f\\1'*t' ' IS U.S. DEPARTMENT OF AGRICULTURE, BUR] Ai OF PLANT IND1 STRY I ircular No. 46. B. r. ■■ W.U'WAY, Chief of Bureau. THE LIMITATION OF THE SATSUMA ORANGE TO TRIFOLIATE-ORANGE STOCK. WALTER T. SWINGLE, Physiologist in Charge <>i- Crop Physiology \m> Breeding I \\ estigations. WASHINGTON : GOVERNMENT PRINTING OFFICE : 1600 r-affi&ii^ U.S. DEPOSITORY BUREAU OF PLANT INDUSTRY. Chief of Bureau, Beverly T. Galloway. Assistant Chief of Bureau, Albert F. WOODS. Editor, J. E. Rockwell. Chief Clerk, James E. Jones. [Cir. 46] 2 B. r. i THE LIMITATION OF Fill-: SATSUMA ORANGE TO TRIFOLIATE-ORANGE STOCK. INTRODUCTION. The Satsuma orange is a variety which has come to be widely grown in the warmer parts of the Gulf States. Without entering into a discussion as to the merits and demerits of this variety, it is proposed in this circular to call attention to the fact that unlike most commonly grown varieties it succeeds onlj when grafted on Trifoliate- orange >tock and is a complete failure on the sour-orange stock upon which almost all other citrus fruits can be grown successfully. In view of the fad thai large experimental and even commercial plantings of the Satsuma orange are being made in nearly all of the Gulf States and that Satsuma trees are being offered for sale on sour- orange stock, it is considered advisable to call at tent ion to t he certain failure which will result from planting Satsuma oranges budded on sour stock. Fortunately a simple method has keen discovered for identifying with certainty Trifoliate stock, which makes it easy to guard against the fradulent substitution of sour-orange or any other stock for t he Trifoliate. HISTORY OF THE TRIFOLIATE ORANGE IN THIS COUNTRY. Growers of citrus fruits in this country have long keen accustomed to use the sour orange and the sweet orange as stocks, while in recent years the rough lemon and to a lesser extent the grapefruit have come into use. These show widely different adaptation to soil conditions, as well as greatly varying powers of disease resistance. Among the stocks which have come into prominence during the past few decades is the hardy Trifoliate orange of China and Japan. '■ During the las! few years then' have been extensive plantings of the Satsuma in the warmer parts of the Gulf States. Withoul entering into a discussion his variety and the prospects for growing and marketing ii suci full - mmercial scale, Mr. Swingle call attention in the present cir- cular to the unusually .-harp limitations of this variety to i the Trifoliate orange. It is believed to be desirable to warn all who desire to tesl the variety against purchasing trees budded on the sour orange, a sb kably well adapted toaln all other kinds of citrus fruits, but which Mr. Swingle finds to fail entirely for this particular variety. mple method i<>r distinguishing the Trifoli from all other stocks in points! out, rendering it easj to protect purchasers of Satsuma oranges against the titution of sour-i ["rifoliate stock.— B. T. Galloway, ( eau. [Cl« 3 LIMITATION OF SATSUMA ORANGE. Pig i -a fruiting branch n r the Trifoliate orange (Natural size.) 1.1 M ! I \ HON OF SATSU tfA ORANi This was introduced into this country by the Department of Agri- culture in L 869 and was at first little more th itanical curiosity. Ii was soon Found to be an excellent bedge plant in the South, and even as far north as Washington, D. ('.. and for many years it was grown for this purpose. The fact that it is able to withstand without injury temperatures as low as zero Fahrenheit, or even lower, makes it suitabli for culture ovei nearly half the area of the United Mates. Those forms of the Trifoliate orange which have fully deveL flowers are handsome ornamentals, especially when they blossom in the spring and again when laden with fragrant yellow fruit in the autumn. Unfortunately many of the Trifoliate orange trees grown in i lii- country do not develop their flowers perfectly, or, at least , not all of t heir flowers, t he petals being stunted and shortened by gland- like growths on the edges near the base. The flowers arc shown natural size in Plate I. A fruiting branch is shown in figure I. and fruits in cross section and in longitudinal section in figures 2 and '■',. hi of a fruit of the Trifoliate orange. (Natural size.) Fig. 3.