fruits ....... 182-188 Orange score-card, 133 — orange standards, 133 — lemon score-card, 184 — lemon standards, 135 — pomelo .score-card, 180 — pomelo standards, 136 — packed box score-card, 137 — packed box standards, 137 — exhibit score-card, 138 CHAPTER IX Selection of Site and Preparation for Planting . 139-140 Selection of site, 139 — score-card for citrus lands, 139 — the frost question, 140 — water supply, 141 — soil adaptations, 142 — clearing and leveling land, 145 — amelioration of hardpan by the use of dynamite, 146 CHAPTER X Planting the Orchard ....... 147-164 Orchard plans, 147 — number of trees per acre, 149 — distance of planting, 149 — contour planting, 151 — time of planting, 151 — root-stocks, 151 — digging the holes, 155 — setting the trees, 156 — intercropping, 159 — the cost of planting, 160 CHAPTER XI Cultivation, Fertilization, Cover-crops . . . 165-186 Plowing, 165 — cultivating, 168 — mulching, 173 — orchard tractors, 174 — fertilizing, 175 — humus, 178 — green manure crops, 181 — summary of soil manage- ment, 184 Contents CHAPTER XII Irrigation .......... Amount of water needed, 188 — atmometer records, 189 — sources and cost of water, 192 — methods of dis- tribution, 193 — time of application, 195 — methods of application, 198 CHAPTER XIII Pruning and Topworking Pruning trees in the nursery row, 205 — pruning oranges, 207 — suckers versus fruit wood, 209 — prun- ing lemons, 213 — disposition of prunings, 217 — prun- ing frosted trees, 217 — reheading young trees, 218 — reheading mature trees, 220 — topworking old trees, 223 — pruning tools, 225 — wounds and dressings, 226 PAGES 187-203 204-229 CHAPTER XIV Frost and Orchard Heating Historical cold periods, 230 — season of frost in Cali- fornia, 231 — forecasting frosts, 233 — factors influenc- ing the occurrence of frost, 234 — local conditions affecting frost, 236 — conditions indicating frost in Cali- fornia, 237 — how plants are injured by cold, 239 — pre- vention of frost injury, 243 — orchard heating with oil, 252 — requirements of orchard heaters, 253 — types of oil heaters, 257 — installation of heaters, 259 — proper- ties of fuel oils, 260 — storage for oil, 262 — oil heating operations, 264 — care of heaters, 267 — cost of oil heat- ing, 268 — separation of frosted from sound fruit, 270 — cooperation in frost fighting, 274 230-276 CHAPTER XV Picking and Packing Oranges ...... Importance of careful handling, 277 — causes of decays, 278 — clippers, 279 — picking bags, 280 — methods of 277-301 Contents xi picking, 281 — the sweating of green fruit, 285 — the acid-sugar ratio, 289 — brushing and washing, 21)1 — grading and sizing, 292 — packing and loading, 295 — precooling, 297 — shipping, 298 CHAPTER XVI Picking and Packing Lemons ...... 302-317 Season of maturity, 303 — market, demands, 302 — sweating autumn lemons, 305 — storage of winter lemons, 306 — packing and shipping, 309 — grading and sizing, 310 — picking pomelos and tangerines, 312 — packing- houses, 314 chaptp:r XVII Blemishes of the Fruit and theiu Prevention . . 318-330 Insect blemishes, 319 — fungus blemishes, 319 — me- chanical blemishes, 321 — bruises, 321 — thorn-stabs, 321 — cultivator vscars, 321 — clipper cuts, 321 — stem punctures, 321 — machine injuries, 322 — fumigation scars, 322 — shoulder spots, 323 — hail scars, 323 — soil scars, 323 — windfalls, 324 — cement dust, 324 — physi- ological blemishes, 324 — sunburn, 324 — frost, 325 — off-bloom, 325 — mottled-leaf, 325 — exanthema, 325 — malformations, 326 — brown spot, 326 — splits and cracks, 326 — puffing, 329 — peteca, 329 — diy center of lemon, 329 CHAPTER XVIII By-products .... .... 331-343 United States importations of citrus by-products, 332 — commercial by-products, 333 — citric acid, 333 — lemon and other oils, 334 — uiifennented orange juice, 38.", — orange vinegar, 336 — orange wine, 337 — candied citron, 337— oil of neroli, 338 — petit grain oil, 338 — xii Contents PAGES tincture of orange flowers, 338 — essence of orange flowers, 338 — dried and candied peel, 339 — lime juice, 339 — orange paste, 340 — crystallized baby oranges, 340 — glacedkumquats,341 — domestic recipes, 341 — orange or lemon jelly, 341 — orange marmalade, 342 — pomelo marmalade, 342 — citrus-rhubarb marmalade, 343 CHAPTER XIX Markkting 344-354 Methods of selling fruit, 344 — independent growers, 344 — independent associations, 345 — California Fruit Growers' Exchange, 345 — the local association, 346 — the district exchange, 347 — the central exchange, 348 — collecting and handling money, 350 — exchange adver- tising, 351 — method of organizing cooperation associa- tions, 351 — Florida Citrus Exchange, 353 — Citrus Pro- tective League of California, 353 CHAPTER XX Profit and Loss 355-363 Average returns, 355 — over-capitalization, 356 — eight requirements for success, 357 — capital recjuired, 358 — cultural costs itemized, 361 —average yields, 362 — average prices received, 362 —judging orchards and lands, 362 — score-card for citrus land, 363 CHAPTER XXI Diseases and theik Control ...... 364-402 Brown rot gum disease, 364 — botrytis gumming, 366 — .scaly-bark, 367 — twig gumming, 367 — leaf gumming, 3(}8 — gumming of seed-bed stock, 368 — exanthema or die-back, ^M) — mal-di-gomma or foot-rot, 372 — toad- stool root-rot, 373 — mottled-leaf, 374 — wither-tip, 380 Contents XI 11 — twig l)light, 382 — cottony mold, 388 — brown rot fruit decay, 386 — blue mold and green mold, 387 — gray mold, 388 — black rot of Navel orange, 388 — brown spot, 389 — damping off, 391 — citrus canker, 392 — melanose and stem end rot, 394 — nail-head rust, 395 — scab or verrucosis, 395 — diplodia rot of oranges, 397 — red blotch of lemon, 398 — yellow spotting of oranges, ;]98 — stem end spot, 399 — trunk rot, 399 — galls and knots, 401 — black pit of lemons, 401 CHAPTER XXII Citrus Insects and thkir Control ..... 403-430 Black scale, 405 — red or orange scale, 411 — yellow- scale, 414 — purple scale, 414 — cottony cushion scale, 417 — soft brown scale, 418 — citricola scale, 419 — hemispherical scale, 420 — greedy scale, 420 — oleander scale, 420 — citrus mealy bug, 421 — citrus red spiders, 423 — silver mite, 424; — orange thrips, 425 — aphis or plant louse, 427 — orange tortrix, 428 — Fuller's rose beetle, 429 — western twelve-spotted cucumber beetle, 430 CHAPTER XXIII Insect Control by Fumigation ..... 431-452 History of fumigation, 431 — fumigation by hydro- cyanic acid gas, 435 — tents, 435 — equipment of tents, 437 — generators, 437 — cyanide, 438 — acid, 439 — oper- ation, 440 — season of fumigation, 443 — dosages, 449 — dosage schedule for sodium cyanide, 446 — new Wood- worth dosage table, 450 — cost of fumigation, 452 CHAPTER XXIV Various Orchard Pests and their Control . Citrus nematode, 453 — the pocket gopher, 456 ground squirrels, 458 — poisons, 459 453-459 xiv Contents CHAPTER XXV PAGE8 Bibliography 460-503 Other bibliographies, 461 — references to literature dealing with particular fruits, 461 — orange growing in United States, 461 — growing in other countries, 463 — varieties, 464 — breeding, 467 — insects, 467 — diseases, 468 — lemon, 469 — lime, 471 — mandarin, 471 — pomelo, 472 — kumquat, 471 — citron, 473 — references to literature dealing with citrus fruits in general, 473 — miscellaneous references, 473 — propagation, stocks, scions, 478 — breeding, 479 — soils, roots, 481 — irriga- tion, 482 — ^fertilization, 483 — cover-crops and green manuring, 484 — varieties, botany, 485 — chemistry, judging, 486 — pruning, 487 — curing, storing, sweating, packing, 489 — marketing, organization, statistics, tariff, 490 — by-products, 492 — frost fighting, frost injured fruit, 494 — insect pests, 496 — fumigation, 497 — diseases, 499 LIST OF ILLUSTRATIONS Washington Navel ()ran2;e ...... Frontispiece km;. l'A shows a representative orange plantation in southern California. In general, the soils of this region are deep and very fertile, being heavier near the coast and lighter in charac- ter toward the interior. The two prevailing soil types are the Placentia series, resulting from the weathering of reddish granite, which outcrops at many places, and the Maricopa series, which are alluvial in nature, being an ancient flood plain. These latter soils are darker in color and often contain smooth cobbles and bowlders in variable amounts. Less important soil types are the black adobe sometimes found on the foothills and the light sandy soils of the river bottoms. While the prevailing breezes are westerly, this section of country is occasionally visited by characteristic hot northers which blow with force for several days at a time from the northeast. At such times the air becomes excessively dry and high temperatures prevail. Such desiccating winds are sometimes quite injurious to vege- tation and cause a severe loss of w^ater from plants and soil. It is fortunate that such winds are not of more frequent occurrence. The southern coast is especially adapted to the growing of lemons, which here produce a larger proportion of high- priced summer fruit. Stored lemons also keep better and expensive storehouses are not needed as is the case in interior valleys. The cool summers also make it possible to hold Valencia oranges on the trees until the follow- ing October and November, when very high prices are often realized. This section of country is also well suited to the production of nursery stock, which is grown in very 30 Citrus Fruits large quantities, the San Gabriel Valley being the center of this industry. The Washington Navel orange here produces very heavy crops, but the fruit ripens later and is somewhat inferior to that produced in interior valleys both as re- gards color, texture, flavor, and shipping qualities. TJw Interior Valley Division The climate of all the interior valleys is characterized by conditions more or less extreme. The air is nearly always dry and this permits rapid radiation, causing a wide range in temperature each day. Rainfall is fairly abundant in winter in the northern valleys and less so toward the south. The air is free from fogs and dew in summer and constant sunshine is the rule. The days are often very hot, while the nights are always cool. The floors of the valleys are, as a rule, frosty in winter and on this account the principal citrus areas are found along the foothills, above the frost line, and where irriga- tion water is available. Such areas are usually at an eleva- tion of from 500 to 1500 feet above the sea, and from 100 to 500 feet above the floor or **draw" of the valley. In such locations a few feet in the perpendicular is of far greater importance to the citrus grower than many miles in the horizontal. That is to say, whether the orchard is planted in a 'Mraw" or on a bluff above it, yet on the same ranch, may mean more for the success or failure of the grove than whether the trees are planted near Holt- ville or at Oroville five hundred and fifty miles distant. Cold air is heavy and on quiet nights flows down and col- Ciini.s (icof/rdplii/ ditd ('liiii.(tt(jl()(/ij of ('(ilifonila '.]{ lects ill the lowlands, leaviiij^ the foothills above the frost line. In the central valleys oranges ripen very early and as some of these are far to the north of the Coast Coun- try, the unusual procedure of shipping earliest ripening fruits southward to market is accounted for. The largest producing district in this division lies on the eastern foothills of Tulare County, including Woodlake and Porterville, at an elevation of four or five hundred feet above sea-level. One of the typical soils of this district is known as the Porterville clay loam adobe, which is a residual soil characteristic of the higher foothill slopes. Lower down the valley slopes are found soils of the San Joaquin series, which are sometimes characterized by ''hog-wallows" and a certain amount of hardpan. The valley floor is composed mostly of alluvial soils of the Hanford series. In the northern Sacramento Valley the soils are very variable, but are mostly of a reddish color. They are in large part sedimentary soils of the San Joaquin, Stockton, Alamo, and other series. While there are many exceptions, it is true that these soils, especially on the east side of the valley, are quite generally underlaid by a stratum of dense, impervious hardpan which occurs at variable depths. Where hardpan is near the surface, the land is not suited to citrus fruits unless it be dynamited and the hardpan thoroughly broken up. The Northern Coast Division In outline this division is very irregular, consisting in places of a narrow strip betw^een the mountains and the 32 Citrus Fruits sea and extending occasionally into valleys where the hills are low and do not entirely shut off the cool, moist sea- breezes. East of the bay region the coast influences extend far inland, following the Sacramento River and tempering the climatic conditions at the junction of the San Joaquin and Sacramento Valleys to such an extent that the region between the cities of Stockton and Sacra- mento is really intermediate in climatic characteristics. The climate of the Northern Coast forms a strong con- trast with that of the interior valleys. It is comparatively free from extremes of temperature, being warm in winter and cool in summer. The winter rainfall is usually heavy and there is much fog in summer. Here green, grass- covered hills are the rule instead of the bare rocky buttes of the interior. There are no large commercial citrus areas within this district, yet oranges and lemons are grown in yards and gardens and the product is used for local consumption throughout the district. The total amount of summer heat is small, and oranges do not yield well as a rule nor is the fruit high in sugar content. The color also is poor on account of the lack of abundant sunshine, and the trees are subject to the ravages of many insect pests and fungous diseases which are not able to survive the hot summers of the interior valleys. The trunks and branches of trees on the coast are apt to become covered with a growth of lichens and algse which should be removed with alkali sprays. The soils of the coast country are chiefly deep rich residual soils formed by the gradual weathering and breaking down of the local rock masses. Citrm (icograpliy and Clunatology of California 33 THE FROST HAZARD It has been asserted that certain districts in California are free from frost. This is hardly true, for a certain frost hazard exists in all districts both north and south. Almost all districts on the other hand embrace certain areas which are comparatively frost free. One thing which usually impresses the stranger from the East most forcibly is the sharpness with which the frost lines are drawn. There are many ranches of a hundred acres or less which are divided by these frost lines into citrus lands, walnut lands, and alfalfa lands. It is often very difficult to accurately judge the frost hazard on any given piece of land unless there be an old orchard alongside upon the history of which, together with the local topog- raphy, an estimate may be based. Failures due directly to faulty judgment in regard to the frost hazard are almost without number. In recent years the science of orchard heating as de- scribed in Chapter XIV has enabled growers to insure their crops against occasional frosts, but where orchards must be heated many nights each winter the expense is quite likely to interfere with the profits. We may conclude then that throughout the citrus divi- sions of the Southwest there are specially favored dis- tricts where citrus fruits grow to perfection and are seldom injured by cold. Within each of these districts, however, there are many localities of irregular outline and extent which on account of local topography are quite out of the question as citrus lands. On this point Lelong ^ writes as follows : ^ "Culture of the Citrus in California," 1902. 34 Citrus Fruits "Wherever cold currents of air from high altitudes flow to the valley without interruption, it will not be safe to attempt citrus culture at any elevation within the sweep of these currents. On the other hand, wherever the descending currents are cut off or turned aside by spurs of the mountains, leaving the warm atmosphere of the days undisturbed during the nights, there orange and lemon culture may be engaged in with little danger from frost. In other words, the eddies of air currents must be selected and the main flow of these currents must be avoided. " Everybody who has traveled along the Sierra foothills, parallel with the valleys, particularly in the winter season and at night, will recall his surprise at the sudden changes of *the temperature of the atmosphere within short dis- tances. He may also remember to have noticed tender plants and shrubs seared and frost-bitten, while just over a ridge or cone the same plants and shrubs were in full leaf and growing luxuriantly. Want of attention to these facts has caused many a disastrous failure in the culti- vation of citrus fruits in California." ATMOSPHERIC HUMIDITY In the interior valleys which are fanned by dry desert breezes, the amount of atmospheric moisture is very low, and this together with the great heat tends to produce oranges of high sugar content and with very desirable deep red color. Dry air also discourages the growth of certain diseases affecting the tree, as well as certain scale insects, lichens, and algae which cannot endure the Citni,s (jleoyraphy and CUniaioUxjy of ('(ilijOntid '.\') desert conditions. On the other hand, lemon trees under such cHmatic conditions tend to bear only one crop a year, and the proper curing and keeping of lemons is made more difficult. The moist and foggy coast country with its cool sea breezes brings about a somewhat different phase of the industry. Here lemons tend to bear a con- FiG. 7. — Typical scene in Los Angeles County. robusta on right. Windbreak of Grevillea tinuous crop the year round, and the fruit may be easily stored in open sheds and kept in good condition for six or eight months. Oranges near the coast are six or eight wrecks later in ripening than those of the interior, and the trees are subject to a larger number of the insect pests and diseases to w hich the citrus tree is heir. 36 Citrus Fruits WINDS Strong winds are a serious hindrance to the citrus grower. The young foHage is badly torn or may even be Fig. 8. — Pinus radiata, a native pine used as a windbreak. blown from the trees ; the fruit is bruised, scarred, and covered with unsightly callous marks ; the trees are pre- vented from forming symmetrical heads ; and in some cases the soil itself is either blown away from the roots Citrii.s' (u'nijraphij and CUmatologi/ of (^(ilijonild 'M or hanked too ilvvp around the trunks of tlie trees. In some extreme eases, the travehn^ sand wears away the hark of younji: trees near the <^r()un(I. As a rule, windy h)cations should he avoided in selecting a site for a citrus Fig. 9. — Orange tree denuded of foliage on windward side by three days of desert wind. orchard. In some cases, however, where all the other conditions are right, the force of the wind may be broken by growing windbreaks of cypress, eucalyptus, or cedar. Care should be exercised that the windbreak is not allowed to grow too thick and become a ''wind-stop," 38 Citrus Fruits as this may interfere with atmospheric drainage and make a frost pocket of the grove. A hve windbreak is ob- jectionable on the ground that the roots appropriate the plant food and water from one or two rows on either side and seriously interfere with the fruiting of the orchard trees. This trouble may be obviated to some extent by digging a trench ten feet from the windbreak and three feet deep every second year and cutting all the feeding roots. Care should be used in selecting varieties of trees for windbreaks that they may not be host plants for insects which affect citrus trees. The pepper tree, Schinus violle, for example, makes an excellent wind- break and is largely used in interior valleys where the black scale is of less importance. Near the coast such trees may have to be fumigated occasionally at great expense. Figs. 7 and 8 show windbreaks of the silk oak {Grevillea rohusta) and Monterey pine {Pinus radiata), which are much used in parts of California. Fig. 9 il- lustrates the damaging effect of the wind. SUNLIGHT While a certain amount of sunlight is absolutely neces- sary for plant growth, there are places in California where citrus plants are over-illuminated. Sunburn of the fruit and tree trunks and even of the leaves often occurs in the dry interior valleys, where the lack of moisture in the air permits the actinic rays of the sun to strike the trees with full force. In such situations, the fruit borne on the outside of the trees and fully exposed to the light is inferior and often ruined, while the fruit which is CItrufi (iC()(/r(iphi/ luid (^limdtologi/ of Calijnniia .'>!) screened by foliage may be of the very finest (juality. It is the custom among nurserymen to shield citrus seedlings from the light by growing them, for the first six or eight months, under lath screens so arranged as to reduce the total light about 75 per cent. Running the lath north and south will provide alternating light and shadow for any given seedling as the sun moves from east to west. I I CHAPTER III CITRUS BOTANY, GROSS STRUCTURE, AND HABITS OF GROWTH Citrus fruits differ from olives, figs, dates, and pome- granates in being of comparatively modern origin. They emerged from the wild state in the Malay Archipelago and southern Asia. Certainly citrus fruits were not known by civilized peoples until comparatively recent times. The ancient Egyptians did not know the citrus fruits. The Romans did not know the orange or any other edible form except perhaps the citron at the be- ginning of the Christian Era.^ While the Old Testament makes frequent mention of olives, pomegranates, figs, and other fruits, no mention is made of any citrus fruit unless we except the word ''hadar" translated "goodly trees" (Leviticus 23 : 40) as referring to the citron. Risso,^ one of the most able of the early writers on citrus, compared the ancient texts and claims that this word merely refers to any beautiful or fine tree. It is likely that the Hebrews became acquainted 'with this fruit at the time of the Babylonish captivity. Be this as it may, the Jews believe this word refers to the citron, or etrog as 1 De Candolle, "Origin of Cultivated Plants," p. 181. 2 Risso and Poiteau, "Histoire Naturelle des Grangers." 40 Citrus Botany, Gross Structure, and I lab Us of (iroidh U it is called by them, and to this day they present them- selves at the synagogue on the day of the Feast of Tabernacles, as commanded in Leviticus, with a citron in their hands together with an unopened date palm leaf, a tliree-parted branch of myrtle, and a willow twig. The citron, known by the Romans as Malum persicum, the apple of the Persians, was transplanted to Italy about the third or fourth century. The lemon was not brought to southern Europe until after the tenth century, and the earliest Italian reference to it is dated 1250 a.d. The bitter or sour orange was unknown to the early Greeks and Romans. It probably originated in eastern India and spread westward slowly. When it reached Mesopotamia it received the Sanskrit name nagarunga, which was changed to vernnga and arangi. In medieval Latin it became aranciumRnd^nsiWyaurantium, the present Latin name from which our English word orange is de- rived. The Crusaders saw the bitter orange in Palestine. It was taken by the Arabs to Sicily in 1002, spread from there to Spain, from whence it was taken to Florida soon after the settlement of that Colony. In Florida the bitter or sour orange ran wild, and dense thickets exist there to-day which yield the greater part of the sour orange seeds planted by California nurserymen. It is most remarkable that so good a fruit as the sweet orange should not have been known to ancient writers, yet they make no mention of it. In fact the sweet orange was not introduced into Europe until the beginning of the fifteenth century, when the Portuguese brought im- proved forms of it from south China. A number of writers 42 Citrus Fruits speak of the sweet orange as cultivated in Spain in the sixteenth century. At a very early date the Portuguese carried the orange to Brazil, where it ran wild as it did in Florida. From Brazil the orange spread southward into Paraguay, part of Uruguay, and northern Argentina where large areas are now covered with a natural growth of wild sweet orange trees. CLASSIFICATION The genus Citrus belongs to the family Rutaceoe and rep- resents the highest development within the family. There » are no species of citrus native to either North or South America. A relative is the prickly ash or " toothache tree," Xanthoxylum americanum, of the southeastern United States. No two systematic botanists appear to be agreed as to the proper classification of the many different species. This is probably due to the fact that several of the species hybridize readily and it is very difficult to determine which of the forms are of hybrid origin. The writer makes no pretense to having solved this perplexing problem by independent botanical research. He has simply studied the different schemes proposed and from them arranged a practicable, working classification for the use of students, fruit-growers, and others who desire a simple bird's-eye view of the ten species in which they are chiefly interested. Persons particularly interested in citrus botany are referred to Hume, '' Citrus Fruits and their Culture " ; to Bonavia, '' Oranges and Lemons of India " ; and to Swingle, ''Citrus" in ''Bailey's Standard Cyclopedia of American Horticulture." Clfnis BoUnij/, (iro.s'.s Structure, and Ilahils of (Iroudh 4)^ f Irijoliala Citrus \ nobilis bergamia, sinensis, Aurantium, tlio deciduous orango (Ponciriis Iri- foliata) . Bergamot orango. common sweet orange. sour stock, Seville, or bitter orange. [ the King orange. I Var. deliciosa — the Mandarin or kid- glove orange. Tangerine. . Var. unshiu — the Satsuma orangO;^ the pomelo (grapefruit), shaddock. kumquats. citron of commerce. sour lemon, sweet lemon. decumana, japonica, Medica, Limonia, aurantifolia, sour lime, sweet lime. All of these ten species are now grown, to some extent at least, in California, although some of course are very much more important than others. Citrus trifoliata. — This is the only deciduous orange. The fruit is not edible. It is highly ornamental and very hardy to cold, being used in yard and garden plantings and for hedges as far north as Washington, D. C. It is used to a certain extent in Florida and more generally in Texas as a stock upon which to bud edible oranges. Its use as a stock in California was never widespread, and is now almost obso- lete. Citrus trifoliata has recently been used to a considerable extent in breeding work, the object being to combine the cold resisting qualities of the trifoliata with the good qualities of the more tender species which bear edible fruit. It is native to Japan and China and was introduced into Europe more than one hundred years ago. This species is now by some put in the genus Poncirus, becoming P. trifoliata. Citrus bergamia. — The Bergamot orange from which the oil of bergamot is made is grown commercially in Europe. In California it is grown only as an occasional specimen or as a hedge plant in gardens. 44 Citrus Fruits Citrus sinensis. — The ordinary sweet oranges including such varieties as Washington Navel, Valencia, Mediterra- nean Sweet, Ruby Blood, and a long list of others. Citrus Aurantium. — This is the sour or bitter bigarade orange, the fresh fruit of which is hardly edible, but which is coming to be used more and more in the flavoring of marma- lades and various other by-products. Seedlings of this orange have almost entirely superseded others as a stock upon which to grow all kinds of citrus fruits in California. The reason for this is its superior resistance to gum-disease and foot-rot. The seed from which this "sour stock" is grown comes chiefly from the wild thickets in Florida. In Europe this form is often called the Seville orange. Citrus nobilis. — The description of this species was based on a form very like the King orange. It includes the var. deliciosa, the ordinary Mandarin oranges such as the Tan- gerine and the var. unshiu, which is the Satsuma orange. Citrus dccumana. — Here are included the pomelos, often incorrectly called "grapefruit,"^ and the shaddock. They are vigorous growing trees with very dark green leaves, very prolific in bearing. The pomelo is growing rapidly in public esteem, but the shaddock is inedible. The shaddock is the largest of all the citrus fruits, but has an extremely thick skin and bitter juice. It is the only citrus which has hairs or pubescence on the young twigs and under sides of the leaves, and is grown only for ornament or curiosity. Citrus japonica (recently referred to the genus Fortunella). — The Kumquats, Kin-Kans, or golden oranges, small bushy plants from Cochin-China. The fruits are small, with mostly acid pulp and sweet aromatic rinds, for preserving and for decorations. ^ The term "grapefruit" has, chiefly through the influence of "the trade," become adopted by common usage, and it is hardly worth while now to insist on the use of the more correct term. Citrn.s Botany, Gros6' Structure, ami Habits of (Jroictli 45 Citrus Mrdica. — The citron from which the candied citron sold by grocers is made. The form known in Cali- fornia as the Chinese lemon and much used in the early days as a stock is thought to belong here. Citrus Limonia. — The lemons including both the sour lemons and the sweet lemons. Citrus aurantifolia. — The limes including both the sour Mexican and Rangpur limes and the sweet limes which latter are considered to be of hybrid origin. THE CITRUS PLANT The Root Citrus trees difi'er from many plants in having no root- hairs whatever upon the fibrous, feeding roots. The feeding roots are comparatively large, very abundant, and grow very rapidly. Those sheared off each year by the plow^ in turning under a cover crop are quickly- replaced. In shallow^ soils, however, where most of the fibrous roots are near the surface, it is unwise to be too reckless with the large turning plow. Under arid conditions the feeding roots are not confined to the surface layer of soil, but where there is no layer of hardpan to interfere they dis- tribute themselves throughout the soil usually between the eighth and thirty-sixth inch levels. In very deep, well aerated soils they may forage much deeper. The large main roots serve in a double capacity ; as braces to hold the tree upright against the wind, and as conveyors of water and food between the fibrous feeders and the trunk. Large perpendicular roots known as tap-roots are not essential to the health or w^ell-being of the trees and are invariably cut w^hen the young nursery 46 Citrus Fruits trees are dug for transplanting. Subsequently the sweet orange root will devote itself mainly to sending out laterals, while the sour orange will usually send down two or three strong tap-roots in the place of the one which was cut. The pomelo shows much variation in regard to the formation of tap-roots. Wood Structure and Groivth Citrus wood is very closely knit in structure, being hard, strong, and tough. It is light in color, with very fine grain and with no apparent heart wood ; that is, there is no difference in color between heart wood and sap wood. The rings observable in a cross section are close together and are of no value in determining the age of the citrus tree, as they are in the case of pine or oak trees. This is on account of the fact that the citrus tree forms several rings each year according to the number of vegetative growths. The citrus tree does not grow at a uniform rate during the season, but makes three or more growths of new twigs and leaves each year, with corresponding rest periods. The heaviest growth is in the spring just before blooming, the flowers being borne on the new shoots. Another smaller and more irregular growth is made in mid-summer, and a third in the late fall. The number of growths made and the times they occur vary with the local weather con- ditions and the method of irrigation. The main framework branches of old lemon trees often present a curious flattened shape next the trunk. The greatest diameter is perpendicular, but the width of the rings is much thicker on the lower than the upper side, the Citnus Botdtii/, C/'/'o.v.v Strudiwc, and lldblls of (iroicih 47 I cciiUt of growth being crowded close to the bark on the upper side. This curious con(nti()n is entirely normal in the lemon and greatly strengthens the branches, enabling them to carry a much larger load without breaking. There are two sap currents in the truid^ and branches, one consisting of dissolved mineral matters taken from the soil water by the roots, which passes up through vessels in the wood to the leaves ; and an- other, consisting of elaborated plant food, and other complex substances, which passes down through the inner bark and nourishes every growing part, even the tips of the longest roots. It should be remembered that the action between root and leaf is reciprocal. The most remote tip of the longest root must await the return of the elaborated sap from the leaves before it is able to grow a fraction of an inch. For sake of emphasis we repeat : the roots of a plant are quite as de- pendent upon the leaves for elaborated food as they are upon the soil for raw^ food, for roots cannot use raw mineral food. That the downw^ard current of elaborated sap takes place through the bark is proved by the sw^elling which occurs just above the point of constriction w^hen a label wire is overlooked and allowed to remain, on a young tree. Fig. 10. — Growth rings in a flattened brace limb of lemon. 48 ('ifm,s' Fruits Advantage is taken of this fact in the process known as "ringing" which is chiefly used with grapes and pears. A ring of bark half an inch wide is removed from the small branch which bears a fruit cluster. The fruit and leaves continue to draw food from the roots through the wood, but as the branch is prevented from returning its pro- portionate share of elaborated food to the trunk and roots, it soon accumulates an extra amount which causes the fruit to grow to an unusually large size. By this method a Navel orange Result of experiment which shows ^^^ produced which ^ pounds and measured 18 inches in circumference.^ Fig. 11 that a girdled orange tree may grow new weighed bark if treated in time. A, untreated ; B, treated. * Scientific American, Dec. 14, 1912, p. 515. Citrus Botany, (irofis Structure, and Jlahils of Growth 49 The line which separates the two currents of sap is known as the cambium and is roughly represented by the line of cleavage when a strip of bark is pulled away from the trunk. It is on this line that growth takes place, the cells dividing continually, one part going to build wood and the other causing a thickening of the bark. Citrus trees are apt to form large quantities of gum along the line of the cambium, when stimulated by the growth of fungous parasites, or by other causes, the exact nature of which are not clearly understood. Many trees are unable to grow^ new bark direct from the cambium, but heal over wounds by pushing new tissue out from the sides of the wounds. The citrus tree will often grow new bark direct from cambium laid bare by gophers or gum-disease. Occasionally a tree which has been entirely girdled will grow new bark and recover. The bark of citrus trees is also peculiar in that it retains some green matter or chlorophyll and continues to function as a leaf until the tree reaches a great age. Leaves With the exception of Citrus trifoliata, all citrus trees are evergreen ; that is, the bulk of the leaves do not fall before the new leaves have expanded. A few of the oldest leaves may fall at any time of the year, but the period of heaviest fall is in April and May after the spring growth has taken place. The normal life of an orange leaf depends on the kind of wood upon which it is borne. Leaves on the fine fruiting brush usually remain on the tree for about fifteen months, while leaves on vigorous upright vegeta- 50 Citrus Fruits tive growths will remain green and in flourishing condi- tion for three and even four years. The leaves on the trunks of nursery trees, if protected and not removed, will usually remain for several years. It is customary to re- move these leaves at the time the tree is dug for the purpose of reducing transpiration. In the case of the trifoliate orange the leaves fall in the autumn, the tree remaining bare during winter and until after the blooming period in spring. Citrus leaves vary in shape and size with the different species ; the pomelo and Seville orange having broad wings on the petioles, while the sweet orange has a very narrow wing and the citron none at all. The width of these' wings will vary a good deal, being wider on the vigorous shoots and very much smaller on the fruiting brush. The edges of the sweet orange leaf are entire, while with the lemon and lime the edges are indented or crenate. Most, if not all, of the stomata or breathing pores are situated on the under side of the leaves, and this is a distinct advantage when the upper surfaces of the leaves become coated with dust from the roads during the dry season, or with cement dust from near-by cement mills. One striking characteristic of all citrus leaves is the pres- ence of numerous glands, which may be easily seen with the unaided eye, although they do not project above the sur- face of the leaf. These glands are filled with a fragrant and aromatic oil which is very volatile and gives to the freshly crushed leaves their characteristic odor. This odor varies with the different species. One method of distin- guishing between sweet and sour stock seedlings in the nursery is by recognizing the odor of the crushed leaves. Citruti Botany, dross Structure, and Habits of (iroLcth 51 Thorm Sharp, slender thorns are characteristic of most kinds of citrus trees. Seedlings of the sweet orange have per- haps the most formidable thorns and these are a serious hindrance in harvesting the fruit and pruning the trees. The trifoliate orange has short, thick thorns which are very numerous. Certain cultivated varieties are practically free from thorns, and this quality adds much to their popularity. Thorns are borne in the axils of the leaves, and their size, in a given variety, depends largely upon the vigor of the shoot upon which they occur, being long on rapidly growing shoots and short and inconspicuous on the fruiting brush. The Navel orange and Eureka lemon are practically thornless varieties ; yet on water-sprouts long sharp thorns may sometimes appear. Thorns are objectionable not only on account of the difficulty occasioned in picking fruit, but also on account of the injury done to the fruit itself. When the wind tosses the branches about, the fruit is stabbed on many sides by the thorns, giving an excellent opportunity for inoculation and consequent fungous decay. In dry weather w^hen small wounds are quickly dried (and perhaps, to a certain extent, cauterized by the escape of oil from the broken oil- cells) there is less decay of fruit on the trees from this cause. While this is true, the constant rubbing or pricking of a fruit against the point of a thorn will so irritate the rind as to cause a very ugly callous to form on the skin and thus ruin the market value of the fruit. There is a widespread belief among citrus nurserymen and others that thorns may be largely ehminated from any 52 Citrus Fruits variety by careful selection of budwood through several bud generations. We know of no published data of scien- tific experiments to determine this point and doubt very much whether the grounds for this belief are sufficient. It can do no possible harm to select only thornless bud- wood for propagation, and where this happens to result in the separation of pure-line mutants which vary in thorni- ness much good may be done. On the other hand it is difficult to conceive of how progress can be made by selec- tion within the pure-line. Flowers Citrus flowers are large, showy, and fragrant, and are borne in great profusion. They are mostly waxy white, although in the lemon and citron the backs of the petals are tinged with purple. The flowers are mostly perfect or complete, consisting of a green calyx with three to five lobes, subtending white petals, four to eight in number, which are thick, fleshy, and covered with oil glands. The stamens are numerous, twenty to sixty in number, their filaments (stalks) being more or less united. The style and stigma are large and conspicuous. The exudation of white mucilage by the stigma is quite copious, as is also the watery nectar in the base of the flower cup. The pollen is golden yellow and is produced in abundance except in certain varieties. The orange has flowers borne in cymes on shoots of the current year's growth. In the case of the lemon, kumquat, and others, the new growths are sometimes so short (the leaves appearing as mere bracts), that the flowers have the appearance of being borne on old wood. I Fig. 12. — Valencia orange blossoms. 