Historic, archived document Do not assume content reflects current scientific knowledge, policies, or practices. Te ; iat teu Dix cae NVA ae ra ls | Circular No. 278, my: Pirie, CURR ia ; cy RAR pod Fruits, Vegetables, and Florists’ Stocks DEAN H. ROSE, Senior Physiologist « R. C. WRIGHT, Physiologist T. M. WHITEMAN, Assistant Horticulturist Division of Fruit and Vegetable Crops and Diseases Bureau of Plant Industry Agricultural Research Administration PELL PLAGE LAELIA IAG ALE AG GOLD LDA GEE tg NEU ALMGIOGE GIP EN ASST EAE Sis Tie Ta 8 OG) For sale by the Superintendent of Documents, Washington,D.C. - - - + +--+. - Price 10 cents UNITED STATES DEPARTMENT OF AGRICULTURE WASHINGTON, D. C.. DECEMBER 1942 Circular No. 278 September 1933 * Washington, D.C. Revised November 1941 > Slightly revised December 1942 UNITED STATES DEPARTMENT OF AGRICULTURE The Commercial Storage of Fruits, Vegetables, and Florists’ Stocks By DrEAN H. ROSE, senior physiologist, R. C. WRIGHT, physiologist, and T. M. WHIIEMAN, assistant horticulturist, Division of Fruit and Vegetable Crops and Diseases, Bureau of Plant Industry, Agricultural Research Administration’ CONTENTS Page | Vegetables—Continued. Page Imitroductioneteeee ses Mer Is See AUT 2 Broccoli (Italian or sprouting) _._-_.___._- 29 Factors involved in cold storage__------_----- 2 IBnuSSeIS|SProltsisete ee eee ee See 29 Temperature of storage rooms-_-_-_--------- 3 Cabbage): Etgek 54 by CET kA RIEL eS ey 29 Humidity of storage rooms_-_-_------------ 4 Carrots ee alse aera ee ee 30 Evolution of heat by commodity ____-_-_- 6 Caulifigwere eeee Ate ee ee 31 Effect of cold storage on subsequent behavior Celeriagict 2 ei ees ws Oe Be Te 31 Ofiniitsiand vesetablestes seen see 10 Celery. fos ee ee eR Se 31 SWAN en eke LEE 10 Corny(ereen) ees ee et 32 WVIAXIT Ooo En as ek el POE le 11 Cucumbers). 3 ee eet 32 Choice of storage conditions_____-_------------ 11 1 Fee ay eWay ee a Net ear eam TE A 32 Hirtitsandmnutse = seen et eee eee 11 Endive or escarole___-_-______-_--_-_-_-__. 33 JAS O} 0) SS eee TR ae Se ee Be Oe a 12 Garlici(Gry) pee sen ee Ee ae oe 33 ATI eCOtShe ee 2 ee ET CS Cee a 14 orseradisha les l peace a WE al Dee eae 33 IASVO CACO Sis a oto ete Ba 14 Jerusalem-artichoke..-....2.-__-..--____- 33 NS VTA YG eerie oe Pn ne He BE Saleen a ae 15 Kohl rabies ae a ee Rene eae 33 IBLaCksDernies stake Seas oh as Tey ye 15 Weeks! (green) it ss2e. Sa eee es eee o 34 Cherries t Faia eee S02 ee Rae ae 15 1 OIA AD Yo, cwiers Seana Rute era oe gees 2c WDE ae Wee 34 Coconuts#2 2 See iO Tas 16 IMelons=t atu 2) ars oe) Fey ea ea 34 Wranberricghi. oie ee NOS, ta 8s 16 Mushrooms (cultivated) ......-..--.------ 35 HD ALCS ie wee eRe ee ht Ae Se MR Aor S 17 Onions and onion sets___------_---------- 35 IDS WADOLTICS ee meee a ea toe ee aL 17 IP arsTil Poesia cena ee a ek emies 36 Grapeirititueeisrt et oe eee 17 Peas (Steen) sass ok ee ee Sie eee 36 Grapes 2st 23 So Aes Oe Et a 18 IPOD DCrS ea 0 ee ee ee 37 GOTT O MS Brae ema ae eters een ete 19 IPOtRLOES so rene eee ee eee 37 Il CS eee nee eS ee Re See 20 Pumpkins and squashes__-__-------------- 38 Kozan blackherriese =o 525 (eee er 20 Radishes: Gyinter)ss eee eee oe ee eee 39 Ohivest (fresh) tae eee ee Se ee ee 20 AW bar biases ES Der aa lel 39 Orangesererseb weit olen 5s te eee ed ix, 21 Rutabagases sous aya ae AF Bias os eee 39 Reachests ) sweat ches AEN tee 21 SaISifiv ieee eae Os Ce ey cee ee eee 39 e@ai Ses Shee te Pees Sek ih eed 22 Spinachijs obs fee fel teat see 39 IRINCADDLOSse ane eee eee au eee 23 Sqtdshos sie ses ae EPS eae caer 39 Plums (including prunes) -_-__---__--_____ 24 Sweet potatoes ta oe seeio 2 we ee ee 39 Qiincesteeee re et SS ees eee ey eee 73 24 MoMAtOes =a ese es oo eae ae 40 RSP Denese eee ee otek ee ee heed 24 TMAPNMIDS co et = eee totam hese 40 Strawberries) ss Soe 5k i eee 24 Hrozem vegetables: 212th site a Fears 40 Driediiniitseee see 2 se eee Te 25 | Cut flowers, florists’ greens, rhizomes, tubers, Frozen fruits and vegetables__-_...__.____ 25 Cormissand bulbseee te ee eee 41 INGUIUS)= 3 ebay 9 pres as sores Oa 2d hosed ela ent 25 Cut flowers: 2.29: 22 a et = ae oe oe 42 Wegelablesene s auto Sec SE oe 26 MlonistSwereensee nee soe ery eee anne 45 ASPARAGUS! tee Ese. 2- Avi Ee ee N 27 Rhizomes, tubers, and corms------------- 46 EB GANS RM aes ee ee ene eae are 28 B til seca eee Sake a) a Ree eee 46 BER is eee ee ei dne een: 2 TAI Aide BSED osiiteratureicited.]-22_ --- tility eee 47 1The writers not only have included results of their own investigations but also have drawn freely on published and unpublished results of other staff members, whose assistance and cooperation have done much to make possible this publication in its present form. Acknowledgment for unpublished information furnished on refrigeration or commodities indicated is due the following members of this Division: W. R. Barger, dates and dried fruits; C. O. Bratley, limes and pineapples; Fisk Gerhardt, A. L. Ryall, and W. H. English, pears; C. W. Mann, lemons; W. T. Pentzer, refrigeration, garlic, olives, pears, and peppers ; Edwin Smith, refrigeration, apricots and pears. Acknowledgment is also due E. B. Lambert, Division of Mycology and Disease Survey, mushrooms; and J. N. Kelley, Fruit Dispatch Co., bananas. Special acknowledgment is made to D. F. Fisher, of this Division, for valuable Sub cesttous and criticisms throughout the preparation of this and earlier editions of the circular. 824484°—41—___1 a Le 2, CIRCULAR 278, U. S. DEPARTMENT OF AGRICULTURE INTRODUCTION The purpose of this circular is to present a series of brief sum- maries of the essential average storage requirements of most of the more important varieties of fresh fruits, vegetables, cut fiowers, and certain other perishable commodities that enter the market on a commercial scale. Many details are of necessity omitted, as the work is intended primarily for general practical reference. The conditions given should not be considered as absolute or final, but rather as the safe limitations under which the various products can ordinarily be stored. Detailed information on the handling and storage of some of the commodities discussed is available elsewhere in the form of bulletins or textbooks; for many of them only general information exists. Fresh fruits, vegetables, cut flowers, etc., intended for storage should be as free as possible from skin breaks, bruises, and decay. They should be neither immature nor overmature, because in either case it may be difficult to keep them from too rapid deterioration, and even if they do not change appreciably in storage, they will not be commercially desirable when removed. The proper degree of maturity in each case can usually be determined by consulting the various sections of this circular or the other publications listed in Literature Cited (p. 47), or on the basis of previous experience. There is a seasonal variation, however, in the storage quality of certain products, particularly fruits ; hence care must be taken not to assume too much from one year’s experience concerning the prob- able behavior of a given commodity grown the next year. Decay and other deterioration in storage is too broad a subject to be discussed in detail in this publication. It is discussed very gener- ally in connection with various fruits and vegetables covered by this circular and in greater detail in other publications (8, 9, 15, 33, 37, 39, Lh, 62, 67, 68, 70, VNR, US (obs Cll S54 O5., Gi, Os) FACTORS INVOLVED IN COLD STORAGE Recommendations for the best conditions for the storage of fresh fruits, vegetables, and cut flowers are subject to change from time to time as more definite information is gained in the handling of these commodities. The conditions and requirements given in this circular are derived from the best commercial practice at the present time and from scientific experimentation. The term “cold storage” as used in this circular refers to storage where temperatures in the approxi- mate range from 30° to 45° i. are maintained by mechanical means or by the use of ice and salt; in “freezer storage,” temperatures are maintained within the range ‘Eom about 15° to —20°, usually close to 0°; “cool storage” refers to storage in the range from about 50° to 65°, or possibly 70°; in “onrefrigerated storage,” temperatures in- side the storage space are allowed to fluctuate with outside tempera- tures; in “common storage,” the temperature best suited for the com- modity 3 is obtained as nearly as possible by insulation and ventilation only. All of the temperature requirements are given in degrees Fahrenheit 2 Italic numbers in parentheses refer to Literature Cited, p. 47. STORAGE OF FRUITS, VEGETABLES, AND FLORISTS’ STOCKS 3 and represent the average air temperatures that should be maintained. The humidities are relative and are expressed in percentage of satura- tion; for example, when it is stated that a certain humidity should be 85 percent, this means that the air should be at approximately 85 per- cent of complete saturation with water vapor at the recommended temperature. Allowance has been made for the facts that the tem- perature of fruits and vegetables in transit is usually higher than the recommended storage temperature and that, except during winter weather, ripening or other changes are likely to go on more rapidly during a given transit period than during the same length of time in cold storage. ‘TEMPERATURE OF STORAGE RoOoMsS If the best results are to be obtained in the cold storage of the prod- ucts discussed herein, it is highly important that the temperature in storage rooms be held fairly constant. Variations of 2° or 3° F. above or below the desired temperature are in most cases too large. They can usually be avoided if the storage rooms are well insulated throughout and have adequate coil surface and if the spread be- tween the temperature of the refrigerant and that of the room to be refrigerated is kept small. For example, in a room where 45° is the desired temperature, using ammonia evaporating at about 26° in the coils, fluctuations of +11/4° may occur in the air temperature in the room; whereas at 32°, with ammonia also at 26°, fluctuations in the room temperature are usually less than +1/° . However, the spread between the temperature of the refrigerant and that of the room is more important in maintaining humidity than in pre- venting fluctuations in the room temperature. This point is dis- cussed in more detail on page 4. Storage rooms should be equipped either with reliable, accurate thermostats or with means for manual control which are ‘given frequent personal attention by someone charged with that duty. Even when reliable automatic controls are used, they should be checked periodically by some responsible person. In commercial cold-storage rooms thermometers are usually placed at a height of about 5 feet, sometimes slightly lower, for con- venience 1n reading. It is important, however, to take temperatures frequently at the floor and the ceiling also, and at any other places where they might be expected to be undesirably high or low. In providing recommended temperatures for given products, considera- tion should be given to differences between the temperatures of the air at the position of the thermometer and at different places around the packages of the stored product, and also to differences between air and commodity temperatures. Often the packages are piled too closely together, or distribution of refrigeration 1s inadequate to reach all parts of the piles of the stored “commodity, and it 1s not unusual under such conditions to have commodities remain for sev- eral days or even weeks at temperatures several degrees higher than those indicated by the thermometer. This condition can be detected by opening the pile and taking commodity temperatures and can be corrected by wider spacing of packages and the use of portable fans and baffles for the direction of air currents to the centers of 4. CIRCULAR 278, U. S. DEPARTMENT OF AGRICULTURE piles. The installation of such equipment will also be useful in pre- venting dead-air pockets that are hard to cool, especially in rooms cooled direct expansion coils or by brine coils and without means for