— Longitudinal section of a fruit of the Trifoli (Natural size.) It would he very easy, however, to breed up a large-flowered race of the Trifoliate orange that could be propagated very rapidly and cheaply from t he superabundant seeds that (ill the fruits. The Trifoliate orange has been used for ages in China and Japan as a stock upon which to hud the cultivated citrus fruits, and about the middle of the last century it was broughl to notice in England as a stock for the kumquat. This latter species itself was, bowever, only a curiosity, and apparently very lew experiments were made in Europe with the Trifoliate orange as a stock for oranges, lemons, and other common citrus fruits. About a quarter of a cent ury ago t be Trifoliate orange began to he used in this country i ck for the Satsuma orange, as well as for other citrus fruits. It w as found that all grow well on this stock, and that it had a tendency to force early and profuse bearing, at the same time dwarfing the tree somewhat. [Cir. 40] 6 LIMITATION OF SATSUMA ORANGE. Although the Trifoliate is naturally a small tree and of slow growth, when used as a stock its growth is so stimulated that its diameter always continues greater than that of the scion. This disparity in size, while not sufficient to make the union a poor one, makes it easy in walking through a grove of citrus fruits budded on this stock to detect the point of union of the scion with the stock because of the abrupt increase in diameter of the latter." The Trifoliate-orange stock has one disadvantage in comparison with sour-orange, sweet-orange, and other commonly used stocks — it does not sprout readily from the root if the top is killed by a severe frost. For this reason varieties grafted on Trifoliate roots and grown where there is danger of occasional severe freezes should always be earthed up a few inches above the point of insertion of the bud, so that in case the top is killed by a severe freeze the budded variety can be reproduced by sprouts issuing from that part of the trunk which is protected by the earth. If this precaution is neglected there is danger of orange trees grafted on Trifoliate stock being killed out- right, root 6 and branch, by an unusually severe winter. THE KUMQUAT SUCCEEDS BEST ON TRIFOLIATE-ORANGE STOCK. There are very few varieties of citrus fruits that do not succeed on the Trifoliate stock, provided, always, the soil is adapted to the stock. Some varieties succeed better on this stock than on any other. Per- haps the most striking example of this is the kumquat, which is the hardiest of the evergreen citrus fruits. On Trifoliate stock it bears heavy crops of fruit while still a mere hush. On the other hand, the kumquat is not adapted for budding on sour- orange stock, and such buds often fail to grow, or even die, alter they have started to push, something very rare among citrus fruits.' THE SATSUMA ORANGE A FAILURE ON SOUR-ORANGE STOCK. Another variety of citrus fruits that behaves very differently on the various stocks is the Satsuma, a very early orange of t he mandarin class introduced from Japan, where it is known as 1 he Unshiu. This variety, which is the earliest and at the same time one of the hardiest " Tli is form of union wherein the stock slightly outgrows the scion has been noticed also in the ease of the loquat grafted on the quince growing at Eustis, Fla. In this case, al ariety so grafted began t<> bear when still very young ami has borne abundant crops since. It is interesting to nolo that in both of these cases we have a ; i :■ ived evergreen plant grafted on a small leaved deciduous and □ >i verj closely related Bpecies. The contrary union, where the scion outgrows decidedlj the stock, is apparently not satisfactory, the scion being likelj to break off and being usually I lived, even w I capes being broken ■ ''The Trifoliate root, strictly speaking, is not. killed outright, but as it produo sprouts it. soon dies from starval ion. < l'i i these facts the writer is indebted to Mr, < .. 1.. Tabor, of Glen St. Mary, Fla [Cir. 46] . Plate A Flowering Branch of the Trifoliate Orange, Showing the Flower Fully Expanded before the Leaves Appear. iNatural Size. Digitized by the Internet Archive in 2013 http://archive.org/details/lisatsOOunit LIMITATION 01 SATSUMA OB INGE. 7 of the oranges," grows \er\ well on sweet-orange stock — better, in fact, than on the Trifoliate orange on most soils- but the fruit is of decidedly inferior quality on the former stock, being coarse, dry, and insipid, besides ripening later than on the Trifoliate stock. ( >n the sour orange the Satsuma is a complete failure, the growth being so slo'w and stunted that it never becomes more than a dwarfed bush. The fruit that is borne by this stunted tup is of very inferior quality. There is every evidence of a considerable