53 54 Citrus Fruits The flowers of the orange and pomelo appear during April and early May. Occasionally a bunch here and there or even an entire tree may bloom at some other season, but the fruits from such off-season blooms will usually be ab- normal in shape and inferior in quality. Lemons bloom and set fruit the year round with the period of most abun- dant bloom coinciding with that of the orange. Lemon trees are peculiar in that they bear flowers of several kinds. Those that produce fruit are perfect, con- FiG. 13. — Lenioii blossoms showing perfect, partly aborted, and aborted pistils. taining both stamens and pistils. There are other flowers borne by the same tree in which the pistils are reduced to a mere rudiment while the stamens are large and well de- veloped. In addition to these there are certain abortive buds, observed on the Eureka lemon chiefly, in which the petals do not develop but remain closed, the stigma forcing its way out between them. Only the perfect lemon blos- soms set fruit, although the second kind mentioned may aid in pollination. Lemons require about nine months from blossom to maturitv of fruit. A few fruits will come Citrufi Botany, Gros.s' Structure, and Habits of (iroidh 55 up to size in six months, while some will remain undersized for a year and finally turn yellow, at which time they are picked regardless of size. Pollination The larger number of fruits, such as apples, plums, grapes, and straw berries, require pollination in order to set fruit. Some kinds of citrus fruits require pollination in order to set and mature fruit, but a large number do not. Many forms of citrus bear parthenocarpic or seedless fruits, and with these pollination is not only unneces- sary, but is apparently a disadvantage, inasmuch as it results in some cases in the formation of seeds which are objectionable. In Florida a large number of varieties are grown com- mercially, and as most of them contain seeds it is probable that a large proportion at least require pollination for their best development. Florida WTiters are strangely silent on this point. In the citrus districts of the Southwest it hap- pens that the five varieties chiefly grown — Washington Navel and Valencia oranges, Eureka and Lisbon lemons, and Marsh pomelo — are more or less parthenocarpic. Those kinds which contain some seeds, as the Lisbon lemon for instance, are able to set and mature fruit without polli- nation, which results merely in the formation of seeds. ^ The Washington Navel orange flowers contain no pollen w^hatever and in the Eureka lemon viable pollen is rare except at certain seasons, yet these varieties produce quite ^ Unpublished Report on Pollination Experiments by the Writer. 56 Citrus Fruits as well when planted in solid blocks of hundreds of acres far from other varieties, as they do in mixed plantings. T. Ikeda ^ in a series of brilliant experiments has shed much light on this interesting subject. His principal results may be summarized as follows : 1. Certain varieties of oranges require pollination in order to set fruit. 2. Certain varieties of oranges which ordinarily contain seeds will without pollination set and mature a small num- ber of parthenocarpic fruits. 3., Many varieties of oranges are uncongenial, cross- pollination being followed by dropping of flowers and young fruit. 4. Cross-pollination between seed bearing and parthe- nocarpic varieties may result in the setting and maturing of fruit containing viable seeds, provided the pollen used is that of a congenial variety. 5. Parthenocarpic varieties do not require the stimulus of pollination in order to set and mature fruit. 6. The pollen-tube may reach the ovule as soon as 30 hours after pollination. Fusion of male and female cells may begin 48 hours after pollination. Fertilization is completed in from 48 to 72 hours after pollination. 7. In the Washington Navel and Satsuma oranges the embryo-sacs usually disintegrate instead of developing into embryos capable of being fertilized. Occasionally a few normal embryo-sacs are produced in both Washington Navel and Satsuma oranges.^ Thus ^ Tomochika Ikeda, "On the Parthenocarpy of Citrus Fruits," Jour. Sci. Agr. Soc. Tokyo, Vol. 63, 1904. 2 The factors which influence the frequency of occurrence of Citrus Botany, (iws.s Structure, and llahils of (/roirtli 57 a few seeds may be produced provided the particular fruits having the normal embryo-sacs happen to be pollinated with viable pollen from congenial varieties. It is the remoteness of the chance of this occurring under ordinary field conditions that accounts for the comparative seedless- ness of these fruits. Apparently there is nothing in the I Fig. 14. — Orange flower X 2. p, pistil; a, stigma; c, style; o, ovary; s, stamen; b, anther; e, filament; d, nectary; g, sepal; /, petal. structure of the blossoms of either the Washington Navel or the Satsuma orange which would interfere in any way normal embryo-sacs have not been fully worked out. Experi- ments now being carried on by the writer seem to indicate that the climate factor is most important. Normal embryo-sacs of Washington Navels occur much more frequently at Riverside than at Whittier where they are very rare. For this reason plant- breeders wishing to use the Navel as a maternal parent in cross- breeding work may expect greater results from crosses made at Riverside or other interior points. 58 Citrus Fruits with the germination of pollen or normal extension of the pollen tube. The occasional seeds sometimes found in Washington Navel oranges as they occur on the market are undoubt- edly due to cross-pollination with some other variety by insects or other agencies. The question as to what would be the result should these seeds be planted and reared to maturity has already been answered by the experiment of W. H. Backus of Riverside, a part of whose report is here quoted.^ *'Some years ago when almost every one was budding over their seedlings to Navels, I thought the result might be too many early oranges. At that time I did not think the Valencia the most desirable late orange, as a Cali- fornia orange should have high color in addition to being late. ''To obtain this desirable feature, together with high color quality and medium size, I tried hybridizing the Mediterranean Sweet on the Washington Navel, three successive seasons, cutting all the oranges when ripe for seed. Altogether I secured about fourteen hundred seeds that were well matured. ''These were planted in the seed bed, but owing to my lack of experience in nursery work, a large percentage of the little trees, of the first and second plantings, died when about three inches high. One peculiar thing to me was that over 90 per cent of the seeds sprouted from two to six shoots each.^ "The young nursery stock was much neglected for three ^ Riverside Daily Press, March 2, 1909. 2 An interesting record of poly-embryony. Citrus Boianii, Gross Structure, and Ildblts of (Irowtli W.) or four years, when 1 took buds from the most thrifty to bud over old trees. Although these buds, stand IG to 18 feet apart in an old grove, still they made a rapid growth, equal to a straight seedling, and are now about 25 feet high. ''The disappointment came when they began to bear. Many were of no value at all ; the best were early, some apparently earlier in ripening than the Navel, but generally of good color, sweet and seedless. The trees were exceed- ingly thorny and some much more thrifty than others ; many appeared to be good bearers while others were shy or very late in coming into bearing. Consequently al- most all have been rebudded or dug up." Polyemhryony A peculiar thing about citrus seeds is the fact that a variable proportion of them will give rise to from one to ten distinct seedlings each. This is known as polyem- bryony and is due to a number of adventitious embryos appearing in the embryo-sac. Some of these bud embryos may develop into seedling plants along with the sexual embryo which requires fertilization in order to develop. This explains why seedlings in the seed bed often appear to grow in bunches even though the seeds were planted sepa- rately. As only one of the seedlings arising from any given seed is the result of pollination and fertilization, it follows that the others must be vegetative seedlings, and, in case the seed is from a known variety, will reproduce the variety true from seed without the necessity of bud- ding. It is impossible, however, to distinguish the sexual 60 Citrus Fruits seedling from the others in the early years of growth, except in the case of crosses between forms which have very differently shaped leaves. It would be imprac- ticable to propagate Navels true from seed on account of the rarity of seeds and the necessity of pollinating the flowers, but it would be a simple matter with seedy varieties were it not for the difficulty above mentioned. Structure of the Fruit According to Bonavia,^ the citrus fruit consists mor- phologically of two whorls of transformed leaves, one going to make the rind and the other to make the group of carpels or sections of the fruit. Each carpel is supposed to be a leaf folded over in such a way that its two edges meet in the center on the axis of the fruit and along which the seeds are borne. The number of these sections or divisions varies considerably even in the same variety. The little juice sacks or vesicles within each carpel are supposed to be transformed oil glands of the leaves. As ^ E. Bonavia, "Oranges and Lemons of India," Vol. I. Fig. 15. — Polyembryony. Two orange seedlings from one seed. Citrus Botany, (iro.sb- Structure, and llahils of (iroirtli 01 varieties of double flowers are formed by the growth of an additional whorl of petals, so varieties of double fruits may come about by the growth of additional whorls of carpels, and this is what has taken place in the case of the Navel orange, as any one may observe by making a num- ber of thin transverse sections through the apical end of a Navel orange, and studying these sections. The vesicles in citrus fruits are multicellular and are attached by a stalk in nearly all cases to the outer wall of the carpel, only a very few being attached to the sides. These vesi- cles are fed directly by fibro-vascular bundles branching from the stem and running through the white spongy tissue which composes the inner part of the rind. The seeds vary in number from none as in the Navel to fifty or more in the trifoliata. They are attached to the inner edges of the carpels. Citrus fruits in common with other fruits are not to be considered as so much dead matter after they are plucked from the tree. They live and breathe (transpire) for many months. They also lose water and shrink in size and weight as a result of giving off carbon dioxide and water vapor. If protected from infection by decay-producing organisms, oranges or lemons will keep one year or more, when kept moist and cool, but will eventually die and collapse from enzymatic fermentation. If they are al- lowed to lose moisture, they will dry up into balls as hard as wood. An understanding of the vital processes going on in citrus fruits is highly important in connection with the curing of lemons and pomelos. (See Chapter XVI.) Chemistry of the Fruit. — Citrus fruits from the same tree may vary much in their composition. Commercial Cali- 62 Citrus Fruits Analyses of California Oranges and Lemons (From Bull. No. 93, Univ. Cal. Agr. Exp. Station) A. Proximate Analyses Name op Variety Average weight in grams Water, per cent . Organic matter, per cent Ash, per cent .... Rind, per cent . . . Pulp less juice, per cent Seeds, per cent . Number of cc. of juice, average Solid contents of juice by spindle .... Total sugars in juice (by copper inversion), per cent Cane sugar in juice (by polariscope), per cent Citric acid, per cent Nitrogen in fresh fruit, per cent .... Albuminoids in fresh fruit, equivalent to nitrogen, per cent Wash. Navel 300 85.82 13.95 .42 28.4 27.7 107 12.80 9.92 Med. Sweet 4.80 1.02 0.211 1.31 202 85.19 14.32 .47 27.0 24.0 0.8 86 12.60 9.70 4.35 1.38 0.154 0'.96 Paper Rind 138 84.76 14.77 .46 19.2 25.9 1.6 65.4 12.10 8.71 3.48 1.35 Malta Blood Eureka Lemon 177 85.68 14.39 .42 31.0 24.0 71 13.55 10.30 5.85 1.61 0.228 0.168 1.43 1.05 104 83.82 15.61 .56 32.0 24.5 0.12 38 11.90 2.08 0.57 7.66 0.151 0.94 B. Analyses of Ash Oranges Lemons per cent Potash (K2O Soda (Na20) .... Lime (CaO) .... Magnesia (MgO) . . Peroxide of iron (Fe203 (AI2O3) Br. oxide manganese (Mg304) Phosphoric acid (P2O5) . . Sulphuric acid (SO3) . . • SiUca (Si02) Chlorine (CI) 48.26 1.76 29.87 4.40 and alumina I Citrus l)()((un/, (h'os.s Slrucfurc, and Habits of (iroirth ()I3 foniia oranges contain ahout oO j)ct cent rind and 40 per cent juice when freshly picked from the trees. The percent- age of juice increases as the fruit is cured for the water in the rind is lost first by evaporation and transpiration. California Navel oranges will analyze about 10 per cent total sugars, 4j per cent of which is cane sugar, the re- mainder being a mixture of other fruit sugars. Navel oranges contain about 1 per cent of citric acid. Lemons contain about 2 per cent total sugars, of which ^ per cent is cane sugar, and 7| per cent of citric acid. Harvest Season In California, oranges and lemons are harvested through- out the year. The orange season begins with Navels about November 15 in central California and moves south- ward. The last Navels are shipped from southern districts about May 1. During May and a part of June miscel- laneous varieties including seedlings and some late Navels are gathered and shipped. The Valencia harvest begins in central California in June and continues southward, the last of the crop going forward from the coast districts in November and thus overlapping the Navel crop of the next season. Lemon trees are picked over once each month or about ten times a year, the trees bearing fruit in all stages of growth from the blossom to the mature fruit at all times. Lemons should not be allowed to ripen on the tree . They should be picked when they have reached a diameter of 2^ inches in summer and 2Yg inches in winter and spring, regardless of color. 64 Citrus Fruiis Longevity Citrus trees are naturally long lived. If planted on deep, rich soil and given good care, they should bear profit- ably for fifty years or more. Much has been said in print about a natural limit of profitableness in the case of the Navel orange. This limit is sometimes placed at twenty- five years. The writer believes this to be a mistake. Navel oranges as well as other kinds of citrus will live and produce generous crops to a very great age, provided they are growing on deep, fertile soil and are well cared for. CHAPTER IV VARIETIES As stated in a previous chapter, the first oranges grown in CaHfornia were seedhng sweet oranges. Unhke the apple and peach, the sweet orange will come fairly true from seed, the fruit from practically all seedlings being marketable. Each tree, however, varies from its neigh- bors in many minor characters, such as size, productive- ness, season of ripening, seed content, flavor, and shipping qualities. The fruit from an orchard of seedHngs lacks uniformity, which is one of the chief requisites of a com- mercial fruit product. Seedling trees grow very large, so large in fact that it is expensive to gather the fruit and often difficult or impracticable to inclose the trees in fumi- gating tents. For these and other reasons the old seedhng orchards have been gradually cut down and replaced by budded trees or top-worked to improved varieties, until at the present time comparatively few remain. During the transition from seedling to budded orchards the question as to which of the many varieties available would prove the most profitable was a favorite subject for discussion. By 1885, enterprising nurserymen had introduced most of the important varieties of the world, and these were F 65 66 Citrus Fruits tested alongside many local seedlings of special merit. Probably as many as one hundred different varieties were given trial. At the early citrus fairs such imported vari- eties as the Du Roi and Pernambuco were to be seen exhib- ited side by side with California productions such as Asher's Best and Bostram's Prize. The ehmination of the less profitable varieties took place rather rapidly, and by the year 1900 we find the Washington Navel orange oc- cupying more land than all other varieties of oranges com- bined. At this time the two fittest survivors, the Navel and Valencia, dominated the field. DESCRIPTIONS OF VARIETIES OF ORANGES Washington Navel {Bahia, Riverside Navel). — Form rounded, slightly tapering at apex, somewhat longer than wide ; small umbilicus ; size variable, 2| to 3j inches in di- ameter ; color orange when grown near coast, deep orange when grown in interior valleys ; juice abundant, orange colored ; flavor excellent, acid and sugar well blended ; vesicles large, spindle shaped ; skin | to J inch thick, varying from smooth to pebbly ; size of secondary orange under umbilicus variable, often f inch in diameter. Seeds none, except in very rare cases. Tree semi-dwarf, vigorous, very precocious, prolific, thornless or with thorns only on vigorous shoots ; appearance of blossoms normal except for the fact that the anthers are cream colored and contain no pollen whatever. Introduced from Bahia, Brazil, 1870, by the late William Saunders, then in charge of U. S. Government propagating grounds at Washington, D. C. The Washington Navel well deserves the title "King of r Oranges." Under the climatic conditions of California and Varieties' 67 Arizona this variety approaches very nearly to the ideal orange. The dry air, bright sun, and cool nights, operating in conjunction with the skill of the grower and packer upon the natural qualities and cliaracter of this orange, have made it the greatest commercial orange in the world. These Fig, 16. — The earliest known illustration of a Navel orange. Ferrarius* " Hesperides," 1646. From thornless trees combine heavy and regular yields with a high color of the fruit, a silkiness of texture, and a general finish which is almost perfect. It is solid and full of juice of exceptionally high flavor, but it is entirely lacking in seeds. It is a very good keeper and travels well to the most distinct markets. It possesses moreover a natural trade- 68 Citrus Fruits mark, in the shape of a navel-Hke mark, which is beyond imitation and which is of great market value. More than eight miUion boxes of Washington Navels are now being grown and shipped out of California annually, and the prices received are encouraging a rapid increase in acreage. In California, the Washington Navel reaches its highest development in quality on the gravelly soils of the foothills in the warmer interior valleys. The yield, however, is not as heavy as it is near the coast, where the fruit tends to ripen later. On the deep heavy soils of the coast country, the skin tends to be somewhat thicker with a rougher surface and paler color. One characteristic of the Washington Navel is its tendency to sport or throw out occasional branches bearing fruit of a different type. By far the larger number of these sports are retrogressions, and careless cutting of bud-wood for prop- agating purposes from trees containing such sports has re- sulted in a great lack of uniformity in existing orchards. Occasionally sports are found which possess some character of supposed value, and by the propagation of these new varieties have appeared. Among such offspring we note the following : Thomson, Buckeye, Navelencia, Nugget, and Australian. Thomson. — Fruit of medium size ; skin thin and very smooth in texture ; ripens early. The quality of the Thom- son is somewhat inferior to the Washington Navel, but it has a superior appearance. For certain markets in some large cities where appearance rather than quality determines demand, it commands a premium of from twenty-five to fifty cents a box over the Washington Navel. For this reason, it is being grown on an increasing commercial scale. The Thomson was introduced by A. C. Thomson of Duarte, Los Angeles County, about 1891, and is generally thought Varieties 69 to bo ji bud sport from tlic Washington Navel. Consider- ing the story told by Mr. Thomson of his method of pro- ducing this form, it is possible that it may be a periclinal chimera ! Buckeye. — Fruit medium in size with peculiar l)ands or ridges of deeper orange color ; skin smooth and of fine texture ; ripens early. Introduced by R. M. Teague at San Dimas, California. Narelencia. — Fruit medium to large, smooth and thin- skinned ; season said to be somewhat later than Washington Navel ; more susceptible to frost than Washington Navel. Originated by A. C. Thomson, at Duarte, California. Nugget. — Fruit oblong, medium in size, smooth, solid, and thick skinned, often with an objectionable but characteristic crack or slit in the skin on one side ; young twigs slender and willowy, tree umbrageous with very brittle wood. Originated by J. P. Englehardt at Glendora. Introduced by R. M. Teague at San Dimas, California. Australian. — Fruit very variable, rough, coarse ; navel often closed ; skin thick, especially near stem end. Tree Fig. 17. — One type of Australian Navel orange. 70 Citrus Fruits large with upright, open growtli, shy bearer. Strictly speaking, there is no such thing as the Australian Navel. The term is a misnomer in the same sense as the term English walnut is when applied to the Persian walnut. In common usage, however, the name applies to a certain rough-fruited and shy-bearing sport of the Bahia Navel, which was un- wittingly introduced into California from Australia in an effort to secure the true Bahia. Some persons go further and call any undesirable sport an Australian, thus using the term as an adjective rather than as a noun. Some other persons apply the term Australian to the rank growing wood resulting from water sprouts in the tops of the trees, which tend to produce coarse, rough fruit. This latter is clearly an improper use of the term. Valencia. — Form oblong, somewhat flattened with de- pressed ring at apex, tapering toward base ; size medium, color pale orange deepening with maturity ; skin smooth or slightly pebbled, thin but tough ; juice plentiful, flavor sub- acid ; seeds variable, sometimes three to six, often none ; season late, from June to November. Tree large, vigorous grower, prolific, thorns few and small. The Valencia hangs on the tree well during the summer but in interior valleys it is apt to turn green again in late summer. When grown in such situations, it should be harvested in May and June. In deep heavy soils near the coast, it can safely be held till November or December. This famous orange originated in the Azores. Thomas Rivers, the English nurseryman, imported it, with other varieties, from the Azores into English glass-houses and first catalogued it in 1865 under the name -*' Excelsior. " S. B. Parsons, a Long Island nurseryman, bought trees from Rivers and brought them to America about 1870. He kept them in his greenhouse for several years and then moved them to Varieties 71 his nursery near Palatka, Florida. Parsons sold some of these trees to E. H. Hart, of Federal Point, Florida, who gave the variety the name "Hart's Late" or "Hart's Tar- diff." Fruit was first exhibited before the Florida Fruit Growers' Association on April 25th, 1877. A. B. Chapman, of San Gabriel, California, imported a number of varieties of citrus from Thomas Rivers about 1870- 72. One variety labeled Navel, turned out not to be a Navel, but of distinct value on account of its ripening very late in the season after other varieties were off the market. Finally, at the suggestion of a Spanish laborer, Mr. Chapman called the orange "Valencia Late" and many trees were propa- gated and sold under this name. California nurserymen early secured stocks of Hart's Tardiff from Florida, and many thousands of trees were planted. When it became evident that these were the same as the Valencia, the latter name was adopted and is now used exclusively in California. This name has become so well fixed in the trade and market reports as well as in the every-day speech of the people that it is idle to attempt to change the name in order to conform to the rules of horticultural nomenclature. The fame and popularity of the Valencia orange has been greatly advanced in California by the wonderful record made by a superb orchard of this variety owned by C. C. Chapman at Fullerton in Orange County. Mediterranean Sweet. — Form round or somewhat flattened ; size medium to small ; color deep orange ; skin of fine texture ; juice abundant, very sweet ; seeds few, small ; season April to May ; tree semi-dwarf with small narrow leaves very thickly set, almost thornless. Introduced and renamed by T. A. Garey of Los Angeles about 1870. Secured from Thomas Rivers of England. 72 Citrus Fruits Paper Rind {Paper Rind St. Michael). — Form round; size small, solid with high specific gravity ; color yellow, or pale orange ; skin very thin and very smooth ; juice abun- dant, colored, with rich vinous flavor ; seeds three to six in number, medium sized ; season March to May ; tree semi- dwarf, medium thorny, very productive. Introduced from the island of St. Michael. Ruby (Blood). — Form round or slightly oblong, sometimes navel marked ; size medium ; color deep orange or reddish when fully mature ; skin smooth ; juice deep orange in color changing to red as fruit matures ; flavor very rich and vinous ; seeds many ; season March and April, tree of medium size, compact growth, almost thornless. Imported from Mediter- ranean districts. Jaffa. — Form round ; size medium ; color deep orange ; skin smooth or slightly pebbled ; juice abundant and of excellent quality ; seeds many, large ; season March to May ; tree medium sized, more resistant to cold than most other sweet oranges, almost thornless. Imported from Palestine, where it is largely grown. Joppa. — Form oblong, slightly shouldered ; skin thin, somewhat pebbled ; juice abundant, sweet, and of fine flavor ; seeds few or none ; season March to July ; tree large, thorn- less. Originated in 1877 by A. B. Chapman of San Gabriel, California, from seed secured from Joppa, Palestine. Crafton (Crafton Late). — A late seedling, originated by Myron H. Crafts, several large budded orchards of which are still in bearing in the vicinity of Crafton, California. It is marketed during May and often brings very good prices. LEMONS In the early days of the industry a large number of Euro- pean varieties were tested, but few were found suitable to Variclies 73 the California conditions. Many seedlings were raised also, most of which proved disappointing in some important respect. At present new plantings are limited chiefly to two varieties, the Eureka and the Lisbon. While a few old orchards of Villafrancas are still maintained, but few are being planted. The Eureka is rapidly gaining in popularity Fig. 18. — Eureka lemon, uncured. over the Lisbon and it appears that this will soon be the only variety planted on a large scale. Eureka. — Form oblong, apex nippled, base tapering ; size medium ; rind smooth, glossy, sweet ; juice abundant, clear, strongly acid, flavor good ; seeds few, often none. 74 Citrus Fruits J. H. Needham, in an essay before the Pomological Society at Covina in 1898, says : "The advantages of the Eureka are its comparative freedom from thorns, its tendency to early bearing, and when properly trained to enormous crops when it comes into full bearing, and its continuous blooming and setting of lemons all the year, especially in sections- com- paratively free from frost. The objections are its tendency to set its fruit on the tips of the branches, and the inclination to grow long canes with but few laterals and to drop its leaves on the long canes or branches, thus leaving the limbs and fruit too much exposed to the hot rays of the sun in the heated term of summer." The Eureka lemon originated from a seed planted about 1870 by C. R. Workman in Los Angeles. Workman and Pres- ton began to propagate it, but later sold all the stock to Thomas A. Garey, of Los Angeles, who propagated it extensively and sold it under the name Eureka. Lisbon. — Form oblong or obovate, apex oblique, nippled with a characteristic crease to one side of the nipple, base tapering sharply to calyx, which is large ; rind thin, smooth, sweet ; juice abundant, clear, and strongly flavored ; seeds few, sometimes none ; tree large, a strong, vigorous grower, foliage thickly set, not precocious, very thorny. The Lisbon bears its fruit uniformly throughout the tree. The heavy foliage protects the fruit from sunburn. The tendency is to bear one large crop maturing in winter, with a small amount of summer fruit. Introduced from Europe. Villafranca. — " Form oblong, slightly pointed at the blossom end, rind thin, without any trace of bitterness ; acid strong, juicy ; nearly seedless. Tree almost thornless, branches spreading and somewhat drooping, foliage very abundant, which protects the fruit from sunburn. The I Varieties 75 trro is a strong gnnvrr and is considcM'cd less snsccptihlc to cold than most varieties. Introduced from Europe. "The advantages claimed for the Villafranca are that it makes a more compact tree and bears its fruit more uni- formly o\ev the entire tree, l)ut it requires at least one year longer to come into bearing, and the fruits on young trees I Fig. 19. — Lisbon lemon, uncured. are shorter when they have the requisite diameter for picking than either the P^ureka or the Lisbon." ^ Other varieties still to be found in old orchards and collec- tions are Bonnie Brae, Genoa, Sicily, Messina, and Milan. POMELOS Marsh. — Form flat or obovate ; size small to medium ; color light yellow ; rind smooth, variable in thickness ; juice ^ Lelong, "Culture of the Citrus in California," p. 167. 76 Citrus Fruits Fig. 20. — Seedless pomelo, flowers and fruit. From Volekamer's " Hesperides," 1708. abundant ; flavor fair ; pith large, open ; seeds none or one to six ; season March to July or later ; hangs on trees well all summer. According to Hume/ this variety was introduced by C. M. 1 " Citrus Fruits and Their Culture," p. 120. I Varieties 77 Marsh of Lakeland, Florida, about 1895 or 1896. The original tree was a seedling growing in Lakeland, and was at the time of the freeze fully sixty years old. The Marsh is the chief variety of pomelo grown commer- cially in California and Arizona, although the following may he occasionally met with and are doubtless deserving of a wider planting. While seedlessness is a very desirable character in a fruit, it should not be allowed to outweigh such characters as flavor, juiciness, and quality. California is in need of a variety of pomelo better suited to the conditions than any now available. Nectar (Duarte Seedling). — A seedling tree brought from Florida and fruited at Duarte, California. The fruit is round and solid with smooth skin of pale yellow color. The seeds are few and the flavor excellent. Duncan. — A flat fruit with rather thick skin and flesh of grayish green color, seeds few, season late, quality good. Introduced from Florida. Triumph. — A fine-appearing fruit and full of juice as well as seeds, of which there are many. Somewhat lacking in flavor. Imperial. — Size medium to large, rind very smooth, medium thin, and of fine texture ; little rag ; juice abundant and of fine aromatic flavor. R. M. Teague says of this variety : " It is one of the best keepers and shippers. The tree is a strong upright grower and a heavy cropper." Colton {Colton Terrace). — A seedling grown at Colton, California. Size medium to large, heavy, subacid, and deli- cately bitter ; seeds many ; skin smooth ; oil cells very small ; light lemon Color, turns slightly orange color when mature. Pink-fleshed. — A prolific variety imported from Cuba. Flesh deep pink, coarse, and of poor quality. Seeds many ; tree very large and ornamental. 78 Citrus Fruits MANDARINS The Mandarin oranges grown commercially in California are practically all of one variety, the Dancy, commonly known as the tangerine. On account of the confusion in name, it may be well to emphasize the fact that "tan- gerine" is the trade name for one variety of Mandarin orange, the proper name for which is Dancy. The Satsuma Fig. 21. — Dancy Mandarin orange. is not grown commercially in California and is represented only by occasional specimens in gardens and nursery collec- tions. Such collections often contain specimens of King, Ik^auty, Mikado, Oneco, and a few others. Dancy. — Form oblate ; size medium ; color very deep orange red ; glossy ; rind smooth, except about stem end, which is nippled, apex depressed ;. segments separating readily; juice abundant, colored; flavor rich and sprightly; seeds five to ten or more, snudl ; season Jamiary to February. Tree of upright growth, fruit borne largely on the extremities J^irirties 79 of the branches ; somewhat thorny. Parent tree raised from seed by Col. George L. Dancy at Buena Vista, Florichi. In- troduced into cultivation about bS72. Satsuma (Unshiv). — Size small to medium, 2 to 3 inches in diameter ; shape flat, a little pointed next the stem ; color bright orange ; skin rough, wrinkled next the stem, very loose and easily separated from the flesh ; core, almost none, represented by a cavity often three-eighths inch in di- ameter in center ; seeds none ; flesh orange color, darker than the skin, not so juicy as some ; flavor very sweet, rich, very aromatic, peculiar ; quality very good ; season early. This variety is thornless and a dwarf grower. It will endure more cold than any other variety of edible citrus fruit except perhaps some of the hybrids mentioned below. Should be worked on Citrus trifoUata stock or sourstock. Introduced from Japan about 187(). MISCELLANEOUS VARIETIES Swingle-Webber Hybrids. — In 1892, W. T. Swingle and H. J. Webber of the U. S. Department of Agriculture under- took to produce new and improved varieties of citrus fruits by hybridization on an extensive scale. Several new types have been produced, examples of which are Citranges and Tangelos. The citranges are crosses between the common sweet orange and the trifoliate orange. The Rusk, Willits, Norton, Colman, Savage, and Rustic have been described. The fruits of these hybrids are intermediate in character between their parents. They are not nearly so good as sweet oranges, but they may be used for making soft drinks, pies, and marmalades. Their special advantage lies in their re- sistance to cold, which enables them to grow a hundred miles or more beyond the northern limit of the sweet oranges. 80 Citrus Fruits In California they are as yet grown only as specimens for exhibition purposes. The Thornton is a loose skinned tangelo which resulted from crossing the pomelo and tangerine. The juice is sweet, lacking the bitter of the pomelo. The Sampson tangelo is the result of crossing the pomelo with pollen of Dancy. The skin is loose like the tangerine, but the flavor includes some of the bitter of the pomelo. The Weshart and Trimble are crosses between the Dancy and Parson Brown. Fig. 22. — Satsuma Mandarin orange. The fruits are larger than the Dancy, which they resemble otherwise. Several thousand hybrid seedlings of several generations are now being grown by the Department of Agriculture and additional varieties of merit may come to light in the future. Citron. — Citron is not grown commercially to any extent in California, although good specimens of the plant may be found in many parts of the state and there is at least one good-sized orchard. The tree is small in stature with a Varieties 81 shrub-Hkc growth. It is more tender to frost than the orange, but less tender than the hme. As early as 1880, experiments showed that California-grown citron, when properly processed or candied, was equal in every respect to the imported article. The consumption of candied citron in the United States is very small compared with that of oranges and lemons, and this probably is the main reason why so little interest has been taken in it. There appears to be no good reason why California should not produce all the candied citron consumed in this country. Most of the varieties of Europe have been introduced for trial. The Corsica appears to be one of the best. Shaddock, — The shaddocks are of no commercial im- portance. Occasional trees may be found in collections and in yards and gardens throughout the citrus belt. They appear to vary in resistance to cold, some being as hardy as the orange. The fruit is very large, round, oblate or pear shaped ; skin very thick, sometimes two inches thick ; seeds many or none; flesh pale yellow or reddish, juice acid and often very bitter ; in some forms the young growth is pubes- cent. Trees ornamental, but not more so than the pomelo, which is both useful and ornamental. Lime. — Three kinds of limes are grown for home use to a limited extent in California. The Sour or West India lime, together with the Rangpur, are used for cooling drinks while the Sweet lime is eaten out of the hand like the orange. Limes have never been grown commercially in California. All but the Rangpur are very tender to frost, even much more so than the lemon. The Rangpur is said to be fully as hardy as the lemon. In the early days a sour form of Mexican lime was much planted as a hedge plant around orange orchards. They proved too tender for most localities and were difficult to fumigate and keep free from Fiu. 23. — Nagami kuniquat. (82) Varieties 83 scale insects. For these reasons they have mostly dis- appeared. Kumquat. — In California the kumquats are used chiefly as ornamentals, although a few find their way into the markets and an occasional small shipment is sent out of the state. They are especially suited to pot culture, when budded on Citrus trifoliata root, and are convenient to move about as desired on verandas and in formal gardens. The fruit is small, about one inch in diameter, with sweet aromatic rind. The fruit may be eaten fresh or made into delicious preserves. The Marumi kumquat is most hardy to cold. It has round fruit, borne in great abundance, ripening in October. Twigs somewhat thorny. The Nagami kumquat is oblong, slightly pear shaped ; fruit golden yellow ; rind smooth, aromatic, and spicy. Tree thornless, slightly more tender to frost than Marumi. Sweet lemon. — This form of citrus is met with only in collections, as there is no market demand for a sweet lemon. It is a question whether this should be grouped with the lemons or with the oranges. The fruit is like a lemon in shape but the flowers are white like those of the orange. The Trifoliata. — In the early days this species was grown to a considerable extent in California as a hedge plant. These hedges have been largely done away with, and as the plant is not needed as an ornament, it is rapidly becoming rare in the state. CHAPTER V THE CITRUS NURSERY The day of the seedling orange grove is past in Cali- fornia. Now all trees for new plantings are budded as a matter of course. Many of the large planters prefer, and find it highly profitable to grow their own trees. Yet the business of raising citrus trees for sale has reached large proportions. Citrus nursery stock not only fills the home demand, but is shipped in large quantities to many foreign countries. THE SEED-BED The first step in the production of a citrus tree is the raising of the root or stock upon which the desired variety is to be budded. The comparative value of all the different stocks will be discussed in Chapter X. We will simply say here that at present the demand is about as follows : sour-stock, 85 per cent ; sweet-stock, 9 per cent ; pomelo, 5 per cent; and all others, 1 per cent. Sour-stock seed comes from the wild thickets of Florida and Cuba, and is sold in California for from $30 to $50 a bushel. Between five and six hundred bushels of sour orange seed was planted in California in the year ending June 30, 1913. 84 The Citrm Nursery 8.