air circulation. The importance of maintaining fairly constant temperatures in cold-storage rooms lies in the effect of such control, or the lack of it on the keeping quality of stored commodities. Most varieties o apples keep best and longest if held constantly at 30° to 32° F.; the best temperature for Bartlett pears is between 29° and 30°. If the air temperature where either of these fruits is stored rises 2° or 3° above the upper limit mentioned, there is danger of increased decay and undue ripening, the danger being greater the longer the period during which the temperature is above 32°. For example, 3 or 4 days at 35° usually would have little or no effect, partly because of a, slower rise in the temperature of the fruit than in that of the air; but 10 days at. this temperature would probably shorten the life of the fruit by about a week and possibly result in more decay. On the other hand, if the temperature goes a degree or two below 29°, there is a chance that freezing will occur. Celery and cabbage al- lowed to remain too warm in storage may show yellowing and decay; potatoes are likely to begin to sprout if the temperature is too high and usually become undesirably sweet if it is too low. Other com- modities undergo these or other kinds of deterioration if the tem- perature variations throughout long storage periods exceed the limits given for them in this circular. In addition, there is always the possibility that fluctuations in temperature will cause condensation of moisture on stored products, which in itself is undesirable because it favors the growth of mold and the development of decay. Control of temperature is usually easier in large rooms than in small ones if both are filled to capacity. This is because of the “fly- wheel” effect produced by the larger mass of material, including both the commodity and the building material. Refrigeration is thus stored up, so to speak, and temperature changes occur more slowly. For this reason small storage rooms generally will require closer attention than large ones. Humiupity oF SToRAGE Rooms The relative humidity of the air in storage rooms has a direct relation to the keeping quality of the products held in them. With only a few exceptions (see especially onions), the most desirable con- dition is that in which the humidity of the air in the storage room is kept at approximately the moisture content of the produce stored therein. If it is too low, wilting is likely to occur in most fruits, vegetables, cut flowers, etc.; if it is too high, it favors the develop- ment of decay, especially in rooms where there is considerable varia- tion in temperature. The exact control of humidity is rather diff- cult, however, and in the past was not often attempted in commercial storage warehouses. However, at the present time new plants are being designed and old ones changed over in such a way that a foun- dation for humidity control in cold storage is being developed. Sufficient refrigeration, whether coils or brine spray, is provided so that the room can be operated with only a small difference in tem- STORAGE OF FRUITS, VEGETABLES, AND FLORISTS’ STOCKS 9) perature between the refrigerant and the air of the room, thus rais- ing the dew point of the air and its relative humidity. This permits the maintaining of high humidity. For low humidity the tempera- ture of the Ba BET is lowered. To build up humidity quickly in cold-storage rooms some operators evaporate water from insulated open-top tanks equipped with insert electrical heaters. Others use a fan to beat water into very fine particles, and to blow this spray into the room. These humidifiers are sometimes made automatic, connecting with humidistats. However, if the coil temperature is too low, that is, if the spread between the temperature of the refrig- erant and that of the room is too great, the effect of these various measures will be short-lived. The relative humidity will soon become undesirably low, and harmful drying out of the stored product wiil occur. When warm products are placed in a cold room the spread between commodity temperature and refrigeration temperature is wide at. first. Such a condition hastens cooling-and shortens the time during which undesirable changes can occur in the commodity. As the spread is reduced, the cooling proceeds more and more slowly. Eventually, if the temperature of the refrigerant is properly adjusted and there 1s adequate refrigerated surface, the desired temperature can be reached without subjecting the commodity to excessive desic- cation. If it could be successfully managed under commercial con- ditions, a temporary reduction in refrigerant temperature below what is desired or safe for long-time operation would be extremely helpful in shortening the initial cooling period. Operators of certain large cold-storage houses have found that when a room is filled with apples or celery, for example, the relative humidity soon becomes constant at a fairly definite level, which for- tunately is about the optimum for the particular commodity con- cerned. The same result has been observed with other commercially important fruits and vegetables and probably is obtained in many of the larger, well-constructed cold-storage warehouses of the country. This is probably due to the fact that when a storage room is nearly full and there is comparatively little air space left the pull on the moisture in the produce is less, and it is easier to maintain the desired humidity. In these cases, however, it must be assumed that the spread between coil temperature and air temperature is kept narrow. For most fruits that are stored commercially the statement is true that a relative humidity of 80 to 90 percent gives the best results. Exceptions are discussed at various places in the text. For leafy vegetables and root crops the relative humidity should be about 90 to 95 percent; for other vegetables, except as noted in the text, 85 to 90 percent. If it seems necessary to increase the relative humidity in rooms used for common or air-cooled storage, this can best be done by sprinkhng the floor occasionally. Earth floors are more desirable in air-cooled storages than floors of concrete because they are more easily kept damp. An increase in air circulation calls for an increase in relative humidity, if wilting of the stored commodity is to be avoided. Allen and Pentzer (2) found that doubling the rate of air movement increased moisture loss by about one-third and was equiva- lent to about a 5-percent drop in relative humidity. The drying effect of increased rate of air movement is particularly marked if the hu- midity of the air is lower than the moisture content of the commodity. 8 CIRCULAR 278, U. S. DEPARTMENT OF AGRICULTURE. It is difficult to determine the heat to be removed in cooling fruits and vegetables to cold-storage temperatures. This depends mainly on the following factors: The specific heat of the poe the rate at which it produces heat (by respiration), and its initial and final temperatures. If the product could be cooled to the storage tempera- ture instantaneously, the heat to be removed would be only the num- ber of British thermal units (B. t. u.) or calories obtained by multiply- ing the specific heat of the product by the difference between the initial and the final temperature, and this result by the weight of the product in pounds or kilograms. This is usually called the sensible heat. The cooling process, however, requires time, and during this interval additional heat is produced by the respiration of the stored fruit or vegetable. In order to determine the amount of this additional heat it is necessary to know the rate of heat production at any temperature and the length of time the product is in each temperature range. For example, if the respiration rate (or rate of heat production) for a given commodity is twice as great at 70° F. as at 50°, the number of hours this commodity is at each of these temperatures must be known before the total heat produced can be calculated. When fruits and vegetables cool, the rate at which they produce heat decreases, and the total heat produced depends not only upon the time required for cooling but also upon how long the commodity stays in each tem- perature range. Table 2 shows the approximate amounts of sensible heat and of heat produced by respiration which must be removed from eight varieties of five kinds of fruit in cooling them from various tempera- tures to a temperature of 35° F. These figures are based on experi- mental determinations of the rate of respiration at various tempera- tures; some of the data are from the tables given by Magness and his associates (44, 46), and the remainder from data reported by Haller et al. (30). The aguas for Bartlett pears are based on the maximum values given by Magness and Ballard (44). The figures given in this table have been obtained by assuming that the heat of respiration is produced by oxidation of a hexose sugar and can be calculated from the rate of production of carbon dioxide, which has been determined experimentally; very few calorimetric measurements of heat produc- tion by fruits and vegetables have been made, and this assumption seems to be the best available basis for calculating heat production at any given temperature. Recent investigations (26) indicate that calculations made on this assumption give values that are within 10 percent of those obtained calorimetrically. ‘The assumption has also been made, although it is believed to be only approximately correct for fruits and vegetables, that the rate of temperature drop at any given time during cooling is proportional to the difference between room temperature and fruit temperature at that time. With this assumption as a basis, the temperature and thus the rate of respiration at any time during the cooling period, as well as the total heat produced during the whole cooling period, have been calculated.® ® The authors wish to acknowledge the valuable assistance given by W. V. Hukill, of the Bureau of Agricultural Chemistry and Engineering, in making the calculations and in pre- paring this statement on the production of heat by fruit and vegetables. STORAGE OF FRUITS, VEGETABLES, AND FLORISTS’ STOCKS 9 As a result of these calculations it has been found that the heat produced by the respiration of fruit while it cools is directly pro- portional to the length of the cooling period. The figures for cool- ing periods of 3, 4, 5, 6, and 8 days are therefore set at 3, 4, 5, 6, and 8 tenths (to the nearest thousand) of the figure for 10 davs. The specific heat has been calculated by the formula S=0.008 a+ 0.20, in which S signifies the specific heat of a substance containing @ per- cent of water; 0.20 is the value that has been assumed to represent the specific heat of the solid constituents of the substance in question (74). TABLE 2.—Approximate amounts of heat of respiration and sensible heat to be removed from certain fruits in cooling them from 60°, 70°, or 80° to 35° F.ina room at 82° F., when the cooling takes place in 3, 4, 5, 6, 8, or 10 days Heat of respiration per ton of fruit during— Initial : Kind of fruit tempera- |————____ ——_ ——__———_ eeugtble ture 3days | 4days | 5days | 6days | &days | 10 days Apples: SE. B.t.u. Batis B.t.u. B.t.u. IBACSat: Boe. B.t.u. 80 8, 000 11, 000 14, 000 16, 000 22, 000 27, 000 80, 000 Winesap_-__-_-__- 70 7, 000 9, 000 12, 000 14, 000 19, 000 23, 000 62, 000 60 6, 000 8, 000 10, 000 12, 000 16, 000 20, 000 44, 000 70 10, 000 13, 000 17, 000 20, 900 26, 000 33, 000 62, 000 60 8, 000 11, 000 13, 000 16, 000 21, 000 27, 000 44, 000 Peaches: 80 13, 000 18, 000 22, 000 26, 000 35, 000 44, 000 80, 000 80 12, 000 16, 000 20, 000 24, 000 32, 000 40, 000 80, 000 Grimes Golden_- Hibertass 22s" 70 10, 000 13, 000 17, 000 20, 000 26, 000 33, 000 62, 000 60} 7,000 10. 000 12, 000 14, 000 19, 000 24, 000 44,000 80 16, 000 22, 000 27, 000 32, 000 43, 000 54, 000 80, 000 Carmantes2 2252. 