degree of incom- patibility between the Satsuma and the sour orange. It is no exag- geration to say that he who plants a Satsuma orange tree grafted on ir stock might better bury a live-dollar l>ill and burn the tree, which, if planted, will linger along for years, <>nl\ to be finally dug up as worthless. Enquiry among growers of Satsuma oranges in Florida. bama, Mississippi, Louisiana, Texas, and northern Mexico has failed to elicit a single instance of successful growth and satisfactory fruiting of this variety budded on sour-orange stock. The writer was stationed for five years in Florida investigating citrus fruits in all part- of the State, and during that time he never saw a vigorous Satsuma tree or any good crops of early-ripening fine-flavored Sat- suma oranges borne on trees budded on sour-orange stock. THE SATSUMA ORANGE BEST ADAPTED TO TRIFOLIATE-ORANGE STOCK. On the other hand, the Satsuma budded on the Trifoliate orange produce- fruits which ripen early and are of excellent quality . smoot h skinned, linn, and juicy. The trees budded on this stock are smaller than those budded on sweet-orange stock, hut they hear earlier and fruit more profusely. They also ripen their fruits earlier in the season and are decidedly hardier. The Satsuma orange is the only one of the commonly grown citrus fruits (besides the kumquat) which shows such marked differences in growth and character of fruit when budded on different stocks. Since the Satsuma orange can succeed on hut one stock, the Tri- foliate orange, it can he grown with hope of commercial success only "ii soils to which the Trifoliate stock i- adapted, namely, on fairly riil hat moist soils, preferably sandy soils with a clay subsoil. It i- almost impossible to successfully grow orange tree- budded upon Trifoliate stock on light, sandy -oil- such as make up the hulk of the -oil of southern Florida and parts of southern Texas. ! ia autumn, and, v ■ the lasl growth has hardened, the tree can endure a consid ither without b< .Hi. This high degree of winter dormancy is what renders i lie Satsuma r culture in the variable < limah As to the quality Phis is dm pari varying quality, depending on the stock upon which ii is budded nd climat « hen- it is grow a. LIMITATION OF SATSUMA OEANGE. Iii case the soil is not adapted to the Trifoliate orange, there is little hope of growing the Satsuma orange successfully unless some new stock not as yet known is found adapted to this variety and able to grow on light soils. As a last resort, grapefruit, citrange, or some other stock could be tested, but it is useless to set out trees of this variety grafted on sour-orange stocks. HOW TO DISTINGUISH TRIFOLIATE FROM SOUR- ORANGE STOCK. In 1887, Prof. Otto Penzig, director of the botanic garden at Genoa, Italy, published a very interesting account of citrus fruits for the Department of Agri- culture, Industry, and Commerce of the Italian Government. In the course of his investigations of the anatomy of the principal types of citrus fruits, he discovered a striking difference in the structure of the pith of the Trifoliate orange •eiis that make as compared with that of other up the imper- . ,, . . , feet cross CltlllS il'iuts." plates. (Mag- if a section be made lengthwise Fig. 4.— Longi- tudinal section of the pith of the Trifoliate orange, show- ing the thick- walled, pitted ni(ied50 diame- ters.) (Drawn of a stem or twig of the Trifoliate hy Dr. Theo. orange, the pith is found to con- tain rows of cells arranged so as to form more or less imperfect partitions some- what like the partitions in the pith of the wal- nut. Such a section of the Trifoliate orange showing the cross plates of thick-walled cells in the pith is shown in figure 4 to be contrasted with figure 5, showing the absence of any such plates in the pith of the sour orange. A few of the thick-walled cells winch make up the imperfect longitudinal cross partitions of the Trifoliate orange are shown under higher magnification in figure 6. Fig. .">. — Longitudinal sec- tion of the pith of the sour orange. Note i he nee of any thick- walled cells. (Magni- fied 56 diameters.) (Drawn by Dr. Theo. Uolm.) a The citrange is a hardy citrus fruit originated by the Department of Agriculture ssing the common orange and the Trifoliate orange. Citranges grow more vigor- ously than cither parent, and some varieties can be reproduced practicallj unchanged from the ihih.it.iuh seeds. Becau e of their vigor and their being half orange, cifc- ranges can be expected to thrive in soils too light for the straight Trifoliate. As the Satsuma oi ■■■ s rapidly on sweet orange stock and fruits well on Trifoliate slock, ii would probably succeed on the citrange, a hybrid of these two stocks. 