^ Fig. 24. — Citrus seed-bed under lath. 86 Citrus Fruits This seed may be secured in the fall and kept in a cool, dark cellar. It should not become excessively dry. Sour seed runs about 30,000 seeds to the bushel, half of which should come up and produce trees. Sweet orange seed is secured from the various seedling orchards in California. It will not endure drying, but must be handled quickly and kept moist. The seed stores do not keep sweet seed on hand in quantity, but on receipt of an order will send a man with a seed separating machine to a cull heap near some packing-house, secure the amount of seed desired, and forward immediately to the purchaser in a wet condition. Such seed must be planted at once. The price is usually from $18 to $25 a bushel, which contains about 85,000 seeds. Pomelo seed is secured either locally or from Cuba. It will stand dry- ing to a small extent only. Rough lemon seed may be handled much like sour orange seed. After the freeze of January, 1913, it was found by experi- ment that the seed in oranges which had been frozen was viable, although dark in color. Almost as good germina- tion was secured with seed from frozen as from sound oranges. It is an established custom in California to grow citrus seedlings under a lath shelter, although one large nursery- man near the coast has broken away from this custom and has secured good results by planting entirely in the open. In the hot interior some shelter is necessary, but the trees grow in height faster and are ready for market quicker if grown under shelter anywhere. The shelters are cov- ered with one-inch laths alternating with one-inch open- ings, supported by uprights set at convenient distances. I The (^itru.s Xyr,s'eri/ 87 The lath are usually nailed to cross pieces in sections of suitable size to be handled by two men. The shelter rests about eight feet from the ground and the lath should run north and south. The soil for the seed-bed should be deep, sandy loam, free from stones and well-drained. Virgin soil is best, but if that is not obtainable, good, rich grain land will answer. It should of course be worked up into a fine state of tilth, leveled, and slightly firmed with a light roller. If dry seed is used, it should be soaked for twenty-four hours before planting. If the bed is to be irrigated by running water through furrows, the ground is laid off in rows twelve inches w^ide with very shallow furrows about eight or ten inches wide. A broad, shallow, slow stream of water is needed to soak through such rows. The seed is planted broadcast on these wide rows, every sixth row being left vacant for a walk. In case the bed is watered from above by automatic sprinklers, as is usually the case, the seed is broadcasted over the entire surface of the ground except for a twelve-inch path every ten feet. In some cases the seed is simply planted about one inch deep in the loose soil and then thoroughly watered. In most cases, however, the seed is gently pressed into the soil with a board and covered from ^ to 1 inch deep with clean coarse river sand especially provided for the purpose. This covering of sand prevents the ground from baking and also keeps the surface dry. The seeds are placed about one inch apart each way and if half of them or even an average of thirt\' to the square foot grow, the stand is considered satisfactory . One of the greatest dangers to the seed-bed is the pos- 88 Citrus Fruits sibility of infestation by the ''damp-off" fungi. This disease works very rapidly, covering a large area in a single night and killing the seedlings just after they come up. This trouble may usually be prevented by keeping the surface of the ground as dry as the requirements of the seedlings will permit. The covering of sand allows the water to pass through to the roots while the surface dries again very quickly. The usual time of planting is April, and most of the plants should be large enough to sell one year after planting. After the seedlings are two months old they may be watered more generously every two or three weeks as necessary. All weeds should be kept out of the beds, and a sharp watch must be kept for gophers, moles, and ants. The plants are sold for from S20 to S50 a thousand when they are about a foot high. The beds are usually gone over twice, the smaller plants remaining for two years. It is hardly necessary to point out that the plants first pulled from the bed are much more desirable than those which require two years to reach marketable size. In ordering seed-bed stock "first pull" plants should always be specified. No manure or compost of any kind should be used in the seed-beds for fear of encouraging the "damp-off" fungi, which are usually more serious in proportion to the amount of freshly decaying organic matter in the soil. A moderate dressing of commercial fertilizer high in nitrogen will accelerate the growth of the plants. Often no fertilizer is used. After the seedlings have safely passed the stage when they are liable to damp-off, they may become infected The CUru.s' Nursery 89 with browii-rot gum-disease. In such cases they will exude gum just above the ground and may be girdled and killed. Where there is any large amount of such gumming, a thorough si)raying with bordeaux-mixture is recommended. Sour-stock is very resistant to gum- disease in the orchard, but this is not always the case in the seed-bed. When seed-bed stock is to be dug, the soil is first thor- FiG. 25. — Citrus seed-bed in the open. oughly wet, the roots slightly loosened with a long tined spading-fork, and the plants drawn by hand. A varying proportion of the plants will have a crooked or Z-shaped tap-root known as " bench-root. '' When the seed-coat is tough, the root has difficulty in piercing it and often makes several turns before getting out. This may be partly pre- vented by soaking the seed over-night before planting. All such plants are inferior and should be discarded. All 90 Citrus Fruits Fig. 26. — Bench-rooted orange seedling. plants which have gum-dis- ease should also be thrown away. After grading, the plants are tied in bunches and their tops chopped off squarely with a hatchet about eight inches above the crowns. They are then packed tightly in boxes or bags with the tops ex- posed and with moist sphag- num moss about the roots. Citrus seed-beds are likely to become infested with scale- insects or other pests, espe- cially if situated near infested orchards. In many counties, horticultural inspectors have strict regulations in regard to the admission of nursery- stock shipped from other counties. Such local regu- lations are by no means uni- form for the whole state. It is wise to confer with the ap- propriate officer in each case before the plants are dug in order to learn just what kind of treatment will be required. Usually the plants are dipped, all but the roots, in the fol- lowing solution : The Citrus Nurs-ery 91 Resin 20 lb. Caustic Soda 8 lb. Fish Oil 3 pt. Water 100 gal. PLANTING SEED-BED STOCK For the planting of seed-bed stock, a deep rich loam, free from stones, should be selected. It should contain just enough clay to stick together well when the trees are balled. The site for the planting should be as free from frost as possible, as newly set buds are very susceptible to cold. The stock is planted eighteen inches apart in rows three and a half or four feet apart. Especial emphasis is here laid upon the fact that the roots of citrus plants are very susceptible to injury from drying, and if a plant is left in the sun, with its roots exposed, for more than a few moments, it is almost sure to fail to grow. The best plan is to take all the plants into the field in the boxes of sphagnum covered with wet sacks. Only a few should be handled at a time and in such a way as not to expose the roots at all. The plants are usually set with a dibble or spade, great care being taken to get the roots in straight and not to set the plants deeper than they grew in the seed- bed. In planting citrus trees of any size or kind, it is a safe rule not to vary the depth of planting. The soil around the plants should be well firmed to bring the roots in close contact with moist earth. Irrigation water should follow the planters down each row as the work proceeds. After the soil is well irrigated the plantation should be gone over and those plants which on account of their small size did not have a part of the top trimmed off 92 Citrus Fruits at the seed-bed should be cut back about fifty per cent. These small plants which escaped the trimmer's hatchet are almost sure to die unless headed back in the same proportion as the others. Budding stock handled as described, and properly culti- vated and irrigated, should be large enough to bud at the end of one or two years, usually eighteen months. An application of about one-half ton per acre of special nursery stock commercial fertilizer will save time in growing the plants to budding size. Every effort should be made to encourage a vigorous growth. It is false economy to bud seedlings which are too small ; the ideal size being from I to -^Q inch in diameter three inches from the ground. PROPAGATION Many writers make the statement that citrus trees are propagated by budding, grafting, cuttage, and layerage. This is somewhat misleading, inasmuch as budding is the universal method employed in America. Lemon cuttings may be made to root, but orange cuttings are so difficult as to be out of the question entirely. The few lemon trees that have been grown from cuttings have been inferior and have mostly passed out of existence. Layering is never used and grafting is very rarely resorted to except in the case of old trees which have been frozen to the ground. Most old trees which are top-worked are budded. The writer has seen buds successfully placed directly into orange trunks which were a foot and a half in diameter, although such a practice is rare and not to be recom- mended. The Citrus Nursery 93 Cutting Bud-wood The success of the citrus orchard depends to a very hxrge extent upon the care used in cutting the bud-wood. This is due to the fact that a certain propor- tion of the trees in many orchards belong to undesirable types. This particular phase of the subject will be reserved for a more extended discussion in Chapter VII. Suffice it to say here that too much pains can hardly be taken in selecting the mother trees from which the buds are to be cut. Citrus buds should be cut from round, plump wood taken from the fruiting branches. It is usually easy to find plenty of suitable bud-wood on lemon trees, but with oranges, Fig. 27. — Orange bud-wood. 94 Citrus Fruits and especially Navel oranges, this is often difficult for the reason that the best trees are devoting their energies to bearing rather than to growing plump bud-sticks. The small angular fruiting twigs are not large enough to use to advantage. On this account it becomes necessary to give Navel mother trees a preparatory pruning a year before the buds are wanted. The trees are thinned out and cut back uniformly in all parts in order that there may be a more vigorous growth of fruiting wood. This pruning should not be carried too far or water-sprouts may result. Bud- sticks about a foot long and the size of a lead pencil made up of one- and two-year-old wood is best. Current growth is too tender and three-year-old wood contains many blind buds or buds which will be very slow to start. Uniformity in starting the buds is much to be desired, and the more care is used in collecting buds of the same degree of matu- rity, the more uniform the nursery will be. The leaves are cut off, leaving a short stub for a handle. The cutting may be done in mid-winter and the accumulated wood buried in slightly moistened sand for two or three months. The wood will cure and callous on the lower end, and cured wood is supposed to give more uniform results. Most budders prefer to keep the bud-wood in boxes of moist sphagnum because the sand will dull the budding knives unless the wood is carefully washed. It is not necessary to cure the buds, but it is often more convenient to cut the buds all at one time and keep them until used. It is best to select bud-wood as free from thorns as possible for the reasons given in Chapter III. A great deal of argument has been indulged in over the question of whether buds from sucker growths or water- The (^itnLs' Nurseri) 95 sprouts are as desirable as buds from the fruiting brush. It is unwise to use buds from rank growing water-sprouts because an excess of food is one of the chief causes of variation ; and as these buds have a great excess of food, they are somew^hat more hkely to grow into sporting trees than are buds from fruit wood. This does not mean, how- ever, that good trees have not been grown and may not again be grown from sucker buds. We simply take the position that it is an unwise policy for the reason given. Time of Budding Citrus stock may be budded at any time of the year or whenever the bark will slip, but the best time is during the months of October and November, in w^hich case the buds usually remain dormant until spring. Stocks upon which the buds fail, may be rebudded in April or May. It often happens, unfortunately, that a certain proportion of fall set buds start into growth immediately, thus ex- posing a few^ inches of very tender growth to the dangers of w^inter. In such a case, the number of orchard heaters set in the nursery should be increased and the fires started at the first indication of frost. Method of Budding In California, the usual method of insertion is the shield or T method. The bud-stick is grasped firmly with the tip toward the operator. With a very sharp budding knife the bud is cut by inserting the blade about one-half inch below and drawing it beneath the bud and out about one-half inch above, thus cutting a bud about one inch 96 Citrus Fruits long. The bud is held firmly between the thumb and the knife blade while a slit is cut in the bark of the stock about three inches above the ground and one-half inch long. At the top of this slit, a cross cut is made with the edge of the blade of the knife inclined downward. The bud is then inserted in this slit, being careful to have the leaf scar or bottom of the bud down. The back of the point of the knife is then placed on the leafscar and the bud pushed down until the upper end is be- low the cross cut, and in any event un- til the pressure of the bud begins to split the bark beyond the previously made slit. A strip of waxed cloth is then wrapped quite firmly around the stock five or six times so as to cover the bud completely. Some budders prefer to leave the eye exposed but this is not necessary. Buds are usually set on any side as re- gards the points of the compass, or in other words, the side most convenient to the budder. The bark usually slips, and the buds take better, directly under a small branch. Some budders prefer to use the inverted T method. The cross cut in the bark of the stock is made lower and Fig. 28. — Cutting a bud. The Citrus Nursery 97 the bud pushed upward instead of downward into phice. The inverted T is somewhat better for fall budding, as the cross cut or obstruction when placed below the bud tends to produce a quiescent state which is desired during winter. The cross cut when placed above the bud tends to produce a strong lateral growth and is therefore best for spring budding. Most seedlings tend to branch close to the ground and as a result buds are often placed quite close to the ground. This is a mistake in most cases, especially when using sour orange as a stock. This stock owes its popularity largely to its resistance to gum- disease, but when buds are placed low this resistance is much reduced. The object should be to keep the wood of the scion as far from the ground as practic- able in order to avoid gum-disease infection, which comes from the soil. If, on the other hand, buds are placed too high, a crooked and ugly trunk will result. While high budded trees are less comely and do not sell as well on account of the crook in the trunk, still they are the more to be desired, especially when intended to be Fig. 29. — Making incision in stock. 98 Citrus Fruits planted on heavy soils or near the coast, where gum-dis- ease is prevalent. After about ten days, the buds should be unwrapped and examined. If they have talcen, as evidenced by a grayish Hne of callous tissue forming around the edges, the wrap- pings are loosened, to be removed entirely after about thirty days in the case of the fall buds and twenty days in the case of spring buds, or whenever the bud is well healed. In the case of fall buds which have re- mained dormant, as they should during winter, the tops of the stock are cut back in the spring to within six inches of the buds in order to increase the sap pres- sure and force them into a more uni- form growth. The promptness with which a bud starts depends to some extent on its age and position on the bud-stick. Uni- formity of growth is greatly to be desired in the nursery, and such cutting back tends to force all the buds to start more nearly at the same time. The six inches or more of stock which is left affords a certain pro- tection to the young shoot and reduces the possibility Fig. 30. — Inserting bud. The Cltrub' Nuracry 99 of the bud being involved in any dying back which may occur. After the young shoot has grown eight or ten inches the stub of the stock is sawed off smoothly, the edges trimmed with a sharp knife, and the cut surface covered with liquid grafting w^ax. In the case of spring set buds, the same custom prevails except that some- times the stocks are only partially cut back at first. With late set buds there is sometimes a dan- ger of the superabun- dance of sap during hot weather ''drow^n- ing out" the buds if all the top of the stock is removed too suddenly. Occasion- ally the tops are ''lopped" or cut half through and bent down in the middles, in order to gradually change the flow of the sap. They are removed entirely after a month or six weeks. Citrus budding is often done by expert budders by con- tract at about $10 a thousand, the budder guaranteeing a 95 per cent stand and furnishing his own buds, wrapping cloth, and the like. Eight and a half dollars a thousand is a common price w^hen buds are furnished. This of course applies to regular fall budding. Fig. 31. — Tying inserted bud. 100 , Citrus Fruits Training the Young Tree In order to insure a perfectly straight trunk the young trees are trained to stakes. The stakes may be set soon after the buds have started growth. The stakes used in CaHfornia are ordinary building laths. They are driven into the ground close by the stock on the side next the scion. As the young shoot grows it is tied to the stake with soft raffia. A tie is made every three inches, the raffia being drawn up snugly under a leaf. The rough unfinished surface of the lath is an advantage, as it pre- vents the raffia from slipping down. Careful attention to tying is necessary in order to secure straight trunks. While going over the trees for tying it is also necessary to remove any side branches which may put out, as well as the numerous suckers which arise from below the bud. These sprouts should be rubbed off with the thumb while still very young, and this necessitates going over the trees every three or four weeks during the first summer. Nursery trees should be allowed to grow three feet tall and then headed back to 27 or 30 inches. This will insure the main branches being set upon stronger wood than if the terminal bud was pinched as soon as it reached the desired height. Branches which are to be the framework of the future tree are encouraged to put out on all sides and distributed over the upper twelve inches. From three to six main branches are sufficient. The old custom was to allow the framework branches to arise from near the same point. Experience has shown that such branches split down badly and require much bolting when the trees grow old. This is being abandoned, especially The Citnis Xurscri/ 01 with lemon trees, in favor of the less comely but more de- sirable distribution of main branches. Fig. 32. — Orange buds in nursery row tied to lath stakes. Often a tree will make several grow^ths before it reaches the top of the stake. The end of each growth is marked by a ring or node of thickened tissue. There is a wide- 102 Citrus Fruits spread belief that a tree with several of these nodes on the trunk is to be preferred to one which made one growth to the top of the stake. The reason assigned is that it indi- cates slow growing and heavy fruiting qualities. It is doubtful whether there is sufficient basis in fact for this belief, although there are some arguments in its favor. It is not unlikely that in the case of the Washington Navel orange there may be some correlation between the num- ber of nodes and fruitfulness, but this is probably not the case with lemons. The citrus nursery should be thoroughly cultivated and irrigated and the trees kept in vigorous growth. Com- mercial fertilizer should be applied liberally, usually a ton to a ton and a half to the acre of a complete fertilizer high in nitrogen. One or two years are required to grow a marketable tree. We find, therefore, that a total of from four to six years is required from planting the seed to set- ting the trees in orchard form. Trees are graded and priced according to caliper measure- ment one inch above the bud. Well-grown one-year trees are often acceptable, but usually two-year trees are much better. Prices in California vary from fifty cents to one dollar and a quarter a tree. PREPARING TREES FOR SHIPMENT Citrus trees may be dug with naked roots, cut back to the trunk, shipped long distances, and planted with perfect success ; but on account of the fact that it is difficult to always see that the tender roots are not exposed, there is much loss from the carelessness of laborers, and the The Citrwi Nur.sery m aistoni of balling trees has become general in California. Balled trees are much less perishable, may be handled with more assurance, do not require all the top to be removed, do not need to be reheaded, and make a somewhat better showing the first year. On the other hand, the cost of Fig. 33. — Healing of the bud union. balling is great and the freight on thirty to forty pounds of earth with each tree adds considerably to the cost. It is recommended, therefore, that trees be balled where the distance to be transported is short or when inexperi- enced men are to do the planting. Where the owner is able to look after the planting personally the trees may be dug with naked roots and a considerable saving on freight and expense of balling will result. Where trees are to be moved only a short distance, as from one part of a ranch 104 Citrus Fruits to another, the following method is sometimes used. Short sections of ten-inch pipe are placed over the trees and driven into the ground, thus cutting all roots but the tap-root, which is cut with a spade. The trees are 1 - ' .J^'-^ > r^- "^^1 f " i. * yf w 7 ifei**w*^:,"** F-* ■^tfe' -JiaMi;S£^>«fl setups?:* i ...,# >. ' ^^W^jm''^''- ^H^^3 ^^^ i^--v/^ IBB §^^^ V^ r^^ J-- ' ^3 p^^t "1 ' ^5 ^ -''^^Mtik li ■» ^ m^ \^^.-^.,^^ ■F*: < Fig. 34. — Balling orange trees in the nursery. then moved and the core of earth containing the trees is slipped out of the pipe into the hole prepared, the pipes being used again and again. When trees are to be balled, a trench a foot wide and fifteen inches deep is dug alongside of a row of trees and' with careful work the tap-root may be cut and the tree The Citrus Nursery 105 lifted with a ball of earth. This is carefully wrapped in old sacking and firmly tied with strong cord. The top is cut back somewhat, the leaves removed from the trunk, and the trees are ready for shipment. A bailer and tyer work together and in good soil should turn out about one hundred and seventy-five trees a day. Counting the men engaged in digging trenches and defoliating, a crew of twenty-five men should dig and ball about fifty trees a day for each man in the crew. When a few balled trees are shipped, they must be boxed at considerable expense. In the case of carload lots, they are simply stacked closely together in ordinary box cars, the balls resting on a layer of moist straw on the bottom of the car. En route the balls should be kept moist, but not so wet as to start growth. California now produces upward of a million and a quarter citrus trees a year, many of which are shipped to various foreign countries including South Africa, New Zealand, and India. Foreign shipments always go forward with bare roots firmly packed in sphagnum moss. CHAPTER VI HORTICULTURAL INSPECTION AND QUARANTINE California has had much experience with horticultural statutes. Many different laws have been passed and amended from time to time during the last thirty years. During this time there has been hardly a session of the state legislature which has not changed the law in some particulars. The citrus industry is so vitally concerned with the activities of the State Commission of Horticul- ture as to warrant a description of this important agency. In March, 1908, the State Commissioner of Horticulture published a handbook containing all the laws together with the court decisions and legal opinions relating thereto, corrected to that date. More recent laws, together with a number of quarantine orders, may be found in the Com- missioner's "Monthly Bulletin," Vol. II, pp. 337-351, 1913. The ordinances of the different counties relating to the movement of nursery stock from one county to another may be secured from the respective County Horticultural Commissioners. THE STATE COMMISSIONER OF HORTICULTURE This official is appointed by the Governor for a term of four years or until his successor is appointed. 106 llorticulfural Inspection and Qnaravilne 107 While the state Iuav, approved Ai)ril 2(), 1911, direets the Commissioner to eolleet hooks, paiii])lilets, and periodi- cals and acquire all p()ssi})le infonnation hy correspondence for the furtherance of the horticultural hidustries, still his principal function is that of a police officer. He is by virtue of his position the state horticultural quarantine officer, and as such is responsible for the rigid exclusion from the state of injurious insects and plant diseases, and the prevention of any further dissemination of such pests as are already established m certain localities within the state. In order to enforce the state quarantine law approved January 2, 1912, the Commissioner maintains an office with a force of inspectors at San Francisco, another at Los Angeles, and a third at San Diego. These inspectors go through the cargoes of every ship arriving from any foreign port or from Honolulu, and the baggage of every passenger. If any plants, fruits, or seeds are found to be infested with injurious insects or diseases, they are fumigated at the expense of the owner, or treated in such a way as to kill the pests. If this is impracticable, the plants are destroyed or, at the option of the owner, returned whence they came. In some cases the State Commissioner may, with the written approval of the Governor, issue a quarantine order against certain fruits or plants from certain countries. Such articles are then considered contraband and, if an attempt is made to introduce them, are confiscated and destroyed by the inspectors regardless of whether they are infested or not. The State Commissioner may appoint the County Horti- cultural Commissioners or their agents special quarantine officers for the purpose of inspecting shipments coming 108 Citrus Fruits from the Eastern states or Europe and billed to interior points in California. The common carriers are by law forbidden to deliver to a consignee within the state any shipment of horticultural goods until such shipment has been inspected, declared free from pests, and formally released in writing by a duly appointed horticultural in- FiG. 35. — A shipment of defoliated balled orange trees. spector. The inspector may exercise his discretion in re- gard to the disposition of infested shipments. He may rid the plants of pests by fumigation or other means and then release them upon payment of the costs ; or if in his judg- ment the infestation is severe or the pest particularly dan- gerous, he may destroy the goods or cause their reshipment out of the state. As an example of a quarantine order now in force we may Horticultural Inspection and Quarantine 109 cite Order No. 21, which forbids tlie shipment of any of the forty listed host plants of the citrus white fly, Aleyrodes citri and Aleyrodes nubifera, from North Carolina, South Carolina, Georgia, Florida, Alabama, Mississippi, Loui- siana, and Texas into the state of California. This order prevents California growers from securing nursery stock or scions of new varieties in any of the above mentioned states. By special arrangement, however, the citrus seeds planted by nurserymen which come from Florida and Cuba are admitted, provided they are sent in care of some desig- nated agent of the Commission, who fumigates them be- fore delivery to consignee. x^nother quarantine order prevents the importation from Hawaii of mangoes, oranges, avocados, and other fruits which are hosts of the Mediterranean fruit fly, Ceratitis capitata. Still another order forbids the shipment into California from Mexico of oranges, mangoes, or other fruits which are hosts of the Mexican orange maggot, Tripeta ludens. These latter, however, have now been superseded by national quarantine orders. It has long been the custom of the State Commissioner of Horticulture to hold two meetings each year which are known as State Fruit Growlers' conventions. One meeting is usually held at some convenient place in the northern part of the state and the other in the southern part. The proceedings of these conventions are brought together, edited, published, and distributed free by the State Com- missioner. The meeting held at Davis in June, 1914, was the forty-fifth such convention. The printed proceed- ings of these conventions represent a very fertile source of information for the student of California citriculture. 110 Citrus Fruiis THE COUNTY COMMISSIONERS OF HORTICULTURE The California State law providing for County Horti- cultural Commissioners has been amended many times. The present law, approved March 25, 1911, provides: that whenever a petition, setting forth the legitimate need for a Commissioner and signed by twenty-five or more resident freeholders who are possessed of horticultural properties, is presented to the county board of super- visors, said supervisors are required to appoint a County Horticultural Commissioner from the list of eligibles, who must have passed the examinations held by the state board of horticultural examiners. The term of the County Commissioner is four years. Many of the duties of the County Commissioner are pre- scribed by county ordinances, and these vary in the differ- ent counties. The Commissioner is usually required to keep informed as to the particular localities within the county where pest infestation is serious. He must have the orchards and ornamental plantings inspected, and when in his judgment the scale insects have increased in any orchard until they constitute a public nuisance, he must serve written notice on the owner to abate the nuisance by fumigating, spraying, or otherwise within a certain time limit. If this order is not complied with, the Commis- sioner may enter the premises and abate the nuisance, the cost of such work becoming a lien on the property. If the cost of the work is not paid, enough of the property may be sold at public auction to satisfy the lien. Such ordinances have been tested in the courts and Ilorticultund In.spccliuii and Quarautlnc 1 1 1 found constitutional, the acts of the County Commissioners being upheld in each instance. County Commissioners may appoint local inspectors in outlying towns and fruit districts within the county. The Commissioner also renders an annual report to the State Commissioner and a monthly report to the board of supervisors of his county. As special state quarantine officers it is the duty of the County Commissioners and their agents to inspect every shipment originating outside of the state, as well as those coming from other parts of the state which arrive in their territory. It is also the duty of the Commissioner to inspect every outgoing shipment of horticultural goods before it is ac- cepted by a common carrier. The law requires common carriers to accept only such packages or lots as bear a statement signed by the Commissioner or his agent certifying that the goods are free from injurious pests. We find, therefore, that every package of horticultural goods is inspected twice, once at the point of shipment and again at the place of delivery. THE NECESSITY FOR INSPECTION The question may arise in the mind of the reader as to whether this complex system of quarantine and inspection is worth while. The answer to this question may be found in the following quotation from California Experiment Station Bulletin No. 214, by H. J. Quayle. '* That insect pests are one of the important factors in the citrus fruit industry of California is shown by the fact 112 Citrus Fruits that more than half a million dollars are expended annually in their control. This amount includes only what is actu- ally expended in fumigation and spraying, and does not take into consideration the loss of fruit from improperly treated trees or trees not treated at all. The cost of fumi- FiG. 36. — Two-year-old orange trees balled, ready for market. gation in one county alone amounts to $200,000 annually. Furthermore each county maintains a horticultural Com- missioner, and many of them a corps of inspectors, pri- marily on account of insect enemies, who are charged with the quarantine and inspection work, the cost of which in some of the counties may run as high as $25,000 annually. All of this vigilance seems to be warranted by thirty Ilorticidtural Inspection and Quarantine 113 years' experience of the most important fruit section of the United States. " It has been estimated that the average cost of fumiga- tion per tree, taking the whole of the citrus belt, amounts to about 30 or 40 cents, which micans an expense of approx- imately S30 to $40 per acre, and this is done on an average about every other year. This is intensive insect fighting, but when the improved market value of the fruit is con- sidered, it is money judiciously spent with such a valuable crop as the orange or lemon." In conclusion we may say that the benefits of exemption from scale insects is clearly reflected in the prices asked for land and bearing orchards in scale-free localities. The annual tax of 15 to 20 cents a tree for fumigation is especially unw^elcome and growers in scale-free localities do well to exercise every possible precaution to prevent the introduction and establishment of such relentless tax-gatherers as the insect pests and plant diseases have proved themselves to be. CHAPTER VII IMPROVEMENT OF CITRUS TREES BY BREEDING The production of citrus fruits in California and Florida is increasing at a rapid rate. The shipments from these two states for the season 1913-14 reached a total of about sixty thousand cars. Thousands of acres of young orchards are just coming into bearing, and the near future will undoubtedly witness a large increase in produc- tion. The problem of how to make a profit in the business in spite of the heavy production will loom large in the future. Undoubtedly a great deal may be accomplished through the marketing organizations by securing better distribu- tion of the fruit and increased consumption through proper advertising. Yet it is a fact that much loss is at present due to a lack of varieties which are well suited to the cli- matic and soil conditions under which they are grown, to ignorance in regard to adaptation of varieties, and to sports or aberrant forms which occur throughout the citrus growing districts much more commonly than is generally recognized. Through carelessness or ignorance in the selection of bud-wood many poor or even worthless types have been 114 Improvement of Citrus Trees by Breeding 115 propagated and widely planted. The poor financial show- ing made by many orchards is due largely to the prepon- derance of trees belonging to aberrant forms. While some progress may be made toward improved varieties through hybridization, the writer is strongly of the opinion that much better and quicker results are to be secured through the careful selection of desirable bud- sports which occur rather frequently on trees of the old standard varieties. HYBRIDIZATION The object of hybridization is to secure seedlings which combine the desirable characteristics of two or more parent trees. The flowers of the selected parent trees are cross- pollinated by hand, using great care in excluding foreign pollen. Cross-pollination is a very easy operation and may be performed successfully by any one willing to use a little care and perseverance. The structure of the citrus flower is very simple and a knowledge of the functions of the different parts is easily acquired by the study of the diagram at Fig. 14. The essential organs of the flower are the stamens and pistil. The anthers bear the pollen grains, each one of which when placed on the stigma will germinate and send a tube down through the style and into the ovary. The male nucleus from the pollen grain passes down through this tube and comes in contact with the female egg-cell of the ovule with which it fuses, thus bring- ing about fertilization and the combination of the charac- ters of the two parents. A separate pollen grain is needed 116 Citrus Fruits for each seed, and the parental characters may be com- bined in a different way in each case. After the ovaries have been fertiHzed they grow into viable seeds. It is not always necessary for citrus flowers to be pollinated and fertilized in order to produce fruit. The Navel orange for instance rarely contains seeds and on that account is known as a parthenocarpic fruit. When cross-pollination is accurately performed, it is necessary to place paper bags over the blossoms which are to be used as a source of pollen, before the buds open. This is necessary in order to prevent the possibility of the mixing of pollen by insects. The pollen may be gathered and dried on papers and stored in small bottles for use, but it is often convenient to cut the twigs, bag and all, and carry them to the tree which is to be used- as a female parent. Large buds just ready to open should be selected and all the smaller buds and open flowers on the twig removed. The petals are pried apart with a small pair of forceps and an anther bearing ripe pollen is taken from a blossom within one of the bags and placed firmly upon the stigma, pressing it down into the drop of white mucilage. If no mucilage appears on the stigma, it is evidence that the bud is immature. The camel's-hair brush commonly used in cross-pollinating fruits is not satisfactory in citrus work on account of the copious excretion of mucilage by the stigma. It is wise to cross- pollinate several buds on each twig, as many are apt to drop off. After the pollen has been placed on the stigma, the small immature anthers must be removed from the flower for fear that the pollen produced later by them may interfere with the results. In the case of the Navel orange luipravement of Citrus Trees by Hrcedlng J 17 this is not necessary, as \\\v antliers do not produce pollen. After the operation has been completed a j)aj)er bag should be })laced over the twig and tied «with string. After two or three weeks the paper bags may be replaced by cheesecloth bags, which remain on till the fruit is picked for seed. The value of crosses or hybrids produced in this way cannot be determined for several years, or until the trees Fig. 37. — Type of standard Washington Navel orange. have been reared to fruiting. By top-working buds taken from the young seedlings into old trees the fruit may be secured earlier. The improvement of citrus fruits by this method is very slow and the results uncertain. Moreover it is doubtful whether an entirely new variety of orange or lemon, how- ever good, could gain much recognition in California in the face of the popularity of the Navel and Valencia oranges and the Eureka lemon. The history of the industry in California has shown a constant elimination of varieties 118 Citrus Fruits rather than the acquisition of new ones. The greatest field for hybridization work Hes with the potnelos. There is at present no thoroughly satisfactory variety of pomelo suited to the climatic and soil conditions of California. The feeling of the growers in regard to better varieties of oranges and lemons was clearly shown some years ago when E. J. Wickson sent out a circular letter to determine the most urgent needs along the line of citrus breeding. The response of the growers was significant. They re- plied that what was needed most was a Washington Navel which would color earlier ; a Navel which, would bang on the tree like a Valencia ; a Navel that would not split; a Navel that would not puff; and a Navel more hardy to frost. Some growers wanted a Valencia that would not turn green a second time, or a Valencia without seeds. The most expeditious way of securing the results desired by the growers is by selecting and propagating those sports from the varieties mentioned which approach most closely the desired types. Such bud variations occur quite fre- quently in citrus trees. They present a vast field for the work of improvement of types. VEGETATIVE MUTATIONS OR BUD-SPORTS Citrus trees, in common with other plants, are observed to vary in several ways. There are fluctuations or un- stable differences which come and go in response to the various complex stimuli produced by changing conditions of soil and climate, or, in other words, changes of food and environment. There are also sudden changes known as Improvement of Citrus Trees hi/ Breeding lli) mutations wliich result in new forms that are stable and form the starting point of new strains or varieties. Fluctuations are of two kinds, regular and fortuitous. As an example of regular fluctuation we may cite certain influences of climate and soil which produce substantially Fig. 38. — Washington Navel oranges showing fluctuations in the navel; such variations cannot be preserved by budding. the same effect upon every plant of the same variety. Navel oranges grown in the hot Imperial Valley are much redder in color than those grown within the influence of ocean fogs near the coast. Oranges grown on light sandy soil are of larger size than those growm on stiff clay soil. Under the head of fortuitous variations may be included 120 Citrus Fruits many of the common malforms and monstrosities such as double oranges, oranges with protruding navels, fingered lemons, and various other teratological curiosities which may be found in the cull-heaps near the packing-houses. Mutations occur as sporting branches which show a different combination of characters from the rest of the tree. The immediate cause of mutations is not at present understood. They originate during the division of some single cell in the vegetative tissue which results in daughter cells containing the same determiners for char- acters but segregated and recombined in such a way as to produce characters visibly different from those of the parent stock. Thus appear new characters which, from the standpoint of the man who is growing the fruit, may be either valuable, neutral, or objectionable. When a shoot arises from tissue which has been formed by mutating cells, the shoot represents a new variety or sport variety which may be propagated by the ordinary method of budding. Sometimes more or less reversion to the old type occurs in the young trees. The cause of this has been observed to be due to the mode of origin of the sporting shoot. If the shoot arises from within the area of mutating cells in such a way that only these cells are used in the forming bud, then the resulting shoot will be com- posed exclusively of new cells and the sport may be prop- agated true without reversion. If on the other hand the shoot arises on the edge of the area of new cells in such a way as to include both kinds of cells in its structure, then there arises a mixed branch or '' sectorial chimera " which may be expected to constantly produce branches of various kinds. Some will be like the original plant, some like the Improvement of Citrus Trees by Breeding 121 new form, and some in turn will be mixed depending upon the kind of cells occurring at the point where each bud has its origin. The " Nomadic Albinism " described by Savastano ^ was probably a sectorial chimera. Fig. 39. — Variegated sport. Note white areas in leaves. Volckamer's " Hesperides," 1695. From Sectorial chimeras are not uncommonly met with in citrus trees. The writer has found excellent specimens in commercial orchards and some have been kept under ^ An. del, Stazione de Agrum. e. Fruit, Vol. 1, 1911, XXIX. 122 Citrus Fruits constant observation and study for five years. A Valen- cia orange tree in an orchard near Whittier was evidently propagated from a bud with mixed cells, for it still bears year after year on all its branches both typical Valencia oranges and a small, very rough, and worthless mutation. A twig here and there will produce typical Valencias, while Fig, 40. — A variegated sport of Valencia orange. Notice white margin of leaves. other's will produce curious mixed oranges having certain sectors of the fruits composed of mutant tissue. The owner of this tree endeavored to get rid of the worthless type by pruning it out, but mutant branches continually returned, and it requires frequent pruning to keep them suppressed. In this case the mutant tissue happens to occur irregularly scattered or mixed with the tissue of the Iniprovcnicnt of C'ltrm Trees by Breedimj \2'.