70 13, 000 17, 000 21, 000 25, 000 34, 000 42, 000 62, 000 60 10, 000 13, 000 16, 000 19, 000 25, 000 32, 000 44, 000 Pears: 70 16, 000 22, 000 27, 000 33, 000 44, 000 54, 000 61, 000 Bartlett==-2s-s=" 60 13, 000 17, 000 22, 000 26, 000 35, 000 43, 000 43, 000 Strawberries: 80 30, 000 39, 000 49, 000 59, 000 79, 000 99, 000 83, 000 Chesapeake 70 24, 000 32, 000 40, 000 49, 000 65, 000 81, 000 64, 000 ES eee 60 19, 000 26, 000 32, 000 39, 000 51, 000 64, 000 46, 000 80 38, 000 51, 000 64, 000 77,000 } 102,000} 128,000 83, 000 Howard 17__-__- 70 31, 000 42, 000 52, 000 63, 000 84,000 | 104,000 64, 000 ~ 60 25, 000 34, 000 42, 000 51, 000 68, 000 84, 009 46, 000 Oranges: 80 9, 000 12, 000 15, 000 18, 000 24, 000 30, 000 81, 000 Florida seedlings? 70 8, 000 10, 000 13, 000 15, 000 20, 000 26, 000 63, 000 : 60 6, 000 9, 000 11, 000 13, 000 17, 000 22, 000 45, 000 1 For any one kind of fruit at a given temperature these figures are assumed to be the same for all cooling periods included in the table. 2'The rate of respiration is practically the same for both Florida seedling oranges and California navel oranges. Column 1 of table 2 shows the kind and variety of fruit and col- umn 2 the temperature of the fruit at the time cooling started. in a room held at 32° F. The next column shows the amount of heat evolved by respiration if the fruit reaches 35° at the end of 3 days. The next five columns show the amount of heat if cooling to 35° re- quires 4, 5, 6, 8, or 10 days, respectively. The last column is the sensible heat (obtained by multiplying the specific heat of the fruit by the difference between initial and final temperatures and this result by the number of pounds in a ton). For any one kind of fruit at a given initial temperature, the specific heat is assumed to be the same for all the cooling periods included in the table. The values given in table 2 are only approximate. However, in view of the results of the investigation mentioned on page 8, it is believed that the two assumptions that have been made—namely, (1) that the heat of respiration is produced only by the oxidation of a 324484°—41—_2 10 CIRCULAR 278, U. S. DEPARTMENT OF AGRICULTURE hexose sugar and can be computed from observed amounts of carbon dioxide produced, and (2) that the rate of temperature drop is always proportional to the difference between fruit temperature and room temperature—probably lead to fairly accurate results. The figures are presented to help cold-storage-plant operators estimate the quan- tity of refrigeration required for cooling the specified fruits under the various conditions given. As an example of how the figures can be used, the following calculation may be of interest: A ton of Bartlett pears cooling from 70° to 35° F. in 10 days in a 82° room is shown to be capable of producing about 54,000 B. t. u. Its sensible heat at 70° (85° above its final temperature) is 61,000 B. t. u. The sum of the two is 115,000 B. t. u. If this be multiphed by the capacity of the room in tons of fruit, say 600 (the capacity of some of the commercial cold-storage rooms in the United States) and divided by 288,000 (the number of British thermal units in a ton of refrigeration); the quo- tient 239 is obtained; this is approximately the number of tons of refrigeration required to cool 600 tons of Bartlett pears to 35° in 10 days under the conditions specified. The corresponding figure for Winesap apples is 177 and that for Grimes Golden apples, 200. EFFECT OF COLD STORAGE ON SUBSEQUENT BEHAVIOR OF FRUITS AND VEGETABLES The belief is rather common among those concerned with the mar- keting of fresh fruits and vegetables that commodities of this kind that have been in cold storage deteriorate more rapidly after removal fromm the low temperature than if they had been held at ordinary temperatures. It is difficult, however, to find a basis for judging whether or not they actually do so because there is no means known other than the use of low temperature for checking the ripening and decay so largely responsible for their deterioration—that is, it is impossible in the present state of knowledge to obtain fruits and vegetables that have not been refrigerated but still have not changed in any way since harvest, for comparison with similar lots that have been in cold storage and are eventually removed. However, so far as is now known, it is correct to say that for many fruits and vege- tables cold storage at or near 32° F’. is beneficial. Important excep- tions are bananas, sweetpotatoes, tomatoes, cucumbers, melons, and certain other horticultural products mentioned herein, the behavior of -all of which in storage is discussed later under appropriate headings. SWEATING When fruits or vegetables are removed from a low temperature to a higher one there is frequently a condensation of moisture from the air on the cool surface of the commodity. This is known as sweating and is more marked the higher the relative humidity of the outside air. It should be prevented whenever possible in the case of onions and the more tender fruits, because it favors the development of decay. This does not mean that when any of these products sweat after removal from an iced refrigerator car or a refrigerated room they are sure to decay; it does mean that they are more likely to decay STORAGE OF FRUITS, VEGETABLES, AND FLORISTS’ STOCKS lel than if they were dry after being unloaded and remained dry until consumed. In this connection dryness means merely the absence of liquid water on the surface. Sweating can be prevented to some extent, as in the British prac- tice with eggs and certain other commodities, by allowing the fruits or vegetables to warm up gradually. Under commercial conditions in the United States this is rarely practicable, however, and the best thing to do in very damp weather 1s to realize the risk, handle the product carefully, and get it into consumption without undue delay. WAXING The application of waxing preparations to certain perishable prod- ucts has been practiced commercially for several years. It probably started with the waxing of citrus fruits and was followed by the wax- ing of rutabagas. Its value for both of these products lies in the fact that it not only improves their appearance but also prevents shrinkage by restricting the loss of water. Recently waxing has been tried on a number of other products. In the case of cucumbers and carrots it gives considerable promise and may come into general use. It has been tried on cantaloups but did not prove to be beneficial. (See 65.) CHOICE OF STORAGE CONDITIONS The storage conditions recommended herein for certain commodi- ties represent either a compromise between two undesirable extremes of temperature or humidity or a choice of the least harmful of two such extremes. Grapefruit, for example, suffer less from decay at low humidities than at high; on the other hand, at low humidities they are subject to a pitting which, in fruit from regions where stem end rot is not prevalent, is usually more damaging to the market value of the fruit, because it is more common than decay. Therefore, it is recommended that grapefruit from all producing regions be held at 85 to 90 percent relative humidity in storage in order to reduce itting. ‘ The J onathan variety of apples suffers less from soft scald if stored at 34° to 86° F. than if stored at 32°. It is susceptible, however, to the more common and more serious condition known as internal break- down and also to Jonathan spot and decay if held continuously at temperatures above 32°; hence this latter temperature should usually be chosen as safer than any higher one. FRUITS AND NUTS By DEAN H. ROSE, senior physiologist The recommended temperature, relative humidity, and approximate length of storage period for the commercial storage of fresh, dried, and frozen fruits, and nuts are given in table 3. Detailed descriptions of these requirements are given in the text. 12 CIRCULAR 278, U. S. DEPARTMENT OF AGRICULTURE TABLE 3.—Recommended temperature, relative humidity, and approximate length of storage period for the commercial storage of fresh, dried, and frozen fruits. and nuts, and the average freezing points F F Average . Tempera- | Relative Approximate length of storage : commen ty, ture | humidity period freezing point ! Yat Percent oF. Applesvst ers ak Coke eee Re eR 230 to 32 S508 | (2) eee eee SS ame ey ee a 28. 4 APHiCOts #243 e eee. FS Ree Bo 31 to 32 OO Si] Wo) Aes 28.1 AV OCAd OSS 252 Saas AE eee (?) 85) Cor0 Ee se ee ee eee meen ree ean 27.2 Bananasi aise ieee eve ee 2 2 A) if SOU E Se See a ee SE (3) iBlackberrieste ses 3- ae ee 31 to 32 SOitO85s | Sisto lO days sass = ees 28.9 @hernies hess se ae eee eo ee 31 to 32 SOMOS | 1Ojton 4 daysee=== sana a ees (4) Cocontts== ete See eee eee 32 to 35 SOitO8h a slatoy2smont hse see eee 25.5 Craniberri cs iss caps ee aoa e a 36 to 40 80) COLOUR LatOna NON GNS as eae eee ene ee 27.3 IDS tes enon set ie ee eee Emer 28 to 32 (’) (2) eee ee ee ink E ces —4,1 IDE WDCLEIGS See ok ees ee ee 31 to 32 SOtOLSS ne tol O da yseen ae et ne elated Ss 6 ale ani. ane an. Grapeinuithss2-622-— eee (?) 85'to 90" | 6:08 weeksi-=---2. <2 ss 28. 4 Grapes: WVinhiferass sa Senet teks 30 to 31 $5)t0190) || s3)to Ganonthskee eas 24.9 JCM GTICANG eo. Sassen ot Sue 31 to 32 SO TOSS FOS wee kS eee ee ee 27.5 WSO TM OTTS Secs ge ee ees ae 55 to 58 HO Dal) Io Crmaoyel pa ee ee 28.1 f Py baal sce ie aes See eR PRE erg Soke eg nae 45 to 48 85)to:90) |/16\torsiweeks 2s Sie 29.3 Logan blackberries_-_------..---_-_- 31 to 32 SOS || uo UW) Ghia 29.5 Olivesi(iresh) Be = =e nes 45 to 50 85'to 90 |24:to6 weeks=2= ss 28.5 Oran eseie ete ee Se ee eae (2) S5ito90 | eSitopl Ohweekc ei =e ee (5) IPOS CHES Soe es aes ae ee oe terre 31 to 32 80)tO'S859|/\25t0r4 WeeksSsness sean eee 29. 4 Pears: IBALtlet tase Bae epee 29 to 30 SHiCOnQO ea) iss ee as See ries 28.5 Fal] and winter varieties______-_ 30 to 31 85'to190! |NG@) Ese see Pees rea aaa es (8) Pineapples: Mature oreene saa eee ee 50 to 60 85 to 90).| S3ito'4 weekses222 =e ee 29.1 1 295 oY pase aay a ease eae 40 to 45 85) to!905|22;to: 4.weeks=as==2= == oe ee 29.9 Plums (including prunes) __-----_-- 31 to 32 80)t0j854|\e3itor8 weeks)! = ee 28.0 QUIN CAS ea ee se See 31 to 32 80) to/85))|P2itoysnmonths Sse ee 28.1 Rasp berniesss. 2.5 ee 31 to 32 SOOSoa | evatoplOdayset= a= ae eee 29.9 SETA WD CELICS eee eee ee ei 31 to 32 80 to 85 |_____ (oa ees ee ES SB See ee Ot eat de 29.9 ID riedsicttits === ee 2 2 9;tosl2 months 25226 es | ee es IB TOZCNUMTU See eee ee ee ae (2) (?) Gito 1Zimonthsse S25 2es ee ee eee INUIT te es Sa EE eee Ee 232 to 50 65)to°75" | 8\to12);monthsf:222-) =e (2) 1 These figures are based on previously published work by Wright (101) and are subject to revision when- ever further investigation makes this necessary. 2 See text. 3 Green: Flesh, 30.2°; peel, 29.8°. Ripe: Flesh, 26.0°; peel, 29.4°. 4 Kastern sour, 28.0°; eastern sweet, 24.7°; California sweet, 24.2°. 5 Flesh, 28.0°; peel, 27.4°. 6 Winter Nelis, 27.2°; Anjou, 26.9°. 