6 Penzig, 0. Studi boi li agrumi e sulle piante affine, in ^nnali di Agricol- tura, L8S7, p. L37, pi. 13, fig. 6 (Ministero di Agricoltura, Endustria e Commercio). e, L887. [Cir. 46] LIMITATION CJMA ORANGE. 9 Fig. 6.— A i thick-walled cells from the pith ofthe I nified 372 diameters.) I Drawn by l> Bolm.) A longitudinal section of the pith of the sour orange is shown in figure 5. li will be noted thai there is an entire absence of cross partitions, and there arc no thick walls to be seen. All of the ordi- nary types of citrus fruits, including the sour orange and all that arc ever used as stocks in this country, have pith of this character without any trace of cross partitions built up out of thick-walled cells. These peculiar cells are of such a striking character as to make it easy, l>v using a low-power microscope, t o distinguish between Trifoliate and sour orange stocks in fact, to dis- tinguish Trifoliate-orange from any othercitrus stock « ii h absolutecer- tainty. To make such an examina- tion it is of course necessary to take out some of the pith of the stock. In the case of nurserj stock this can even be done, if desired, without killing the plant, since a cut extending half way through— necessary to take out the pith- will soon heal up. WARNING AGAINST THE PURCHASE OF SATSUMA ORANGES ON SOUR-ORANGE STOCKS. In >pite of the fact that Satsuma oranges budded on sour-orange stock are known to be a total failure, some nurserymen have budded them largely on this stock and are even offering them for sale on round thai the Trifoliate stock <\<>vs nol succeed on light, sandy soil, whereas sour-orange stock does succeed in such -it nations. All tin- is perfectly true, hut no mention i- made of the additional and very important qualification that the Satsuma orange budded on sour-orange stock i- perfectly worthless from a commercial point of view on au\ soil. In \ iew of these facts, this occasion is taken to urge intending purchasers of Satsuma oranges to insist thai they be budded on Trifoliate-orange stock. In no case should they be accepted mi sour-orange stock. If the experiment is to be made of growing S.-ii^' oranges in a region where the soil is light, especially in south* i Florida and southern Texas, it may be wort h while to experi- ment with the Satsuma on certain other stocks, such as grapefruit or seedling citrange, but there is little hope for financial success in growing Satsuma oranges in such situations. [Cir 10 LIMITATION OF SATSUMA ORANGE. In order to make it possible for orange growers to be sure that they are getting plants grafted on Trifoliate-orange stock, the De- partment of Agriculture will undertake temporarily to determine, free of charge, whether or not nursery stock of citrus fruits is grafted on Trifoliate-orange stock. It is hoped that this method will be adopted by state horticultural inspectors and by stale experiment stations, as well as by growers themselves. It is the purpose of this temporary offer of the Department to make known the possibility of distinguishing readily whether or not the stock used is the Tri- foliate orange. SUMMARY. It is not the purpose of this circular to discuss the merits or demerits of the Satsuma orange or to attempt to define the regions in which it can be grown with reasonable hope of success. The Satsuma orange is almost a complete failure on sour-orange stock on any soil and in any climate, ami succeeds well only when budded on Trifoliate-orange stock. It can be grown, but less suc- cessfully, on sweet-orange, grapefruit, ami perhaps rough-lemon stocks. The Satsuma orange, being limited to the Trifoliate-orange stock, can be grown with reasonable hope of success only on soils to which this stock is well adapted, namely, fairly rich, fairly heavy soils, preferably with a clay subsoil. Purchasers of Satsuma orange trees should insist that they be grafted on Trifoliate-orange stock, and to protect purchasers against substitution of trees grafted on sour-orange stock the Department of Agriculture will undertake for the present to determine whether or not the stock is Trifoliate orange. Do not buy Satsuma oranges budded on sour-orang< stock! If you suspect substitution, send a, sample to the Department of Agriculture for determination. Approved : James Wilson. Secretary of Agriculture. Washington. 1). ('.. December 6, 1909. [Cir. 46] o UlNIVbKbllY Ul- l-LUKIDA 3 1262 08928 9713