\ original form. Such a mixture has been called a " hyi)er- chimera." ' Mutations often occur in the cells which begin the formation of the minute ovaries in the blossom buds. As the ovary grows in size the mutation appears as a sector of the fruit which differs in color, ripening season, or thick- ness of skin from the rest of the fruit. Such curious fruits have been called ''spontaneous chimeras." These striped oranges and lemons are often found by the pickers, who usually incorrectly attribute the phenomena to the in- fluence of cross-pollination. When we consider that these mutations are always formed before pollination takes place, the inadequacy of the theory of pollen influence is evident. When mutation occurs at the base of the ovary it is not possible to continue it by propagation as no buds occur on the fruit. When, on the other hand, mutation occurs on the trunk or branches in a position where an adventi- tious bud may arise, then propagation is easy. As before stated, many mutations showing various types of fruit and different bearing habits have occurred in the orchards, and through ignorant and careless cutting of bud-wood many of the worthless forms have become widely disseminated and now make up a considerable proportion of the trees in our commercial orchards. A vital need at the present time is a careful study of indi- vidual trees by each grower, who should determine which trees, if any, belong to unprofitable types and top-work ^ H. Winkler, "Uber Propfbastarde und Pflanzliche Chi- maren," Ber. Deuts. Bot. Ges., 25: 568-576. E. Baur, "Propf- bastarde, Periklinalchimaren und Hyperchimaren," Zoc. C27., 27 : 603-605. 124 Citrus Fruits them to the most desirable types. In this way the aver- age cost of production may be greatly reduced. The great need for a study of the performance of individual citrus trees was emphasized by the writer in 1910.^ Since then many such studies have been made, by far the most comprehensive of which are those of A. D. Sham el. ^ Out of a mass of ma- terial the follow- ing condensed quotations have been selected from the studies of J. H. Norton,^ formerly Super- intendent of the Citrus Experi- ment Station at Riverside : "The Navel orange grove from which the following data are taken is located in West Highlands, San Bernardino County. The trees are the same age and the soil condi- ^ Coit, J. Eliot, "The Relation of Asexual or Bud-Mutation to the Decadence of California Citrus Orchards," Rpt. 37th California Fruit Growers' Convention, 1910, p. 32. 2 Shamel, A. D., "A Study of the Improvement of Citrus Fruits through Bud Selection," U. S. Dept. of Agriculture, Bureau Plant Industry, Circular No. 77, 1911. 3 Norton, J. H., "Variations in the Productivity of Citrus Trees," California Cultivator, Vol. XL, No. 10, 1913. Fig. 41. — Sectorial chimera of Valencia orange. Improvement of Citrus Trees by Breeding 125 tioiis uniform. This grove contains 1525 trees planted 90 to the acre. The trees are about 16 years old and the grove is considered somewhat above the average in pro- ductiveness, yet the trees vary in yield from nothing to 426 pounds of fruit per tree. '* The following is the annual expense of this grove per tree : " General care including taxes, water, pruning, and fumigating, 11.14 Interest on Investment, 1.11 Total annual expense per tree, $2.25 "The fruit from this grove was sold for if cents per pound on the tree. The trees that bore less than 150 pounds of fruit were maintained at a loss, while those yielding more than 150 pounds paid a profit. This is graphically shown in Figure 44. " The curved line represents the yield per tree in pounds arranged in the order of yield. The horizontal line AB is the ^ dead line,' and any tree the yield of which falls below this line was maintained at a loss. The shaded part of the curved line shows the trees that the owner realized no profits from. The shading above the line AB is due to the loss sustained by the trees recorded below the line. There were 490 trees or 32 per cent that yielded less than 150 pounds of fruit. This loss was made up by the profits from the next 646 trees, that is, the profit from 42 per cent of this grove was required to offset the loss sustained by 32 per cent. Seventy-four per cent of this grove therefore gave neither profit nor loss. This leaves 126 Citrus Fruits the net income to be derived from 389 trees, or 26 per cent of the grove. " The total yield of the grove was 280,254.5 pounds of Fig. 42. — Orange showing sectorial chimera. From Ferrarius, 1646. oranges which at ij cents a pound, gave a gross in- come of $4203.81. The expense was $3431.25, leaving a net income of $772.56 or an average net profit per tree of Improvement of Citrus Trees by Breeding 127 51 cents, ('ould the loss due to the 490 poor trees have been elhninated without increasing the production per tree, then the net profits from the remaining 101)5 trees would have been $1125.90 or $1.09 per tree as compared with 51 cents profit per tree which was actually the case." The record of this West Highlands orange grove may be considered fairly typical of a large proportion of the Fig. 43. — What is known as the "wrinkled sport" of Eureka lemon compared with normal fruit. Both from same tree. groves in California. The differences of yield noted were due both to fluctuations and mutations, but the extreme differences were undoubtedly due to mutations. The average yield would be greatly increased by top-working those of the 490 poor trees which proved to be mutative to buds carefully selected from the tree which yielded 426 pounds. Many of the most progressive growers now keep accurate performance records and top-work 128 Citrus Fruits the unprofitable trees as soon as they are discovered. In the case of the AustraUan and some other worthless mutations of Navel orange trees performance records are hardly necessary, as any experienced man should be able to recognize such poor types at a glance. For the segre- gation of trees which represent undesirable mutations, whose chief difference is that of yield, the performance record is indispensable. There is no scientific evidence to warrant the belief that anything worth while may be gained by the selection and propagation of trees whose high yield is due to fluctua- tion. It is vital that the high yield be due to a true muta- tion in order that the type may be propagated and progress made. As a matter of fact, the standard type of Wash- ington Navel is normally a heavy bearer and the majority of mutations observed are retrogressive. It is chiefly to counteract retrogression that top-working is practiced. Occasionally, however, mutations of peculiar value appear, The Thomson and the Navelencia may be cited as exam- ples. It is not unlikely that a general increase in the amount of individual tree study by many growers may lead to the discovery of new mutations which may be of great value to the industry. For him who brings such mutations to light is awaiting both honor and financial reward. THE SELECTION OF BUD-WOOD The foregoing discussion emphasizes the fact that the selection of bud-wood is an exceedingly important matter, for if one does everything else in the most approved way fl ) 5< > ■i i \ <; \ S \ \ \ *V1 •5 11 \£,f? ^ ^ Cil u1 i \ \ V > V \ V V s^ ^ sy=u„ 1 ^ n ^^'X t CT-Mt Picking and Packing Oranges 301 to the car. The fire hazard is high and losses are rather frequent. INIost of the houses belong to a local mutual insurance association which prorates and assures the losses as they occur. There are at present about 200 packing-houses in active operation in California, besides a large number of sheds and old houses which operate only at infrequent intervals. The capacity of the houses varies from one to twenty cars a day. The associations which are affiliated with the Exchange enjoy the privilege of buying ranch and packing-house supplies through the Fruit Growers' Supply Co. This is a non-profit cooperative organization through which the growlers pool their orders at low cost. The Sup- ply Company has an authorized capital of one million dollars and in 1914 did a business of $3,319,062.04 at an operating expense to the members of f of one cent on each dollar of business transacted. CHAPTER XVI PICKING AND PACKING LEMONS The picking and packing of lemons differs radically from that of oranges as described in the previous chapter. Lemons are usu- ally picked from ten to twelve times a year, the heaviest pickings coming in March and April and the lightest in August and Sep- tember. It is a peculiar and un- fortunate fact that the heavy pickings come at a time of year when there is lit- tle demand for lemons and the lightest pickings come during the picnic and lemonade season, Fi(i. 114. Picking Icinons. 302 Picking (ind PdcL-inij Lriihoiis 303 wlieii the (leniand is greatest. For tliis reason tlie pr()])er storage of si)ring lemons becomes one of the imj)ortant fnnctions of the lemon paeking-honse. The following tyj)ical example of an actual yield of a 9j acre mature lemon orchard of mixed Eurekas and Lisbons growing near Covina, Los Angeles County, gives a good comparison of the various pickings : Record of Lemon Pickings. Season 1910-11 Orchard of Mr. N. D. Mussey Pool Date Lug-boxes 76 Pounds ■ 1 Sept. 19 3,698 2 Oct. 19 60 2,880 3 Nov. 17 289 13,852 4 Jan. 3 520 24,470 5 Feb. 1 832 39,415 6 Mar. 18 1,122 50,906 7 May 3 1,120 51,350 8 May 30 196 9,268 9 July 21 298 14,224 10 Aug. 30 52 2,506 Total 4,565 212,569 The method of picking lemons from the trees is much the same as with oranges except that the use of the ring and consequent searching about in the foliage among fruit of all sizes makes picking slower and more expensive. Es- pecial care should be used to prevent dead twigs and other trash from falling int(^ the picking sacks as the w^eight of 304 Citrus Fruits the lemons against such objects in handUng will cause scratches in the skin. In some sections special picking sacks with closed tops are used to prevent this. In this type of sack the fruit is introduced at the side near the top. For hauling to the packing-house the growers generally use a factory-made wooden wagon with steel skeins Fig. 115. — Two-story lemon packing house, Glendora, California. on which they place a wide flat rack usually about 8 feet wide and 14 feet long. The racks are made locally and are set on the gears over bolster springs. It is not un- common to see a string of three or more of these wagons hooked together and being drawn by the gas tractor which is used for cultivating the orchards. Lemons differ from oranges also in being valued for their acid rather than for their sugar content. A green Picking a fid Packing Lemons 305 lemon therefore is better than a yellow " tree ripe " one provided it is fully sized and mature. For these reasons lemons are ])icked altogether according to size rather than color. The pickers carry wire rings which are slipped over each lemon, and every fruit which fails to pass through the ring is picked. In summer a ring 2 J inches in diameter, inside measurement, is used ; while in winter and spring a ring one-sixteenth of an inch larger is used, inasmuch as the fruit will be held longer and will undergo greater shrinkage. On account of the demands of the markets mentioned above, there is a tendency to pick often in summer, care- fully searching for every lemon which may be up to size. This fruit is quickly colored in the sweat-room and hurried to market while prices are high. SWEATING AUTUMN LEiMONS The sweating of lemons is for the purpose of quickly changing the green color to a whitish \'ellow. While the practice of sweating oranges is sometimes abused, lemon sweating is always legitimate as it in no way de- ceives the buyer. In fact the mature but green lemon properly colored in the sweat-room and hurried to market is usually sourer, and therefore better, than the lemon which has been kept in storage for several months and has consumed a small portion of the acid in the process of respiration. For best results, lemons should be fired intermittently. The air of the sweat-room should be kept saturated with moisture, and beads of water should be in evidence on 306 Citrus Fruits the ceiling at all times. If the air is allowed to become dry, the lemons will quickly shrivel. The temperature should be kept at 90° F. or ten degrees lower than for oranges. So far it has been impossible to fully color green lemons in five days and retain the buttons, as the same quality of the gas mixture which changes the color causes the buttons to drop off. Inasmuch as sweated lem- ons are sold and consumed quickly, the loss of the buttons is not as serious a matter as would otherwise be the case. STORAGE OF WINTER LEMONS In the late winter and spring when it becomes advisable to hold the fruit for summer markets, the problem of the lemon packer is very different from that of early fall. Instead of sweating the fruit and thus accelerating the life processes as much as possible, he now wishes to retard to the greatest possible degree these same life processes. The fruit is therefore picked with very great care in order to prevent abrasions. On arriving at the packing-house the lemons are carefully washed in a brush washer. For disinfection against brown rot, one pound of bluestone is added to each 1000 gallons of wash water in the morning and one-half pound added to the same water at noon, the water being changed each morning. To prevent the bluestone from corroding metal tanks it is well to apply a thick coat of asphaltum paint to the inside of the tank. The lemons are now separated into three grades accord- ing to color alone, known as green, silver, and tree-ripe; the silver being those fruits which are just beginning to lose the deep green color. Fach of these grades is placed Picking and Packing Lemons 307 loosely ill packing boxes and stacked up, a car in each stack, on the storage floor. Lemons are often kept in this way six or even eight months, but the fruit picked after April 1 is much shorter lived than that picked earlier. Lemons picked green will keep much longer than those alloAved to turn yellow on the tree. These tree-ripes are kept separate and shipped first. Lemons will also keep much better near the coast than in the in- terior valleys, where much more expensive storage houses must be provided in order to control the humidity. The great problem is to give plenty of ventilation in damp weather in order to prevent decay and to reduce the Fig. 116. Lemon washing machine and sort- ing table. 308 Citrus Fruits ventilation, or withhold it entirely in warm dry weather to prevent the fruit from losing moisture and shrivel- ing. The relative humidity of the air in the storage house should be held as near 80 per cent as possible, but this is very difficult to accomplish in interior valleys, where the humidity of the air varies from 90 per cent to as low as 10 per cent. In order to control the temperature and humidity each carload stack of lemons is inclosed in a heavy duck tent. These tents are usually made of 8 oz. special army duck, and are 10' wide, 10' high, and 20' long. This size includes one carload of lemons. This tent is open at the bottom, and is open at the four corners, which are laced so that any part of the fruit may have ventila- tion, without interfering with fruit that it is not necessary to ventilate. These tents are also built in other sizes, which is sometimes necessary to fit the space in a packing- house, but this is the size that is most generally used. The tent is hung from the ceiling on a frame, there being eyelets in the top to fasten to frame. In some of the packing-houses in interior districts the tents have been abandoned and the fruit is stored in large basements, usually built of concrete, with outside shutters which provide for ventilation. Unless the lemons have been very carefully handled from the orchard to the packing-house, a great deal of decay is almost sure to develop in storage. Lemons are always handled more carefully than oranges and the brush washer is about the only piece of machinery they are allowed to pass through. On account of the absence of machinery, a lemon packing house presents a very different aspect from an orange packing house. Picking and Packing Jjcmoiui 300 When the fruit is taken from storage it is f^rjided \)y hand into fancy, choice, and stanchird, each grade being placed one hiyer deep in broad flat trays. Stacks of these trays of fruit are weighed and the proporticMi of the differ- ent grades credited to the grower of the fruit. All through washing, storing, and grading each grower's fruit is accom- panied by a ticket attached to the guide box. When each Fig. 117. — Lemon curing tents in packing-house near the coast. of several hundred growers has four or five pickings in greens, silvers, and tree-ripes, all in storage at one time, the task of keeping account of each lot of fruit necessitates a well-organized system. In the packing-house lemon varieties are not kept separate, and the name of the variety is not stenciled on the end of the box as is customary with oranges. Lemon packers use the same packing stand that is 310 Citrus Fruits used for oranges, but instead of packing from bins contain- ing fruit all of one size, they pack from the trays, sizing the fruit by eye and hand, the range of sizes in each grade running from 210 to 540 per box. Lemons sizing 300 to 360 to the box are in greatest demand on the markets, Southern markets preferring the smaller and Northern the larger sizes. In one or two of the newer lemon packing houses, sizing machines built especially for lemons have Fig. 118. — Truck for handling stacks of lemon trays. been installed. These are operated very slowly in order to avoid injury to the fruit. Most packers still regard sizing machines for lemons with suspicion. The standard lemon box has an outside measurement of 11 by 14^ by 27 inches and is divided in the center by a partition. For the computation of freight charges a box of lemons is estimated to weigh 84 pounds. The standard car of lemons contains 312 boxes. I Pi('kiu(j and P((('l:'n}(j Lcni.oiis Fiti. 110. — Packiiijr IciiioMs fioin sorting trays 312 Citrus Fruits — Lemons Size Average Diam- eter IN Inches 210 2| 240 2f 270 2i 300 2| 360 2\ 420 2i 490 2 540 1| Lemons were formerly shipped under ventilation from November to March, and under ice the remainder of the year. Some shippers who have learned to handle their fruit with extreme care have abandoned ice altogether to their great profit. In 1912-13 only 14 per cent of the lemons shipped were iced. The average haul to market is 2283 miles, being 304 miles less than the average haul for oranges. This difference is accounted for by the fact that a larger proportion of California lemons are marketed west of the Missouri River, thus avoiding, to a certain extent, the sharp competition with Italian lemons through- out the Atlantic seaboard. The freight rate on lemons from California to New York, Chicago, and intermediate points has been fixed at $1.00 per hundredweight after a long and expensive contest in the courts, the lemon growers finally winning their con- tention. PICKING POMELOS AND TANGERINES Pomelos are picked from the middle of December to the following August and many growers keep some fruit for home use on the trees the year round. The total ship- Picking and Packing Lernonji ol3 ment of pomelos iroiii ('{ilifoniia. is not lar<^(', hciii^ about 200 cars per year. Ordinarily the fruit is stored in luj^- boxes for a few days until the rind becomes soft and pliable. After this the fruit is packed in orange boxes and handled like oranges. Pomelos imj^rove somewhat in flavor with storage and proper curing, and for best results, this fruit should be very carefully picked in February or March and held in storage precisely as are lemons until May, June, and July. Pomelos Size Average Diam- eter IN Inches 64 31 80 3^ 96 3f 126 3i 150 3 Large quantities of pomelos are grown in Florida, Cuba, Porto Rico, and the Isle of Pines, and these dominate the markets of the eastern United States. California pomelos are marketed mostly within the state and to some extent in the intermountain country and the Pacific Northwest. Only a few are sold in New York. On account of the state quarantine, Eastern pomelos cannot be brought into California for sale. At present a large portion of the California pomelos found on the markets are poor in quality. This is due to the fact that but little attention has been paid to pomelos and most growers tend to treat them in every respect like oranges. That the climatic and soil conditions in some parts of California are well suited for the production of a first-class pomelo 314 Citrus Fruits is evidenced by the fact that a few skillful growers market their fruit in New York at very remunerative prices in competition with Eastern fruit. Tangerines are the only variety of mandarin orange grown to any extent in California. They are picked, packed, and shipped in much the same fashion as oranges except that, being a fancy fruit and in limited demand, they are not shipped in car lots. It is customary to market tangerines gradually, including a dozen boxes or half-boxes in a car of oranges. /-eA/e/v 7^c^// J<»iilSTMl^UiTCei Fig. 121. — Typical lemon box label. Cleanliness is very important. Xo decaying fruit should be allowed in the house, as the spores given off tend to increase the amount of decay. All culls should be conveyed by belt from the grading table to some bin or outhouse entirely separate from the main packing- house and situated to leeward of it. 316 Citrus Fruits The comfort of employees should be provided for by rest rooms and lunch rooms. The main packing floor should be well lighted by glass skylights, for it has been found that the efficiency, comfort, and spirit of the em- ployees are greatly improved by clean, airy, and well lighted work-rooms. ^^ ^i.^ K San DiFGO^^^^ Fig. 122. — Combination box label. Some packing associations confine their work to packing and shipping, while others take charge of all picking, pruning, and in some cases fumigating of the groves. In packing lemons, especially, it is a good plan for the packing-house manager to control the picking. The San Dimas Lemon Association, for instance, keeps account of the fruit picked by each crew of pickers, and as this Pick'uKj and Packnuj Lemons 'Ml fruit comes out of storage and is sorted over a careful account is kept of the percentage of each kind of decay. In this way a check is kept on the pickers, and if decay due to careless handling occurs it may be traced back and the blame placed where it belongs. Each foreman of a picking crew knowing that he is responsible for any decay which may develop in his lemons takes pains to instruct his men in the best methods of handling the fruit. At the end of each season a substantial prize is awarded the picking crew in whose fruit the least amount of decay has developed. Pickers are drawn from many nationalities. Americans receive about $2 a day, while Japanese and Hindus are "paid twenty cents an hour. A responsible picking foreman of considerable experience in handling lemons and men may receive $75 or more a month aside from a variable bonus at the end of the season. CHAPTER XVII BLEMISHES OF THE FRUIT AND THEIR PREVENTION A LARGE increase in the production of citrus fruits will mean, if it means anything, a keener competition in the markets. In order to meet this increased competi- tion, California growers and packers are being encouraged to adopt higher ideals in grading and packing. With more rigid grading the cull-heaps near many of the packing-houses assume large proportions. A conserva- tive estimate places the direct loss from cull oranges alone, aside from frozen fruit, in excess of a half-million dollars a year. It is well worth while, therefore, to make a study of the cull-heap, classifying and determining the relative im- portance of the various blemishes which cause oranges to be thrown into a lower grade or into the cull-heap. We will also consider how far it is practicable and by what means the proportion of culls to packed fruit may be reduced. The blemishes of citrus fruits may be classified according to their causes. For couvcuicnce we may grou]) them uuder four heads, uamely : insect, fungus, mechanical, and physiological blemishes. 318 W('))iish('s of the Fruit a ml I heir PrcN'nt'ion 319 As a result of counts of Xa\(^l <'iills niadc in twelve ])acking-h()iises durinii: January and February, 1910 and 1911, it appears that on the averaj^e, the most prolific causes of culls are as follows, according to their impor- tance : splits, bruises, thorn stabs, thrips scars, sunburns, and worm holes. These six kinds of blemishes are re- sponsible for upwards of seventy-five per cent of the culls. These counts, how^ever, did not take into consid- eration the brown spot which usually does not develop until the fruit has left the packing-house. INSECT BLEMISHES Insect pests and their control will be discussed rather fully in Chapter XXII and it is only necessary here to name those blemishes of the fruit w^hich are due to insects. They are : thrips scars ; tortrix worm holes ; scale insects such as red, yellowy purple, and the sooty mold w^hich follows and growls upon the excretions of the black, gray, and brown scales ; mealy bugs ; red spiders ; silver mites ; grasshoppers ; katydids ; and some others. The presence of a few^ scale insects on fruit intended for some markets in the East need not condemn it, but there are other markets, such as certain ones in British Columbia, where inspectors condemn all scaly fruit even though citrus fruits be not grown in the region. FUNGUS BLEMISHES The fungi W' hich produce injury to the fruit are : brown rot, Pythiacystis citrophthora; blue mold, PeniciUium 320 Citrus Fruits italicum; green mold, Pcnicillium digitatum; gray mold, Botrytis cinerea; sooty mold, Meliola camellioB ; cottony mold, Sclerotinia lihertiana; gray scurf, fungus not as yet identified; wither-tip, Colletotrichim gloeosporioides ; black rot of the Navel, Alternaria citri; and stem-end spot, Cladosporiinn sp. (secondary). Most of the fungus diseases which cause blemishes on the fruit result in complete loss. The nature of these diseases, together with control measures, will be discussed in detail in Chapter XXI. The fungus causing gray scurf or scab on lemons has not as yet been identified. The fungus apparently acts as a secondary agent ; the primary cause is probably the ^ slight bruising of the young tender fruit by the wind. The best remedy for this trouble is the growing of windshields and close planting of the lemon trees. By proper pruning also the branches may be made stiffer and more resistant to the swaying and whipping effect of the wind. The stem-end spot of oranges is a very different thing from stem-end rot, and occurs mostly on Navels and on fruit which has hung late on the trees. It consists of a breaking down, browning, and shrinking of the skin in certain small spots near the stem. Ordinarily this causes little injury, but occasionally during rainy weather a species of Cladosporium grows on the dead tissue of these spots, giving them a black color which detracts very much from the appearance of the fruit. The only remedy at present available for this trouble is to pick the fruit early in those orchards where the trouble becomes serious. Blemishes of the Fruit and their Pretention o2\ MECHANICAL liLEMISIIES Much otherwise ^ood fruit is ruined by carelessly in- juring the fruit mechanically. Growers and packing-house men rarely realize how serious are the losses resulting from such causes. Bruises. — Fruit which is bruised by careless handling is almost sure to decay. Careful handling should be the cardinal principle of every picker and packer. When a stack of boxes of fruit is accidentally overturned in the packing-house, the fruit should be set aside for ten days and then sorted over, the decaying fruit being eliminated. Thorn stabs. — Much fruit is ruined by thorns. In wet weather such thorn-pricked fruit decays, but in dry weather the broken skin may cauterize and result in a spot. Sometimes a fruit continually swinging against a thorn will develop a thick horny rind at that point, which ruins its appearance. Thornless varieties, careful pruning, and windbreaks are the remedies. Cidtivator scars. — Cultivators and other tillage im- plements should be covered by a smooth tin shield which will allow low-hanging fruit to slide over them without injury. Metal projections on harnCvSS are also objection- able. When it is necessary to cultivate close up under the trees a great deal of fruit will be ruined unless pro- tected by some sort of shield attached to the implements. Clipper cuts. — When the use of pointed clippers was in vogue the loss from clipper cuts was very great. Now, however, round pointed clippers are used, and there is no excuse for clipper-cutting the fruit. Stem punctures. — When the stems are not properly 322 Citrus Fruits cut off square and close, they puncture a great deal of fruit in the box, and as they pass through the packing- house machinery. A close watch kept on the pickers should prevent this. Machine injuries. — Some years ago a certain packing- house foreman complained of excessive decay which could not be explained. Finally one of the employees dis- covered a loose screw in one of the guide bars of the brushing machine hopper. The sharp head projected an eighth of an inch and made a little nick in every orange which rolled by. Passing over the brushes each nick was thoroughly inoculated with decay germs. The guilty screw head was driven home, after which the decay in transit dropped from 35 per cent to 4 per cent. The remedy for this is to keep a close watch for screw heads or splinters on all ma- chinery and for pro- jecting nails in field boxes. Fwnigation scars. — Oftentimes fruit is pitted and burned by carelessly overdosing trees with gas during fumigation. Fumiga- tors should be held re- sponsible for such in- jury. Occasionally, however, it happens that a sudden change in the weather or condition of the atmosphere Fii>. \'2'A. — Fiiinifrtitioii scars. Blemishes of the Fruit and their Prevention 323 will result in wholesale pittiii<]; of fruit even with the same dosage which was harmless a few hours earlier. No remedy has been found for this difficulty, and fumigators are not 1;o blame. Fortunately such occurrences are rare. Shoulder spots. — Where two oranges grow touching each other the point of contact is often shown by a light colored area with a reddish spot in the center. Such spots are not very serious and cannot be remedied unless the fruit be thinned. Thinning citrus fruits has never been practiced in California. Hail scars. — Hail storms are of rare occurrence in the citrus districts. When they do occur they pit the fruit. If the hail is followed by dry weather, most of the pits will dry and little injury will result. In wet weather, however, some fruit will de- cay on the tree with blue or green mold, while in some cases a species of Cladosporium will grow on the pits and turn them black in color. Soil scars. — Where heavy crops of fruit bend the branches down much fruit often rests on the ground. When the wind moves the branches the rubbing of the fruit on the ground causes a gray callous spot which ruins its appearance. Fig. 124. — Scar caused by rubbing on the ground. 324 Citrus Fruits Windjalls. — Occasionally strong winds will whip a large part of the orange crop from the trees, as was the case in September, 1911. It is rarely safe to send a windfall to the packing-house, as it is very apt to develop decay. Cement dust. — In certain localities the fruit is coated on the upper side with a crust of cement dust which comes from near-by cement mills. This dust collects in the pores of orange skin and sets, being very difficult to remove. It injures the appearance and reduces the grade. PHYSIOLOGICAL BLEMISHES This class of blemishes is not only large and the losses serious but the causes are as a rule not well understood. The total number of troubles of this kind is very large and now ones are continually appearing. Only the most important will be mentioned here. Sunburn. — Both oranges and lemons which hang fully exposed to the sun are often injured. The exposed side becomes dwarfed in growth, resulting in malformation, and the skin of oranges becomes thick and pale colored and adheres tightly to the flesh. In interior valleys where the sun is very hot the skin mav' die and a hard black spot result. In such situations the trees should be pruned in such a way as to encourage the production of inside fruit, which is always much finer in appearance. Lemons are often noticed in the markets which are lop-sided, the dis- tance from stem to apex being greater on one side than the other. This is caused by slight sunburn and is a sure 'sign that the lemon grew in an exposed position on the tree. There is a curing house trouble of lemons known as Blnnishcs of flic Fruit and their PreucHtiofi IVI^) rod rot, or, more ])rojHTly, rod hlotcli, which develops as a rusty brown color, gradually drying down into a sunken condition with a dark red or black color. This has been attributed to sunburn, as it is most common in lemons from exposed parts of the trees. Frost. — The losses from frost are of course very large, but many fruits are only slightly frosted, and while they should be packed under a frost label they are good for consumption. Oranges usually exhibit no outward signs of frost unless severely frozen. Occasionally, however, certain oranges, especially those having more or less thick skins and growing low down on the north side of the tree ^^'ill show a number of characteristic brownish spots on the exposed side even though but slightly frosted. Off-bloom. — Occasionally orange and pomelo trees will blossom out of their regular season. The cause of this is not always apparent, although it is often due to irregu- larities in irrigation. PVuits developing from oflF-blooms are usually malformed and inferior. Navel off-blooms produce fruits with sunken instead of protruding navels. Pomelo off-blooms produce fruits which are distinctly pear-shaped as compared with the regular crop. Regu- larity and thoroughness of irrigation and cultivation will reduce the amount of off-bloom fruit to a negligible quantity. Mottled-leaf. — This disease is not at present well understood. It results in the production of very small oranges and lemons of a whitish color, often quite unfit for packing. (See Chapter XXI.) Exanthema. — This trouble appears on the fruit as dark reddish blotches or crusts. In severe cases the fruit is 326 Citrus Fruits dwarfed in growth and cracks open on the trees. (See (^hapterXXI.) Malformation, — Many kinds of malformations are common. They may be divided into two classes : those due to sporting such as corrugations and color stripes of the rind, bottled-necked fruits, and others, which may be remedied by pruning out all of the sporting branches ; and those due to an excess of food and teratological factors. Many Navel oranges, especially those borne on the top- most branches^ exhibit a double or proliferated navel. Often this takes the form of a small secondary orange superimposed upon the navel. These are very common and are always thrown into the cull-heap because the small orange would have to be broken off before packing and this would result in decay. Often twin oranges partly attached are met with which are discarded for the same reason. The fruit borne near the large upright central branches often has coarse, grooved skin about the stem. This is caused apparently by the superabundance of food and may be largely prevented by proper pruning. Brown spot. — The brown spot of the Navel orange may be described as occurring irregularly over the surface of the orange. From one to fifty or more spots may develop on a single fruit. The spots vary in size from a mere point to one inch in diameter, averaging about one-fourth inch. This brown spot occurs only on the Navel oranges, and is uniformly worse on fancy, smooth, thin-skinned fruit. The total money loss from this particular spot is very large. P'or further particulars see Chapter XXI. Cracks and splits. — Cracks differ from splits in being Blemishes of the Fruit and their Prevention 1327 transverse rather than longitudinal ()j)enings in the rind of the orange. They are of rare occurrence and their cause is unknown. Splits, on the other iiand, are very common and cause heavy losses, especially with Navel oranges in interior valleys. Splits are of two kinds : Fig. 125. — Orange splits. Side splits above and navel-cnd splits below. side splits and navel splits. Side splits are caused by teratological cavities or seams in the skin. Thus weakened the skin is unable to withstand the growth ])ressure, and a split results. A Navel orange which is split even a fourth of an inch at the navel must not be packed for long distance shipment, for such an opening is almost sure to be inoculated with decay. 328 Citrus Fruits All such oranges must be graded out but may often be sold to local peddlers for enough to pay for picking and hauling. The most common theory in regard to the cause of splits is that an irregular water supply, causing wide variations in the moisture content of the soil, produces a greater fluctuation in the growth of the interior than in the skin of the orange. Such a theory is quite reasonable, but such a cause should be regarded as contributory only, inasmuch as only a part of the fruit on any given tree will split. If a number of navel-split oranges are cut in longitudinal sec- tions, it will be found, almost without excep- tion, that the thickness of the rind varies, being quite thick and often creased at the stem end, and as thin as paper near the navel. Specimens „ . ^ , , with uniform thickness Fig. 126. — Horizontal cracks are very . ,. different from splits. of skin Very rarely split. Hot, dry spells of weather alternating with damp cloudy weather, together with careless irrigation, cause a high percentage of splits among this class of oranges. While much may be done toward overcoming this loss by careful irrigation and cultivation, the most important remedy is probably the propagation of trees from carefully selected bud-wood. By this means we may largely eliminate from our future orchards the un- Bloji.i.shr.s of the Fruit and their Pre rent ion ']29 desirable types whieli are so prone to si)lit (lurin<,^ lui- fa^'()^al)le weather. Puffing. — When oranj^es arc left too lon^ on the trees, they will often become puffy. The rind becomes weak, with many cross creases and much unevenness. Finally the whole orange becomes soft and structureless. The walls of the juice vesicles become much thickened and the juice partly disap- pears, leaving the fruit dry, crumbly, and insipid. The remedy for this trouble is to pick the fruit earher in those localities where puff- ing is serious. P eteca. — Thi s trouble appears in the form of deep sunken pits in the rind of lemons after they have been in the curing house for some time. The tissue at these spots is found to be dried and shrunken prematurely, somewhat after the fashion of the brown spot of the Navel orange. The cause of peteca is not known. Dry center of lemon. — X peculiar trouble which has be- come quite general in recent years. The vesicles collapse Fig. 127. — Peteca of lemon. 