7 Persian (English) walnuts, 20.0°; pecans, 19.6°; and chestnuts (Italian), 23.8°. APPLES (Temperature, 30° to 32° F.; relative humidity, 85 to 88 percent) There is a wide variation in the storage quality of the different varieties of apples, and of the same variety grown in different re- gions. For example, McIntosh grown in the Middle Atlantic States 1s practically an early fall apple not suitable for more than 2 or 3 weeks’ storage, whereas if grown in northern New York or New Eng- land it can be held for as long as 4 or 5 months. Such varieties as Northern Spy, Baldwin, and Rhode Island Greening grown in the Cumberland-Shenandoah Valley district or in the hot, irrigated valleys of the Pacific Northwest behave like fall varieties and are short-lived in storage, although suitable for winter storage when grown in New England, New York, Michigan, and other northern producing districts. The keeping quality of apples in storage is also definitely related to the cultural and orchard sanitation practices of the grower, who alone is responsible for the production of sound, properly matured fruit. To have good keeping quality, apples should be mature and well colored. When they have reached this stage, they are less likely to scald in storage and are in better condition generally to be held in STORAGE OF FRUITS, VEGETABLES, AND FLORISTS’ STOCKS 13 storage for the maximum period than if they are either immature or overmature (46, 47). To insure soundness and good keeping quality, apples must be not only properly grown and at the proper stage of maturity, they should also be handled in all the operations of picking, grading, packing, and hauling with that degree of care necessary to prevent serious bruising, skin punctures, or other mechanical injuries; and they should be stored as quickly as possible after they are picked. Apples should not be handled while frozen, if such handling can possibly be avoided. Water core does not develop or spread in storage, and in varieties such as Yellow Newtown and Winesap it may actually disappear after a few months’ storage, especially if originally present only in a mild form. When large portions of the flesh are affected, especially in soft-textured varieties hke Jonathan, Delicious, Stayman Winesap, and Rome Beauty, there is danger of subsequent break-down, and prompt disposal of the fruit is advisable. The diseases of apples in storage are figeliared in Farmers’ Bulletin 1160 (9) and Miscel- laneous Publication 168 (77). For the storage of most varieties of apples the best results are obtained by maintaining a temperature of 30° to 32° F. and a relative humidity of 85 to 88 percent. However, as the storage temperature approaches the freezing point of the fruit the hazard of freezing increases unless the temperature is well controlled and there is good air circulation. Yellow Newtown apples from the Pajaro Valley, Calif., and McIntosh and Rhode Island Greening apples from New York should be held at 35° to 38° rather than at 32° to prevent the development of internal browning or brown core. Grimes Golden apples should be held at 34° to 36° instead of at lower temperatures (67) in order to avoid soggy break-down. It should be remembered, however, that at these higher temperatures the fruit cannot be held as long as when stored at 30° to 32°, because of the possible develop- ment of Jonathan spot and internal break-down. (See 10, 31, 61, 62, 63, 64.) If air-cooled storage is used, the temperature obtainable will usually not be much lower than the average of the prevailing outside tempera- tures. The nearer this is to 32° the better. The length of time apples can be held successfully in cold storage will vary with the variety and with the district where grown, as well as with their condition when harvested. Table 4 shows the normal or average storage period and the maximum storage period for the more important apple varieties when picked at proper maturity and stored immediately at 30° to 32° F. TABLE 4.—Normal and maximum Storage period for important apple varieties Storage period Storage period Variety — eS Variety Sey Normal | Maximum Normal |Maximum Months Months Months Months Jonsathane.n 4 2 se 2to3 Ara || es a wae See 2 see pe 3 to 5 6 to7 Grimes! Goldens sas = 2to3 4 || Stayman Winesap__________ 4to5 5 to6 Miclatoshiss.23 4." te. oF 2to3 AstO) On| lOLkelmnperiala-saee ee 4to5 5 to6 Golden Delicious___________ 3 to4 5 || Arkansas (Black Twig)____- 4to5 6 Cortlanda es aes ee 3 to 4 ON INOLLRERnS Dyanna 4to5 6 ID CliCiOHS: 22 34 ae 3to4 6) ||» Rome Beauty. === 2 4to5 6 to7 Rhode Island Greening_-___- 3 to 4 6s] | BenyD ayise ss ee 4to5 8 Yellow Newtown__________- 5 to7 8 Esap seat Let a 5to7 8 14 CIRCULAR 278, U. S. DEPARTMENT OF AGRICULTURE In determining when to remove apples from storage the dealer must, of course, consider the market, but he must also allow for the more rapid softening that takes place at the higher temperatures to which they will usually be removed. Investigations by the United States Department of Agriculture (46) have shown that apples soften approximately twice as fast at 70° as at 50° F., twice as fast at 50° as at 40°, and about twice as fast at 40° as at 32°, whereas at 30° the rate is about three-fourths that at 32°. Apples in cold storage should be inspected frequently, in order that they may be removed and sold while still in good condition. It is highly desirable that apples intended for storage be wrapped in oiled paper or packed in shredded oiled paper, in order to reduce damage by scald as much as possible (8). Apples should not be stored in the same room with potatoes because of the danger that the former will absorb undesirable odors. On the other hand, the odors given off by apples are readily absorbed by dairy products; consequently the two should not be stored in the same room. (See 9, 69, 76.) APRICOTS (Temperature, 31° to 32° F.; relative humidity, 80 to 85 percent) Apricots are not stored commercially to any extent, although they will keep well for 1 to 2 weeks at 31° to 832° F. When harvested at a firmness permitting storage and shipping, the fruit lacks flavor and has poor dessert quality after ripening but is satisfactory for canning purposes (/). : AVOCADOS (Temperature, see text; relative humidity, 85 to 90 percent) Investigations in California (53) on the storage of avocados have shown that the best temperature for all varieties grown there, except the Fuerte, is about 40° F. The Fuerte discolors internally at this temperature but holds up well at 45°. At temperatures below 40° all the varieties investigated are likely to become discolored internally and do not soften when removed to a higher temperature. When properly stored, the Dickinson, Royal, Taft, and Queen are said to hold up well for about 2 months, the Spinks, Sharpless, and Chal- lenge for 5 to 6 weeks, and the Rey, Fuerte, and Kist for about 4 weeks. Most of these varieties are of the Guatemalan race. No general recommendations can be made concerning the storage of varieties of avocados grown in Florida, Central America, or the West Indies, because of the wide variation among them in susceptibility to injury by low temperatures. Many varieties of the West Indian race are injured by exposure to temperatures of 50° to 53° F. for 15 days (86, 87), whereas others (Pollock, Trapp) remain in good con- dition for 3 weeks when held at 42° (43). Varieties of the Guate- malan race are more resistant to cold, and those of the Mexican race are the most resistant of all. Some of the varieties that are least affected by cold (Lula, Taylor) can safely be held at 37° to 42° for 4 weeks (43). At the higher temperatures mentioned above, anthracnose, a fungus disease of avocados, will probably be an important factor in the storage STORAGE OF FRUITS, VEGETABLES, AND FLORISTS’ STOCKS 15 of this fruit. At the lower temperatures decay is not lkely to be troublesome except after long storage. BANANAS (Temperature: ripening, 62° to 70° F.; holding ripe fruit, 56° to 60°; relative humidity : green fruit, 90 to 95 percent; ripe fruit, somewhat reduced but not below about 85 percent) The banana is one of the fruits that must be shipped to market green, because in this condition it can be handled for a longer time without becoming overripe and without serious injury from bruising during the marketing process. Furthermore, bananas of the Gros Michel variety, which make up the great bulk of banana shipments into this country, if allowed to ripen on the plant become mealy, lack fiavor, and are subject to splitting, with subsequent decay. The bunches of green bananas as they are received from the Tropics are usually ripened at a temperature of about 64° F., with a relative humidity of 90 to 95 percent or higher. If it is desired to hasten the ripening process, a higher temperature can be used (up to 70°) for the first 18 to 24 hours, but temperatures should then be reduced to about 66°. In any case relative humidity should be kept at 90 to 95 percent or higher until the fruit becomes thoroughly colored. After this it should be reduced shghtly, but not below about 85 percent. Pro- longed exposure to high temperatures will cause poor color and flavor and weak necks and will hasten decay. The lowest temperature at which green bananas can safely be held in order to delay ripening is about 56° ; below this they suffer an injury known as chilling—a form of peel injury to which both green and ripe bananas are susceptible, caused by low but not freezing tempera- tures. Ripe fruit is slightly less susceptible to chilling injury than green fruit. Fruit chilled in the green stage does not develop a bright- yellow color on ripening, but instead a smoky dull color. Fruit chilled after ripening will develop a dull-brown color when later exposed to higher temperatures and is very susceptible to handling marks, the slightest bruising causing discoloration. The best holding temperature for ripe bananas is generally con- sidered to be between 56° and 60°. At this temperature they will retain their good appearance and flavor and remain edible for a week or 10 days, although ordinarily they will not keep firm enough for shipment more than half that time. (See 22, 90.) BLACKBERRIES Short storage only. See Raspberries. CHERRIES (Temperature, 31° to 32° BF. ; relative humidity, 80 to 85 percent) The extreme limit for the suieeesefil commercial cold storage of fresh cherries at shipping point is probably about 10 days to 2 weeks. It is doubtful whether fresh cherries from California and the Pacific Northwest can be held satisfactorily in cold storage for more than about 2 week after arrival at eastern markets. This would mean about 16 days from harvest. If held longer than the period indicated they 16 CIRCULAR 278, U. S. DEPARTMENT OF AGRICULTURE begin to lose flavor and the bright attractive appearance characteristic of the fresh fruit. The stems may also dry out noticeably, especially if the relative humidity is low. Color changes and decay can be retarded by the use of carbon dioxide gas in transit (24). In fact, the treatment has proved to be so beneficial in this respect that it is now being used commercially for shipments of cherries from the West and Northwest to eastern markets. The sweating discussed on page 10 is particularly troublesome on cherries, because of the dull appearance that it produces on the fruit when displayed for sale soon after removal from iced cars. CocoNuTSs (Temperature, 32° to 35° F.; relative humidity, 80 to 85 percent) Coconuts are best stored at 32° to 35° F. and can be held satisfac- torily within that range for 1 to 2 months. CRANBERRIES (Temperature, 36° to 40° F. ; relative humidity, 85 to 90 percent) A large part of the cranberry crop is held at the bog every year until wanted for Thanksgiving and the Christmas holidays. When so held it is usually kept either in common (air-cooled) storage or in artificially refrigerated warehouses. The storage period is usually not longer than about 3 months and for that length of time the range from 36° to 40° F. (whether obtained in air-cooled storage or under artificial refrigeration) has been found to be the most desirable. Occasional lots of poorly colored fruit may be held at 45° to 50° for a few weeks in order to permit more rapid coloring than would occur at lower temperatures. Storage for more than about 4 months, in the range from 36° to 40°, is not satisfactory because of the common occurrence of end rot, a fungus disease, which can develop at low temperatures (102). Shrinkage of the berries asa result of water loss is also a limiting factor. Further facts that need to be kept in nund are that keeping quality depends to some extent on the maturity of the fruit, that some varieties keep better than others, and that there may be a difference in keeping quality from year to year in crops from the same bog. Cranberries for long-time storage are best held “in the chaff” in the picking crates as they come from the field. Thus handled they keep better than if sorted and cleaned previous to storage. Cleaned and sorted cranberries can safely be stored at the market for 5 or 8 weeks if held at a temperature of 32° F., but fruit held for a longer time at that temperature is likely to develop a “low-temper- ature break-down.” Berries in this condition are “rubbery” when pressed between the fingers, the flesh is permeated with red pigment from the skin, and some of the natural luster has disappeared. Such berries closely resemble those that have been frozen. Fruit held at 36° to 40° is less likely to discolor and become rubbery, but if it has been cleaned and