330 Citrus Fruits ill groups, turn brown, and dry up. Injury is always greatest near the blossom end and is often accompanied by germination of the seeds while still within the fruit. In advanced cases the interior of the lemon may become filled with a mass of roots from the seeds. While this trouble results in a loss of juice, the housewife who cuts the lemons through the center is not apt to discover their inferiority as there is little surface indication of dry center. In many ways this trouble resembles bitterpit of the apple. At present neither the cause nor a remedy is known. ■"-^ CHAPTER XVIII BY-PRODUCTS Until very recently it has been the custom in CaHfornia to haul the cull fruits from the packing-houses and dump them in waste places. A very few growers returned the culls to the orchards and plowed them into the soil for the sake of their humus value and the small amount of plant-food they contain. But the bulk of the culls have been thrown away, and when we consider the enormous waste resulting from this practice the question arises as to whether a part at least of this large tonnage of fruit may not be profitably converted into valuable by-products. That citrus by-products are in strong demand in the United States is proved by our annual importation of these items from abroad. The imports of the year 1909 are fairly typical of other years and are given on page 332. The values given are the appraised wholesale values at the port of export and would be considerably higher if appraised in this country. At the present time nearly all citrus by-products are produced in Europe, while small amounts come from Paraguay, China, and California. The chief reason why citrus by-products have not been more largely produced in the United States is that the 331 332 Citrus Fruits cost of labor is from three to five times greater than in the citrus producing regions of Europe. At present, however, there is a widespread interest in this subject in Cahfornia. Several small factories are already in operation, and several more are in process of construction. Importation of Citrus By-products into the United States for the Year ending June 30, 1909 Citric acid — lb Citrate of lime — lb Lemon, lime, and sour orange juice Orange and lemon peel not candied, preserved, or dried Citron or citron peel, candied or dried — lb Citron preserved in brine — lb. Orange and lemon peel, preserved, candied, or dried — lb Oil of bergamot — lb Lemon oil — lb Lime oil — lb Oil of neroli or orange flower — lb. Orange oil — lb Total Quantity Value 243,010 $74,209 3,917,274 489,031 81,386 4,833 991,341 79,519 4,075,835 100,224 436,129 20,692 89,957 281,211 405,695 358,197 21,991 9,973 23,184 170,342 87,591 151,860 .,821,477 In Europe the citrus by-product industry is largely centered on the Island of Sicily and in Calabria. In these districts the two chief products are citric acid and lemon oil. About one-third of the total lemon crop of this region is consumed in the manufacture of citrate of lime, and from the peel of these same lemons comes the By-Products 333 enormous quantity of essential oil, or essence of lemon, which furnishes practically the world's supply. COMMERCIAL BY-PRODUCTS P'or convenience those by-products at present manu- factured on a commercial scale will be grouped separately from a number of domestic recipes which are included. Several of the products described under domestic recipes may of course be produced on a commercial scale, should the demand warrant. Citric acid. — Citric acid is manufactured from the juice of the lemon chiefly, although lime juice is used to some extent. The peel is first removed and used for the pro- duction of lemon and lime oil which will be described later. The lemons are halved and the pulp scooped out with a sharp spoon. The pulp is then passed through toothed cyhnders which shred it, and the juice is extracted from the mass by a high power press. The crude juice con- tains water in abundance, citric acid, malic acid, several kinds of sugar, albuminoids, and mucilage. The crude juice is filtered, placed in boilers, and heated nearly to the boiling point. Finely powdered chalk, mixed to a cream in water, is slowly added, while the hot liquid is being constantly stirred. The chalk or carbonate of lime unites with the citric acid, forming calcium citrate, which is insoluble and precipitates from the juice as a white powder, which is collected, washed, and dried into cakes. Great care is used to add just enough chalk to take up the citric acid as shown by litmus tests. As citric acid must pay a duty of seven cents a pound on entering the 334 Citrus Fruits . United States and citrate of lime is free, most of the Italian product is shipped to this country as citrate of lime, and the final step in the process is completed in this country. This final step consists in treating the citrate with dilute sulphuric acid, which forms sulphate of lime and leaves citric acid in solution. This solution is evaporated in leaden boilers until the pure citric acid crystaUizes out, and is washed and dried. Citrate of lime contains about 65 per cent of citric acid. Lemon oil, orange oil, hergamot oil, and lime oil. — The peel of all citrus fruits is thickly dotted with small glands yielding an essential or highly volatile oil. The oils from the different kinds of citrus differ considerably in their characteristics. These oils are in great demand for flavoring extracts and perfumery, and the demand for the different kinds is in the order given. Of these, lemon oil is used in much the largest quantities. Any person may easily demonstrate the presence of this vola- tile oil by squeezing a piece of fresh peel in such a way as to cause the oil to spurt out into the flame of a lighted match. It will burn with a flash, showing its high vola- tility. The major part of the oils now on the market come from Sicily and Calabria. The contrivances for extracting the oil are very crude, much hand labor being necessary. As before stated, the fact that labor in Italy costs only one-third as much as in California is the chief reason why California has not produced a larger amount of citrus oils. After the pulp has been removed from the halved lemons and pressed for citrate, the peels are soaked in cold water for a few hours to increase the turgidity of the cells. They By-Pwduris 1^35 are then taken by men who press out the oil entirely })y hand. The pressers sit on low stools with a small lipped bowl between their feet. Across the top of the bowl rests a strong notched stick which supports a large sponge. Each half lemon is placed against the sponge and given three or four sharp squeezes, using almost the entire weight of the body. The oil spurting out of the peel is caught by the sponge and drips through it into the bowl below. From time to time the bowl is raised and the oil is blown off by the breath into a graduated glass receptacle, the lip retaining the small amount of water and residue. After the oil is filtered through a paper filter it is ready for market. In Calabria a crude machine is used in which is a bowl lined with sharp metal points. The fruit is placed w^hole in this bowl and revolved, the points puncturing the peel, from which the oil drips through an opening in the bottom of the bowl. This device is called an ecuelle, and is used chiefly in the making of bergamot oil, for the reason that bergamot oranges are round in shape and revolve to better advantage in the machine. Some few operators lacerate the rinds of lemons or oranges and distill the oil, but the use of this method results in water white oil of very inferior grade. A large amount of oil of limes is made in the West Indies. The oil is extracted from whole fruit by hand in ecuelle pans, the pulp being later pressed and the juice concentrated by evaporation and sold as lime juice to be used as a drink. Unfermented orange juice. — *' A very palatable and attractive beverage can be made from oranges. The chief difficulty is the mechanical one of rapidly and eco- 336 Citrus Fruits nomically separating the juice from the solid parts of the fruit. The juice can easily be made perfectly and per- manently clear by settling and filtration. Sulfurous acid in very small amounts (4 ounces potassium metabisulfite to 100 gallons of juice, an amount well below the Hmit allowed by law) is necessary to prevent fermentation and the production of a bitter taste during settling. The cleared juice keeps perfectly after bottling if pasteurized at 180° F., which does not injure the flavor perceptibly. Good oranges will yield over 130 gallons per ton; frozen oranges a much less amount." ^ Orange oil, for which there is a good demand, may be extracted from the skins of the oranges used in the manu- facture of juice. Orange vinegar. — A good quality of vinegar may be manufactured from the juice of cull oranges which are well matured and have a total sugar content of 10 per cent or more. Cruess ^ has shown that orange juice con- taining 11 per cent will, on fermentation, give about 5,5 per cent of alcohol, and that this on conversion into acetic acid will yield about 5.5 per cent of acid, which is consid- erably over the legal limit of 4 per cent of acetic acid. Inasmuch as many samples of orange juice may be expected to contain 9 per cent or less of total sugars, it is apparent that the resulting vinegar will closely approach or even fall below the legal limit unless considerable care be used in the selection of the raw material as well as in the fermentation process. iW. V. Cruess, "Utilization of Waste Oranges," Calif. Exp. Sta., Bull. No. 244, 1914. ^ Ibid., p. 164. By-Products :\:\7 Orange wine. — Most of the so-called orange wines found on the markets are made from orange juice flavored with orange oil, fortified by the addition of alcohol or brandy, and sweetened by the addition of sugar or sirup. Such liquids, of course, have no right to be called orange wine. An agreeable pure orange wine can be made by the use of proper methods. Such methods consist in ** defecating the fresh juice after the addition of moderate amounts of potassium metabisulfite to prevent fermentation for a short time, fermenting the clear juice with pure yeast, and filtering the finished wine to clear it. This cleared wine may be turned into sparkling orange wine by the addition of a small amount of sugar and by subsequent fermentation in bottles." ^ Candied citron. — Most of the citron consumed ill the United States comes from the Mediterranean region and especially from the Island of Corsica. The chief reason why citron is not more largely produced in California is the difference in the cost of labor. Citron is admitted to the United States from Corsica duty free when it is shipped pickled in brine or ordinary sea water. Practically all imported citron is candied in this country. There is one firm now engaged in the growing and processing of citron near Riverside, California. The fruit as it first begins to assume a bright yellow color is picked and placed in brine for a month or longer, the brine being renewed occasionally. Sometimes tender young leaves of the citron tree are soaked with the fruit to deepen the green color. The fruit is then boiled in fresh water to remove the salt and soften it. It is then 1 Ihid., p. 170. 338 Citrus Fruits halved, the pulp and seed scooped out, and immersed m cold fresh water to intensify the greenish color. After this it is covered with hot sugar sirup and allowed to stand three or four weeks, during which time the strength of the sirup is gradually increased. The fruit is then put into boilers with crystallized sugar sirup and cooked ; then allowed to cool, more sugar is added, and it is cooked again until it will take up no more sugar. It is then dried and packed in wooden boxes, each piece being coated with white sugar crystals and wrapped in tissue paper. Oil of neroli. — This product is made chiefly in the vicin- ity of Grasse in the PVench Riviera. Neroli is made by distilling the flowers of the bitter or bigarade orange, known in California as sour-stock. Both oil and water pass through the still ; and as they condense the oil col- lects on the surface, is skimmed off, and sells for a very high price (from $20 to $50 a pound). Three hundred pounds of flowers are required to make one pound of neroli. The water which distills over absorbs some perfume from the oil and is sold as eau de fleur d'oranges, bringing about twenty-five cents a gallon. Petit grain oil. — This oil is used in perfumery and is prepared by distilling the young and tender leaves and shoots of both bitter and sweet oranges. It sells for from two to five dollars a pound. A large part of the petit grain oil now comes from Paraguay, where orange trees have run wild and occur in forests over a large area. Tincture of orange flowers. — This is a perfume which is prepared by steeping the fresh flowers in alcohol until all the perfume has been absorbed by the alcohol. Essence of orange flowers. — This perfume is produced Ihi-Produrts XW) ill large quantities in Europe and imported into tins country. Apparently there is no reason, except the hij^li cost of labor, to account for the lack of production in the United States. As orange trees produce many times the number of flowers that are needed for setting a crop, and most of them fall off normally, the preparation of essence need not hinder fruit bearing. The making of the per- fume is a simple matter, and the preparation of a small supply for home use might furnish a pleasing pastime for young people living among orange groves. In the early morning orange blossoms are collected as soon as the petals begin to fall, by shaking the tree over a sheet spread on the ground. A tree yields from two to ten pounds of flowers. The perfume is generally extracted by enfleurage. Shal- low trays containing layers of fresh blossoms are slipped into the grooved sides of a large air tight box. The box is filled with trays, but between each two trays is inserted a sheet of w^ire gauze or linen holding a thin layer of wax or mixed grease. The odor of the flowers is absorbed by the grease, the flowers being replaced by fresh ones every morning for a month, when the grease, or " pomade " as it is called, is collected and treated with alcohol for a month. The odor leaves the grease and passes to the alcohol, which is then known as essence of orange flowers. Dried and candied peel. — Both orange and lemon peel are in good demand, both candied and dried. When dried, the peel is simply removed from the pulp, cut into thin shreds, and dried in the sun. When candied, the process is very similar to that used for citron, and the orange and lemon peels are not shredded, but left in halves. Lime juice. — Large quantities of limes are grown on the 340 Citrus Fruits islands of the West Indies. The green limes are harvested and shipped to market in barrels, turning yellow on the way. The ripe fruit which falls to the ground is gathered up and converted into several different by-products, such as citric acid, lime oil, and lime juice. In making raw lime juice which is to be used as a beverage, only clean, sound fruit is used. The juice is expressed by passing the fruit be- tween heavy granite rollers. The juice is allowed to stand until the mucilage or albuminous matter is thrown down, after which it is filtered and bottled. If the fruit used is clean and sound, the raw juice should keep without any preservative being added. Lime juice cordial is made by mixing the raw juice with various brandies and other ingredients. Orange paste. — A large amount of orange paste is used by confectioners. It is made by grinding and macerating fresh orange peels, and after the addition of an equal weight of sugar evaporating down into hard cakes which are broken up and packed in wooden buckets. This or- ange paste is one of the few citrus by-products which is already being manufactured in California. Crystallized baby oranges. — The small green oranges which drop from the trees during June and known as the "June drop " may be gathered and made into a pleasing confection known as crystallized baby oranges. Fruits between one-half and one inch in diameter are best and should be gathered frequently and not allowed to wilt on the ground. The fruits are placed in brine, gradually in- creasing the strength until fermentation is prevented. They may remain in brine indefinitely, provided the brine is changed occasionally. When ready for processing, the I By-Prod nets- 341 fruits are boiled in several ehanu i Tliis sliowed that mot- tled-leaf is not trans- mitted l)y l)nddin*;-. In 1910 R. R. Snow- den ^ advanced tlie. theory that mottled- leaf was dne to an ex- cess of magnesia or an improper ratio be- tween magnesia and lime in the soil. Snowden showed that the soils of some healthy groves aver- aged about 2.5 parts of lime to 1 of mag- nesia, while the soils from sickly groves averaged 1.18 of lime to 1 of magnesia. This theory was much dis- cussed at the time, but subsequent study brought to light so many exceptions to the supposed rule that the theory was greatly weakened. Heavy ap- plications of lime moreover ha\'e by no means proved a cure for the disease. Fig. 132. — Advanced stage of mottled- leaf disease showing formation of mul- tiple buds. California Cultivator, Aug. 11, 1910. 378 Citrus Fruits Some prominent citrus growers have held that starvation or a lack of humus in the soil is the cause of the trouble. In answer to this it may be said that some of the worst affected groves in the state are situated on apparently ideal soil and are among those best fertilized and otherwise well cared for. Mottled-leaf is much more prevalent on sandy and gravelly soils than on heavy adobe soils. In orchards where a certain area or streak of mottled-leaf runs through the orchard this usually corresponds to an area where the subsoil differs much from the top soil, usually being more coarse and open. This has led Smith ^ to conclude that " the most prevalent and typical form of mottled-leaf is due to an irregular supply of moisture and plant food." In 1912 J. R. Hodges, an horticultural inspector at Covina, California, noticed nematode worms in the soil near the roots of trees suffering from mottled-leaf. He advanced the theory ^ that the disease was caused by these nematodes. The matter was further investigated at the University of California Pathological Laboratory at Whittier where it was discovered that the nematodes were actually parasitic on the roots. E. E. Thomas of the laboratory staff published a preliminary report ^ on the distribution of nema- todes in the state and the possible relation between the worms and the disease. The nematode theory was by far the most plausible of any offered up to that time and at once attracted the attention of many scientists to the problem, which was now attacked from an entirely new angle. The name with a description of this nematode worm is given in Chapter XXIV. Several years will be required for the definite working out ^ R. E. Smith, Cal Sta. Bull. No. 218, p. 1139. 2 Cal. State Com. Hort. Mo. Bull, Vol. II, No. 6, p. 555. 2 University of Cal. Agr. Exp. Sta. Cir., No. 85, February, 1913. Dweaacs and their (\)ntr()l ^)79 of the relation between nematodes and mottled-leaf. Mean- while a great deal of survey work is being done. The theory is still held in abeyance on account of the fact that the worms are not always found on the roots of mottled trees and they are occasionally found in small numbers oil the roots of apparently healthy trees. Experiments are now being carried on with potted trees in sterilized soil which has been inocu- lated with the nematodes. In May, 1914, Kellerman and Wright ^ published the theory that mottled-leaf was commonly caused by nitrogen starva- tion following the plowing under of mature straw rather than a green cover-crop. It was explained that the mature straw contained large amounts of cellulose and that the molds and bacteria which decomposed the cellulose in the soil used up the available nitrate- nitrogen present in the soil. They suggested further that in maintaining the humus of citrus soils, green, succulent materials be used rather than mature or dry straws. While this theory appears to be borne out by greenhouse experiments it is considered inadequate to ac- count for any large proportion of the mottled-leaf disease in California. Perhaps the most plausible theory yet offered is that recently published by Chas. B. Lipman.^ It is explained that a poor nitrifying power on the part of the soil, with the ammonifying power remaining normal, may result in the change of practically all the nitrates in the soil to ammonia compounds. It is further shown that while some plants, such as rice for example, prefer their nitrogen in the form of ammonia compounds, that such compounds are actually 1 Jour. Agr. Research, Vol. II, No. 2, pp. 101-113. 2 "The Poor Nitrifying Power of Soils a Possible Cause of Die-Back in Lemons." Science, n. s.. Vol. XXXIX, No. 1011, May 15, 1914. 380 Citrus Fruits poisonous to citrus trees, which show a decided preference for nitrates. With the condition in the soil favoring slow nitrification and rapid ammonification the trees are forced to take ammonia compounds or go without nitrogen entirely, as in many California soils the ammonia resulting from the decomposition of organic matter is actually set free in the air and lost entirely. Experiments are now being performed in the hope of finding a practicable method of treating orchard soils which may accelerate nitrification and at the same time retard ammonification. Fig. 133. — Spot on old lemon leaf due to wither-tip. Wither-tip (Colletotrichum gloeosporioides) This disease is said to be quite common in Florida and especially on limes in Cuba, causing a spotting of the old fruit and leaves, killing back the twigs, and causing the young newly set fruit to drop off.^ In California, however, it ap- 1 A recent investigation at the University of California has shown that in Cuba and Florida, two distinct diseases have been confused. The kiUing and deforming of young foliage and fruits of the lime are due to a fungus which somewhat resembles Colleto- trichum glceosporioides but is entirely distinct from it. This Diseases and their Control 381 pears to he of little practical importance, for although the fungus has long been present in abundance throughout the citrus growing areas, it very rarely attacks healthy trees as an active parasite. On senile leaves or young leaves weakened by fires, frost, fumigation, or otherwise, it causes dead spots, on the surface of which may be seen the minute black fruiting bodies of the fungus. The fungus occurs also on twigs weakened from any of the above mentioned causes. Trees suffering from gum-disease, foot-rot, gopher injury, alkali, or from other troubles, often show an abundant growth of wither-tip. Spraying with bordeaux mixture will reduce the amount of the fungus, but perhaps a more logical procedure would be to remove the causes of weakness and promote a healthy and disease-resistant growth. In certain rare cases, especially in very wet, cold weather and near the coast, it is possible of course that this fungus may occasion- ally act as a true parasite, in which case spraying with bordeaux mixture is a simple remedy. Certain very small red or salmon colored spots which sometimes occur on lemons in Ventura County have been found to be due to this fungus. It may be added that chiefly on account of its common name, "wither-tip," orchardists are very apt to refer to a large number of their tree troubles as wither-tip which are in no way attributable to CoUetotrichum gloeosporioides. new fungus has been called Gloeosporium limetticolum. It causes a very injurious disease of limes and may attack lemons under artificial conditions but has not been known to do so under natural field conditions. Oranges and pomelos are not attacked. Extremely warm and humid atmospheric conditions are neces- sary for the development of the fungus, and it is not known to occur in California. See Clausen, R. E., "A New Fungus Concerned in Wither-Tip of Varieties of Citrus Medica," Phyto- pathology II, 6, 217, December, 1912. 382 Citrus Fruits When lemons which have been grown in the warmer sec- tions are stored for a long time they finally break down with a soft rot at the center known in the packing-houses as " old age decay" or "core rot." The general exterior appearance of the lemons may be normal, but when pressed between the fingers they collapse. This decay is not yet clearly under- stood but is probably due primarily to the wither-tip fungus, which usually kills the buttons after they have been weakened by age. Later, as the fruit ages and becomes less resistant to encroaching organisms, a species of Alternaria penetrates the fruit by way of the dead button, following and turning brown the central core of pith and also the fibrovascular bundles as they radiate through the spongy tissue of the rind. The juice vesicles seem to be the last to be affected. After the vascular system is broken down the lemons lose their elasticity and appear dead to the touch. Fruit in such a condition should not be shipped, as it has very poor carrying qualities and decays very quickly when exposed for sale in warm weather. The chief remedy for this trouble is to avoid allowing the fruit to ripen on the trees, and to store in houses where the temperature may be accurately controlled. When the buttons succumb to wither- tip the fruit should be closely watched and hurried to market at the first indication that the fungus is entering the fruit. Twig blight (Sclcrotinia libertiniana) All kinds of citrus trees sometimes exhibit a sudden withering and dying of small twigs and occasional branches up to one inch in diameter. The green leaves suddenly wither and remain attached to the twig, which dies from the point of infection outward, and with its dead leaves shows very prominently in the green foliage of the tree as though it had been broken and remained hanging. At the point Diseases and their Control 383 of infection a few (lr()])s of ^nnn usna.lly form. During rainy weather the sclerotia (small black bodies a little larger than a grain of wheat) will often be formed on the outside of the bark near the point of infection. Sclerotia rarely form in hot, dry weather. Apparently, infection can only occur by spores finding lodgment in abrasions of the bark. While the spores of this fungus are very plentiful in southern California, often causing serious losses in the packing-houses, yet for reasons not at present understood, blighting of the twigs is so rare as to cause but little damage. While the casual observer may notice a blighted twig here and there in almost any orchard either of oranges or lemons, it has never been reported as doing sufficient damage to the trees to w^arrant remedial measures. This trouble is very often mistaken for wither-tip. As a matter of course all blighted branches should be removed when the frees are pruned. This fungus has also been found on the bark and roots of old trees. The bark is decayed and, when dried out, comes away in fibrous shreds very characteristic of this fungus. Remedial measures for this form of the disease have not been worked out. Meanwhile the treatment advised is to cut away all diseased tissue and paint the wound thoroughly with bordeaux paste. Cottony mold {Sclerotinia libertiniana) The same fungus described above develops not only on citrus twigs but upon the vetch used as a cover-crop and on orchard soils. The sclerotia which form on the twigs and on the vetch finally dry and fall to the ground. The following rainy season, after being thoroughly moistened they give rise to small funnel-shaped toadstool-like bodies w^hich produce the spores of the fungus in great quantities. These spores apparently require an abrasion in order to germinate and 384 Citrus Fruits grow in the fruit. Once the fungus has begun growth in a lemon its progress is rapid. A large amount of white Fig. 134. — A " nest" of cottony fungus. cotton-like mycelium is produced in which the characteristic black sclerotia are formed. An important point to bear in Diseases and their Control 385 mind is the fact tliat while the spores of the fundus require an abrasion for inoculation, the white mycelium is abun- dantly able to grow into and infect a perfectly sound lemon at any point. The decay is often very serious in stored lemons, the fungus spreading rapidly in all directions from the lemon originally infected. Unless discovered and re- moved in time cottony mold often destroys an entire half- box or even a whole stack of stored lemons. For this reason packing-house men are always on the watch for "nests" of the cottony fungus, carefully removing the source of infection as soon as discovered, and disinfect- ing the contaminated boxes with very strong bluestone solution. The disinfecting solution used in the wash-water against brown rot does not kill the thicker walled spores of this fungus ; in fact, bluestone solution of sufficient strength to kill the spores would produce serious spotting of the lemons. Preventive measures must therefore be taken in the orchard when the lemons are picked. It is suggested that the lug- boxes be placed on bare ground or at least not left standing for days in the vetch where the spores of the fungus are pro- duced. Empty boxes so placed may easily become dusted with spores, and inasmuch as it is the custom in many houses to submerge the full lug-boxes in the wash-water as the lemons are gently emptied, the spores are readily transferred to the water. The cut surface of the stem of the lemon where it was severed from the tree affords ample opportunity for spore infection in the washing-tank. Cottony mold is most severe on lemons and occurs sporadi- cally, being worse in certain sections and in certain years. It may be wise to temporarily discontinue the use of vetch as a cover-crop in orchards where cottony mold has become well established. 2c 386 Citrus Fruits Brown rot fruit decay (Pythiacystis citrophthora) It has been shown that this fungus causes gum-disease of the tree. It also causes a serious decay of the fruit. The fungus hves normally in the soil even at considerable depths. It comes to the surface during wet weather in winter and produces spores on the surface of the ground, especially in damp, shady places, such as under citrus trees. The spores are motile and can swim around in a thin film of water. The drip from the tree splashes these spores upon fruit hang- ing within two or three feet of the ground. The spores enter the stomata or breathing pores, germinate, and grow within the fruit, producing a soft, watery decay which has a peculiar brown color and a characteristic odor. All citrus fruits are affected, but lemons are especially susceptible. During wet winters, the losses from this cause are often very great. The decay spreads rapidly in the packing-house as the mycelium is able to infect perfectly sound fruit by con- tact. If not discovered and removed, the decay starting from one lemon may run through an entire box or a stack of boxes in storage, and, in a short time, reduce the whole to a watery mass. Fortunately a simple and very effective remedy is now in use in all packing-houses. The spores of the fungus being very thin walled are extremely susceptible to copper sulfate, and in order to free any packing-house of this pest it is only necessary to add bluestone to the wash-water. The common practice is to add Ij pounds of bluestone to each 1000 gallons of water in the morning and then fortify this with an addi- tional pound at noon after considerable fresh water has entered the tank. As bluestone attacks metal, wooden or cement tanks should })e used. Some prefer metal tanks coated with asphaltum. Should the wash-water contain Diseases and their Control 387 alkali the hluestono may \)v neutralized, and in such cases a chemist should be employed to study the water and advise as to the proper procedure to keep the solution of hluestone as near as possible at a strength of -^-jj of one per cent. In order to reduce to a minimum the loss of lemons on the trees it is advisable to keep the branches pruned up some- what from the ground, and summer cultivation should extend well under the trees. It has been found well worth while also to spray the ground under the trees each fall before the rains begin with bordeaux mixture, as this largely pre- vents the fungus from fruiting at the surface of the ground. Blue mold {PcniciUium iialicum) and green mold (P. digitatum) Most of the decay of citrus fruit is due to blue and green molds. Being only very slightly parasitic on uninjured fruit, the decay is practically confined, under ordinary conditions, to fruit which has been injured in handling. The spores of these fungi are very common in the air everywhere and are almost sure to get into any slight abrasion of the skin of fruit. They produce a soft rot while the fungi fruit abundantly over the surface, the spores appearing as a blue or a greenish powder according to which species is present. Frequently the two kinds occur together, although the green is the most universal. For all practical purposes these two species of penicillium may be treated as one. About the only difference is the color of the spores and the fact that in pure culture the blue mold shows a wider band of white exposed mycelium between the fruiting area and the sound skin. The universal preventive for these decays is careful handling of the fruit in field and packing-house, which, if conscientiously enforced, will reduce the losses to a minimum. 388 Citrus Fruits Gray mold (Botrytis vulgaris) Occasionally lemons while in storage will develop what is known as gray mold. It appears as a dark brown discolora- tion and softening which is followed by the mycelium which appears at the surface and produces gray or mouse- colored spores. The fungus is apparently dependent on abrasions for access to the fruit and would no doubt be much more abundant were it not for the fact that the blue and green molds usually monopolize such opportunities for development. Black rot of Navel orange (Altcrnaria citri) Navel oranges only are subject to black rot which may be recognized by the premature ripening, abnormally large size, and very deep red color. The affected fruits are very conspicuous on the trees before the main crop has col- ored up. The spores of the fungus gain entrance at the navel end through slight imperfections of the peel or per- haps through the stigma of the blos- som, and produce a black, decayed area under the skin. This decay does not immediately spread through the entire Fig. 135. — Black rot of Navel. Diseases and their Control 3S0 fruit, hut remains for weeks as a small l)laek mass of fun^nis. Decayed tissue may occasionally extend to the surface, hut more often this is not the case and the fruit finds its way into the hands of the consumer. There is no known remedy for this trouble which occa- sionally affects as much as one per cent of the crop in certain localities. It is suggested, however, that all affected fruits should be gathered up and burned in order to reduce the num- ber of spores in the orchards. Brown spot of Navel orange The brow^n spot of the Navel orange may be described as occurring irregularly over the surface of the orange. From one to fifty or more spots may develop on a single fruit. The spots vary in size from a mere point to one inch in diameter, averaging about one-fourth inch. In outline they seem to follow no rule and may be quite irregular, although the cir- cular spot is most common. The color of the spot varies in different localities from a pale brown, which attracts little notice, to almost black, in which case the good appearance of the fruit is ruined. The eating qualities of spotted oranges are not injured in the least. The color of the spot seems to be lighter near the coast and darker in the interior valleys. Losses from brown spot have been heaviest from the upper San Gabriel and Santa Ana valleys, because in these regions the spotting is more common and the color changes to a darker brown. On the other hand, the fruit from many of the pack- ing-houses near the coast shows brown spots of such a pale tint as to attract no notice on the market. The spots are darker on early picked fruit, and it seems to be true that if the fruit is left on the trees until very late it will not spot at all. The spots are slightly sunken on account of the fact that the surface cells have collapsed. The dead and col- 390 Citrus Fruits lapsed tissue extends from the surfiice to ahout one-fourth the thickness of the rind. No spots are visible while the fruit is on the trees and as a rule the spots are not noticeable till from 15 to 25 days after picking. On this account it is not possible to grade against this spot in the packing-houses, unless storage houses of sufficient capacity are built to hold the pickings of three or four weeks. The brown spot has been observed so far chiefly on the Wash- ington Navel orange, and dealers have com- plained of it only on this variety. In 1914 the writer received specimens of Valencia oranges from Highland which had been picked about the first of June which showed almost typical brown spot. The color was lighter and less damaging than usually occurs on the Navel. Spotting is uniformly worse on fancy, smooth, thin-skinned fruit. The fruit which grades highest as it comes from the orchard always spots much more than the rough fruit, which often remains exempt. Examination of the spots with a hand lens fails to show any abrasion or opening in the epidermis. Orange packers have been complaining of the brown spot for only four or five years, but it is probable that it has existed, though varying in severity, as long as the Navel orange has been cultivated in California. Fig. 13G. — Brown spot of Navel orange. Difieasefi and their (Umtrol 1^91 Up to the present time neither the primary cause nor a remedy has been discovered. After an extended investiga- tion the writer was led to conclude ^ "That the direct cause of brown spot is the oxidation of the protoplasm by enzymes which occur in the protoplasm itself but which arc prevented from acting as long as the orange is joined to the tree and receiving water and certain nutritive substances from the tree. Thus the resistance of the protoplasm to enzyme en- croachments gradually grows less from the time the orange is picked." This conclusion merely takes the real question one step farther back, for the practical citrus men will, of course, wish to know the primary causes which bring about such premature death. This question cannot be answered at the present time. Damping-off (Rhizoctonia sp. and Fusarium sp.) Citrus seed-beds are often seriously injured by damp-off fungi. The very young plants begin to die in spots which, rapidly extending, involve large areas if not checked. Two forms of the disease are recognizable, one caused by the Rhizoctonia which kills the stem just above the ground, while the other shows itself in dead spots on the stem at any point. These troubles should be prevented by strict attention to proper methods of planting and watering. No manure or freshly decaying organic matter should be applied to the seed-bed, commerciarfertilizers being used exclusively. The seed should be covered with a layer of clean, fresh sand which will prevent the surface from becoming too wet. For the inexperienced grower, particularly, it is better to make wide furrows, two inches deep, about a foot apart, planting the seed broadcast on the ridges between. The water may then ' "The Brown Spot of the Navel Orange," Proc. Soc. for Hort. Sci., 1900. 392 Citrus Fruits be run in these furrows and allowed to soak into the ground laterally, thus keeping the surface of the sand dry. Where the seed is sown broadcast over the whole surface of the bed and the water applied by sprinkling, watering should always be done on sunny mornings and no oftener than is absolutely necessary. In most cases a good watering once a week is sufficient to keep the soil under the sand sufficiently moist. Should the seedlings begin to damp off in spite of all precau- tions, it is advisable to allow the bed to go as dry as is reason- ably safe, and then spray the surface of the bed with a rather weak bordeaux mixture, being careful to wet the entire surface of the soil. Citrus Canker Very recently a new disease has appeared in the Gulf States which is described as the most serious which affects the pomelo. Sweet oranges are apparently immune. It exists in Florida and Alabama, the first specimens being collected in 1912. So far it has not been reported from California. H. E. Stevens describes the trouble as follows:^ "The disease appears as small, circular spots, from less than one- sixteenth to one-quarter of an inch across. They may occur singly, or several together may form an irregular area. They are raised above the surrounding tissue, are light brown, and composed of a spongy mass of dead cells covered by a thin (white to grayish) membrane that finally ruptures and turns outward, forming a ragged margin around the spot. The general appearance of the spots is much the same whether they are found on the leaves, fruit, or twigs. The older spots often become overgrown with saprophytic fungi, and may be pink or black on account of secondary infection by species of Fusarium or Cladosporium. 1 "Citrus Canker." H. E. Stevens, Florida Exp. Sta. Bull. No. 122, 1914. Diteaseff and their Control ')93 "The infections on the leaves aj)pear first as small watery bulging dots, which are usually of a darker green than the surrounding tissue. They may appear on either surface of the leaf, but do not penetrate through the leaf tissue at this stage. The spots gradually increase in size, change to a light brown color, and become visible on both sides of the leaf. The spot may project from the surface on one or both sides of the leaf. Each spot is surrounded by a narrow yel- lowish band or zone. Later the surface of the spot becomes white to grayish, and finally ruptures, exposing a light-brown spongy central mass. "The spots on the fruit are similar to those on the leaves. They project from the surface and retain a circular outline. They do not penetrate far into the rind, and may be scattered singly over the surface, or several may occur together, forming irregular masses. "The spots on the older twigs are more prominent and usually larger and more irregular in shape. They show the same spongy tissue and the same color as those on the leaves. On growth more than a year old, the spots assume a cankerous appearance and the membrane covering the surface disap- pears. The spots do not penetrate to the wood, but are con- fined to the outer tissues of the bark. "The organism causing the disease has not been deter- mined, but it is probably a fungus. Several different fungi have been found associated with the spots, among which a species of Phyllosticta ^ occurs most frequently. This fungus is suspected of being the cause of the trouble, and experi- ments are now in progress to determine this. "The disease is infectious, as is show^n by the results of some experiments in which it was transferred from diseased material to healthy leaves and shoots of grapefruit." ^ Later found to be a species of Phoma. See Wolf and Massey, Circular 27, Alabama Experiment Station. 394 Citrus Fruits Control measures have not yet been fully worked out. On account of the presence of this fungus, the state of Florida is now quarantined against the introduction of nursery stock or bud-wood from Alabama. Melanose and Stem End Rot (Phomopsis citri) These diseases, which are both caused by the same fungus, have been prevalent in Florida for many years. The fungus occurs in Australia, Jamaica, Porto Rico, and Algeria, but so far has not been found to exist in California. The disease lives normally and produces spores on dead twigs in citrus trees. The spores are washed by the rains over the surface of the fruit, causing, particularly on pomelos, peculiar brownish streaks known as tear-staining or melanose. These marks are nearly the same on leaves, stems, and fruit, and consist of raised areas of brown gum-filled cells forming dots, lines, rings, or irregular spots which greatly injure the general appearance of the fruit while not injuring the eating quality. Stem-end rot causes the fruit to drop, beginning with im- mature fruit in August and continuing till after the fruit has been sent to market. It even causes decay after the fruit has reached market. The softening begins at the stem end and is especially common on fruits which have scale insects about the stem end. It is more severe during a warm fall and winter, and infection seems to be more common in damp shady situations. Sound picked fruit can be infected by contact with diseased fruit. The fungus inhabits the soil under infected trees and the spores develop in spring and summer on dead twigs, bark, and on mummified fruits. The application of fungicides to the trees or disinfectants to the wash-water does not control the disease. The most successful method of control is to keep the trees carefully Diseases and fhrir Control 395 pnmed and free from all dead twips, stubs, and mummified fruits. The prunings should not he plowed into the soil, l)ut should be removed from th(^ orchard and burned before the fungus has time to grow and produce spores upon this ma- terial. All diseased fruit which falls to the ground should be collected and destroyed. Careful culling at the packing- house and refrigeration in transit are aids to control. Also it is advisable to keep the trees as free as possible from scale insects. Nail-head Rust {Cladosporium herbarum var. citricolum) In Florida the nail-head rust is quite common, while it has not as yet been found in California. It is often called scaly- bark in Florida, but it is very distinct from the California scaly-bark, the cause of which has not yet been discovered. The disease appears on the twigs and small branches as slightly raised rusty spots, as implied by the name. The fungus also produces spots on the fruits which are hard, cir- cular, sunken, and more or less corky. Affected fruits color and drop prematurely. The spots due to this fungus are found only on sweet oranges. Various control measures have been suggested, such as top-working the trees to pome- los ; heading back and spraying with bordeaux, followed by an insecticide ; and carefully pruning out all dead wood. Scab or Verrucosis {Cladosporium citri) Citrus scab is another disease which occurs in Florida and other parts of the world but has not so far been found in California. The following description of scab is from the Florida Experiment Station Bulletin No. 108, page 41. "This disease, which is especially common on sour oranges and lemons, makes its appearance on the fruit as irregular 396 Citrus Fruits light brown or corky projections from the surface. It is caused by a fungus which attacks the fruit or leaves when quite young. Its attack on sour oranges and lemons (and sometimes on Satsumas and grapefruit) often results in making them misshapen and unsightly. In severe attacks, projections of a dark gray to corky or even tan color will be seen extending out from the surface. The surface of the fruit between the warts is usually of a normal color. Often these irregular corky projections coalesce to form a large raised corky scab. In less severe attacks, especially when scab occurs on grapefruit and on tangerines (or rarely on sweet oranges), the warty irregular projections are wanting, and there will be seen more or less raised platform-like patches variable in shape and extent. The surface of the raised portion is finely scabbed or lightly scurf ed, as is seen in the case of thrips marks or silver scurf. In this milder form it can usually be distinguished from thrips marks or other forms of scurf by its being raised, but can be distin- guished with certainty only by the use of the compound microscope. " The scab can be completely controlled by the use of weak bordeaux mixture (3-3-50). Since (in Florida) the use of bordeaux on orange trees, however, kills the friendly fungi ^ and allows a rapid increase of scale insects or white-fly, this 1 It should be explained for the benefit of those not familiar with conditions in Florida that there are a number of kinds of fungi which prey as parasites upon the scale insects and white-fly larvae and are thus of very great benefit to the citrus growers. Some of these friendly fungi occur in India and other places, but so far none have been successfully established in California, where the air is too dry perhaps for their success. In spraying with bordeaux for fungus diseases in Florida, the killing off of these friendly fungi has to be considered, for an application of bordeaux usually must be followed by an insecticide on account of the great sudden increase of scale insects. Diseases and their Control .397 spray is not recommended except when it is absolutely neces- sary. When it must be resorted to, a good insecticide should be used as soon as the scale insects begin to increase rapidly. Some of the harm from increase of scale insects may be pre- vented by spraying the bordeaux as much as possible only on the fruit, and keeping the spray off of the larger limbs and the inside of the tree where the friendly fungi may be left alive." Diplodia Rot of Oranges (Diplodia natalensis) A form of fruit decay which occurs in Florida and South Africa but has not so far been reported from California. H. S. Fawcett gives the following description of it in Florida Exp. Sta. Bull. 108, p. 46 : " In the early stage this rot shows as a patch about the stem end similar to stem-end rot. The discoloration becomes darker as the decay proceeds, and appears as dark wide bands corresponding to the divisions between the segments. The fruit becomes black as the decay advances and very light in weight. The rot often advances quickly through to the 'blossom' end, and a patch of discoloration shows there before all the peel is involved. The Diplodia rot often starts also in thorn punctures or similar injuries. It is usually accompanied by the exudation of a small amount of thin gum, or a considerable amount of amber-colored sticky juice. This amber-colored juice less frequently accompanies the stem-end rot. Many of the characteristics of the two rots are so similar that for practical purposes they may be classed together. The citrus fruits are much more resistant to Diplodia rot than to stem-end rot. Diplodia rot appears to be less common on immature fruits on the tree, and the fungus causing it is less parasitic. The same methods of treatment given for stem-end rot hold good for the Diplodia rot." 398 Citrus Fruits Red Blotch of Lemon It is in stored fruit alone that red blotch develops. It is often called "red rot" by packing-house men but as it is apparently not due to any parasitic organism the latter name is misleading. It is characterized by the rind shrinking and turning to a dark color in large spots or blotches. The discoloration is usually limited to one side of the fruit and gradually changes from rusty bronze to dark red and finally to black. On cross section, affected fruit shows the discolora- tion about the seeds, the central core, and along the parti- tions, while the vesicles appear normal. The disease does not spread among the lemons by contact. It is unusual for red blotch to develop in large amount in any one house, although the losses in the aggregate are large. It has been suggested that red blotch may be caused by sunburn or overheating of the lemons on the tree, but so far neither the true cause nor a remedy has been demonstrated. Yellow Spottiiu/ of Oranges In all the interior valleys of southern and central California and in Arizona it is the usual thing for oranges of all varieties to develop small 1) right yellow spots before the oranges are mature. Often these spots are very conspicuous on account of the contrast with the green rind. Usually all the oranges on the exterior of the trees and especially those near the ground show the spots. When the fruit colors naturally there is no longer any contrast and the spots are no longer visible to any but an experienced eye. As these spots do not damage the fruit for eating or for sale but little interest has been shown in determining the cause. They are probably due to the bites of some small insect such as a leaf-hopper, many species of whicli are common in the orchards. At Dlsea.ws and their (^mlrol \\\)\) onr time it was tli()U*^'^*^ // 9/ S/ £/ d/ //- 0/ 6 8 I 9 S S 6 7 8 9 to II ■IB 13 14 IS 16 17 Z/- 91 SI ^1 €1 Zl II 01- 6 9- 9- S S € 7 8 9 10 It 12 13 14 IS 16 17 W)V)N*<^5^5!<55;$jotv s 6 -7 8 9 to -It -12 -13 -14 -ts -16 -17 Fig. 150. — Method of marking fumigating tent. (After Woglum.) lating the dosage for a tree was mostly guesswork, the operator gauging the size of the tree by eyesight and basing the dosage upon previous experience. Such methods sometimes produced fairly good results but in bisect Control by Fumigation 437 general the work was very irregular and j)()()r. The tents now in use are plainly marked, as shown in the accom- panying diagram, the measurements being marked in feet from the center of the tent. When the tent is enfolding a tree, the distance over it can readily be determined by adding the number that touches the ground on one side of the tree to the number that touches the ground on the opposite side. The two auxiliary lines are necessary, as in actual practice the middle line may not fall over the middle of the tree but to one side, and in such a case the line nearest the center is used for measurement. The two side lines may be either three or four feet from the middle line. Equipment of Tents For elevating the tents over the trees, either poles or derricks are used, the latter being necessary only for very tall trees. Fourteen- and sixteen-foot poles are most commonly used. One end is sharpened to prevent its slipping on the ground. To the other end is fastened a rope about three feet longer than the pole. Sometimes rings are attached to the edge of the tent, and these are slipped over the ends of the poles; it is usually more satisfactory, how^ever, to double-lap the edge of the tent over the ends and secure it firmly by a half-hitch of the pulling ropes. Generators Another part of the outfit is the set of earthen jars or containers called generators. These are made especially for the purpose, usually w ithout covers, and of tw^o gallon capacity. The tw^o gallon size is preferred, as it is large 438 Citrus Fruits enough to accommodate 20 ounces of cyanide in medium sized lumps without boihng over. When trees requiring more than this amount are to be fumigated, two or more generators may be used under one tent. Generators with lids are desirable as the lids not only aid in throwing the gas outward but prevent spattering of the acid on to the tent. Acid holes in tents cause serious leakage, reduce efficiency, and necessitate frequent and expensive patching. So far, however, no lids manufactured have proved entirely satisfactory. The most improved type of generator has the outside of the bottom flat as usual but the inside of the bottom is cup-shaped, with the depres- sion in the center. This is a great advantage when work- ing with very small trees as it assures a more thorough decomposition of the small quantity of cyanide used for each charge. Still another part of the fumigating outfit is the supply cart in which are carried the cyanide, sulfuric acid, water, scales for weighing the cyanide, graduated glass for meas- uring the acid and water, rubber gloves, dosage schedules, and lantern. There is on the market an excellent supply cart designed especially for this purpose which is highly desirable where funds will permit, although simpler and less expensive carts answer very well. Cyanide Potassium cyanide was used in all fumigation work until recently. Now, however, sodium cyanide is used exclu- sively for the reason that it is not only cheaper but will supply a larger amount of hydrocyanic acid gas. The Insect Control by Fumigation 439 cyanide should be kept dry in storage and exposed to the air as Httle as possible, since moisture decomposes it. Acid Sulfuric acid for fumigating should be about 66° Baume, which is approximately ninety-three per cent pure. It is sold either in iron drums containing about 2000 pounds or in glass carboys of about ten gallons capacity. On account of its corrosive action glass or earthenware containers are used for distributing the acid in the field. A replaceable copper or glass pipe fitted into the bottom of the container on the supply cart is con- nected with a rubber tube bearing a large pinch-cock for regulating the flow. Care must be used in handling the acid as it will quickly burn wherever it comes in contact with the skin ; for this reason, rubber gloves are advisable. It has been found that the 1-1 J-2 formula recom- mended by the Bureau of Entomology is most economical and produces a complete reaction. This formula calls for 1 fluid ounce of commercial sulfuric acid, I2 ounces (avoirdupois) 129 per cent sodium cyanide, and 2 fluid ounces of water. The w^ater is measured and placed in the generator first, then the acid is measured and poured into the water. Lastly, when everything is in readiness, the cyanide is weighed and placed in the solution, the operator quickly retreating and closing the tent. The addition of water to the acid is very important. It dilutes the acid and raises the temperature of the mixture, thus accelerating the evolution of gas. The by- product resulting from the reaction is sodium sulfate, 440 Citrus Fruits a solid. The water dissolves this solid as fast as it is formed and prevents it from forming a coating over the lumps of cyanide and retarding the reaction. If sufficient water is not used, the sulfate will solidify, thus '' freez- ing'' the residue, as it is called. This necessitates extra labor in emptying the generators. When concentrated acid is diluted with an equal amount or more of water, nearly pure hydrocyanic acid is given off. If the con- centrated acid is used without water another gas known as carbon monoxide is formed. The cyanide should always be used in lumps about the size of a hen's egg. If finely powdered cyanide is used, the reaction is too violent and endangers the operators. If the cyanide should be dissolved in water before the acid is added, the reaction will be so violent as to be classed as an explosion, greatly endangering the operators and injuring tents and trees. Paper bags are no longer used for depositing the cyanide in the generators. . Cakes of compressed cyanide weighing one ounce each are now on the market, and have proven very satisfactory and convenient. Under proper conditions the evolution of gas will have been completed in about five minutes. Operation An orchard requiring fumigation should be thoroughly examined regarding the slope of the land, length of tree rows, convenience to water supply, smoothness of the ground over which the supply cart is to be drawn, and similar factors which influence the ease of operation. A tent and a generator are unloaded at each tree and the Tiisect Control by Fumigation 441 tents unfolded on the side away from tlie direction in which they are to be moved. Commencing at one end of the row, the tent pullers fasten the two poles to the edge of the tent in the manner previously described, place the sharpened ends of the poles on the ground at the sides of the tree opposite the trunk, and holding the bottom of the pole to the ground with one foot, pull on the rope. When the poles are so elevated that they no longer slip, each puller moves away from the bottom of the pole and out from the tree so that the continued pulling will bring the edge of the tent over the tree and down on the other side. When thus covered, the edge of the tent should be kicked in so that it hangs evenly all around and does not inclose unnecessary space. After the tree has been fumigated the required length of time, the tent can be pulled over on to the next tree by this same process with- out lowering it entirely to the ground. The next step in the process is the calculation of the approximate space inclosed by the tent and the proper dosage to use. Schedules given on pages 450 to 453 indicate the proper dosages for the principal citrus in- sects which require treatment. Knowing the distance over the tree (found as previously directed) and the cir- cumference of the tent near the base, one will have no difficulty in using the tables. The number found at the in- tersection of the vertical and horizontal rows on the table indicates the number of ounces of cyanide to be used. With the ordinarv outfit of five men, the w^ork mav be distributed as follows : two men handle the tents, a third takes the measurements and calls them out to the men at the supply cart, who immediately consult the dosage Insect Coiifrol hi/ Finii.igftfio)} 443 table, weigh out the cyanide, and nu^asure the sulfuric acid and water into the generator. While the cyanide man lifts th(^ edge of the tent, the other places the generator underneath. I'he former then puts in the cyanide and drops the tent. While the chemi- cal men are thus applying the proper dosage to one tree, measurements are being made on the next and the process is repeated until the entire row is fumigated. Fumigation gangs are usually equipped to handle about thirty tents at a ''throw," as they call it. When kept busy these 30 tents are "thrown" or moved once in every forty-five minutes or once every hour as the variety of scale will determine. Thus, except with very large trees, the number of trees fumigated per night does not vary according to the size of the trees, the difference simply being a difference in the time the men have to rest between throws, as all must be left over the trees a stated period of time. As a rule fumigators, when the nights are favor- able, begin work about 5 p.m., and if the night is not too cool or a fog arises, will work till 6 a.m., giving a twelve- hour night if an hour is taken off at midnight for lunch and rest. Thus with twelve-hour nights and throws every hour, a gang operating 30 tents will fumigate about 3^ acres provided the trees are planted regularly twenty feet apart each Avay. Fumigating in short row^s, on contours, or in rough ground is slower, of course. 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X 1 c: 1 ~l Ol ~l OI ' Ol 1 S 1 Xj 1 1 1 1 X CO 1 cc (N 1 (M 1 C^l iS Ol f) 1 ~4 , Ol i O) 1 ^ c*^ 1 c^ Of 1 -^ 1 t C^) 1 C^ 1 (N 65 lo5 Im 1 c^ 1 1 ■* (M i (N CO 1 CO 1 CO (M 1 C^ 1 C^ t O) ! > K ■< u O !m a f) s ^ p <1 s rfl Ul m a HH -«! a U R & (J O o (JJ PLh ^ 448 • Citrus Fruits the condition of the tree and fruit. Most of the fumiga- tion in CaHfornia is carried on between the latter part of August and the middle of January, as during these months the black scale is most successfully reached and the fruit is large enough to escape the injury which sometimes occurs when it is young and tender. As previously men- tioned, fumigation is ordinarily done at night when the air is cool. Occasionally the work may be done on dark cool days, but day work is quite apt to result in burned foliage and fruit. Fumigation is not advisable when the temperature falls below 38° F. or rises above 65° F. as the operator runs some risk of injuring the trees if the work is done much outside these limits of temperature. Another natural factor which operates against successful work is a strong breeze, which may either hasten the escape of the gas from the tent or greatly injure the side of the tree on which the gas becomes densest. Cases of serious injury to trees which were said to have resulted from fumigation when the foliage was wet have been frequently reported. Careful experiments along this line, on the other hand, show that the presence of moisture on the trees can be fgnored so far as direct action of the gas is con- cerned. Due, however, to the fact that the tents become so heavy and retain so much more of the gas on a wet than on a dry night, it is advisable to stop fumigating after the foliage and tents become thoroughly damp. The insect pests against which fumigation is generally directed are the black, purple, red, yellow, and citricola scales. The susceptibility of these scales to the gas varies more or less, and accordingly several dosage schedules have been worked out. Experiments by Woglum in fumigating Insect Control by Fuinicjation 149 for the piir])le scale deinoiistrated that the best results were obtained by one and one-half ounces of potassium cyanide to every one hundred cubic feet of air space under the tent, the fumigation continuing for one hour, by the end of which practically all gas had escaped. This is designated as dosage schedule A and upon this the other schedules are based. The three-quarter schedule for 129 per cent sodium cyanide is the one almost univer- sally used at the present time. Dosages For the purple scale, dosage schedule No. f sodium cyanide should be used with an exposure of one hour. For red and yellow scales, dosage schedule No. f is recommended with an exposure of forty-five minutes to one hour. For black scale, the dosage varies. When the insects are in the young and tenderer stages, f of schedule A is sufficient, and it is during these stages that fumigation is advisable. Dosage schedules A for sodium cyanide and No. 110 per cent A are reproduced on pages 446, 447 and 444, 445 respectively. They have been tested out experimentally in actual field operations by Woglum. Copies of these schedules printed on cardboard may be secured from the U. S. D. A. Bureau of Entomology, or from dealers in fumigators' supplies. While using the dosage sched- ule in the orchard, it should be framed with a clear celluloid or glass cover, as otherwise it will soon become so worn and dirty as to be illegible. 2g 450 Citrus Fruits New Woodworth Dosage Table C. W. Woodworth has recently suggested a new way of calculating dosage which appears to have the advantage of -greater simplicity and accuracy. Dosage Table — Sodium Cyanide Relative Size Dose Purple Scale Dose Black Scale 64 ft. 40 oz. 20 oz. 61 ft. 46 oz. 18 oz. 58 ft. 32 oz. .16 oz. 55 ft. 28 oz. 14 oz. 52 ft. 24 oz. 12 oz. 50 ft. 20 oz. 10 oz. 47 ft. 18 oz. 9 oz. Minimum Dose 44 ft. 16 oz. 8 oz. 41 ft. 14 oz. 7 oz. Leakage 38 ft. 12 oz. 6 oz. .40% 36 ft. 10 oz. 5 oz. ' 33 ft. 9 oz. 4^ oz. 30 ft. 8 oz. 4 oz. .35 % 28 ft. 7 oz. 3^ oz. 26 ft. 6 oz. 3 oz. 24 ft. r 5 oz. 2ioz. .30% 21 ft. 4 oz. 2 oz. 19 ft. 3| oz. If oz. 16 ft. 3 oz. 1^ oz. .25% 21 oz. li oz. 2 oz. 1 oz. .20% 1| oz. I oz. 1 oz. h oz. .15% 5 oz. i oz. .10 % (Relative size equals distance over plus 1 for each 5 ft. difference between measurements.) of Insect Control hi/ Fuuiu/ation 451 In explanation of this new system Prof. Woodworth has submitted the following : " The possibility of adding to the distance over an amount dependent on the difi'erence between the two measurements which will indicate the proportionate size of a tent gives us what we may call the ' relative size ' of the tent. If the proportions of a tent remained constant, the difference over could then be taken as the relative size. Since the distance around ahvays equals or exceeds the distance over, we may select as standard a tent wath these tw^o measurements equal. The amount to be added to this to allow for wider and shorter tents is one-fifth of the difference between the two measurements. Thus a tent 20 X 30 w^ould have a relative size of 22, and should have a dose equal to that of a tent 22 X 22. *' The adoption of this plan of relative sizes makes it possible to present a table of dosage in a very simple form, and to make the adjustments for different degrees of leakage also very easy. '* In the foregoing table the first column gives the rela- tive sizes corresponding to the series of doses shown in the second and third columns suitable for tents having the average leakage of 25 per cent. '' The adjustment for leakage is equally simple. Oppo- site each per cent given in the table is the minimum dose. No matter how small the tree, if a tent leaks 40 per cent, the dose for purple scale should not be less than 12 oz. Indeed, it is unwise to attempt to fumigate wdth a tent of this degree of leakage except w^hen big enough to hold a sufficient body of gas without its being too concentrated at the time of generation for the safety of the tree." 452 Citrus Fruits Costs Cyanide costs by the ton about 22 cents a pound. Con- tract fumigators usually furnish the cyanide at 30 cents a pound, including the acid for generation. The sulfuric acid alone costs about 1 J cents a pound. Laborers receive pay by the hour. The rate is usually 35 cents an hour, while the foreman receives 50 cents an hour. Most trees fumigated require between five and eighteen ounces of cyanide. A supply cart completely equipped may be had for about S35. Two gallon generators cost about 45 cents each. Tents cost from S12 to $50 each, according to size. The thirty-six foot tent costs ready-made from S25 to S30 each. The cost of thirty 45-foot tents of special 7-ounce drill, together with the other equipment necessary to complete the outfit, will cost about $1400. Recently a fumigating machine has been invented which quickly generates the gas in a large metal drum by mixing a water solution of cyanide and acid. The gas is discharged directly into the tent through a four-inch hose. The use of this machine makes generators unnecessary and prevents all acid holes in the tents. It is now being widely experimented with. CHAPTER XXIV VARIOUS ORCHARD PESTS AND THEIR CONTROL There are several pests other than insects with which citrus growers are apt to have to deal. A knowledge of the habits of animals such as gophers and ground squirrels is necessary before intelligent methods of repression can be adopted. Recently the citrus root nematode has at- tracted much attention, and a rather detailed account of its habits and life history will no doubt prove of quite general interest. Citrus Nematode {Tylenchulus semipenetrans) As stated in Chapter XXI this worm has been suggested as the cause or one of the causes of mottled-leaf. On account of the popular interest in the nematode and the great diver- sity of opinions regarding it, space is given to a more or less detailed account. The data here presented has been largely condensed and adapted from Cobb.^ This citrus nematode was first noticed by J. R. Hodges of Covina, California, in 1912, and first mentioned in print by B. R. Jones.^ A preliminary report was later published by E. E. Thomas of the University of California. ^ N. A. Cobb, "Citrus-root Nematode," Journal of Agri- cultural Research, Vol. II, No. 3, June, 1914, pp. 217-230. ^ Los Angeles County Hort. Com. Bull. No. 1, 1913, pp. 72- 73. 453 454 Citrvs Fruits This species of nematode is found only on the roots of citrus trees although it occurs in all parts of the world where citrus trees have been grown for any length of time. The worms are very minute, being barely visible to the unaided eye. The males are smaller than the females and probably do not attack citrus roots. In fact, it is thought that the males do not take food while in the perfect stage. The eggs are large and thin shelled, and are deposited one at a time in batches of twelve to twenty or more, and are sometimes incased in gummy matter. The eggs hatch in a day or two into colorless larvae which make their way to the nearest citrus root to which the females attach themselves in more or less well defined groups. These groups are very quickly scattered along the fine fibrous feeding roots in enormous numbers. The effect is to sap the vitality of the tree and kill the feeding roots. The movements are slow and weak and the worms cannot migrate through the soil to any great distance. The females possess an oral spear with which they force the head end into the tissues of the root. That part of the body within the root enlarges somewhat so that it is impos- sible for them to withdraw. They remain fixed for the rest of their lives, although the exposed part of the body may be moved back and forth. The food consists of sap and pro- toplasmic cell contents. The entire life cycle occupies from six to eight weeks. A predaceous nematode of large size (Mononchus papil- latus) has been found to occur also in the soil about citrus roots. The Mononchus preys regularly upon the males and larvae of Tylenchulus, swallowing them whole. To what extent the Mononchus may be able to control the citrus nematode is not at present known. The citrus nematode affects the different stocks about I\//'/o//.s' Orrlutrd Prsfs (inrl their (^otifrof 455 (H]ua.lly. It has so far horn found in ahiindaiice on the sour, sweet, and trifoliate oranges and on pomelos. " There ean be no doubt that Tylenchulus semipenetrans is an injurious parasite. There is conclusive evidence that it kills the feedin^i: roots of citrus trees. The roots die either as a direct result of the attack of this parasite or of the attack of other organisms following in its wake ; in other words, the nematode is a primary cause of the death of the feeding roots. Many cases have come under observation in which it was apparent that, had it not been for the nematode, the roots would have remained in a healthy condition. The evidence along these lines is of the same character as that which is relied on in demonstrating injuries due to insects and other macroscopic parasites. " The extent of the damage which may properly be charged up against this parasite is a different matter, and it will be necessary" to collect evidence along this line for several years before a final statement can be made. Up to the present the data obtained indicate unquestionably that the investi- gations should be continued." The citrus nematode is very readily distributed from place to place on the roots of nursery stock, and this is especially true when the trees are balled for shipment. The question as to just how much importance to place upon inspection and quarantine in connection with this parasite cannot be an- swered at the present time. In order to be on the safe side it is well for buyers to specify that the trees be free from nematodes. Control measures such as injecting carbon bisulfide and lime water into the soil are being widely ex- perimented with, but so far without any very promising re- sults. Vaile^ has shown that nematodes are killed by sub- mersion in hot water at a temperature of 120° F. for ten 1 Annual Rpl. Ventura County Hart. Com., 1913, p. 10. 456 Citrus Fruits minutes. This treatment did not kill the roots entirely, al- though some of the fine feeding roots were injured. This is not considered important because when trees are trans- planted with bare roots they put out new feeding roots anyway. It is possible that some such method of treatment may soon be devised by which infested nursery stock may be freed from the pest. The Pocket Gopher (Geomys bursarius) Gophers often cause serious damage to citrus trees by girdling young trees at the surface of the ground and by chew- ing the bark from the crown roots of older trees. They are especially troublesome in orchards near alfalfa fields in sec- tions where open ditches are used for irrigation. Gophers will run for considerable distances over the surface of the ground at night, and entering an orchard without warning begin to dig their runways. The runs extend for long dis- tances underground and are vexatious nuisances when irri- gating. Gophers may be controlled both by poisoning and by trapping. In trapping use a small wire spring trap and set it delicately so it will spring easily. Then open the run under a recently made pile of fresh dirt and insert the trap, pushing it well back into the run. If the run goes both ways, put in two traps to make sure. Then close up the holes with grass or sod so that just a little light can enter. The gopher will soon notice the light, and in attempting to close the opening will be caught. It is well to attach a long string to the trap to prevent their being lost if pulled for some distance back into the hole. Any attempt to drown a gopher by turning irrigation w^ater into the hole will not succeed unless the entire surface of the ground can be flooded as is possible in alfalfa fields. Strychnine is probably the most effective and safest poison Various Orchard Pests- and fhrir Control 457 for <::(>ii(M'iil iiso. A sirup poisoiKMl with slrychniiic is very easily propjiivd jind will he found v(M*y efreetiv(\ It is made according to the following formula recommended by the U. S. Bureau of Biological Survey : " Dissolve an ounce of strychnia sulfate in a piut of boiling water. Add a pint of thick sugar sirup and stir thoroughly. The sirup is usually scented by adding a few drops of oil of anise, but this is not essential. If preserved in a closed vessel, the sirup will keep indefinitely." This quantity will poison about thirty pounds of shelled corn or grain, preferably corn. The grain should })e soaked in w^ater overnight and then soaked for several hours in the poisoned sirup. The dry strychnine may also be used by introducing a very small quantity on the point of a knife into carrots, beets, sweet potatoes, entire raisins, or prunes. Such poisoned bait is then placed carefully in the freshly open holes, or in the runways. There are many prepared gopher poisons on the market which may be pur- chased if one does not care to go to the trouble of mixing the strychnine as directed. The use of carbon bisulfide for killing gophers is recom- mended where the soil is moist and the burrows not too ex- tensive. In dry soil, the gas escapes too rapidly to make its use effective. The bisulfide may be poured over a bunch of cotton waste or other material and this pushed quickly- into the burrow, which should be closed at once. Since carbon bisulfide is highly inflammable a very common method of ap- plication is to ignite the cotton waste after it is placed in the burrows as deeply as possible ; the gases produced by ignition are poisonous and seem just as effective a killing agent as the liquid bisulfide. On account of the danger of explosion to the operator and the liability of starting grass fires, the use of bisulfide by ignition is not so advisable as by the former method. Special injectors for forcing the bisulfide 458 Citrus Fruits into the burrows are on the market and are more effective than the hand method. Recently a new method of attack has been discovered which is said to work well where only a few gophers have to be dealt with. An automobile is placed over the hole and a short hose attacked to the exhaust, the other end being inserted in the gopher hole and packed with moist soil. After turning an extra amount of lubricating oil into the cylinders for the purpose of making a smoky gas, the engine is started. If smoke is emitted from any hole in the vicinity it is promptly plugged. A few minutes of this treatment naturally pro- duces a condition fatal to the gopher. Ground Squirrels (CiteJJus bcecheyi) These animals overrun California, occurring by millions in the interior valleys, where they destroy large quantities of grain, almonds, and dried fruit. They may do great dam- age to citrus orchards and nurseries but, unlike the gopher, their depredations are largely confined to orchards situated near grain fields or brush land. Railroad embankments, canal banks, and roadsides are favorite places for squirrel burrows. The animals live mostly on grain, nuts, acorns, and weed seeds, but during the rainless summer and fall, when the green herbage dries up, they are apt to visit citrus trees and gnaw the bark. A few squirrels may quickly ruin a large number of trees when the young trees have just been planted out. Ground squirrels may be poisoned in the same way as gophers, poisoned barley or wheat being most commonly used for this purpose. Whole barley threshed but still retaining its rough outer husk will not be eaten by birds, so it should always be used in this form. The following formula and di- rections for preparing poisoned barley are suggested : l^arioiis Orchard Prfffs (tud their Control 459 Whole barley 20 pounds Vinegar H pints Strychnia sulfate 1 ounce Honey 1 pint Cyanide of potassium IJ ounces Eggs 1 dozen Pulverize the strychnine in the vinegar and see that it all dissolves. Dissolve the cyanide in a little water. Beat the eggs thoroughly. Mix all the ingredients together and stir well before adding to the barley. Stir at intervals during the next few hours and dry before using as it will mold if put away wet. Grain coated with poison is more effective than grain soaked in poison for the reason that much of the grain being gathered, carried into the burrows and stored for winter use is not immediately effective. When the grains are coated with poison, enough will be absorbed by the cheek pouches during transit to produce death. Another very effective poison during the dry season is halved ripe cull oranges, upon the cut surfaces of which strychnine has been smeared. i CHAPTER XXV BIBLIOGRAPHY OTHER BIBLIOGRAPHIES Waters, Carrie S. "Citrus Fruits and Their Culture," a Bibliog- raphy classified according to subjects. Published 1913 by San Bernardino Free Public Library. Ferrari, E. Extensive Bibliography of the Lemon. Bol. Abor. Ital. 5 (1909), pp. 145-80. Savastano, L., and Parrozzani, A. List of about Fifty Articles on Citrus in European Literature. Annals Royal Italian Ex- periment Station for Agr. and Fruit Culture, Vol. 1, 1911. Cook, A. J. "Bibliography of Citrus." In " California Citrus Cul- ture," Calif. State Com. Hort., 1913. Hume, H. H. "American Citrus Literature." In Chapter XIV, "Citrus Fruits and Their Culture," 1907. REFERENCES TO LITERATURE DEALING WITH PAR- TICULAR FRUITS Orange Growing in United States Craw, A. "Working Over Old Orange Trees." Pacific Rural Press, May 9, 1885. Garey, T. a. "Orange Culture in California." San Francisco, 1882. Jackson, J. R. "Notes on Oranges." Garden. Copied in U. S. D. A. Yearbook, 1887, p. 56. LuMMis, C. F. "Oranges 250 Years Ago." The Land of Sunshine, Vol. XVI, Feb., March, and April, 1902. 461 462 Bibliography Spalding, W. A. "The Orange, Its Culture in California." River- side, 1880. Skinner, L. B. "Orange Culture in Florida." Proc. Am. Pom. Soc. 1911, pp. 70-6. Whitney, J. P. "Educational Orange Growing." Sunset Maga- zine, Vol. 70, pp. 161-70, Aug. 1906. Wallace, T. C. "The Cultivation of Oranges." Pacific Rural Press, Oct. 24, 1908. Saunders, Wm. "Notes on Orange Culture." Rpt. of U. S. Dept. of Agr. 1886, p. 687. Hart, E. H. "The Orange." The American Fruit Culturist, 1908, p. 621. Onderdonk, Gilbert. "The Orange in Texas." Texas State Dept. Agr. Bui. 9, p. 7. Manville, a. H. "Practical Orange Culture." Jacksonville, Ashmead Bros., 1883. Powell, E. P. "The Orange, Another of our First Families." Independent, Vol. 60, p. 1089, May, 1906. Meyers, W. A. "How to Grow and Cultivate an Orange Grove in Louisiana." La. State Hort. Soc. Proc. 1906, p. 71. Brown, E. "Oranges in Northern California." Scientific Ameri- can, Vol. 88, pp. 138-9, Feb. 1903. [Carnes, E. K.] "Development of the Orange Industry in Cali- fornia." Natomas News, Vol. 3, No. 1, March, 1913. Horgan, H. V. "Growing Oranges under Tents." Country Californian, Vol. 1, pp. 717-19, 750, Dec. 1905. WiCKSON, E, J. "The Orange in Northern and Central California." San Francisco Chronicle, Jan. 1, 1903. Reprinted by State Board of Trade. Williamson, Robert. "Orange Growing in Central and Northern California." Pacific Rural Press, Vol. 39, p. 2, Jan. 4, 1890. Kinney, A. "The Orange, History, Analyses, Varieties." Pacific Rural Press, March 21, 1885, p. 282. Guinn, J. M. "From Cattle Range to Orange Grove." Pacific Monthly, Oct. 1910. Bibliography 463 MoREMEN, M. S. "Present Condition and Treatment of Orange Groves." Florida Agr. Exp. Sta. Bui. 33, 1896. Bennett, J. E. "Roofing ; Over Orange Orchards." Current Literature, Vol. 27, pp. 146-7, Feb. 1900. Orange Growing in Foreign Countries Ferrarius, J. B. "The Hesperides or About the Golden Apples. Their Culture and Use. In Four Books." Rome, 1646. Pye, Thomas. "History and Culture of the Orange." Dept. Agr., New South Wales, Bui. 1, 1890. Alderton, G. E. "Treatise and Handbook of Orange Culture in Auckland, New Zealand." Wellington, 1884. Moody, J. F. "The Cultivation of the Orange." Dept. of Agr., West Australia, Bui. 34, 1912. Trabut, L. V. "L'Oranger en Algerie." Direction de I'agriculture gouv. gen. Algerie, Bui. 44, 1908. Freeman, L. R. "The Orange in the West Indies." Pacific Rural Press, June 21, 28, and July 5, 1913. Bell, H. H. "Cultivation of Oranges in Dominica." Imp. Dept. of Agr., Barbados, Bui. 37, 1905. Abella, a. "Orange Culture in Montevideo." Min. Indus. (Uruguay) Insp. Nac. Gan. y Agr., Bol. 7 (1913), p. 48. [Anonymous.] "Orange Growing in Lower California." Pacific Rural Press, Nov. 22, 1884. Amoore, H. E. "Japanese Orange Growing." Pacific Rural Press, No. 19, 1887, p. 411. Orchard, P. W. "A Study of the Orange Districts of Spain." The Florida Grower, Oct. 11, 18, 25, 1913. Newcomer, E. J. "Oranges at Seville." Pacific Rural Press, June 7, 1913. Shamel, A. D. "Orange Growing in Brazil." Pacific Rural Press, Jan. 10, 1914, p. 41. Bertoni, G. T. "The Oranges of Paraguay." An. Rpt. Estacion Agron. de Puerto Bertoni Para 1911 y 1912, p. 195. 