sorted it is more likely to suffer from decay than if held at 32°. (See 4, 20.) STORAGE OF FRUITS, VEGETABLES, AND FLORISTS’ STOCKS 17 DarTEs (Temperature, 28° to 32° F.; relative humidity, 65 to 75 percent; or 28° F. and no humidity control for cured grades) Dates absorb moisture and odors readily from the air. The rate of absorption is much less at temperatures below 32° F. than at those above 32°. Deterioration caused by humidity above 75 percent is slow at storage temperatures below 28°. The dates of commerce are of three grades with respect to storage life—dried, cured, and non- cured. The cured and noncured grades are perishable. A tempera- ture as low as 0° has no deleterious effect upon dates but is actually beneficial to them. Dates are of two different types, and fruits of each type are likely to be either dry, cured, or noncured. The “cane sugar” type is usually firm, light-colored, and comparatively dry, whereas the “invert sugar” type is usually softer, darker colored, and inclined to be shghtly sticky or sirupy. Degiet Noor, the most important variety grown in this country, is of the cane-sugar type. Dates of this variety, cured grade, keep well until March at 28° to 32° F. and for a year at 24° to 26° or lower, whereas the noncured grade requires 18° or lower for storage until March, and 0° to 10° for a year. In Deglet Noor dates that have become overripe or have been held under unfavorable storage condi- tions the cane sugar is inverted and the dates become soft, sirupy, and darker in color. Such dates are commonly graded as “dark soft.” If they can be dried down somewhat, they can be stored at 28° to 32° until Christmas without becoming objectionably dark and sirupy, although a temperature of 0° to 10° will be needed if they are to be stored until March. If such dates are not cured, a temperature of O° to 10° is necessary for even short-time storage (75). Halawy, Khadrawy, Zahidi, and Saidy dates are all of the invert- sugar type, and the cured grades can be kept until Christmas at 28° to 32° F. without forming sugar spots but require a temperature of 18° or lower if stored until March. Noncured grades of these varieties require 0° to 10° for even short storage. After Christmas it is well to shift all dates of the invert-sugar type remaining in storage to “freezers” at 0° to 10° F. (5). DEWBERRIES Short storage only. See Raspberries. GRAPEFRUIT (Temperature, see text; relative humidity, 85 to 90 percent) Storage rooms for grapefruit should have a relative humidity of 85 to 90 percent. Lower humidities are favorable to pitting, and higher ones may increase decay. For short-time storage, grapefruit can be held satisfactorily at a temperature of 32° F. For longer periods the temperature to be used will depend on the character of the fruit and the troubles most likely to be encountered. For fruit grown in sections where stem end rot 224484°_41-__-8 18 — CIRCULAR 278, U. 8S. DEPARTMENT OF AGRICULTURE is prevalent, this disease is likely to be the determining factor; it will generally be advisable to use a comparatively low temperature range (32° to 384°). On the other hand if the fruit 1s grown in regions where stem end rot is not prevalent, the limiting factors are likely to be storage pitting and watery break-down, which develop most seriously at temperatures of 40° or lower. For fruit from these regions a temperature of 45° to 55° is satisfactory, and the more rapid develop- ment of undesirable high color and the increase in blue mold and green mold rots at the higher temperatures have not been found as objec- tionable on such fruits as the pitting that results from storage at lower temperatures. Sound fruit that is not overmature or likely to suffer from stem end rot can usually be held for 6 weeks without serious spoilage at the higher temperature ranges mentioned above, and this storage period can sometimes be doubled with satisfactory results. Weak or overmature fruit requires close watching from the time it is removed from the tree, regardless of storage conditions. The percentage of stem end rot in Florida and Texas grapefruit will be greatly reduced if the fruit is properly treated with borax or sodium metaborate, pulled from the tree instead of being clipped (98), and precooled before being shipped. The disbuttoning that may occur during handling and packing is also effective in reduc- ing loss from stem end rot. As compared with stem end rot, blue mold and green mold rots are relatively less important on Florida grapefruit in storage. Stem end rot is net known to occur on California and Arizona fruit. (See 11, 21,77, 78, 79, 97, 98, 99.) GRAPES VINIFERA . (Temperature, 30° to 31° F.; relative humidity, 85 to 90 percent) - Large quantities of the European or vinifera grapes, grown princi- pally in California, are stored every year. The most important of the varieties stored are Emperor and Ohanez (Almeria). Olivette de Vendemian, Malaga, Sultanina (Thompson Seedless), Cornichon, and Alphonse Lavallee (Ribier) are also occasionally stored. All of these have low freezing points, lower in fact than that of any other im- portant fruit, largely because of their high sugar content. Although for most varieties there is no danger of freezing injury at tempera- tures as low as 28° F. (14), they are usually held at temperatures of 30° to 31°. At low air velocities a humidity of 85 percent prevents excessive wilting of stems and berries without favoring the formation of mold growth. At air velocities of 100 to 150 feet per minute a humidity of 90 percent is desirable (57). California grapes for cold storage are packed in kegs or drums in sawdust or in various types of lidded lugs with or without sawdust. Good results are usually obtained, although if the fruit or the sawdust is damp at packing time or becomes so in storage there is danger of damage by mold. Mold may develop also if the grapes have been handled carelessly and if there are numerous cracked or loosened ber- ries scattered through the pack. Varieties differ in keeping quality. STORAGE OF FRUITS, VEGETABLES, AND FLORISTS’ sTocKs 19 The best storage varieties when properly handled can be held 3 to 6 months in storage at 30° to 31°. Emperor, Ohanez, and Alphonse Lavallee (Ribier) seem to keep better than any of the other storage varieties. Treating grapes with sulfur dioxide has helped to reduce spoilage in storage. In recent years the display type of lug has erown in favor for storage, because grapes packed in it can be re- fumigated. The common practice is to fumigate with concentrations of about 1 percent of sulfur dioxide before storage and to refumigate with about 0.2 percent of the gas at intervals of 10 days. Under these conditions fruit has been held fully as long in this type of package as in the more expensive sawdust chests or kegs. When fruit packed in display lugs cannot be refumigated in storage, 5 grams of sodium bisulfite is often added to the pads before packing, and this is fol- lowed by the usual prestorage fumigation. Mixing 5 grams of sodium bisulfite (per lug, chest, or keg) with the sawdust used in packing grapes has also been effective in checking decay (56). Storage quality varies considerably from season to season and seems to be adversely affected by rain just before and during harvest. Grapes picked before rains usually keep better than those picked after rains. (See 14, 55.) AMERICAN (Temperature, 31° to 32° F.; relative humidity, 80 to 85 percent) The eastern or American varieties of grapes, the most important of which is Concord, are not adapted to long storage; and most of them do not hold up well under storage conditions for more than 8 or 4 weeks, depending on the variety. After that time they begin to deteriorate in flavor and may suffer heavily from decay if the temper- ature ¥s not kept close to 32° F. The Catawba keeps better than most other eastern varieties and, if in good condition when stored, can be held for 3 to 8 weeks even in common storage in the districts where this variety is grown on a commercial scale. Too low humidity is undesirable for grapes, since it causes shrivel- ing, especially of the stems. Stock intended for storage should be handled carefully to avoid cracking of the berries or loosening at the cap stem, because such injuries allow juice to exude and thus furnish favorable conditions for the beginning of decay. Muscadine grapes are shipped only short distances if at all and are not known to be held in cold storage anywhere in commercial quan- tities. (See 2, 47.) LEMONS (Temperature, 55° to 58° F.; relative humidity, 85 to 90 percent) From the standpoint of preventing decay (blue mold rot, green mold rot, and alternaria rot) in stored lemons, the lowest temperature that can be used without freezing the fruit would seem to be the most desirable. The difficulty is that at low temperatures certain non- parasitic troubles develop which are fully as serious as decay; among these are red blotch, pitting, and membranous stain. With proper 20 CIRCULAR 278, U. S. DEPARTMENT OF AGRICULTURE humidity and at temperatures above 50° F. red blotch and pitting practically never occur and membranous stain is greatly reduced. The best results are usually obtained by storage at 55° to 58° in a relative humidity of 85 to 90 percent. Under such conditions lemons can be expected to hold up satisfactorily for periods of 1 month to as long as 4 months, depending on their maturity and condition when stored (12). Tree-ripened lemons, which are yellow when picked, do not keep well in storage. | It is of the utmost importance that lemons be handled carefully during picking and packing in order to avoid clipper cuts, scratches, and bruises and consequent damage later by green mold rot and blue mold rot. The fungus that causes the latter is able to penetrate the uninjured skin of lemons but is likely to cause more loss if the skin of the fruit is broken at numerous places. It can also spread from one fruit to another in the package and for this reason is frequently referred to as “blue contact rot.” Air conditioning as now used in some of the lemon storage houses in California furnishes a means of preventing condensation of moisture on fruit and so decreases the danger of decay. Lemons and other citrus fruits should not be stored in the same rooms with dairy products because of the readiness with which the latter absorb odors. Lemons in storage should be examined fre- quently to avoid loss from the development of decay or other deteriora- tion. (See 72, 16, 36.) LIMEs (Temperature, 45° to 48° F.; relative humidity, 85 to 90 percent) Preliminary investigations with Tahiti (Persian) limes indicate that fruit from a well-kept grove may be stored satisfactorily at a temperature of 45° to 48° F. for 6 to 8 weeks, provided that the rela- tive humidity is kept above 85 percent or the fruits are wrapped so as to prevent moisture loss. Prevention of desiccation is very important. For best quality, the Tahiti lime should be picked while still green but after the fruit has become “full” and smooth, having lost the “dimpled” appearance around the blossom end. Key (Mexican or Dominican) limes can be stored satisfactorily at the temperatures recommended for Tahiti limes. The preferred color for this variety on the markets of the United States is yellow. Temperatures above those recommended permit the development of stem end rot, which is often a serious factor in the marketing of limes from Florida and the West Indies. Locan BLACKBERRIES Short storage only. See Raspberries. Oxtves (FREsH) (Temperature, 45° to 50° F.; relative humidity, 85 to 90: percent) The best storage temperature for fresh olives (57) lies between 45° and 50° F., and the safe storage period is 4 to 6 weeks. At iower temperatures the flesh of green fresh olives becomes brown, beginning STORAGE OF FRUITS, VEGETABLES, AND FLORISTS’ STOCKS 2] around the seed and at the stem end. Ripe fresh olives develop more browning than green ones, showing severe discoloration even at 50°, if stored for more than about a month. ORANGES (Temperature, 32° to 34° F.; relative humidity, 85 to 90 percent) Although oranges are ordinarily stored at about 38° F., experi- mental results have