464 Bibliography Shepstone, H. J. ''Jaffa Orange Culture." World's Work (London), Vol. 17, pp. 199-203, Jan. 1911. EiSEN, G. "The Jaffa Orange in Egypt." Calif. Cultivator, Jan. 23, 1913, p. 100. [Anon.] "The Orange Industry of Palestine." Hacherouth, No. 20, 1913. Aaronsohn, a., and Soskin, S. "The Orange Groves of Jaffa." Tropenpflanzer, Vol. 6. Aaronsohn, A. "Jaffa Oranges in Palestine." U. S. D. A. Bureau Plant Industry, Bui. 180, 1910, p. 25. [Anon.] "An Orange Farm." South African Agr. Journ., Feb. 1913, p. 176. McIlwaine, R. "The Possibilities of Rhodesia as a Citrus Growing Country." Dept. Agr. Rhodesia, Bui. 2, Feb. 1908. Farmer, C. E. "Citrus Fruit Trees from Seed to Grove." Dept. Agr. Rhodesia, Bui. 153, Aug. 1913. "Citrus Fruits in Rhodesia." Dept. Agr. Rhodesia, Bui. 164, Dec. 1913. "Rhodesian Citrus Fruit." Dept. Agr. Rhodesia, Bui. 166, Dec. 1913. McIlwaine, R. "Some Citrus Growing Experiences in Rhodesia." Dept. Agr. Rhodesia, Bui. 182, June, 1914. Varieties Chapman, C. C. "Orange Varieties and Their Respective Merits." Rpt. 28th Calif. Fruit Growers Convention, 1903, p. 163. Saunders, Wm. "Washington Navel Orange, Its History and Pollen Production." U. S. D. A. Yearbook, 1887, p. 640. Van Deman, H. E. "History of the Washington Navel Orange." American Garden, June, 1888, p. 231. Hart, E. H. "History of the Various Navel Oranges under Culti- vation." Semi-Tropical Planter (San Diego), May, 1887. Van Deman, H. E. "The Navel Orange, Another Chapter in Its History." Semi-Tropical Planter, June, 1887. Bibliograpfi}/ 465 "Bahia or Washington Navel Orange." Rpt. U. S. Dept. Agr., 1886, p. 267. "History of the Washington Navel Orange." IJ. S. D. A. Year- book, 1887, p. 640. "History of the Introduction of the Washington Navel." Rural New Yorker, June, 1899. CoiT, J. Eliot. "The History of the Washington Navel or Bahia Orange." Calif. Cultivator, April 18, 1912. Chapman, C. C. "Introduction of the Australian Navel." History of Orange County, 1911, p. 74. Reasoner, p. W. "The Navel Oranges in Florida." American Garden, April, 1888, p. 135. Mills, J. W. "Origin of the Golden Nugget Navel Orange." Calif. State Bd. Hort. Rpt. 1902, p. 256. Taylor, W. A., and Gould, H. P. "The Thomson Orange." U. S. D. A. Yearbook, 1911, p. 436. Hume, H. H. "The Surprise Navel Orange." Proc. 29th Am. Pom. Soc. 1905, p. 169. Earle, S. F. "The Navel Orange in Cuba." Calif. Cultivator, Jan. 1, 1914. Saunders, Wm. "History of Hart's Late or Hart's Tardiff Orange." U. S. D. A. Yearbook, 1887, p. 640. [Anon.] "Origin of the Valencia Late Orange." Pacific Rural Press, Sept. 18, 1909, p. 180. Williams, P. F. "The Satsuma Orange." Alabama Exp. Sta. Bui. 157, 1911. Taber, G. L. "The Satsuma Orange." American Garden, 1890, p. 590. Saunders, Wm. "The Satsuma Orange." U. S. D. A. Yearbook, 1887, p. 638. McFarland, J. Horace. "The Satsuma Orange." American Garden, 1890, pp. 268, 590. Carney, J. L. "History of the Parson Brown Orange." Florida Grower, Oct. 4, 1913, p. 10. 2h 466 BibliograijJiy Webber, H. J. "The Rustic Citrange." U. S. D. A. Plant In- dustry Circular, 1907. Shinn, C. H. "The Japanese Oranges." Amierican Garden, 1890, p. 333. KoETHEN, E. L. "The Jaffa Orange in California." Calif. Cul- tivator, March 6, 1913. Hume, H. H. "Oneco Mandarin Orange." Proc. 28th Am. Pom. Soc. 1903, p. 248. Close, F. "The Sour Orange and its Product." Pacific Rural Press, Feb. 18, 1888, p. 149. Lelong, B. M. "Varieties of the Orange." Calif. State Bd. Hort. Rpt. 1888, p. 33. "Orange Varieties Popular in California." Pacific Rural Press, June 16, 1888, p. 521. [Anon.] "Thomson's Improved Navel Orange." Pacific Rural. Press, Vol. 41, p. 525, May 30, 1891. [Anon.] "Navel Oranges." Pacific Rural Press, April 14, 1883, p. 326. [Anon.] "The Lue Gim Gong Orange." Calif. Cultivator, June 5, 1913, p. 694. Van Deman, H. E. "Onshiu or Satsuma Orange." Pacific Rural Press, April 7, 1888, p. 317. [Anon.] "Onshiu, a Fine Japanese Orange." Pacific Rural Press, Feb. 12, 1887, p. 125. [Anon.] "Canton Hybrid Orange Better Than Onshiu." Pacific Rural Press, June 18, 1887, p. 538. [Anon.] "The Satsuma, a Fine Japanese Orange." Pacific Rural Press, Feb. 16, 1889, p. 152. Berger, H. "Oranges in Japan." Pacific Rural Press, Sept. 10, 1882, p. 206. Parsons, S. B. "The Sweet Seville Orange." U. S. D. A. Year- book, 1877, p. 565. [Anon.] "The Lue Gim Gong Orange." Proc. 32d Am. Pom. Soc. 1911, p. 172. Bibliography 467 Tayloh, W. a. "The Luc Gim Gong Orange." U. S. I). A. Year- book, 1<)13, p. 1()9. Breeding Oranges S\\ iNciLE, W, T. "Citrus TrifoHata in Relation to Citrus Culture." Proc. 32d Session Am. Pom. Soc. 1911, pp. 218-21. Smith, C. B. "Improving the Orange by Selection." 37th Calif. Fruit Grow. Convention, 1910, p. 100. Paine, C. R. "Variation in the Branches of the Navel Orange." Calif. Cultivator, July 6, 1911, p. 4. [Anon.] "Do Different Buds on the Same Orange Tree Produce Like Fruit? " Calif. Cultivator, March 13, 1913. Belling, J. "Polyembryony of the Orange." Florida Sta. Rpt. 1908, p. cix. Mills, J. W. "Improvement of the Orange." Rpt. Calif. State Bd. Hort. 1902, p. 255. Insects Affecting Oranges Hubbard, H, G. "Insects Affecting the Orange." U. S. D. A. Div. of Entomology, 1885. AsmiEAD, W. H. "Orange Insects." Jacksonville, Fla., 1880. Sasscer, E. R. "The Cork-colored Orange Tortricid." Journal Econ. Ent., June, 1911, p. 297. Gandara, Guillermo. "Enfermedades y Plagas Del Naranjo." Mexico. Sec. de Fomento. Callejon de Bettemitas, No. 8, 1910. JoNES,P. R.,andHoRTON,J. R. "The Orange Thrips." U. S. D. A. Bureau of Entomology, Bui. 99, part 1, 1911. QuAYLE, H. J. "The Orange Tortrix." Journal Econ. Ent., Oct. 1910, p. 401. Herrera, a. L. "The Morelos Orange Worm." Journal Econ. Ent. 1908, No. 3, pp. 169-74. [Anon,] "Trypeta Ludens in Mexico." Calif. State Hort. Com. 1905. MouLTON, Dudley. "The Orange Thrips." U. S. D. A. Bureau of Ent. Tech. Series, No. 12, part VII, 1909. 468 Bibliography CoMSTOCK, J. H. "The Angular-Winged Katydid On Orange." U. S. D. A. Rpt. Sec. of Agr. 1880, p. 249. Dew, J. A., and Wolf, F. A. "The Satsuma Orange, Its Insect Pests and Diseases." Bui. 1, Insecticide Dept. Van Antwerp's Seed Store, Mobile, Ala. Orange Diseases Reed, J. H. "Black Rot of the Navel Orange." Calif. Cultivator, Vol. XVII, No. 11, p. 160, 1901. Pierce, N. B. "Black Rot of Navel Orange." Calif. Cultivator, Vol. XVII, No. 12, p. 181, 1901. "Black Rot or Navel Rot of Orange." Bot. Gaz. Vol. 33 (1902), No. 3, pp. 234-5. Fawcett, H. S. "Black Rot of the Navel in Florida." Florida Exp. Sta. Rpt. 1911, p. Ix. Amundsen, E. O. "Black Rot of the Navel Orange." Calif. State Com. Hort. Monthly Bui., Vol. 2, No. 5, May, 1913. Fawcett, H. S. "Stem End Rot of the Oranges." Florida Exp. Sta. Rpt. 1911, 1912. "Diplodia Rot of Oranges." Florida Exp. Sta. Rpt. 1911. "Three Fungus Enemies of Orange Trees." Proc. Am. Pom. Soc. 1911, p. 190. "The Scaly Bark Disease of the Orange." Florida Exp. Sta. Rpt. 1907, p. xliii. "Orange Scab or Verrucosis." Florida Exp. Sta. Rpt. 1911. CuRTiss, A. H. "The Prevention of Orange Rust." Florida Exp. Sta. Bui. 2, 1888. Webber, H. J. "Sooty Mold of the Orange and Its Treatment." U. S. D. A. Div. Veg. Phys. & Path. Bui. 13, 1897. Powell, G. H. "The Decay of Oranges While in Transit from Cali- fornia." U. S. D. A. Plant Ind. Bui. 123, 1908. Smith, R. E. "The Soft Spot of Oranges." Bot. Gaz. Vol. 24 (1897), No. 2, pp. 103-4. Messenger, C. B. "Orange Dropping and Its Causes." Calif. Fruit Grower (1896), No. 19, pp. 450-1. Bibliography 409 Wehheu, II. -I. "Molanoso of tlic Orango." Florida Farmer and Fruit (Irower, 7 (LSIH)), p. 419. Underwood, L. M. "Diseases of the Orange in Florida." Journal of Mycology, Vol. VII, No. 1, Sept. 10, 1891, p. 63. ScRiBNEU, F. L. "Orange Leaf Scab." U. S. I). A. Rpt. 1886, p. 120. Smith, R. E. "Brown Spot of the Orange." Calif. Exp. Sta. Bui. 203, 1909, p. 47. CoiT, J. Eliot. "The Brown Spot of the Navel Orange." Proc. Soc. Hort. Sci. 1910, p. 62. Galloway, B. T. "Gum Disease or Foot-Rot of the Orange." U. S. D. A. Div. Bot. Bui. VIII, 1889, pp. 51^. Smith, R. E., and Smith, E. H. "Orange Diseases." In Calif, Sta. Bui. 218, 1911. The Lemon Holt, L. M, "Lemon Culture for Profit." Proc. Pom. Soc. of Southern Calif. 1892, p. 30. Powell, G. II. "The American Lemon Industry." U. S. D. A. Yearbook, 1907. Powell, G. H., and Chase, E. M. "Italian Lemons and Their By-Products." U. S. D. A. Plant Industry, Bui. 160, 1909. [Anon.] "History of the Lemon Rate Case." Calif. Cultivator, Aug. 29, 1912. Powell, G. H., and Wallschlaeger, F. O. "The California Lemon Industry." Citrus Protective League, Bui. 9, Jan. 1913. Powell, G. H. "The Italian Lemon Industry." Citrus Protective League Circular 10, Jan. 1913. [Anon.] "Cost of Producing Lemons in California." Citrus Protec- tive League, Brief of Facts Presented to Ways and Means Com- mittee of Congress. Jan. 20, 1913. Cheney, A. S. "The Lemon Industry in Sicily." U. S. Consular Rpt. 1908. Works, J. D. "The Tariff on Lemons." Speech in U. S. Senate, July 24, 1913. 470 Bibliography Garcelon, G. W. "Fifteen Years with the Lemon." Calif. State Board of Hort. Pamphlet, 1891. Newcomer, E. J. "Italian Lemon Culture." Calif. Cultivator, May 29, 1913. Kimball, F. A. "Lemon Culture and Lemon Curing." Rpt. Calif. State Bd. Hort. 1888. Conger, O. H. "Lemon Culture." Rpt. Calif. State Bd. Hort. 1889. Tenney, W.A. "Ventura Lemon Culture." Overland Monthly, Vol. 60, pp. 150-7, 1905. Ferrari, E. "Extensive Bibliography of the Lemon." Bol. Abor. Ital. 5 (1909), pp. 145-80. Lelong, B. M. "Varieties of the Lemon." Calif. State Bd. Hort. Rpt. 1888, p. 39. Kimball, F. A. "Lemon Culture." Proc. Am. Pom. Soc. 1897, pp. 95-9. Blanchard, N. W. "The Lemon and Its Treatment." Pacific Rural Press, Vol. 39, p. 378, 1890. Teague, C. C. "Curing and Shipping Lemons." Calif. Fruit Grower, July 11, 1903. Allen, W. J. "Curing the Lemon." Dept. Agr. New South Wales, Farme'rs' Bui. 47, 1912. Harwood, N. S. "Growing American Lemons." World's Work, Vol. 5, pp. 3315-22, April, 1903. Tylor, a. R. "Gray Mold of Lemons." Calif. Cultivator, Feb. 1, 1912. Smith, R. E., and Smith, E. H. "Brown Rot of the Lemon." Bot. Gaz. Vol. 42, pp. 215-21, Sept. 1906. Smith, R. E. "Brown Rot of the Lemon." Calif. Exp. Sta. Bui. 190, 1907. Fawcett, H. S. "Tear Staining of Lemons." Calif. Com. Hort. Monthly Bui., June, 1913, p. 560. "Two Fungi as Causal Agents in Gummosis of Lemon Trees in California." Calif. Com. Hort. Monthly Bui., Aug. 1913. Bibliography 471 "Treatment for Gummosis of Lemon Trees." Calif. Cultivator, July 24, 1913. Smith, C. O. "Black Pit of Lemon." Phytopathology, Vol. Ill, No. 6, Dec. 1913. Rolfs, P. H. "Lemon Scab." Florida Grower, June 6, 1914. The Lime Watts, Francis. "Lime Cultivation in the West Indies." Imp. Dept. Agr. for West Indies, Pamphlet No. 72, pp. 136, 1913. NiCHOLLS, H. A. A. "The Lime." In Chapter VI, "Text-Book of Tropical Agriculture." [Anon.] "The Lime Tree and Its Products." Nature, Vol. 79, p. 22, 1908. TiMEHRi. "The Lime Industry of Dominica." 1883. Tempany, H. a., and Jackson, T. "Lime Industry of Antigua." West Indian Bulletin, Vol. 12. [Anon.] "Feeding and Manurial Value of Lime Skins." Agricul- tural News, Vol. 11, p. 288. Ballou, H. a. "Notes on Lime Cultivation." West India Bui., Vol. 11, p. 93. Brooks, A. J. "Development of the West Indian Lime Fruit." West Indian Bui., Vol. 12, p. 506. Sands, W. N. "British West Indian Limes in New York." West Indian Bui., Vol. 11, p. 153. Jones, G. A. "The Keeping Qualities of Lime Juice." Agricul- tural News, Vol. 11, p. 180. Watts, F., and Jones, J. "Citrate of Lime and Concentrated Lime Juice." West Indian Bui., Vol. 9, p. 159. Mandarin Oranges Hume, H. H. "The Mandarin Orange Group." Florida Exp. Sta. Bui. 66, 1903. Shinn, C. H. "The Japanese Oranges." The American Garden, Vol. 11, pp. 333-6, June, 1890. 472 Bibliography Wester, P. J. "Mandarin Orange. The Situation in the Citrus Districts of Batangas." Phil. Agr. Rev., Vol. 6, pp. 125- 30, March, 1913. The Pomelo Lelong, B. M. " The Pomelo in California." Calif. State Bd. Hort. Rpt. 1894, p. 63. Baker, C. F. ''The Grapefruit in Southern California." Rpt. Proc. 39th Calif. Fruit Grow. Convention, 1911, p. 81. Hume, H. H. "Pomelos." Florida Exp. Sta. Bui. 58, 1901. Boyle, H. H. "Notes on Siamese Pomelos." Phil. Agr. Rev., Vol. VII, No. 2, Feb. 1914. Baker, C. F. "Siamese Seedless Pomelos." Am. Breeders Mag., Vol. IV, No. 4, Dec. 1913. [Anon.l "Siamese Seedless Grapefruit." U. S. Daily Consular and Trade Rpt., Aug. 28, 1911, p. 925. Harriss, H. "Grapefruit." Bui. Dept. Agr., Jamaica, n. s., Vol. 2, No. 6, Jan. 1913, p. 166. Boyle, H. H. "The World's Best Pomelo." Phil. Agr. Rev., Vol. 5, No. 11, Nov. 1912, p. 614. Ward, C. W. "The Grapefruit Game and How to Play It." Out- door World and Recreation, Vol. 48, No. 3, Feb. 1913. MoTT, J. "The Pomelo, Shaddock, or Grapefruit." American Garden, Vol. 11, p. 715, Dec. 1890. Morris, D. "Grapefruit and Shaddocks." Garden and Forest, Vol. 9, 1896, p. 163. Hume, H. H. "Anthracnose of the Pomelo." Florida Exp. Sta. Bui. 74, 1904. The Kumquat Hume, H. H. "The Kumquats." Florida Exp. Sta. Bui. 65, 1902. [Anon.] "Citrus Japonica." Pacific Rural Press, March 5, 1887, p. 205. Chapin, L. p. "Kumquats." Good Housekeeping, Vol. 52, pp. 479-81, April, 1911. i Bibliography ' 473 The Citron Ferrari, E. "History and Relationships of the Citron." Atti. R. 1st Incoragg. Napoli, G. ser. 7 (1909), p. 21. Contains a good bibliography of Citron. Richardson. "A Chapter on Citron." Pacific Rural Press, March 31, 1883, p. 284. Calhoun, J. J. "California Should Grow Citron." Orchard and Farm (San Francisco), April, 1913. [Anon.] "The Home of the Citron." Rural Californian, March, 1905, p. 91. [Anon.] "Citrous in Mogador." Gardeners' Chronicle, 1884, 2, p. 601. [Anon.] "Citron of Commerce." Pacific Rural Press, Vol. 39, p. 244, March 8, 1890. (Fruiting at Riverside.) [Anon.] "Citron." Pacific Rural Press, Vol. 40, p. 352, Oct. 25, 1890. Sturtevant, E. L. "Citron." Mem. Tor. Bot. Club, Vol. 1, No. 4, p. 158, 1890. [Anon.] "The Troon or Tabernacle Citron." Gardeners' Chronicle, Nov. 8, 1885, p. 601. WiCKSON, E. J. "Candied Citron." Pacific Rural Press, Nov. 2, 1907, p. 275. REFERENCES TO LITERATURE DEALING WITH THE CITRUS FRUITS IN GENERAL Miscellaneous References Ferrarius, J. B. "The Hesperides." 1646. Macfayden. "Citrus of Jamaica." In Hooker's Bot. Misc., Vol. 1, p. 295, 1830. Targioni, D. a. "Citrus Fruits." Journal Hort. Soc, London, Vol. 9, p. 171, 1855. 474 * Bibliography Gallesio. "History of the Citrus." English translation in appen- dix to "Orange Culture," by T. W. Moore. De Candolle, a. "Origin of the Citrus Fruits." In "Origin of Cultivated Plants." [Anon.] "Citrus Culture in Foreign Lands." U. S. D. A. Year- book, 1886, pp. 693-703. Simmons, P. L. "Products of the Orange Family." In "Tropical Agriculture," p. 438, 1877. White, W. N. "The Orange Family." In "Gardening for the South," New York, 1868. Hart, E. H. "Citrus Fruits." In Thomas' "American Fruit Culturist," various editions. Henderson, Peter. "Citrus." In "Handbook of Plants," New York, 1889. Klee, W. G. "Citrus Fruits." U. S. D. A. Div. Pom. Bui. 1, 1887. Davis, G. W. "A Treatise on the Culture of the Orange and Other Citrus Fruits." Jacksonville, Fla., 1881. Downing, A. J. "The Orange Family." In "Fruits and Fruit Trees of America," New York, 1849. GoFF, E. S. "Citrus Fruits." In "Lessons on Commercial Fruit Growing," Madison, Wis., 1902. Reasoner, p. W. "Orange, Pomelo, Lemon, etc." U. S. D. A. Div. Pom. Bui. 1,1887. Jones, J. W. "On the Culture of the Genus Citrus." Gardener's Chronicle, April 20, 1844. Bona VIA, E. "Oranges and Lemons of India." London. 2 vols. WiCKSON, E. J. "California Citrus Industry." Proc. 32d Meet- ing Am. Pom. Soc, 1911, pp. 245-54. RoEDiNG and Wood. "Citrus Fruits in California." Los Angeles, 1913. Cook, A. J. " California Citrus Culture." Calif, State Com. Hort. 1913. Call, A. F. "The Culture of Citrus Fruits." Calif. Cultivator, Feb. 5, 1914, and continued in subsequent numbers. Bibliography 475 BoYNTON, S. S. "Citrus Culture in Northern California." Pacific Rural Press, Vol. 41, p. 32, Jan. 10, 1890. Chubb, O. P. "The Future of California Citrus Fruit." Pacific Rural Press, April 28, 1888, p. 371. Holt, L. M. "The Future of Citrus Culture in California." Pacific Rural Press, June 2, 1888, p. 482. Holmes, E. W. "California Citrus Fruit Growing." Pacific Rural Press, March 31, 1883, p. 279. RuDisiLL, H. J. "Limits of Profitable Citrus Culture." Pacific Rural Press, Feb. 25, 1888, p. 159. CoiT, J. E., and Condit, I. J. "Citrus Fruits." The text for a series of 24 lessons given as a correspondence course by Univer- sity of California, Sept. 1913. Chapman, C. C. "The Citrus Industry in Orange County, Cali- fornia." In "History of Orange County," 1911, p. 71. Mills, J. W. "Citrus Fruit Culture." Calif. Exp. Sta. Bui. 138, 1902. Lelong, B. M. "Citrus Culture in California." Calif. State Bd. Hort. 1888. Lelong, B. M. "Culture of Citrus Fruits in California." Calif. State Bd. Hort. 1902. WiCKSON, E. J. "The Orange, Lemon, Lime, etc." In "Cali- fornia Fruits, and How to Grow Them," San Francisco, 1913. Wood, W. R. "Citrus Fruits in the San Joaquin Valley." Rural Californian, March, 1909, p. 80. Chapman, C. C. "Details of Citrus Culture." Calif. State Com. Hort. Monthly Bui., Vol. 2, Nos. 2 and 3, 1913. CoiT, J. E. "The University of California Citrus Experiment Station." Calif. State Com. Hort. Monthly BuL, Vol. 1, No. 9, p. 685, 1912. Whitney, J. D. "The Possibilities of the Central California Citrus Country." Pacific Rural Press, May 18, 1912, p. 461. CoiT, J. E. "Citrus Culture in the Arid Southwest." Arizona Exp. Sta. Bui. 58, 1908. 476 Bibliography Hume, H. H. "History of the Citrus in Florida." Rpt. Am. Pom. Soc. 1907, p. 128. "Citrus Fruits and their Culture." Jacksonville, Fla., 1904. "Cultivation of Citrus Groves." Florida Exp. Sta. Bui. 69, 1904. Harcourt, H. "Cultureof Citrus Fruits in Florida." In "Florida Fruits and How to Raise Them," Louisville, 1886. BusHWAY, R. H. "Citrus Culture in Texas." Proc. 32d Meeting Am. Pom. Soc. 1911, pp. 65-9. Potts, A. T. "Experiments on Citrus Fruits." Texas Exp. Sta. Bui. 148, 1912. Waschka, S. a. "Citrus Fruits, Report of Progress." Texas Exp. Sta. Bui. 118, Feb. 1909. Hume, H. H. "Citrus Fruits in Texas." Texas State Dept. Agr. Bui. 3, Nov. 1909. Rolfs, P. H. "Culture, Fertilization, and Frost Protection of Citrus Groves in the Gulf States." U. S. D. A. Farmers' Bui. 542, July 9, 1913. "Sites, Soils, and Varieties for Citrus Groves in the Gulf States." U. S. D. A. Farmers' Bui. 538, May, 1913. "Citrus Fruit Growing in the Gulf States." U. S. D. A. Farmers' Bui. 238, 1906. Swingle, W. T. "Hardy Citrus Fruits for the Cotton Belt." Georgia State Bd. Ent. Bui. 33, 1910. Stubbs, W. C, and Morgan, H. A. "The Orange and Other Citrus Fruits from Seed to Market." Louisiana Exp. Sta. Special Bui. 1893. HiGGiNS, J. E. "Citrus Fruits in Hawaii." Hawaii Exp. Sta. Bui. 9, 1905. Wester, P. J. "Citriculture in the Philippines." Phil. Bureau of Agr. Bui. 27, 1913. "The Situation in the Citrus District of Batangas." Phil. Agr. Review, Vol. 6, No. 3, March, 1913. KiNMAN, C. F. "Citrus Fruits in Porto Rico." Porto Rico Exp. Sta. Report, 1912, p. 23. Bibliography 477 "Report on Citrus Fruits in Porto Rico." Porto Rico Exp. Sta. Report, 1911. MiLLis, J. M. "Citrus Fruit Culture." Bui. Dept. Agr. Jamaica, 1903, pp. 161-8. Ikeda, T. "Citrus Fruits in Japan." In "Fruit Culture in Japan," p. 28. Georgeson, C. C. "Citrus Fruits of Japan." The Am. Garden, Vol. 12, No. 9, 1891. Cook, S. A. "Citrus Culture in Victoria." Journal Dept. Agr. Victoria^ 1913. Prescott, E. E. "Citrus Fruit Culture." Dept. Agr. Victoria, Bui. 7, 1911. "Citrus Fruit Culture." Journal Dept. Agr. Victoria, Vol. 9, pp. 371 and 515. Meyer, F. N. "Citrus Fruits in China." In Bulletin on plant explorations in China, U. S. D. A. Plant Industry Bui. 204, 1911. Sercy, C. de. "Nouveau Traite des Grangers et Citronniers." Paris, 1692. Alino, B. G. "Trabado Complete del Naranjo." Valencia, 1893. Maylin, a. "Manual Practico Para el Cultivo del Naranjo." Valencia, 1905. Palmer, G. L. "Citrus Culture in Sicily." Florida Grower, Nov. 15, 1913. May, D. W. "Shade in Citrus Culture." Porto Rico Hort. Soc. Rpt. 1912, p. 44. "Windbreaks for Citrus Fruits." Porto Rico Hort. Soc. Rpt. 1912, p. 36. Call, A. F. "Work Stock for Citrus Orchards." Calif. Culti- vator, Feb. 19, 1914. Trabut, "L'Oranger en Algerie." Gov. Gen. de L'Algerie, Bui. 44, 1908. 478 Bibliography Propagation, Stocks, Scions Wood, W. "Selection of Seed an Important Factor in Laying the Foundation for a Citrus Orchard." Rpt. 37th Cahf. Fruit Growers' Convention, 1910, p. 25. Webber, H. J. "The Reproduction of The Orange from Seed." Gardeners' Chronicle, Ser. 3, 19 (1896), Nos. 496 and 497. "Methods of Propagating the Orange and Other Citrus Fruits." U. S. D. A. Yearbook, 1896, p. 471. [Anon.] "Planting Citrus Seed." Rural Californian, June, 1910, p. 193. Morris, O. M. "Seed from Frozen Oranges Viable." Calif. Cul- tivator, Feb. 20, 1913, p. 234. Hendricksen, H. C. "Propagation and Marketing of Oranges in Porto Rico." Porto Rico Exp. Sta. Bui. 4, 1904. Austin, C. F. "Propagation of Citrus Fruits." Cuba Exp. Sta. Los Vegas, Circular 24, 1906. Lelong, B. M. "Propagation of Citrus Trees from Seed." Calif. State Bd. Hort. 1892. Baldridge, M. "Propagation of Orange Trees." Calif. State Bd. Hort. Rpt. 1888. [Anon.] "The Greatest Citrus Nursery in the World." Pacific Rural Press, May 11, 25, June 8, 1907. Swingle, W. T. "Inarching Young Hybrid Citrus Seedlings." Georgia State Bd. Ent. Bui. 33, p. 42. Robertson, G. R. "The Art of Budding Citrus." Calif. Cul- tivator, Aug. 24, 1911, p. 170. Teague, R. M. "Budding Citrus Trees." Calif. Cultivator, March 20, 1913. CoiT, J. E. "Pedigree versus an Official Seal for Citrus Nursery Stock." Calif. Cultivator, May 23, 1912, p. 644. KiZANO, M. "Effect of Stock on Color of Kumquats." U. S. D. A. Bureau Plant Ind. Bui. 207, p. 15, S. P. L No. 26568. Allen, W. J. "Effect of Stock on Valencias ' Turning Green Again," Agr. Gazette, New South Wales, May 2, 1911, p. 417. Bihiiof/raphy 479. Cook, S. A. "Citrus Root-stocks in Victoria." Journ. Dcpt. A^r. Victoria, 1913, Vol. XI, part 0. Swingle, W. T. "The Limitation of the Satsuma Orange to Tri- foliate Orange Stock." U. S. D. A. Bureau Plant Ind. Cir. 46, Dec. 1909. BoNNs, W. W. "Results of Experiments with Citrus Root-stocks." Calif. Cultivator, Dec. 25, 1913. Taber, G. L. "Citrus Trifoliata versus Sour Orange as a Stock." Exp. Sta. Record, Vol. XIV, p. 441, 1902. Cutter, J. E. "Citrus Stocks — Sour versus Sweet." Proc. Pom. Soc. South. Calif. 1892, p. 13. Van Deman, H. E. "Relative Merit of the Various Stocks for the Orange." U. S. D. A. Div. Pom. Bui. 4, 1891, p. 21. [Anon.] "Influence of Lemon Stock on Quality of Oranges." Calif. Cultivator, Feb. 23, 1911 and continued in subsequent numbers. Bernard, A. "Citrus Triptera as a Grafting Stock." Revue Horticole, Vol. 80, p. 140, 1908. Swingle, W. T. "Citrus Trifoliata in Relation to Citrus Culture." Proc. Am. Pom. Soc. 1911, p. 218. Wolf, F. A. "A Field Method for Distinguishing between Certain Orange Stocks." Alabama Exp. Sta. Circular 17, July, 1912. WiCKSON, E. J. "Citrus TrifoHata in California." Pacific Rural Press, June 20, 1907. Citrus Breeding Webber, H. J. "Complications in Citrus Hybridization caused by Polyembryony." Bot. Gaz. Vol. 29, 1900, p. 141. "New Citrus Fruit Creations of the Department of Agriculture." U. S. D. A. Yearbook, 1904, p. 221. "New Citrus and Pineapple Productions." U. S. D. A. Yearbook, 1906, p. 329. "Present Status of Citrus Breeding." Proc. Am. Pom. Soc. 1907, p. 5. Swingle, W. T. "Some New Citrus Fruits." Am. Breeders' Mag. Vol. IV, No. 2, 1913. 480 Bibliography Swingle, W. T. "Citrus Breeding Experiments." In article on Crop Improvement. U. S. D. A. Plant Ind. Circular 116, 1913. "Variation in First Generation Hybrids (Imperfect Dominance) : Its Possible Explanation through Zygotaxis." IV Confer- ence Internat. de Genetique, Paris, 1911, pp. 381-394. White, O. E, "Swingle on Variation in F 1 Citrus Hybrids and the Theory of Zygotaxis." Am. Nat., Vol. 48, No. 567, 1914. Shamel, a. D. "A Study of the Improvement of Citrus Fruits through Bud Selection." U. S. D. A. Plant Ind. Circular 77, 1911. "A Study of Bud Selection in Citrus Fruits." Proc. 39th. Calif. State Fruit Growers' Convention, 1911, p. 89. "Breeding Citrus Fruits." Calif. State Com. Hort. Monthly Bui. Vol. 1, No. 9, p. 441, 1912. "Good and Bad Oranges and Orange Trees." Pacific Rural Press, June 13 and 20, 1914. "Bud Selection in Citrus Fruits." Pacific Rural 'Press, Jan. 31, 1914. Vaile, R. S., and Reed, F. "Citrus Breeding Discussions." Calif. State Hort. Com. Monthly Bui. Vol. 1, No. 9, p. 479, 1912. Norton, J. H. "Variations in the Productivity of Citrus Trees." Calif. Cultivator, March 6, 1913. \yiCKSON, E. J. "Improvement of Citrus Fruit Varieties." Am. Breeders' Assoc. Rpt. 1907, Vol. 3, p. 271. Babcock, E. B. "The Improvement of Citrus Fruits." University of Calif. Journal of Agr. Vol. 1, No. 7, Feb. 1914. Vaile, R. S. "Improvement of Citrus Stock through Bud Selec- tion." Pomona Calif. Journ. Econ. Bot. Vol. 1, Sept. 1911. Kraus, E. J. "Bud Variation in Relation to Fruit Markings." Oregon Crop Pest and Hort. Rpt. 1913, p. 71. CoiT, J. E. "The Relation of Asexual or Bud Mutation to the Decadence of California Citrus Orchards." Proc. 37th Calif. State Fruit Growers' Convention, 1910, p. 32. CoiT, J. E. "Budding Wood." Calif. Cultivator, Apr. 25, 1912. Bibliography 481 Hartin, E. H. "The Ultimate Orange." Pacific Rural Press, Vol. 40, Aug. 16, 1890, p. 140. Barrett, O. W. "Natural Citrus Hybrids." Phil. Agr. Rev. Vol. 5, No. 6, p. 334, 1912. Emerson, R. A. "The Possible Origin of Mutations in Somatic Cells." Am. Nat. Vol. 47, p. 375, 1913. Savastano and Parrozzani. "Some Natural Hybrids of Citrus Fruits." Annals Royal Italian Station of Agr. and Fruit Culture, Vol. 1, 1911. Also contains a bibliography of European citrus literature. Savastano, L. "Nomadic Albinism in some Orange Trees." Annals Royal Italian Station Agr. and Fruit Culture, Vol. 1, 1911. Kerner and Oliver. "Citrus Bizzaria a Graft Hybrid." In " Nat. Hist, of Plants," Vol. 2, p. 569. Trabut, Dr. " L'Hybridation des Citrus: Une Nouvelle Tangerine 'La Clementine.'" Revue Horticole, 1902, p. 232. Andre, Ed. "Oranger Hybride de Montanbau." Revue Hor- ticole, 1905, p. 243. Citrus Soils and Root Systems Reed, J. H. "Penetration of Orange Tree Roots." Calif. Culti- vator, 14 (1900), No. 21, pp. 321-3. "Root Systems in the Orange Orchard as Affected by Irrigation, Cultivation, and Fertilization." Pacific Rural Press, 61 (1901), No. 1, pp. 4-5. LiPMAN, C. B. "Humus Discussion, Cover Crops." Calif. Culti- vator, Dec. 4, 1913. "Essentials in the Management of California Soils." Calif. Com. Hort. Monthly Bui. Vol. 3, No. 1, Jan. 1914. "The Use of Lime and Gypsum on California Soils." Calif. Exp. Sta. Circular 111, 1913. Call, A. F. "How to Handle Citrus Soils." Calif. Cultivator, Feb. 5, 1914. HiLGARD, E. W. "Acidity of the Root Sap of Citrus Trees." Calif. Exp. Sta. Rpt. 1895-97, pp. 181-3. 2i 482 Bibliography HiLGARD, E. W. "Marly Subsoils and the Chlorosis or Yellowing of Citrus Trees." Calif. Exp. Sta. Circular 27, 1906. "Hardpan and Cultivation." Calif. Exp. Sta. Report, 1898- 1901, p. 149. Chase, E. "Investigation of Citrus Subsoils." Proc. 37th Calif. State Fruit Growers' Convention, 1910, p. 61. LouGHRiDGE, R. H. "Alkali Tolerated by Oranges." Calif. Exp. Sta. Bui. 133, 1901, p. 17. Paine, C. R. "Soil Treatment in Citrus Orchards." Calif. Culti- vator, March 6, 1913. Bristol, W. M. "Sand on Heavy Citrus Soils." Calif. Culti- vator, March 6, 1913. Mills, J. W. "The Use of Dynamite in Orchard Planting." Calif. Cultivator, Nov. 20, 1913, p. 500. Irrigation LouGHRiDGE, R. H. "Distribution of Water in the Soil in Furrow Irrigation." U. S. D. A. Office Exp. Sta. Bui. 203, 1908. Etchevery, B. a. "The Selection and Cost of a Small Pumping Plant." Calif. Exp. Sta. Circular 117, 1914. "Irrigation and Cultivation of Orchards." Dept. Agr. British Columbia, Victoria, Bui. 44, 1912. WiCKSON, E. J. "The Water Needs of Citrus Trees." U. S. D. A. Farmers' Bui. 116, 1900. Tait, C. E. "Cost of Irrigating Citrus Fruits." Pacific Rural Press, June 3, 1911. "Irrigation of Citrus Orchards." U. S. D. A. Office Expt. Sta. Bui. 236, 1911. Kritzer, W. H. "Definitions and Equivalents for Irrigation and Hy- draulic Computations." Pacific Rural Press, July 27, 1912, p. 28. Adams, F. "Irrigation Resources of California and their UtiHza- tion." U. S. D. A. Office Exp. Sta. Bui. 254, 1913. Whitney, D. J. "Overhead Irrigation in the Citrus Grove." Pacific Rural Press, July 13, 1912. Bibliography 483 WoEHLKE, W. V. "The Water Savers." The Outlook (New York), March 25, 1910, Vol. 94, p. 659. WalIuAce, T. C. "Irrigating Oranges." Pacific Rural Press, Oct. 31, 1908, p. 276. Forbes, R. H. "Irrigating Citrus Trees in Alkali Soil." Arizona Exp. Sta. Bui. 44, 1902, p. 171. KoETHEN, E. L. "Irrigation, the Citrus Growers' Catechism." Pacific Fruit World, May 20, 1911, p. 4. Stanley, F. M. "Irrigation of Citrus Groves." Florida Grower, May 17, 1913. Fertilization HiLGARD, E. W. "Fertilizers for California Orange Trees." Pacific Rural Press, Nov. 7, 1908, p. 294. Webber, H. J. "Fertilization of the Soil as Affecting the Orange in Health and Disease." U. S. D. A. Yearbook, 1894, pp. 193-202. Colby, G. E. "Ingredients withdrawn from the Soil by Citrus Fruits." Exp. Sta. Record, Vol. 5, pp. 5-89. "Effect of Fertilizers on Fruit of Navel Oranges." Calif. Exp. Sta. Rpt. 1895, pp. 172-7. Floyd, B. F. "Problems in Citrus Nutrition." Florida Exp. Sta. Rpt. 1911. Wright, George. "Fertilizing Citrus Fruits." Calif. Cultivator, Oct. 30, 1913. Webber, H. J. "Fertilizer Experiments with Citrus Fruits." Calif. Cultivator, Dec. 11, 1913. Call, A. F. "Fertilizing California Citrus Orchards." Calif. Cultivator, Feb. 19, 1914, p. 228. Painter, E. O. " Fertilizers. for Citrus Fruits." Proc. 32d Session Am. Pom. Soc. 1911, pp. 54-9. MuRTADO, D. J. "Fertilizing Oranges in Spain." Calif. Culti- vator, Dec. 4, 1913. Chapman, A. C. "Fertilization of Orange Orchards." Calif. State Bd. Hort. Rpt. 1888, p. 150. 484 Bibliography Wallace, T. C. ''Fertilizing Orange Orchards." Pacific Rural Press, Nov. 7, 1908. Blair, A. W. "Experiments on Citrus Fertilization." Florida Exp. Sta. Rpt. 1911. WiCKSON, E. J. "Oranges and Potash." Pacific Rural Press, Nov. 20, 1909, p. 323. Hilgard, E. W. "Effect of Citrus Culls on Soil." Calif. Culti- vator, June 6, 1912. Robertson, G. R. "Citrus Culls as a Fertilizer." Calif. Culti- vator, June 15, 1911, p. 208. Cover-Crops and Green Manuring GoEZE, E. "Early Green Manuring of Oranges." Gardeners' Chronicle, July 27, 1867, p. 785. Davy, J. B. "Lupines for Green Manuring in California." Calif. Agr. Exp. Sta. Rpt. 1897-98, p. 203. McKee, R. "Orchard Green Manure Crops in California." U. S. D. A. Plant Ind. Bui. 190, 1910. Messenger, C. B. "Buckwheat for Humus." Calif. Cultivator, June 4, 1914, p. 680. Call, A. F. "Green Crops in the Citrus Orchard." Calif. Culti- vator, Feb. 12, 1914, p. 196. Waterbury, G. W. "Cover-Crops in Citrus Orchards." Calif. Cultivator, Jan. 15, 1914. Mertz, W. M. "Citrus Cover-Crops." Calif. Cultivator, Jan. 8, 1914, p. 36. Geraldson, G. "Green Manuring." Calif. Cultivator, Oct. 5, 1911, p. 314. LiPMAN, C. B. "Green Manuring in California." Calif. Exp. Sta. Circular 110, 1913. "The Function of Cover-Crops." Orchard and Farm (San Fran- cisco), Jan. 1914, p. 201. Adamson, J. E. " Cover-Crops for Citrus Fruit." Pacific Rural Press, Sept. 20, 1913. Bihliographii 485 Norton, J. H. "Citrus Cover-Oops," Calif. Cultivator, Jau. 27, 1910. KoETHEN, E. L. "The Best Citrus Cover-Crop." Pacific Fruit World, June 17, 1911. Whitney, D. J. "Advantages of Alfalfa in Orchards." Pacific Rural Press, Dec. 13, 1913. LiPMAN, C. B. "Citrus Cover-Crops." Proc. 39th Calif. State Fruit Growers' Convention, 1911, p. 124. Piper, C. V., and McKee, R. "Vetches." U. S. D. A. Farmers' Bui. 515, 1912. Varieties — Botany Swingle, W. T. "Eremocitrus, a New Genus of Hardy Drouth-Re- sistant Citrous Fruits from Australia." Journ. Agr. Research, Vol. 2, No. 2, May, 1914. Swingle, W. T., and Kellerman, Maude. "Citropsis, a New Tropical African Genus Allied to Citrus." Journ. Agr. Re- search, Vol. 1, No. 5, 1914. "Citrus Ichangensis, A Promising, Hardy New Species from Southwestern China and Assam." Journ. Agr. Research, Vol. 1, No. 1, Oct. 10, 1913. Parish, S. B. "Botanic View of the Orange." Proc. 37th Calif. Fruit Growers' Convention, 1910, p. 21. Andre, Ed. "Oranges Monstrueuses." Revue Horticole, 1900, p. 423. [Anon.] "Ringing Oranges." Scientific American, Dec. 14, 1912, p. 515. Cutter, J. E. "Varieties of Citrus Fruits." Calif. State Bd. Hort. Rpt. 1894, p. 250. Lelong, B. M. "New Varieties of Citrus Fruits." Calif. State Bd. Hort. 1891. [Anon.] "New Citrus Varieties." Pacific Rural Press, Vol. 41, p. 21, Jan. 10, 1891. 486 Bibliography Chcrnisfri/ — Judging Colby, G. E. "Analyses of California Oranges." Calif. Exp, Sta. Bui. 93, p. 6, 1891. "Analyses of California Oranges and Lemons." Calif. Exp. Sta. Rpt. 1893-94, pp. 240-56. "Comparison of Shipping Navel Oranges from Northern, Southern, and Middle California." Calif. Exp. Sta. Rpt. 1898-1901, p. 244. "Composition of Citrus Culls." Calif. Exp. Sta. Rpt. 1898, p. 259. PiCKELL, J. M., and Earle, J. J. "Analyses of Oranges." Florida Exp. Sta. Bui. 17, 1892. Collision, S. E. "Sugar and Acid in Oranges and Grapefruit." Florida Exp. Sta. Bui. 115, 1913. Henry, A. M. "The Chemical Composition of Florida Oranges." Florida Dept. Agr. Quar. Bui. Vol. 23, No. 2, April, 1913. Rose, R. E. "Immature Citrus Fruit." An. Rpt. Florida State Chemist, Dec. 31, 1913. "Report of Commission Appointed to prepare Immature Citrus Fruit Standard." Florida Dept. Agr. Quar. Bui. Vol. 22, No. 4, Oct. 1, 1912. "Analyses of 280 Samples of Oranges." Florida State Chemist, Aug. 15, 1912. "Immature Citrus Fruit : Laws, Rules, and Regulations." Pub- lished by state printer, Florida. Not dated. "When is an Orange Mature and Wholesome?" Address before Assoc. Am. Food, Drug and Dairy Officials, Portland, Maine, July 16, 1914. "Details of the Acid Test Law in Florida." Florida Grower, Sept. 13, 1913. "Florida Green Fruit Law in Detail." Florida Grower, Aug. 23, 1913. Bahadur, Rana. "Composition of Fibrous Part of Japanese Orange." Univ. Tokyo, Col. Agr. Bui. Vol. VII, No. 1, 1906. SouTHERST, W. F. "Sugar Content of Oranges." Calif. Culti- vator, May 18, 1911, p. 612. Bibliography 487 Bancroft, A. L. "Where is the Orange the Sweetest?" Pacific Rural Press, July 8, 1911, p. 25. Van Deman, H. E. "Judging Citrus Fruits." Proc. Am. Pom. Soc. 1889, p. 145. Hume, H. H. "Judging Citrus Fruits." Citrus Fruits and their Culture, p. 155, 1903. "Judging Citrus Fruits." Proc. 23d Session Am. Pom. Soc. 1891, pp. 152-6. Cutter, J. E. "Scale for Judging Citrus Fruits." Calif. State Com. Hort. Rpt. 1889, p. 365. [Anon.] "Judging Citrus Fruit." Rural Californian, Dec. 1910, p. 364. Shamel, a. D. "Rules for Judging Citrus Fruits." Calif. Culti- vator, May 15, 1913. (See also June 5, 1913, p. 694 for judging trees in the orchard.) [Anon.] "Citrus Standard Score Card." Pacific Rural Press, Jan. 10, 1914, p. 42. Pruning CoiT, J. E. "The Pruning of Citrus Trees." Calif. Cultivator, Oct. 21, 1913. Englehardt, J. p. "The Pruning of the Washington Navel Tree." Proc. 37th Calif. State Fruit Growers' Convention, 1910, p. 97. Paine, C. R. ''Pruning to Improve the Orange." Proc. 28th Calif. State Fruit Growers' Convention, 1903, p. 169. "Orange Pruning." Calif. Cultivator, Jan. 22, 1904, p. 75. "Renovation of the Orange Tree by Systematic Pruning." Proc. 37th Calif. State Fruit Growers' Convention, 1910, p. 28. "Pruning out the Australian Type." Calif. Cultivator, May 16, 1912. 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Vol. 1, No. 13, Dec. 1912, p. 937. "Citrus Scab." Monthly Bui. Calif. State Com. Hort. Vol. 1, No. 11, Oct. 1912, p. 833. "Two Fungi as Causal Agents in Gummosis of Lemon Trees in California." Monthly Bui. Calif. State Hort. Com. Vol. 2, No. 8, Aug. 1913. Smith, R. E. "Mottled-Leaf of Citrus Trees." CaHf. Cultivator, May 25, 1911. Thomas, E. E. "A Preliminary Report of a Nematode Observed on Citrus Roots and Its Possible Relation with the Mottled Appearance of Citrus Trees." Calif. Exp. Sta. Circular 85, Feb. 1913. Vaile, R. S. "Citrus Nematode." Annual Rpt. Ventura County Hort. Com. 1913. Cobb, N. A. "Citrus Root Nematode." Jour. Agr. Research, Vol. II, No. 3, June, 1914. Thomas, E. E. "The Nematode Worm on the Roots of Citrus Trees." Calif. Cultivator, July 9, 1914, p. 28. Kellerman, K. F., and Wright, R. C. "Relation of Bacterial Transformations of Soil Nitrogen to Nutrition of Citrus Plants," Journ. Agr. Research, Vol. 2, No. 2, May, 1914. I Bihlingraphji 501 (iiLK, P. L. "Relation of Calcareous Soils to Pineapple Chlorosis." Porto Rico Exp. Sta. Hul. 11, 1911. Floyd, B. F. "Frenching, Yellow Spotting, Die-Back, and Melanose of Citrus." Fla. Exp. Sta. Rpt. 1910. "Yellow Spotting of Citrus Groves." Fla. Exp. Sta. R[)t. 1909. HiLGARD, E. W. "Marley Subsoils and the Chlorosis or Yellowing of Citrus Trees." Calif. Exp. Sta. Circular 27, 1906. CoiT, J. E. "Mottled-Leaf of Citrus not Spread by Budding." Calif. Cultivator, Jan. 18, 1912, p. 68. Snowden, R. R. "Magnesia-Lime Chlorosis of Citrus Trees." Calif. Cultivator, Aug. 11, 1910. LiPMAN, C. B. "Chlorosis of Citrus Trees and the Physical Condi- tion of the Soil." Calif. Cultivator, June 1, 1911. "Poor Nitrifying Power of Soils a Possible Cause of Mottled- Leaf and Die-Back of Lemons." Science, N. S. Vol. 39, No. 1011, pp. 728-730, May 15, 1914. CoiT, J. E. "Exanthema or Die-Back of Citrus Trees." Calif. Cultivator, March, 12, 1914. EssiG, O. E. "Exanthema or Die-Back of Citrus Trees." Pomona College Journal of Econ. Bot. Vol. 1, No. 2, May, 1911. Brittlebank, C. C. "Exanthema of Orange Trees in Australia." Journ. Agr. Victoria, July, 1912, p. 401. Tenny, L. S. and Hosford, G. W. "The Decay of Florida Oranges while in Transit and on the Market." U. S. D. A. Plant In- dustry Circular 19, 1908. Stevens, H. E. "Melanose and Stem End Rot." Florida Grower, Nov. 1, 1913. " Citrus Melanose." Fla. Exp. Sta. Rpt. 1912. Floyd, B. F. "Experiments with Citrus Die-Back." Fla. Exp. Sta. Rpt. 1912. "Melanose of Citrus." Fla. Exp. Sta. Rpt. 1911. Cobb, N. A. "Alternarias of Citrus." Dept. Agr. New South Wales, Misc. Pub. 666, 1904. 502 Bibliograj^hy Floyd, B. F., and Stevens, H. E. "Melanose and Stem End Rot." Florida Exp. Sta. Bui. Ill, 1912. Savastano, L. "Leforne teratoligiche del fiore e frutto degli Agrumi." Agricoltura Portici, Vol. IV, 1884. Grossenbacher, J. G. "Experiments on the Decay of Florida Oranges." U. S. D. A. Plant Ind. Circular 124, 1913. Hedges, F., and Tenney, L. S. "A Knot of Citrus Trees Caused by Sphaeropsis tumefaciens." U. S. D. A. Bureau Plant Ind. Bui. 247, 1912. Stevens, H. E. ''Citrus Canker." Fla. Exp. Sta. Bui. 122, March, 1914. Rolfs, Fawcett,' and Floyd. "Diseases of Citrus Fruits." Florida Exp. Sta. Bui. 108, 1911. Clausen, R. E. "A New Fungus Concerned with Wither-tip of Varieties of Citrus Medica." Phytopathology, Vol. 2, No. 6, Dec. 1912. Rolfs, P. H. "Wither-tip and other Diseases of Citrus Trees and Fruits." U. S. D. A. Plant Ind. Bui. 52, 1904. Cook, M. T., and Horne, W. T. "Wither-tip." Cuba (Santiago de Los Vegas) Bui. 9, 1908. Smith, R. E. "Wither-tip." Calif. Cultivator, July 27, 1911. Essig, E. O. "Wither-tip and Its Treatment." Calif. Cultivator, May 25, 1911. "Wither-tip of Citrus Trees." Pom. Col. Journ. Econ. Bot. Feb. 1911. Rolfs, P. H. "Fall Dropping of Citrus Fruits." Fla. Exp. Sta. Press, Bui. 60, Oct. 15, 1906. "Citrus Bloom Dropping." Fla. Exp. Sta. Press, Bui. 84, March 9, 1908. Floyd, B. F. "Experiments on Die-Back of Citrus." Fla. Exp. Sta. Rpt. 1909. ^ Home, W. T. "Root Rot of Citrus Trees." Proc. 37th Calif. Fruit Growers' Convention, 1910, p. 93. Rolfs, P. H., and Fawcett, H. S. " Fungus Diseases of Scale Jiihli(H/ I'd pill/ 50.S Inserts and White Fly." Florida Exp. Sta. Hul. !)l, 190S. CoiT, J. E. "Blemishes of Citrus Fruits." Proc. .'Wtli Calif. State Fruit Crowers' Convention, 1911, p. 22. Butler, O. " A Study on Gummosis of Citrus and Prunus, with Observations on Squamosis and Exanthema of Citrus." Annals of Botany, Vol. 25, No. 97, Jan. 191 1, p. 107. Cook, M. T. ''Diseases of Citrus Fruits." In "Diseases of Tropical Plants," pp. 116-30, 1913. INDEX ABrasions, how caused, 278. Absentee ownership, 356. Acid, contained in fruit, 63 ; sul- furic for fumigation, 439 ; loss of in respiration, 287. Acreage, citrus, in California by counties, 22 ; in California in- creasing, 354. Advertising, division of Exchange, 350, 351. Agents, bonded salesmen of Ex- change, 348. Air, importance of in soil, 165. Alfalfa, as interculture crop, 159 ; as a mulch, 173 ; as cover-crop, 182. Alignment, of fruit in box, 138. Alternaria, affecting stored lemons, 382. Alternaria citri, causing fruit decay, 388. Ammonia compounds, prejudicial to citrus trees, 372 ; as a cause of mottled-leaf, 379. Analyses of soils, 175. Antiquity of citrus fruits, use in Hebrew ceremonies, 40. Aphids, 427. Aphis gossypii, 427. Aramigus fulleri, 429. Arizona, citrus production in, 23. Armillaria mellea, 145, 373. Artesian wells, for irrigating, 192. Artificial coloring, by sweating, 284 ; federal legislation regard- ing, 285. Asher, J. M., 20. Asphaltum, paint for wounds, 227 ; in fuel oil, 260 ; for wash tanks, 386. Aspidiotus hederae, 420. Aspidiotus rapax, 420. Assessments, for expenses of Ex- change, 348. Associations, 345 ; affiliated with Exchange, 301 ; first organized, 8; organization of, 351. Atmometer, records at Whittier and Riverside, 189. Atmospheric humidity, effect on citrus trees and fruit, 34. Aurantium, derivation of word, 41. Australia, frost in, 25 ; introduc- tion of Navel orange, 15 ; ship- ping oranges to, 344 ; source of cottony cushion scale, 6. Australian Navel orange, introduc- tion of, 16. Australian type, 128. Automatic weighing, of individual grades, 292. Automobile, used in killing gophers, 458. Azores, 15, 70. Backus, W. H., 58. Bacteria, in soil, 165. Bacterium citriputeale, 401. Bags, for picking, 280. Bahia, Brazil, birthplace of Navel orange, 13. Balling, nursery stock, 104. 