shown that for long storage (8 to 10 weeks) a range of 32° to 34° gives better results. However, within this range some decay, chiefly blue mold rot or green mold rot, may occur during storage of 2 months or more, and some fruit may begin to show pit- ting and brown stain of the rind. If stored for longer periods, decay increases, and the spotted fruit may gradually turn brown over all or most of the surface. Watery break-down may develop, as in grapefruit. Stem end rot is likely to develop in Florida fruit if the storage temperature is higher than about 34°. Among California varieties, Washington Navel oranges are more subject to decay (blue mold and green mold rots) than Valencia oranges. The Washington Navel is also subject to alternaria rot. Careful handling is necessary at all times to avoid injury to the fruit and the decay, chiefly blue mold rot or green mold rot, that frequently follows injuries. A free circulation of air around the boxes is desirable for oranges, as for other citrus fruit. A relative humidity of 85 to 90 percent is sufficient to hold the shriveling of packed oranges to a minimum and retards decay more than does a higher humidity. Oranges should not be stored with eggs or butter or in places where it is possible for the orange odor to penetrate into egg or butter storage rooms. It is desirable that oranges in storage be examined regularly and often to avoid loss from the development of pitting or decay. After such examinations, a decision as to how long the fruit can safely be left in storage should take account of the fact that if pitting and decay are found they may increase rapidly after the fruit is removed to higher temperatures. (See 13, 77, 78, 79, 97, 99.) PEACHES (Temperature, 31° to 32° I’. ; relative humidity, 80 to 85 percent) Peaches are not adapted to cold storage. However, if they are sound and well-matured but not overripe, they can be held at 31° to 382° F. for 10 days to 4 weeks, depending on the variety, with little or no bad effect on the flavor, texture, or appearance of the fruit. Storage for longer periods is usually harmful to all of these charac- ters. ‘The peaches lose their flavor and natural bright color, become dry and mealy, or wet and mushy, and show marked browning of the flesh, especially around the stone. The loss in flavor is more rapid at 86° and 40° than at 32°, and break-down develops sooner at 36° and 40° than at either lower or higher temperatures. The best stor- age varieties, and the periods they can ordinarily be held in storage, are: Tuskena (Tuscan), 8 weeks; Early and Late Crawford, and Salwey, 4 weeks; Elberta and J. H. Hale, 3 to 4 weeks. Belle, Cham- 22 CIRCULAR 278, U. S. DEPARTMENT OF AGRICULTURE pion, Hiley, and Carman are less desirable as storage varieties and cannot be expected to hold up well even under optimum conditions for more than 2 or 3 weeks. (See 1, 25, 29, 32, 33.) PEARS (Temperature: Bartlett pears, 29° to 30° F.; fall and winter pears, 30° to 31°; relative umidity for all varieties, 85 to 90 percent) BARTLETT PEARS The suecessful storage of Bartlett pears (44, 45) depends not only on the temperature and humidity in the storage room but also on the condition of the fruit when stored. If the highest quality is to be obtained, Bartlett pears for storage should not be removed from the tree until the ground color begins to lighten and the lenticels have corked over. If picked before reaching that stage, they have a marked tendency to wilt, scald, and break down in storage. They also tend to break down in storage if picked when too ripe. The most desirable temperature for the storage of Bartlett pears is 29° to 30° F. The relative humidity should range from 85 to 90 percent. The maximum period for storage for canning and local fresh markets is about 90 days, and for storage at shipping point and at terminal markets, 45 to 60 days. FALL AND WINTER PEARS For fall and winter varieties of pears (57, 58), such as Anjou, Bosc, Clairgeau, Comice, Easter Beurré, Hardy, Seckel, and Winter Nelis, the most desirable storage temperature is 80° to 31° F. A relative humidity of 85 to 90 percent is most commonly used. However, a relative humidity of 90 to 95 percent is maintained in some pear stor- age rooms in order to prevent shriveling. Such humidities are main- tained in connection with air velocities of 100 to 200 feet per minute. The length of time for which it is safe to store these pears depends on the variety and when it is picked and also on whether the fruit is shipped directly to a consuming center and there stored or is stored at the shipping point for a time and later shipped to market. In- fermation on these points is given in table 5. In using the table it should be remembered that wide differences in keeping quality are often found in pears from various producing sections of the country. If Bosc, Flemish Beauty, and Comice pears are held in cold storage beyond their season they do not ripen satisfactorily or they may not fipen at all (23). For best ripening, these and other varieties of fall and winter pears should be held at a temperature somewhere in the range from 60° to 70°, preferably about 65°. The commonest and most serious decays of fall and winter pears in storage are gray mold rot, caused by the fungus Botrytis, and blue mold rot, caused by the fungus Penicillium. Gray mold rot is able to spread from decaying to sound healthy fruit and for that reason is frequently called nest rot. Losses from this rot can be reduced by the use of paper wrappers impregnated with copper (75). In the Pacific Northwest blue mold rot, in the form known as pinhole rot, STORAGE OF FRUITS, VEGETABLES, AND FLORISTS’ STOCKS 23 is sometimes more important on pears, particularly Winter Nelis, than gray mold rot. Losses from blue mold can be greatly reduced by careful picking and handling, prompt storage at 30° to 31° F. after harvest, and the use of paper wrappers to ‘prevent direct contact between diseased and sound fruit. TABLE 5.—Length of time at 80° to 31° F. for safe storage of certain varieties of pears at shipping point and after shipment to market (58) Length | Storage treatment and variety of storage End of storage period period Stored immediately after harvest Months PEL iy eee ee ee ee er oe ane ee as 2to3 | September to November. @ OMI COR BSSe EE ees cee ae ae ee a Ee 2to3 | November to December. BOS Cree Bee een oe oe AR on eek ote oe ee cae 3 to 3144 Do. (Oi Ree Le LS a Bese ee eee CES 8 Bee ee ees 6 | February. - WamtersNeli Sis 2s 22 ee en eee es se eee ees 6to7 | March to May. aes TES © ULIST, Get ees are ea tee Sn ee re eae ae 5 to7 Do. See es ae eee a ae Ce eee Ee aE peewee cme ery 5 to6 March. DAN OURS aoe eet TEE HRS S PSS RE PE Sy OS ere aE 4to5 | January to February. 1 BOIS OSes re ae 2 a a Se es See ee Seer 1to2 October to November. CUE LEY Des a ae ne eee ea os ge ge Sg aie a 2to6 | October to February. SWrlnibegaINIG LIS ene Sette are bg Fee Syne te te EL Lh Pe PS 2to4 | October to January. AIS COTES CULT Cpe et ree pee hn ace eo te at Oe, 4to6 | January to March. Stored after 12-day transit period (preccoled): PASTA] OU ieee obra ey eae Bet Rina ake 4to5 | March. PENETRATE eh SS 2 SRE eS 2to3 September to November. (WOMmi Ce ark ae Se ee ee ee Bd ON bees re eRe I 2to3 | November to December. TBO SOS esas a Se apiece ta ee A ae eee er ele eee eee 2to3 Do. Claire awl See ee ee REET ee at ae eaves PNG ate 2 OP 3 to6 | November to February. BVVGITEGOTOIN CG LIS eres eee Mee a eee 6 to7 March to May. Kieffer pears, if they are sound, firm, and still green when stored and are held under the conditions recommended for other fall and winter pears, can be expected to keep satisfactorily for 2 or 3 months. If intended for storage, they and other varieties should be handled with extreme care during the picking and packing process, because even slightly bruised or rubbed places are very likely to turn black and seriously damage the sales value of the fruit. Recent investiga- tions (42) by the United States Department of Agriculture have proved that a ripening temperature of 60° to 65° F. is essential for the attainment of maximum quality in Kieffer pears for either dessert or canning purposes. PINEAPPLES (Temperature : mature green, 50° to 60° F.; ripe, 40° to 45° F.; relative humidity, 85 to 90 percent) Pineapples are not adapted to long storage. Fully ripe fruits can be held satisfactorily at 40° to 45° F. for 2 to 4 weeks. Mature green fruits should not be held at temperatures below 50° and even at this temperature some of them will retain part of the green color in the skin and will fail to develop good flavor in the flesh after removal to room temperature. The maximum storage period for such fruit at 50° is 8 or 4 weeks. When held at 60°, mature green fruit ripens slowly, but after 2 or 3 weeks losses from decay, “chiefly black rot, may be expected. The relative humidity for pineapples in storage should range from about 85 to 90 percent. (See S9, 96.) 24 CIRCULAR 278, U. S. DEPARTMENT OF AGRICULTURE Piums (INcLupING PRUNEs) (Temperature, 31° to 32° F.; relative humidity, 80 to 85 percent) Plums and prunes (fresh) are not stored extensively and are not adapted to long cold storage. Such varieties as Wild Goose and those of the damson type store better than the softer fleshed plums, such as Santa Rosa, Beauty, Wickson, and Duarte. The storage period, at 32° I’., ranges from 3 to 8 weeks depending on the variety. After that time the soft-fleshed varieties are likely to become too soft for commercial handling, may suffer some darkening of the flesh, and lose somewhat in flavor. One of the most important commercial shipping and storage varie- ties is the Italian Prune. Ata temperature of 32° F., 2 weeks is about the maximum cold-storage period for this fruit, if a shipping period is necessary before it goes on the market. After arrival at market prunes shipped immediately after harvest can ordinarily be held in cold storage for about 3 weeks. If held longer there is danger that shriveling and internal browning, as well as abnormal flavor, will develop. Too much confidence should not be placed in the appearance and condition of the fruit while it is in storage, as more deteriora- tion—decay, shriveling, and internal browning—may take place in 3 days after removal from storage than during the whole storage period. Prunes shipped out of storage at shipping point cannot safely be stored again after arrival at eastern markets. (See 7, S4.) QUINCES (Temperature, 31° to 32° F.; relative humidity, 80 to 85 percent) The behavior of quinces in storage is about the same as that of early varieties of apples such as Jonathan and Grimes Golden. RASPBERRIES (Temperature, 31° to 32° I.; relative humidity, 80 to 85 percent) Fresh raspberries, blackberries, Logan blackberries, and dewberries are not adapted to storage and are usually not stored commercially. For short periods, 7 to 10 days, most of them can be kept in fair cond1- tion by storage at 31° to 32° F. in a relative humidity of about 80 to 85 percent. Young and Boysen dewberries cannot be stored satis- factorily for more than 3 to 4 days. | STRAWBERRIES (Temperature, 31° to 32° F.; relative humidity, 80 to 85 percent) Fresh strawberries are not stored commercially except for very short periods; 10 days is probably the maximum. Even for so short a time as this the temperature must be kept below 40° F. to prevent loss from decay caused by certain low-temperature fungi such as eray mold and Phytophthora, the fungus which causes leather rot; 31° to 32° is still better. After about 10 days, sometimes sooner, the fruit loses its fresh bright color, shrivels more or less, and deterio- rates in flavor (100). STORAGE OF FRUITS, VEGETABLES, AND FLORISTS’ STOCKS 25 Driep Fruits (Temperature and relative humidity, see text) For the preservation of natural color in storage, cut dried fruits and dried berries that are not subject to sugaring are held at 26° F. with no humidity control, or at 32° with a relative humidity of 70 to 75 percent. Figs and prunes are best stored at 40° to 45° F. The relative hu- midity should not be over 70 to 75 percent, to prevent excessive ab- sorption of moisture. Dried apples, apricots, and peaches keep best at 26° to 82°. Raisins should be stored at 40° to 45° and require a relative humidity of 50 to 60 percent to keep them from absorbing moisture. The holding of dried fruit in high humidity at tempera- tures above 32° is likely to result in mold. The dried fruits men- tioned can be kept in marketable condition for 9 to 12 months at the temperatures and humidities specified. Dried fruit can be tightly stacked, without stripping, in large solid blocks in storage rooms without injurious effect, and this method of handling the packages minimizes the absorption of moisture from the storage-room air. When nonventilated packages, such as those used for dried fruit and dates, are removed from cold rooms, the sweating that results occurs mostly on the outside of the package and the moisture can be prevented from penetrating into the fruit by allowing the packages to warm up before they are opened (6). : FROZEN FRUITS AND VEGETABLES (Temperature, see text) Frozen fruits should be held at —10° to 0° F. if they are to be stored for several months. For the freezing of fruits a temperature of 0° F. or lower is de- sirable for both small containers and barrels. If freezing takes place too slowly the same undesirable conditions may develop that are en- countered if the fruit is stored at too high a temperature after being frozen (17, 18, 83). For best results frozen fruits should be held in airtight containers. The best temperature for freezing vegetables is from —10° to —5° F. For storage after freezing —10° to 0° is satisfactory if ample provision is made for rapid cooling until the product reaches the freezing point. Nuts (Temperature, 32° to 50° F.; relative humidity, 65 to 75 percent) Most of the commercial nut crop, including walnuts of all kinds, filberts, almonds, Brazil nuts, peanuts, and sometimes pecans, is usually held in ordinary warehouse storage through the winter follow- ing harvest. The portion of the crop (except pecans) that is to be kept through the following summer should be placed in cold storage early in March. Pecans become stale and rancid much sooner than most other kinds of nuts, and it is safer to put them in cold storage at 32° F. shortly after harvest. Brazil nuts can usually be kept satis- 824484°_41-__4 26 CIRCULAR 278, U. S. DEPARTMENT OF AGRICULTURE factorily in warehouse storage during the winter, but that portion to be held over summer should be stored at 32° before warm weather. Brazil nuts should be carefully inspected before being accepted for storage to see that they are well dried out or cured. Walnuts, filberts, and almonds usually need not be stored below 40° to 45°. Chestnuts are rarely held in any other way than in cold storage at 32° to 40°. Shelled and unshelled peanuts can be held at common warehouse temperature during the winter, but during spring and summer shelled peanuts should be kept in cold storage both for protection against insects and to prevent development of rancidity. If cold storage is not available, common storage can be used, but the peanuts should be stored in the shell, and shelled out as needed, because if stored shelled they are likely to darken and become rancid. In common storage care should be taken to prevent infestation by insects. Fumigation is de- sirable for both shelled and unshelled peanuts if they are to be held in common storage during the summer for any censiderable time. _.As all varieties of nuts keep better unshelled than shelled, it is usually the best practice to store nuts in the shell and crack them as needed unless the kernels can be sealed in vacuum, which will pernit them to be kept even longer than in the shell. Generally nut kernels should be stored at 32° F. The relative humidity of the storage room should be 65 to 75 per- cent. At higher humidities there is danger of mold growth, and at lower humidities there will be undue drying. (See 101a.) VEGETABLES By R. C. WRIGHT, physiologist The recommended temperature, relative humidity, and approximate length of storage period for the commercial storage of vegetables are given in table 6. Detailed descriptions of these requirements are given in the text. TABLE 6.—Recommended temperature, relative humidity, and approximate length of storage period for the storage of various vegetables, and the average freeez- ing points : P Average a Tempera- | Relative Approximate length of : Commodity ture humidity storage period pee SINE Percent 4a INSDATAgU SS 22 eee termes ie ee 32 85. to) 90h s3:to 4 weekse aes len ee ee 29.8 Beans: Greentonisnap ee eee 32 to 40 S5ito 90) 2)to4 weeksis.- 2-23 ae 29.7 DGD anh eet aoe re apd st ab al poe, SS 32 to 40 85 to 90)|-2 === (0 lg ees Berane yes Sn Se 30. 1 Beets: Topped isso eva eee eee 32 O5it0198) | iatoys months ea. ee nee 26. 9 Banc hits eee ee ke 32 S560) 90h eLO COR 4s ay ci ee a ane Broccoli (Italian or sprouting) _____- 32 to 35 GOTO Nee LOLOL ay Sea ween see eee 29.2 Brusselsisprouts=--s) a ee 32 to 35 90'to 95 4); Sito 4 weekse $< 522s 58 pes eco ee @abbarests.) <2) wee se eee 32 9009513 to mon thshes ses aoe ee 31.2 Carrots: Topped. hs.) - oe a ee ee 32 05) toi98 |4,to,5;months)— ae 29. 6 BUN CHE see ces sae ena eee 32 S5'torSOn | LOMOnI Ardy Sees = ee ee | een @aulifiower_ Share. Dares 32 85/to 90! 22 tos iweekss2e2_ sa5! 2 ese 30. 1 GB er AC ra eee Sean 32 95) GO! 98 ul oh bOna TONGS ea ne ot @Gelery22 Sat Oe ed tee ee 31 to 32 G00) 95si22) to 4monthses a2 sss ease 29.7 @orna(ereen) +... 5-15 oe 31 to 32 85:tO390: | E(S) 223 se ee eae 28.9 Cuichin bers see eee ene 45 to 50 SO toss LO ton adayss2. eee BO. 5 See footnotes at end of table. STORAGE OF FRUITS, VEGETABLES, AND FLORISTS’ STOCKS Dik TABLH 6.—Recommended temperature, relative humidity, and approximate length of storage period for the storage of various vegetables, and the average freezing points—Continued fis ie Average : Tempera- | Relative Approximate leneth of eS Commodity ture humidity storage period Bote CIN Percent oF. Heeplantsesse ee oi Sh 2 er 45 to 50 Yay HO) CLO) |) MONG Gin oe ee ee 30, 4 TI Gye teas ees en tees 32 GOHORO SHS 25C0; wi OK Shaye ee eee 30. 9 Chan C) (Gisy,) eo es eee ee 32 OO R Zon GO \COrSsmon thse sale a ee 25.4 HO TSETA GIS ee ae ee te eee ae 32 Hoston9Sn| LOM ORL Zanonthsa eo Fe 26. 4 Jerusalem-artichokes____.__--_----- 31 to 32 S0tto) 95.) 2) CoS) months). 2222252 se Se 27. 5 Koh rab ities See ao ee eae eee 32 95 to 98 | 2 to 4 weeks_._____...--_-________ 30. 0 Teeksi(ereen) et ee ae 32 85: to90. eto monthss 222 ces ea eee 29. 2 lettuce... SS Se ee 32 90 to 95 | 2 to 3 weeks_____________-________ 31. 2 Melons: soda j~ . Watermelon == oetces ee 36 to 40] 75 to 85 |_---- GOAL MN Re k 6GRE Muskmelon (cantaloup) _------ 320. 34) ne 7otor78 |) 7 tol0daysa 22) rte teens les cery Honey Dew and Honey Ball___| 36 to 38 75 to 85 | 2 to 4 weeks________ bccn ali \ : ae Casaba and Persian________-__- 36 to 40 1D°CO?85) | oto GrwieeksSs =< e222 ae. Se ee Ra ea Mushrooms (cultivated) __--___-___- 32 to 35 80)to 85:) 2 to 3 days.. 2) siseceu0 Leese. 30. 2 CES (0) aye eae IE lip po ge, Se = 32 70 to 75 | 6 to 8 months __________________ 30. 1 Onionisets=4 35-29 sf See 32 70 to 75 | ._--- COVE ADEE CATS ON 18" 29. 5 IRAarsnipseae. 5. eae Ee ee se 32 90 to 95 |} 2. to. 4 monthse. ___.-s_._2+-__ 28. 9 Peast(ereen) ee sen en ante eee eee 32 85 to 90 | 1 to 2 weeks_________-________ 2. 30. 0 Peppers: Chili (iy) eesti eee epee ee (4) QO MEORTO) || 6) COO eM Ont hse as we ae eA IE riage Sweetasee titer fips. eo fps 32 85 to 90 u OG Weeks Liters 90 2 ee 30. 1 Rotetoes ee acess eae MR 436 to 50 SSCL Opie) Fae Sa ela aes eel a 28.9 Rump kin Sets e= nee USS SRO 50 to 55 70 to 75 > COG IMOM TS ase eee SAAN ae 30. 1 Radishes (winter) _________-_-___-- 32 95) tor 98.1: 2-60: 4;months ae ek eee ea ee ee = Rn Wbar beac ses ees eee es he oe 32 90 to 95 | 2 to 3 weeks____________________- 28. 4 Rutabacas 20 se F ee) es 32 95 to 98 | 2to 4 months ____________2____- 29.5 STIS A Ve Be REE Se RE es os OS 32 95 to 98 |__--- COR ene eee Bn 7 4. 5 arireie 28. 4 SOUT aC Hee me rmenrers ote ct caus eaihaees 32 90 to 95 | 10 to 14 days. ____-______-__ 2 30.3 Squashes (winter) _---------------- 50 to 55 70 to 75 | 2to6 months ~__-_.---------__- 29.3 Sweetpotatoes.___ = = 42 = = 55 to 60 4075't0 80 | 4 to G months. 2-2 ee 28. 5 Tomatoes: TRO Ree a ee te ena Lee Lk 40 to 50 85, to 90 de tonlOmdayse sss se cee 30. 4 Mature oreen=— s-e=see== saan 455 to 70 85: t0/90"1"3) tod: weekse2 222202 aa 30.4 Turnips Peet #2 ee owas ane yt ee 32 95 to 98 | 4 to 5 months ._______-__----_-_- 30. 5 1 These figures are based on previously published work by Wright (101) and aresubject to revision when- ever further investigation makes this necessary. 2 Flesh. 3 Rind. 4 See text. ASPARAGUS (Temperature, 32° F.; relative humidity, 85 to 90 percent) Fresh asparagus 1s not usually stored except temporarily when the market is overstocked. Experiments have shown, however, that it can be kept successfully for 3 to 4 weeks at a temperature of 32°F. At this temperature, growth of the stalks, which takes place at higher tem- peratures, is practically nil. The original tenderness of fresh aspara- gus, which at ordinary room temperatures is lost soon after cutting owing to the formation of woody tissue, is preserved at the lower tem- perature. Furthermore, the sugar content, to which asparagus owes some of its flavor and which after cutting rapidly diminishes at higher temperatures, remains practically the same as when the asparagus is cut, if it is put in storage at this temperature immediately after cutting. Therefore, the sooner asparagus is placed in proper storage after harvesting the better will be its condition when used. The loss of water while in storage or transit is likely to be great if the stalks are not stood on wet moss or other moist absorbent material placed in the bottoms of the crates. In storage, asparagus bunches are some- 28 CIRCULAR 278, U. S. DEPARTMENT OF AGRICULTURE times set in water in shallow trays or pans. After a long haul to market, asparagus should not be expected to keep in storage for more than 38 to 6 days, although the preservation of quality will depend largely on how the product was handled before being received for storage. Asparagus that has been precooled immediately after being packed will arrive at the market in better condition than if not so treated. The principal decays of asparagus in storage are bacterial soft rot and gray mold rot. (See 59.) BEANS (Temperature, 32° to 40° F.; relative humidity, 85 to 90 percent) e GREEN OR SNAP Green beans are usually stored for only short periods. When held at 32° F. they may be expected to keep 2 to 4 weeks provided they are in good condition and are placed in storage promptly. At 46° the storage period will be about a week shorter. The humidity should not be lower than 85 percent, to prevent wilting, and the hampers or other containers should be so stacked as to allow abundant air circu- lation. If the containers are packed close together the temperature may rise somewhat because of the heat given off by the commodity, and more or less rapid decay may be expected. If the beans are stored too long, the pods may become moldy or shmy, and stick or “nest” together. The principal kinds of decay favored by too high storage temperature or too long holding period are: Watery soft rot, slimy soft rot, rhizopus rot, and gray mold rot. Beans should be free from surface moisture when stored and should be kept from contact with ice, which may cause water-soaked areas resembling freezing injury. LIMA Shelled lima beans are sometimes stored in quart baskets and, if fresh and sound when stored, can be expected to keep in good salable condition for about 15 days at 32° F. and about 4 days at 40°. If stored too long, the beans tend to fade to a light color and become sticky. Unshelled lima beans can be held satisfactorily for 2 to 4 weeks at 82° and 10 days at 40°. BEETS (Temperature, 32° F.; relative humidity: topped, 95 to 98 percent; and bunch, 85 to 90 percent) Late beets stored at 32° F. may be expected to keep 1 to 3 months under suitable storage conditions. Hither cold storage or cool cellar storage is suitable, provided the humidity is kept