505 506 Index Bare rooted, trees for planting, 157. Bark, effect of Botrytis vulgaris on, ' 366 ; gnawed by squirrels, 458 ; new growth of, chlorophyll in, 49 ; of sour orange resistant to gum-disease, 366. Barnyard manure, cost of, 361. Barometer, indicating frost, 237. Baronio system of pruning, 214. Bench-roots, 89. Bergamot oil, imported, 332 ; tariff on, 9. Beveling machines, 293. Bibliography, general, 461. Bigelow, W. D., 288. Bioletti, F. T., quoted, 240. Bisulfide of carbon, for killing gophers, 457. Biting insects, 405. Bitter orange, origin of, introduc- tion into Florida, 41. Black leaf extract, as a spray for thrips, 427. Black pit of lemon, 401. Black rot of Navel, 388. Black scale, general discussion of, 405. Black smut, 290. Blasting, to facilitate irrigation, 203 ; hard soil, 156 ; to ame- liorate soil, 146. Blemishes, importance in judging, 134 ; of fruit, 318. Blizzards, 237. Blue mold, 387. Bluestone, as a disinfectant, 385. Bolting split limbs, 229. Bolton, J. P., 252. Bonavia, E., 60. Boosting plants, 193. Bordeaux mixture, for seed-bed gumming, 89, 369 ; for wither- tip, 381 ; for damp-off, 392. Bordeaux paste, for gum-disease, 366 ; for pruning wounds, 228. Botany of citrus, bibliography, 485. Botrytis vulgaris, causing gum- disease, 366 ; causing fruit decay, 388. Box, dimensions of lemon box, 310 ; material, kind of, 293 ; cost of, 293 ; shooks, 292. Boxes, machines for making, 293 ; materials for, 292 ; size, 293. Breeding, references to literature, 479 ; for frost resistance, 244. ._ Brehm, 14. Brokerage charges, compared with Exchange costs, 351. Brown rot fruit decay, 386. Brown rot fungus, transmission by rain, 281 ; regions most seriously affected, 282. Brown rot gum-disease, 364. Brown spot, of Navel orange, 326 ; description of, 389. Bruises, 321. Brushing, removal of dust by dry brushing, with water, 291. Buckwheat, as cover-crop, 182, Budding, time of, 95 ; nursery stock, 92; method of, 95; high bud- ding on sour-stock, 97 ; dormant buds, 98 ; cost, 99. Bud-sports, 120; how pruned, 211. Bud variation, 118. Bud-wood, selection of, 93, 128. Burr clover, as cover-crop, 182. By-product industry, needed in California, 354. By-products, references to litera- ture, 492; importation of, 331. California FruitGrowers' Exchange, history and organization of, 345. California Navel Orange, chemical analysis of, 62. California pruning saw, 225. Canada field peas, as cover-crop, 182. Canker, description of, 392. Capital, estimating amount needed, 360 ; of Exchange, 348. Index 507 Capital required, 358. Ctipitalization, 350. Carbon bisviltido, for killing gophers, 457. Carbon dioxide, loss of from fruit, 61. Car-load, number of boxes con- tained, 310. Cars, standard, 295 ; other than standard, 275 ; air spaces in, 296 ; bracing of boxes in, 296 ; freight on, 297 ; icing charges, 297. "Car Squeeze," 296. Cement dust, on fruit, 324. Central exchange, 348. Ceratitis capitata, 109. Chambers of Commerce, influence of, 11. Chapman, A. B., 16. Chapman, C. C, 71. Characters, segregation of, 120. Chemical Analyses of California Oranges and Lemons, 62. Chemical fertilizer, cost of, 361. Chemistry, references to literature, 486. Chemistry of citrus fruits, 61. Chenopodium, as a cover-crop, 183. Chimeras, 120. Chinese lemon, as a root-stock, 154. Choice, grade, 292. Chrysomphalus aurantii, 411; var. citrinus, 414. Citellus beecheyi, 458. Citranges, 79. Citrate of lime, imported, 332 ; tariff on, 9. Citric acid, imported, 332 ; manu- facture of, 333 ; tariff on, 9. Citricola scale, discussion of, 419. Citron, preparation of, 337 ; bibliog- raphy, 473 ; grown in California, susceptibility to frost, variety Cor- sica, 80 ; imported, 332 ; introduc- tion into Italy, 41 ; susceptibility to frost, 242 ; tariff on, 9. Citrus areas of California, southern coast, interior valleys, northern coast, 26. Citrus aurantifolia, 43, 45. Citrus aurantium, 43. Citrus bergamia, 43. Citrus bibliography, 473. Citrus canker, description of, 392. Citrus d(H'umana, 43, 44. Citrus jajjonica, 43, 44. Citrus linionia, 43, 45. Citrus mealy bug, 421. Citrus medica, 43, 45. Citrus nobilis, 43. Citrus Protective League, 353. Citrus sinensis, 43. Citrus species in North and South America, 42. Citrus trifoliata, 43. Cladosporium citri, 395 ; herbarum var. citricolum, 395. Classification, 42. Clausen, R. E., cited, 381. Clearing land, cost of, 359. Cleats, proper position of, 138. Climate, interior valleys, 30 ; north- ern coast, 31 ; southern coast division, 28. Clipper cuts, 321. Clippers, abrasions caused by, 278. Clouds, as affecting frost, 235. Cobb, N. A., cited, 449. Coccus hesperidum, 418. Colby, G. E., 288. Cold periods, historical, 230. College of Agriculture, service of, 358. Colletotrichum gloeosporioides, 380. Collins, J. F., cited, 228. Color, importance in judging, 136. Coloring process, results of too rapid forcing, 290. Combustion, in orchard heaters, 253. Commission men, 344. Concrete irrigating pipe, 194. 508 Index Conduction, 233. Consumption, increase of, 354. Contour, planting, 150. Convection, 233. Cooperation, first tried, 8 ; in frost fighting, 274. Cooperative packing-houses, 345. Copley, Edward, 252. CoquUlett, D. W., 431. Core rot, of stored lemons, 382. Correspondence course, in citrus fruits, 358, 11. Cost of production, 355. Costs, of bringing orchard into bear- ing, 359. Cotton Exposition, held in New Orleans, 6. Cottony cushion scale, discussion of, 417 ; fumigation for, 431 ; in- troduced, 6. Cottony mold, 383. Cottony-mold fungus, on vetch cover-crop, 182. County Commissioners of Horti- culture, 110. Cover-crop, advantages of, 181 ; disadvantages of, 182 ; kinds, 182 ; references to literature, 484 ; harbors cottony mold, 383 ; plowed under, 166 ; relation to mottled-leaf, 379. Cover, T. D., first exhibited Navel orange, 18. Cowpeas, as cover-crop, 182. Cracks, in oranges, 326. Craw, Alexander, 20. Creosote, 227. Cross-furrowing, for irrigation, 201. Cross-pollination, 123, 115, 116. Crown gall, occurs on citrus, 401. Cucumber beetle, 430. Culls, removal of, 315. Cultivation, 165 ; depth of, fre- quency of, 168. Cultivator scars, on fruit, 321. Curing, advantages of, 278 ; refer- ences to literature, 489. Cuttings, propagation by, 92. Cyanide, 438. Damp-off fungus, in seed-bed, 88. Damping off, of seed-bed stock, 391. De CandoUe, 40. Decay, in pruning wounds, 226 ; in transit, effect of icing on, 297 ; in oranges, causes of, 277 ; in dropped fruit, 279 ; in stored lemons, 308 ; splits a cause of, 327. Defoliation, by frost, 242. Degenerate types of trees, 357. Degeneration of trees, due to suckers, 209. Demonstration trains, influence of, 11. Desiccating winds, cause of twig gumming, 367. Dew, as affecting frosts, 235. Dew point, raising of, 246. Diabrotica soror, 430. Die-back, see exanthema, 369. Digging holes, for trees, 155. Dimorphic branches, of orange trees, 208. Diplodia rot, due to Diplodia natalensis, 397. Discount, in cars other than stand- ard, 295. Diseases, prevention important, 357 ; bibliography, 499 ; control, 364. Disinfection, of wash water, 385. Distance apart, of trees, 149. Distillate oil, as a spray for scale, 432. Distributing costs, 352. Distribution, of fruit by Exchange, 348. District exchange, 347. Diversion of cars, right of, 298. Domestic recipes, 341. Index 509 Dosage for fumigation, calculating, 441,444; schedules, 444-447. Double clipping, 279. Dressings for wounds, 227. Dropped fruit, decay of, 279. Dry center, of lemons, 329. Drying, of fruit, 291. Dynamite, 146. Early ripening, of oranges in Northern California, 288. Early shipments, losses in, 283. Electric orchard heaters, 250. Electric railways, influence of, 10. Elevation, effect of in Interior Valley, 30. Elm, affected by mottled-leaf, 376. Employees, provision for, 316. Englehardt, J. P., 69. Enzymatic fermentation, of fruit, 61. Eriophyes oleivorus, 424. Erodium, as cover-crop, 183. Essence of orange flowers, 338. Essential oils, manufacture of, 334. Etrog, 40. Eucalyptus, affected by mottled- leaf, 376. Eureka lemon, pollination of, 55 ; chemical analysis of, 62 ; how pruned, 214. Euthrips citri, 425. Evaporation, as affecting tempera- ture, 233 ; from porous cup atmometers, 189; from soil, 165. Ever-sporting trees, 211. Exanthema, causing blemishes on fruit, 325 ; description of, 369. Exchange, relation to other selling agencies, 345 ; cost of operating, 351 ; Southern California Fruit Exchange first organized, 8. Exhibitions, judging fruit at, 132 ; influence of, 12. Explosions, in orchard heaters, 255. Fairs, first citrus fairs, 5. Fancy, grade, 292. Fawcett, H. S., cited, 397. Feature exhil)ils, judging, 138. Federal Board of Food and Drugs Inspection, ruling regarding col- oring of green citrus fruits, 285 ; effect of ruling regarding artificial coloring, 285. Fenugreek, as cover-croj), 182. Ferrarius, John Baptiste, 13. Fertilization, of seed-bed, 88; bib- liography, 483 ; of nursery stock, 92 ; of orchards, 175 ; a type of, 178. Fertilizer, in planting holes, 157 ; cost of, 359. Field box, ratio of to packed box, 295. Filaree, as cover-crop, 182. Fingered lemons, 120. Flavor, importance in judging, 136. Florida Citrus Exchange, organiza- tion of, 353. Flowers of citrus, description, season, 52 ; of lemon, different kinds of, 54. Fluctuations, 118, 128. Foot-rot, 372. Form, importance in judging, 133. Fortunella, 43. Freezing in transit, prevention of, 298. Freight, cost of, 360. Freight rate, on lemons, 312. Freight rates, 297. Friendly fungi, 396. Frost, effect on fruit on lower branches, 281 ; in countries pro- ducing citrus fruits, 25 ; hazard, 33 ; air currents, 34 ; effect on value of land, 140 ; where to be expected, 140; of January, 1913, 231 ; losses from, 232; factors influencing, 234 ; local conditions affecting, 236 ; relative resis1> 510 Index ance to, 242 ; causing blemishes on fruit, 325 ; a frequent cause of failure, 357. Frost fighting, bibliography, 494. Frost hazard, judgment of, 141. Frost-injured fruit, references to literature, 494. Frost injury, to vegetable tissues, 239 ; on leaves, 368 ; prevention of, 243. Frost protection, average cost of, 361. Frosted fruit, separation of, 270. Frosted trees, how pruned, 217. Frosts, as affected by winds, 233 ; in Florida, 230 ; in California, 231 ; season of in California, 232 ; forecasting, 233. Froude, Charles, 252. Frozen fruit, changes in, 241 ; edible, 241 ; loss of juice, 241. Fruit Growers' Supply Co., organi- zation, 301 ; purpose, 301 ; ac- complishments, 301. Fuel oils, properties of, 260 ; stor- age of, 262. Fuller's rose beetle, 429. Fumigating, machine, 452 ; cost of materials, 452 ; cost of, 361 ; done by associations, 347 ; large seedlings difficult to cover with tents, 65. Fumigation, 431 ; season of, 443 ; operation, 440 ; cost of, 448 ; efficiency of, 403 ; bibliography, 497; scars, 322. Fumigator's supply carts, 438. Furrows, for irrigation, 201. Fusarium, causing damp-off, 391. Galloway, B. T,, quoted, 239. Galls, on citrus trees, 401. Garey, T. A., 4, 71, 74; introduc- tion of varieties, 16. Generators, fumigation, 437. Geomys bursarius, 456. Germ-plasm, 211. Glaced kumquats, 341. Gloeosporium limetticolum, 381. Gopher, 456. Gore, H. C, 288. Grades, of fruit, 292. Grading, fruit, 292 ; land, cost of, 359. Grafting, nursery stock, 92. Grape fruit, see4)i)ni£lo, 75. Gravity frost, 237. Gray mold, of fruit, 388. Gray scale, 419. Greedy scale, 420. Green manure crops, 181. Green manuring, references to litera- ture, 484. Green mold, 387. Ground squirrels, 458. Growth rings, in wood of lemon, 47. Guaymas, citrus industry at, 24, Gum-disease, of seed-bed stock, 89, 368 ; in pruning wounds, 229 ; caused by tillage implements, 172 ; carried by shoes of pickers, 280. Gum-diseases, 364. Gum, formation along cambium, 49. Gumming, resistance of sour stock to, 152. Hail scars, 323. Hairy vetch, as cover-crop, 182. Hammon, W. H., cited, 235. Hardpan, 143 ; presence of, in In- terior Valley, 31 ; as affecting irrigation, 203. Harrowing, 168. Hart, E. H., 71. Harvest season, of oranges, of lemons, 63. Hauling fruit, average cost of, 360. Heading back, nursery trees, 100. Heading trees, 205. Heat, loss of, 233. Index 511 Hedges, Florence, cited, 401. Homisphorical scale, 420. Herniosillo, citrus planting at, 24. Hcspcridcs, The, 13. Hcsperidin, 241. Hexagonal planting, 14S. Hilgard, E. W., quoted, 196, 431. Hodges, J. R., cited, 378, 449. Hoeing, under trees, 172. Holes, for tree planting, 155. Holt, L. M., 18. Honey-dew, 407 ; excreted by mealy bug, 421. Hongkong, shipping oranges to, 344. Horticultural inspection, cOvSt of, 111. Hume, H. H., 76. Humidity, for stored lemons, 308. Humus, produced by mulch, 173 ; general discussion of, 178 ; lack of, a cause of mottled-leaf, 378. Hybridization, 115. Hybridizing, facility of between species, 42. Hybrids, production of, distribu- tion of, 79. Hydrocyanic acid gas, first used in fumigation, 431. Icerya purchasi, description of, 417 ; introduced, 6. Icing charges, 297. Icing of cars, effect of precooling on, 298. Icing, of lemons in transit, 312. Ikeda, T., 56. Immature fruit, sweating of, 282 ; shipment of, 283 ; losses in ship- ments of, 283 ; Florida law on, 283 ; acid test for, 284. Improvement through bud selec- tion, 115. Independent shippers, 345. Infection, by spores, 277. Injuries, to fruit in packing, 322. Insect pests, bibliography, 496. Insects and control, 403. Inspection, horticultural, 6. Insuranc(>, division of Exchange, 350. Intercropping, 159. Interstate Commerce Commission, re-icing rate of, 298. Investment, in citrus properties, 359. Irrigating system, cost of, 359. Irrigation, 179 ; as frost protection, 247 ; overhead, 199 ; by basins, 200 ; by furrows, 201 ; depth of, 195; frcfiuency of, 195; cli- matic conditions affecting, 188 ; of newly planted trees, 158 ; of nursery stock, 91 ; of seed-bed, 87; bibliography, 482. Itinerant packers, 344. Jacobs, Louis, 21. Japan, frost in, 25. Japanese privet, affected by mottled-leaf, 376. Jelly, orange and lemon, 341. Jobber, 353. Jones, B. R., 449. Judging orchards and land, 363 ; references to literature, 486. Juice, importance in judging, 134. Katydids, 430. Keeping qualities, effect of careful picking, handling and packing on, 297. Kellerman and Wright, cited, 379. Kerosene emulsion, formula for black scale, 410. Knots on limbs, 401. Koebele, Albert, 6. Kumquat, 43, 44 ; bibliography, 472 ; description of, varieties, Marumi, Nagami, 83 ; suscepti- bility to frost, 242 ; glac6d, 341. Labeling, of boxes, 293 ; "Sunkist" label, 292. 512 Index Labor, cost of, 360. Ladders, picking, 280. Ladybird beetle, 417 ; for cottony scale, 7. Land, judging, 363 ; cost of, 359 ; stony land, development of, 145 ; clearing and leveling, 145. Lath house, for seed-bed, 86 ; as protection from frost, 244. Lavanja de Umbigo, 13. Layering, propagation by, 92. Leaf-gumming, 368. Leaves, season of fall, 49 ; age of, 49 ; variation in size and shape, 49 ; oil glands in, 50. Lefferts, D. C, 272. Legal division of Exchange, 350. Lelong, cited, 13, 11 ; quoted, 33. Lemon, black pit of, 401 ; jelly, 341 ; peel imported, 332 ; grades, 309 ; storage, 306 ; buttons dropping, 306 ; sweating, 305 ; picking rings, 305 ; pools, 303 ; susceptibility to frost, 242 ; as a root-stock, 154 ; length of period of development, 54 ; introduction into Italy, 41 ; bibliography, 469. Lemon oil, imported, 332 ; tariff on, 9. Lemon peel, tariff on, 9. Lemons, core rot of, 382 ; cost of producing, 355 ; picking, 302 separating frosted fruit, 273 varieties, descriptions of Eureka 73 ; Lisbon, 74 ; Villafranca, 74 Bonnie Brae, 75 ; Genoa, 75 Sicily, 75; Messina, 75; Milan, 75 ; tariff on, 9 ; standards, for judging, 135 ; sweet, description of, 83. Lepidosaphes beckii, 414. Level, for laying off contours, 151. Leveling land, 145. Lime (agricultural), 144; as a cure for mottled-leaf, 377. Lime (tree), bibliography, 471 ; susceptibility to frost, 242 ; tariff on, 9 ; description of, suscepti- bility to frost, varieties, sour, West Indian, Rangpur, Sweet, Mexican, 81 ; juice, preparation of, 339 ; imported, 332 ; oil, im- ported, 332. Lime-magnesia ratio, 377. Lipman, C. B., cited, 379. Lisbon lemon, pollination of, 55. Litigation, handled by Exchange, 348. Local Exchange, 346. Location, for grove, 357. Longevity of citrus trees, 64. Los Angeles, headquarters of Ex- change, 346. Loughridge, R. H., quoted, 196. Lug-boxes, as carriers of infection, 385 ; fumigating for scale, 409. McAdie, A. G., cited, 237. Magnesia, effect on mottled-leaf, 377. Maintenance and repairs, average cost of, 361. Mal-di-gomma, 372. Malformation, of fruit, 326. Malforms and monstrosities, 120. Malnutrition, 371. Malva, as cover-crop, 183. Mandarin oranges, bibliography, 471. Mandarins, varieties, description of tangerine, 78 ; Satsuma, 79 ; Unshiu, 79 ; Dancy, 78 ; King, 78; Beauty, 78; Mikado, 78; Oneco, 78. Manifest cord, 296. Maple, affected by mottled-leaf, 376. Marketing, 344 ; bibliography, 490 ; disaster of 1892-93, 7. Marmalades, 342. Marsh, C. M., 76. Marsh pomelo, pollination of, 55. Index .513 Moaly bug, discussion of, 421. I\Ie{lit(>rriuu'!in fruit l\y, (luanuitinc jif!;aiiKst, 109. Mclanoso, 394. Mcliola camolliic, 290, 407. Melon aphis, 427. Membership, in Exchange, 349 ; in Association, 357. Mesembryanthemum, 150. Mexico, citrus industry of, 24. Miller, Frank A., 22. Miner's inch, 191. Mission orchards, distribution from, 2. Moisture content, of soils, 196. Money, remitted by salesmen of Exchange, 350. Mononchus papillatus, 454. Monstrosities, 120. Morelos orange worm, 24. Morse, F. W., 431. Mother trees, for bud-wood, 94. Mottled-leaf, description of, 374 ; causing blemishes on fruit, 325 ; relation to nematodes, 449. Mulching, 173. Mules, as work stock, 174. Mussey, D. N., 303. Mutations, 120, 211. Mutual protection, division of Ex- change, 350. Nail-head rust, 395. Nailing, proper method, 138. National Orange Show, 132. Navel, importance in judging, 134. Needham, J. H., quoted, 74. Nematodes, discovered on citrus, 378 ; on citrus roots, 449 ; life history described, 454. Neroli, imported, 332 ; tariff on, 9 ; manufacture of, 338. Newland, Victor, 355. Nitrification in soil, 379. Nitrogen, as a crop limiter, 177 ; from atmosphere, 165. North, Judge, founded Riverside, 17. Northern California, early ripening in, 288. Northers, as affecting frosts, 238. Norton, J. H., quoted, 124. Novius cardinalis, 7. Nursery stock, 84 ; packing for shipment, 102 ; cultivation, irri- gation, 102; fertilization, 102; balling, 103 ; naked roots, 102. Nutrition, derangement of, 374. Oak trees, hosts for Armillaria mellea, 373. Off-bloom, 325. Oil, as a fuel for orchard heating, 252 ; of anise, used in gopher poison, 457 ; of bergamot, im- ported, 332 ; of lemon, imported, 332 ; of lime, imported, 332 ; of neroli, imported, 332. Old age decay, of stored lemons, 382. Oleander scale, 420. Ontario Fruit Grower, cited, 20. Orange, tortrix, 428. Orange, jelly, 341; paste, 340; marmalade, 342 ; wine, 337 ; juice, unfermented, 335 ; vine- gar, 336 ; peel imported, 332 ; susceptibility to frost, 242 ; cause of navel in, 61 ; pollination ex- periments with, 56 ; derivation of word, 41 ; time required in transit, 298 ; shipping under ice, 298 ; number of fruits per box, 195 ; boxes per car, 295 ; arrange- ment of boxes in car, 295 ; sweat- ing of, 282 ; thinning of fruit, 282 ; picking to size, 282 ; decays, 277 ; respiration of, 277 ; wrap- pers, cost of, 355 ; varieties, bit)liography, 464 ; oil, imported, 332 ; tariff on oil, 9. Orange diseases, bibliography, 468, 2l 514 Index Orange growing abroad, bibliog- raphy, 463. Orange growing in United States, bibliography, 461. Orange insects, bibliography, 467. Orange peel, tariff on, 9. Orange standards, for judging, 133. Oranges and lemons of India, 60. Oranges, cost of producing, 355. Oranges crystallized, 340. Oranges, grades of, 292 ; tariff oij, 9. Oranges, varieties of, Valencia, 70 ; Excelsior, 70; Hart's Late, 71; Hart's Tardiff, 71 ; Valencia Late, 70; Mediterranean Sweet, 71; Paper Rind, St. Michael, 72; Ruby, 72; Ruby Blood, 72; Jaffa, 72; Joppa, 72; Crafton, 72 ; Asher's Best, 66 ; Bostram's Prize, 66 ; Washington Navel, 66 ; Bahia, 66 ; Riverside Navel, 66 ; Thomson, 68 ; Buckeye, 69 ; Navelencia, 69 ; Nugget, 69 ; Australian, 69. Orchard heaters, requirements of, 253 ; leakage of, 255 ; types of, 257 ; installation of, 259 ; care of, 267. Orchard heating, 230 ; cost of, 268 ; as insurance, 33. Orchard heating operations, 264. Orchard plans, 147 ; traotors, 174. Orchards, judging, 362. Organization, references to litera- ture, 490. Origin of citrus fruits, 25. Over-capitalization, 356. Overhead irrigation, as a protection from frost, 199, 247. Overholtzer, David, 199. Packed box standards, for judging, 137. Packers, 293. Packing, references to literature 489 ; process of, 295 ; speed in 295 ; number of fruits in a box 295 ; ratio of field to packed box 295 ; average cost of, 360 lemons, 309. Packing-houses, for lemons, 314 arrangement, 299 ; fire hazard in, 301 ; losses from fire, 301 ; insur- ance for, 201 ; number of, in Cal- ifornia, 301 ; capacity of, 301 ; designing and construction of, 299.' Palestine, source of Jaffa orange, 72 ; frost in, 25. Parsons' Navel orange, 15. Parsons, S. B., 70, 15. Parthenocarpic fruits, 55. Pedigreed stock, 130. Penicillium italicum and P. digi- tatum, causing fruit decays, 387. Performance of individual trees, 125. Performance records, 128. Permanganate of potash, use as dis- infectant, 291. Pests, other than insects, 449 ; dis- tribution of, 404 ; financial loss caused by, 403 ; inspection and quarantine, 107 ; 145. Peteca, causing blemishes, 329. Petit grain oil, preparation of, 338. Phoma, 393. Phomopsis citri, 394. Phosphoric acid, as a crop limiter, 177. Phyllosticta, 393. Physiological derangements, 374. Pickers, competition between, 317; payment of, 282. Picking, done by associations, 347 ; average cost of, 360 ; lemons, 316 ; ladders for, 280 ; oranges to size, 282 ; oranges, care in, 277 ; bags for, 280. Picking bags, 280. I ltd ex 515 Picking lemons, 3();>. Picking season, onmgo, 277. Pipe lin(>s, for fuel oils, 2G3 ; for water, lO.i. Placing of fruit in boxes, 13S. Plant-food,' amount in citrus culls, 177 ; effect of bacteria on, 165. Planting, cost of, 359, IGO ; balled stock versus bare root, 157 ; depth of, 156; time of, 151; selection of site, 139 ; seed-bed stock, 91; 147. Planting-board, us:^ of, 156. Planting plans, 147. Planting seed, 87. Plant lice, 427. Plowing, 165 ; depth of, 166 ; time of, 166. Plows, kinds of, 166, 170. Plow-sole, 166 ; as affecting irriga- tion, 203. Pocket gopher, 456. Poison, for gophers, 457 ; for ground squirrels, 459. Poiteau, 40. Pollination, 123 ; in citrus fruits of Florida, 55 ; in citrus fruits of Southwest, 45. Polyembryony, in hybrids, in citrus seeds, causes of, sig- nificance of, 59. Pomelo, subject to canker, 392 ; susceptibility to frost, 242 ; as a rootstock, 152 ; improvement by hybridization, 118; bibliography, 472; picking, 312; tariff on, 9; standards for judging, 136. Pomelos, varieties, description of Marsh, 75 ; Nectar, 77 ; Duarte Seedling, 77; Duncan, 77; Triumph, 77 ; Imperial, 77 ; Colton, 77 ; Pijik-fleshed, 77. Potash, as a crop lirhiter, 177. Potassium cyanide, for fumigation, 449. Powell, X). H., quoted, 353, 346. l*recooling, value to citrus fruits, 29(S ; definition of, 297; com- parison with icing, 297 ; amounts of ice refjuired, 298. Precooling plants, 297. Prickly ash, 42. Privet, Japanese, affected by mottled-leaf, 376. Production, 114, 25; in California, 9. Profit and loss, 355. Propagation, 92 ; references to literature, 478. Propping trees, cost of, 361. Protective duties, tariff, 9. Protective League, 353. Pruning, as a prevention of brown- rot, 387 ; orange trees, 207 ; cost of, 359 ; done by associations, 347 ; frosted trees, 217 ; time of, 216; maxims of, 215; lemons, 213 ; training nursery trees, 205 ; general considerations, objects of, 204 ; bibliography, 487. Prunings, disposition of, 217. Pruning tools, 225. Pruning wounds, 226. Pseudococcus citri, 421. Puddling roots, 155. Puffing, 329. Punctures, caused by stems, 278 ; box-nails, 279 ; thorns, 279. Purple scale, 414. Pythiacystis citrophthora, 365 ; causing fruit decay, 386. Quality, in tropical grown citrus fruits, 25. Quarantine, horticultural, 6. Quincunx planting, 148. Radiation, 234 ; checking of, 244 ; of electric orchard heaters, 251. Rag, importance in judging, 134. Railroads, early shipments by rail, 5. 516 Index Rainfall, 26 ; as affecting irrigation, 188. Recipes, 341. Red blotch of lemon, described, 398. Red rot, see red blotch. Red scale, discussion of, 411; dis- tribution of, 404. Red spiders, discussion of, 423. Reed, J. H., 23. Refrigeration, cost of, 360. Reheading, mature trees, 220 ; young trees, 218. Re-icing, cost of, rate case con- cerning, 298. Relative humidity of air, as affect- ing irrigation, 188. Relative size in fumigation dosage, 451. Respiration, of oranges, 277. Reversion, 120. Rhizoctonia, 391. Right of diversion, 298. Rind, importance in judging, 133 ; variation in thickness of, 328. Ringing, 48. Rings of growth, 47. Ripening season, Northern Valley, 31. Risso, 40. Rivers, Thomas, 70, 15. River's Navel orange, 16. Riverside, first settled, 3 ; citrus fairs, 19, 5. Riverside Press and Horticulturist, quoted, 19. Roosevelt, President, 22. Root-rot, due to sclerotinia, 383 ; due to toadstools, 373. Roots, distribution in soil, effect of shearing, 45 ; effect of hardpan on, 143 ; injured by exposure to air, 91 ; cut by plow, 156 ; of lemon, susceptible to foot-rot, 372 ; affected by nematodes, 454. Root-stock, 151 ; trifoliata suitable for kumquats, 83 ; trifoliata best for Unshiu, 79 ; cold resisting, 155 ; proportion of different kinds planted, 84 ; Chinese lemon, 6. Root systems, references to litera- ture, 481. Rose beetle, 429. Rutacese, 42. Saissetia hemisphaerica, 420. Saissetia olese, 405. Sales, classification of, 344 ; divi- sion of Exchange, 350. Salesmen, of Exchange, 348. Salt River Valley, 23. San Gabriel Mission, site of first orchard, 2. Santa Fe Railway, 5. Sap Currents, nature of, 47 ; rela- tion to tree parts, 47. Satsuma orange, production of seeds in, 56 ; susceptibility to frost, 242. Saunders, William, 17. Savastano, 121. Saws, for pruning, 225. Scab, description of, 395. Scale insects, effect of climate on, 404 ; exclusion of, 357 ; ridding seed-bed stock of, 90; red, 411; yellow, 414; black, 405 ; purple, 414 ; brown, 418 ; gray, 410 ; cottony cushion, 417 ; greedy, 420; citricola, 419; hemispheri- cal, 420 ; oleander, 420. Scales, for judging, 132. Scaly-bark, 367 ; Florida type, 395. Scars, on fruit, 321. Schedules, fumigation dosage, 444- 447. Schizophyllum commune, 399. Scientific American, 48. Scions, references to literature, 478. Sclerotinia libertiniana, causing fruit decay, 382. Score-card, for citrus land, 139 ; for bearing groves, 363 ; for Index 517 oranges, 133; for lemons, 134; for poniolos, 136 ; for packed boxes, 137 ; for feature exliihits, 138. Scratches, caused by shoes of pickers, 280 ; caused by finger- nails, 279 ; gravel, 279 ; thorns, 279. Scutellista cyanea, 409. Season, of picking, 63. Seed-bed, planting, 84. Seed-bed stock, price, method of pulling, 88 ; trimming back when transplanting, 92. Seed, citrus, description of different kinds, 84 ; cost, 84 ; method of keeping, 86 ; number per bushel, 86. Seedlessness, importance of in pomelos, 77. Seedling trees, compared with budded trees, 65 ; 84. Seeds, presence of, in judging, 134, 136 ; time of planting, 88 ; effect of freezing on germination, 86 ; first planted in California, 1. Seeds of citrus fruits, number of, 61. Selected buds, importance of, 357. Selection of bud-wood, effect of poor bud-wood, 114. Selling, average cost of, 360. Separators, for frosted fruit, 272. Setting of fruit, as affected by plow- ing, 166. Seville orange, susceptibility to frost, 242. Shaddock, description of, 81. Shading, of nursery plants, 38. Shamel, A. D., 124. Shears, for pruning, 225. Shields, for tillage implements, 170. Shipments, annual, in carloads, 9. Shipping, lemons, 312 ; first car shipped east, 3 ; nursery stock, 103. Shorh, J. d(> Barth, 18. Shoulder spots, 323. Silver mite, discussion of, 424. Silverware, as premiums, 351. Site, for i)lanting, 139. Six-spotted mite, 423. Size, importance in judging, 135. Sizing, lemons, 310; machines, 292. Slitting bark, of young trees, 206. Slope, of land for irrigation, 201 ; best for planting, 150. Smith, C. O., cited, 401. Smith, R. E., quoted, 378. Smoke, from orchard heaters, 253. Smudge fuel, 250. Snowden, R. R., cited, 377. Sodium cyanide, for fumigation, 449. Sodium sulfate, a waste product of fumigation, 439. Soft brown scale, discussion of, 418. Soil, nitrification and ammonifica- tion, 379 ; heavy soil may en- courage gum-disease, 365 ; most desirable, 357 ; samples, 196 ; inoculation, 183; tillage of, 165; alkali, 144 ; ideal for citrus, 144 ; for seed-bed, 87. Soil acidity, 144. Soil adaptations, 142. Soil analysis, 144. Soils, relation to mottled-leaf, 378 ; kinds as affecting method of irri- gation, 200 ; kinds not benefited by cover-crop, 183 ; humus con- tent, 179 ; analyses of, 175 ; cul- tivation and management, 170 ; for seed-bed stock, 91 ; northern coast division, 32 ; Interior Valley division, 31 ; Southern Coast division, 29 ; references to literature, 481. Soil scars, on fruit, 323. Soil types, 142. Solanum nigrum, 404. 518 Index Sonora, citrus production in, 23. Sour clover, as cover-crop, 182. Sour-stock, as a root, 152. South Africa, 14 ; frost in, 25. Southern Pacific Railway, 5. Spain, frost in, 25. Special equipment, for packing- houses, 299. Speculation, encouraged by over- capitalization, 356. Speculators, 344. Sphseropsis tumefaciens, 401. Sphagnum, for packing bud-wood, 94 ; for packing seed-bed stock, 90. Splits, as blemishes, 326. Splitting of bark, effect of frost on, 219. Spores, of fungi in wash water, 385. Spotting, of Navel oranges in tran- sit, 389. Spraying, cost of, 361. Spraying under trees, as prevention for brown-rot, 387. Square planting, 148. Squirrels, as pests, 458. Staking young trees, in orchard, 218. Standard car, number of boxes in, 295 ; arrangement of boxes in, 295 ; air spaces in, 296. Standard grade, 292. Standpipes, for irrigation, 194. State Commission of Horticulture, influence on industry, 1 1 ; descrip- tion of, 106. State Fruit Growers' Convention, 109. Statute inch, 192. Stem, importance in judging, 133. Stem end rot, 394. Stem end spot, in California, 399 ; of oranges, 320. Stem punctures, 321, 278. Stenciling, of boxes, 293 ; hnpor- tance in judging, 137. Stevens, H. E., cited, 392. Stock, see Root-stock, 152. Stocks, references to literature, 478. Storage, 306. Storing, references to literature, 489. Strap, proper position of, 138. Straw, plowed under, a cause of mottled-leaf, 379. Structure of the fruit, morphologi- cal, 60. Strychnine, as poison for gophers, 457. Subsoiling, 166. Subsoils, 143. Sucker growths, 208. Sucker-nests, 226. Suckers, effect of presence of, 209 ; not desirable for bud-wood, 95. Sucking insects, 405. Sugar, reduction of, during respira- tion, 287. Sugars, in citrus fruit, 63. Sulfur, remedy for red spider, 424. Sulfuric acid, for fumigation, 439. Sunburn, of bark, encourages schizo- phyllum, 400. Sunburn, of leaves, 368 ; of fruit, 324. Sunburning, bark of pruned trees, 219. "Sunkist" label, 292, 351. Sunlight, effect of over- illumina- tion, 38 ; as affecting irrigation, 188. Sun protectors, 157. Supply cart, for fumigators, 438. Supply Department, of Exchange, 350. Sweating, lemons, 305 ; oranges, 282 ; of Valencia oranges, 282 ; references to literature, 489. Sweat room, description of, 289, 305 ; construction of, 289 ; tem- perature of, 290 ; heating of, 290 ; arrangement of fruit in, 290. I ndc.v 51!) Sweet orange, antiquity, introduc- tion into Europe, iiitroduclion into Brazil, 41. Swingle, W. T., 79. Swingle-Webber hybrids, varieties. Rusk, 79; Willits, 79; Norton, 79; Colman, 79; Savage, 79; Rustic, 79 ; Thornton, 80 ; Samp- son, 80 ; Weshart, 80 ; Trimble, 80. Taber, G. L., cited, 155. Tait, C. E., quoted, 170. Tangelo, 79. Tangerines, picking, 312. Tanking newly planted trees, 158 Tannin, treatment for fumigating tents, 435. Tar, for pruning wounds, 228. Tariff, references to literature, 490 ; protective duties, 9. Taxes, 357 ; and incidentals, cost of, 359. Teague, R. M., 77, 69. Temperature, effect on fumigation, 448 ; of air, as affecting irriga- tion, 188. Tent fumigation, of citrus trees, 435. Tents, for storing lemons, 308 ; cost of, 452 ; acid holes in, 438 ; equipment of, 437 ; methods of marking, 436 ; fumigation, 435. Teratological forms, 326, 120. Terraced planting, 150. Tetranychus mytilaspidis, 423. Tetranychus sexmaculatus, 423. Texture, importance in judging, 136. Thawing, of frozen fruit, 249. Thermal belts, 236. Thinning, of fruit, 323 ; advis- ability of, 282. Thomas, E. E., cited, 378, 449. Thomson, A. C, 68. Thorns, 51. Thorn-stabs, 321. Thrii)s, discussion of, 425. Tibbet, Luther ('., and wife, 17, IS. Tillage, 165. Tincture of orange flowers, 338. Toadstool root- rot, 373. Tomocera calif ornica, 410. Tools, for pruning, 225. Topography, as affecting frosts, 238. Top-working, 223, 92. Tortrix citrana, description of, 428. Tractors, for plowing, 168. Traffic, division of Exchange, 350. Training young trees, 100. Transit, time required for, dis- tance covered, 298. Transpiration, in fruit, 61. Trapping gophers, 456. Tree protectors, 157. Tree-ripes, 305 ; lemons, suscep- tible to black pit, 401. Trees, cost of, 359 ; number of, to the acre, 149. Triangular planting, 147. Trifoliata, susceptibility to frost, 242 ; as a root-stock, 153. Trifoliate orange, rare in California, 83. Tripeta ludens, 24 ; quarantine against, 109. Trunk rot, 399. Turgidity of rind, dangers from, 278. Twelve-spotted beetle, 430. Twig blight, 382. Twig-gumming, 367. Tylenchulus semipenetrans, 449. Types, of fruit, 123. Underwood-Simmons tariff, 9. University of California, 11. U. S. Department of Agriculture, citrus hybrids distributed by, 79 ; influence on industry, 11. U. S. Supreme Court, decision in pre-cooling case, 298. 520 Index Vaile, R. S., 455. Valencia orange, how pruned, 212 ; sweating of, 282 ; origin of and conditions best suited for, 70 ; pollination of, 55. Varieties, descriptions of, 65 ; bib- Tiography, 485. Vegetables, grown between trees, 159. Ventilation, for stored lemons, 308. Verrucosis, 395. Vesicles, as affected by frost, 274 ; arrangement of, 60. Vetch, as host for cottony mold, 383 ; common, as cover-crop, 182 ; hairy, as cover-crop, 182. Vicia sativa, as cover-crop, 182. Vinegar, from oranges, 336. Wages, of lemon pickers, 317. Wagons, 304. Wallace, J. C, 16. Washington Navel orange, descrip- tion of, climatic and soil condi- tions best suited to, sporting habits, sub-varieties, 66 ; com- position of, 62 ; seedlings of, 59 ; production of seeds in, occur- rence of normal embryo sacs in, 56-57 ; pollination of, 55 ; his- tory of introduction, first ex- hibited in California, 19 ; present location of two trees first brought to California, 23 ; sports of, 128 ; how pruned, 207. Wash water, disinfection of, 291. Water, amount necessary for irri- gation, 188 ; application to young trees, 158 ; disposition of waste, 150, 144 ; loss of, from fruit, 61 ; average cost of, 361 ; methods of application, 198 ; time of application, 195 ; temperature of, 196 ; methods of distribution, 193 ; lifting, for irrigation, 193 ; underground, laws in regard to, 192 ; cost of, 193 ; sources of, 192; measurement, 191. Watering seed-beds, 391. Water right, 142 ; cost of, 359 Water supply, importance of, 357 ; for irrigation, 141. Webber, H. J., 79. Weeds, as hosts for scale insects, 404. White, A. S., 19. White fly, quarantine against, 109. Whitewash, for pruning wounds, 228 ; prevents sunburn of bark, 219. Wind, as affecting^ frost, 233, 235 ; as affecting irrigation, 188 ; arti- ficial, as frost protection, 248 ; causing blemishes of fruit, 320 ; effect on fumigation, 448. Windbreaks, 37, 38. Windfalls, 324. Winds, effect on trees, 36. Wire baskets, 250. Wither-tip, description of, 380. Woglum, R. S., 433. Wolf & Massey, 393. Wolfskin, Louis, 17. Wolfskin, William, first commer- cial orchard, 2. Wood, structure, 46. Woodworth, C. W., 446; dosage table, 450. Workman, C. R., 74. Works, J. D., cited, 161. Wounds, dressings for, 226 ; heal- ing of, 49. Wrappers, redeemable for pre- miums, 351. Wrapping, value in judging, 138. Xanthoxylum americanum, 42. Yellow scale, discussion of, 414. Yellow spotting of oranges, 398. Yields, 127, 129, 359; lemon and orange compared, 191 ; average obtained, 362. Yuma, citrus planting at, 23. i The following pages contain advertisements of books on kindred subjects I Two Important Books Rewritten and Brought Up to Date Principles of Fruit-Growing By L. If, BAJLEY. New Edition, revised and rewritten Illustrated, 12mo, $1.75 postage extra Since the orii;inal publication of this book in 1807, it has 2:one through a total of nineteen editions. The progress of fruit-growing in the nieantinie has been very marked and it has now become necessary to rewrite this work. The present issue of it brings the accounts of the new practices and discoveries as they relate to fruit-growing up to date. It gives the latest information and points of view on fertilizers and different kinds of fruits, the heating of on-hards to protect them from frost, the treatment of diseases and insects, full discussions with dia- grams of the methods of laying out orchards and much other subject matter. This revision contiiuies the text as standard. The illustra- tions represent new hand drawings, with the complete elimination of half-tones, thereby giving an artistic appearance to the volume. Plant-Breeding By L. H. bailey. New Edition Revised by A. W. GILBERT. Professor of Plant-Breeding in the New York State College of Agriculture Illustrated, cloth, 12mo, $2.00 jjostage extra The original foundation for this book is Professor Bailey's standard text, Plant-Breeding, first published in 1895. As now issued the material in the old volume has been thoroughly revised and brought down to date. New discussions of mutations, INIendelism, heredity and the recent applications of the breeding of plants are all included. The work is now adapted to the classroom as well as to the needs of the general reader. Extensive laboratory exercises have been added ; the bibliography, which has been a prominent feature of previous edi- tions, except the first, has been retained and extended. 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The long and persistent demand for a uniform (edition of these little classics is answered with the publication of this attractive series. The Country Life Movement Cloth, l2mo, 220 pages, $1.25 postage extra This hitherto unpublished volume deals with the present movement for the redirection of rural civilization, discussing the real country-life problem as distinguished from the city problem, known as the back-to-the- land movement. The Outlook to Nature (New and Revised Edition) Cloth, 12mo, 195 pages, $1.25 postage extra In this alive and bracing book, full of suggestions and encouragement, Professor Bailey argues the importance of contact with nature, a sjTnpa- thetic attitude toward which "means greater efficiency, hopefulness, and repose." The State and the Farmer (New Edition) Cloth, 12mo, $1.25 postage extra It is the relation of the farmer to the government that Professor Bailey here discusses in its varying aspects. He deals specifically with the change in agricultural methods, in the shifting of the geographical centers of farming in the United States, and in the growth of agricultural institutions. The Nature Study Idea (New Edition) Cloth, 12mo, SI. 25 postage extra "It would be well," the critic of The Tribune Farmer once wrote, "if 'The Nature Study Idea' were in the hands of every person who :*"avors nature study in the public schools, of every one who is opposed to it, and most important, of every one who teaches it or thinks he does." It has been Professor Bailey's purpose to interpret the new school movement to put the young into relation and sympathy with nature, — a purpose which he has admirably accomplished. THE MACMILLAN COMPANY PUBLISHERS 64-66 Fifth Avenue NEW YORK CYCLOPEDIA OF AMERICAN AGRICULTURE Edited by L. H. BAILEY With 100 full-page plates and more than 2,000 illustrations in the text; four volumes', the set, $20.00 half morocco, $32.00 Vol. I — Farms Vol. Ill — Animals Vol. II— Crops Vol. IV— The Farm and the Community This is unquestionably the most important agricultural cyclopedic work published in this country. The leading experts in the United States and Canada, both investigators and practical farmers, con- tribute to its chapters, which are arranged not alphabetically, but topically, each subject being treated in its various aspects by men especially familiar with it. It contains advice for the city man who is seeking a home in the country, as well as for the professional farmer. The book is strictly new and up-to-date in its methods and advice, thoroughly readable, and a standard work of reference. It is profusely illustrated, about one-third of the .total space being assigned to illustrations — all original. "Indispensable to public and reference libraries . . . readily comprehensible to any person of average education." — The Nation. "The completest existing thesaurus of up-to-date facts and opinions on modern agricultural methods. It is safe to say that many years must pass before it can be surpassed in comprehensiveness, accuracy, practical value, and mechanical excellence. It ought to be in every library in the country." — Record-Herald, Chicago. THE MACMILLAN COMPANY PUBLISHERS 64-66 Fifth Avenue NEW YORK " The Bible and Britannica of the Garden-folk'' — The Nation The Standard Cyclopedia of Horticulture Edited by L. H. BAILEY With the assistance of over 500 collaborators New edition, entirely rewritten and enlarged with many features, with 24 plates in color, 96 full-page half-tones and over 4,000 text illustrations. To be complete in six volumes. Each volume: Cloth, $6.00; Leather $10.00. Sold only in sets by subscription. Two opinions of Volume I of the new Cyclopedia: "No one who knows anything at all about the literature of garden- ing needs to be told that the Cyclopedia is unique. It is the Bible and Britannica of the garden-folk, amateur and professional ahke. And the remarkable thing is that, while it is fundamentaly a work of reference, it also contains hmitless quantities of good reading of the sort dear to the heart of the garden enthusiast." — The Nation. "It is no exaggeration to state that Bailey's new work is the best cyclopedia obtainable for all who are connected, either remotely or intimately, as amateurs or professionals, with horticultural pursuits. It is the best for the student of botany who is investigating the subject in a purely scientific way; best for the commercial grower who hkes to be well informed on matters in general and his own trade in par- ticular, and best for the other sort of commercial grower, who does not bother himself particularly about hunting for any information except such as will give him immediate help in producing a better crop." — The Florist's Review. THE MACMILLAN COMPANY PUBLISHERS 64-66 Fifth Avenue NEW YORK ?l I m University of British Columbia Library DUE DATE 1 ^ JR!' - r s Xffi '5 __ wm* 5> ^ RBW 4 ^^5»- ' FORM 310 ' rsr 03 > FORESTRY AGRICULTURE LIBRARY iilli