sufficiently high to prevent wilting. Cellar storages often have a higher average tem- perature range than is recommended, and under these conditions the period of successful storage will be comparatively shorter. The tem- perature in such storage should not go above 45°. Beets are subject to wilting because of the rapid loss of water and should be kept where the humidity is sufficiently high to prevent excessive evaporation. Before going into storage, beets should be topped and well sorted STORAGE OF FRUITS, VEGETABLES, AND FLORISTS’ STOCKS 29 to remove all diseased specimens and those showing mechanical injury, in order to prevent undue shrinkage because of storage decay. Beets may be stored in ventilated barrels or better in slat crates. Storage in large bulk should be avoided. Bunch beets may be stored at 32° for 10 days to 2 weeks. See dis- cussion of bunch carrots, as the same conditions apply as for bunch beets (p. 30). Brocco! (ITALIAN OR SPROUTING) (Temperature, 32° to 35° F. ; relative humidity, 90 to 95 percent) Italian or sprouting broccoli does not keep well in storage and is usually held for only very short periods. The best storage tempera- ture is 82° F. If in good condition and stored with sufficient ventila- tion between the packages, broccoli should keep satisfactorily for a week or 10 days. Longer storage is undesirable because the leaves are likely to discolor and the buds may drop off (66). BrussELs SPROUTS (Temperature, 32° to 35° F.; relative humidity, 90 to 95 percent) Brussels sprouts are stored only occasionally but when stored they require the same conditions as broccoli. They should be held in small containers to prevent yellowing and the development of mold. The maximum storage period is probably not longer than 3 to 4 weeks. CABBAGE (Temperature, 32° F.; relative humidity, 90 to 95 percent) A large percentage of the late crop of cabbage is stored and sold during the winter and early spring, or until the new crop from the Southern States appears on the market. If stored under proper con- ditions, cabbage should keep for 3 to 4 months. The longest keeping varieties belong to the Danish Ballhead class. Cabbage is most suc- cessfully held in common storage in the Northern States, where a fairly uniform inside temperature from 32° to 35° F. can be main- tained. Many such storage houses are to be found, principally in New York, Pennsylvania, Michigan, and Wisconsin. Cabbage in quantity usually is not held in cold storage because its value does not justify the expense of handling. Storehouses should be insulated sufficiently to prevent freezing, for although slight freezing does no harm, hard freezing is likely to cause considerable loss. More ventilating capacity than is required for most other vegetables should be provided to carry away the ex- cessive moisture given off by the active respiration of this product and to obtain the maximum advantage of the cold night air during mild weather. Cabbage wilts quickly if held under too dry storage conditions; hence the humidity should be high enough to keep the leaves fresh and turgid. Bin storage is common, the bins usually be- ing 4 to 5 feet wide and 10 to even 20 feet long and about 5 feet deep. They are best separated by tight board partitions and ventilating slat floors. Tiers of bins may be built as high as it is convenient to elevate the cabbage, and while the bins are being filled ample air space 30 CIRCULAR 278, U. S. DEPARTMENT OF AGRICULTURE between the tiers of bins should be allowed for ventilation. The use of slat shelves with the heads piled one or two layers deep is con- sidered the best method, but it is too expensive when large quantities are to be stored. Cabbage should be handled carefully from the field to the storage. Before it is stored, the roots and all loose leaves should be trimmed away, and the damaged and misshapen heads should be culled. On being removed from storage, the heads should be trimmed again to remove loose and damaged leaves. Early cabbage, especially southern grown, should not be expected to keep over 3 to 6 weeks even at 32° F. The most common decay found in stored cabbage is slimy soft rot. CARROTS (Temperature, 82° F.3; relative humidity: topped, 95 to 98 percent; and bunch, 85 to $0 percent) Carrots are stored in fairly large quantities during the winter. The marketing period for stored carrots extends to late winter or early spring. They are usually held in common storage in those sec- tions where the storage temperature can ordinarily be held sufficiently - low. In the larger markets stored carrots must be sold in competition with fresh stock, which is being shipped practically the year around from either southern or western producing sections. Carrots are sometimes held in cold storage, although the prices obtained for them do not usually justify this kind of treatment. It is generally considered that very light freezing causes practically no injury, but carrots should be protected from severe freezing and are best stored at a temperature of 32° F. They are subject to wilting or drying out if the humidity is not fairly high; for this reason they are more easily kept in a well-ventilated cellar or bank storage than in an above-ground storage. The relative humidity should be main- tained at 95 percent or slightly higher. Before being placed in storage, carrots should be topped and all misshapen or injured specimens sorted out. The latter are especially objectionable, because their presence in a storage lot favors the devel- opment of two serious diseases of stored carrots, namely, watery soft rot and bacterial soft rot. Carrots are best kept in slat crates or ven- tilated barrels, and provision should be made for air circulation be- tween the containers. Under good conditions they should keep 4 to 5 months. Bunch carrots may be stored at 32° F. for 10 days to 2 weeks, and the tops will still retain a fresh appearance if they are not crowded in storage. If cold storage is not available bunch carrots from dis- tant production areas may be packed in crushed ice and should keep at least a week. If it is desired to carry over such carrots for only a day or two icing may not be necessary. Under these conditions, however, the crates or containers should be opened and the contents loosened so as to allow air to circulate through; otherwise, heating will take place, and the foliage will soon become yellow or discolored, which, of course, is undesirable. Foliage will discolor sooner if kept warm and wet than if kept cool and dry. STORAGE OF FRUITS, VEGETABLES, AND FLORISTS’ STOCKS 31] CAULIFLOWER (Temperature, 32° F. ; relative humidity, 85 to 90 percent) Cauliflower is not usually kept in cold storage; however, an over- supply on the market can be stored for a short time to await more favorable conditions. If in good condition cauliflower can frequently be held satisfactorily for 2 to 3 weeks at 32° F. Successful storage depends not only on preventing decay but also on retarding the ma- turing of the head or curd. Overmaturity is marked by a browning of the otherwise white curd and the development of a ricey appear- ance. The leaves also become yellowish and may drop off. During storage or transportation the crates should be stacked with the flower heads down to protect the curds from discoloration by dirt and mois- ture. When it is desirable to hold cauliflower temporarily out of cold storage, packing it in crushed ice will aid in keeping it fresh. Treez- ing causes a grayish-brown discoloration and softening of the curd, accompanied by a water-soaked condition. CELERIAC (Temperature, 32° F.; relative humidity, 95 to 98 percent) Celeriac should be stored under the same conditions as those for carrots and should keep 3 to 4 months. CELERY (Temperature, 31° to 32° F.; relative humidity, 90 to 95 percent) Much of the late celery grown in the Northern States, notably New York and Michigan, is put into cold storage to supply the market up to the period in late winter when the competition of new ce:ery from California and the South renders further holding unprofitable. Con- siderable celery from the South and West is also put into cold storage toward the end of the shipping season and held to supply the market during the summer, or until supplies of early, northern-grown stock appear on the market. elery is a rather perishable commodity and under unsuitable storage conditions may suffer severely from watery soft rot. This dis- ease originates in the field and is caused by a fungus that is able to develop to some extent even at temperatures of 34° to 36° F. For this reason celery intended for storage should be as free as possible from infection. If held in rooms where a uniformly low temperature can be maintained, it should keep for 2 to 4 months. It is best stored at a temperature of 31° or 32° F., with a relative humidity high enough to prevent wilting (90 to 95 percent), and with sufficient air circulation to keep the temperatures at the top and bottom of the room as nearly equal as possible. Considerable heat is given off by celery because of active respiration, and the air at the top of a storage room is likely to be 8° to 4° warmer than at the bottom unless special precautions are taken to avoid such a condition. Air circulation can be maintained around the crates by using 1- by 2- or 2- by 2-inch dunnage strips between the crates, which should be stacked so as not to touch at the sides. If wall or ceiling refrigerating coils are used, fans should be located at such positions as will insure adequate air circulation. 32 CIRCULAR 278, U. S. DEPARTMENT OF AGRICULTURE Celery should not be piled more than four crates high in storage; otherwise there is danger of overheating even with stock that is in prime condition. If it 1s piled five to eight crates high, as is sometimes done, the room should be watched carefully to see that overheating does not occur. Some growth takes place in celery while in storage. The central stalks lengthen considerably, obtaining their food at the expense of ‘the outer stalks and the roots. Blanching of the stalks also takes place in most varieties that are put into storage. Some celery is trimmed and washed as it comes from storage, but probably the larger part is moved out in the original crates in which it was received (SZ). Corn (GREEN) (Temperature, 31° to 32° F.; relative humidity, 85 to 90 percent) Green corn is seldom stored, although there are occasions during the southern shipping season when it may be desirable to put an excess supply of this commodity temporarily into cold storage; however, storage for more than a few days will result in serious deterioration. The sugar content, which so largely determines quality in this product and which rapidly decreases at ordinary temperatures, is reduced very little if the corn is quickly cooled and kept at a relatively low temperature. In order to keep this loss of sugar to a minimum and preserve the flavor, corn in the husks as it comes from the field for consumption in the fresh state should be cooled as quickly as possible. This is sometimes done by submerging it in tanks of ice water Immedi- - ately after removal from the field to reduce the temperature to as near 32° as possible. Corn should not be handled in bulk because of its tendency to heat but should be put in baskets or crates, which allow air circulation and the more rapid removal of field heat and heat produced by respira- tion. This commodity as it usually arrives on ihe market should not be expected to keep in marketable condition in cold storage for more than 4 to 8 days. CucUMBERS (Temperature, 45° to 50° F.; relative humidity, 80 to 85 percent) Cucumbers are usually held in storage for only short periods and cannot be expected to keep satisfactorily for much over 10 to 14 days. The most favorable storage temperature range seems to be between 45° and 50° F., with a relative humidity of about 85 percent. When cucumbers are held at 45° or below for longer periods than recom- mended dark-colored watery areas, which are an indication of low- temperature injury, appear. These areas soon become infected, and mold growth develops. If the cucumbers are held at 50° little or no break-down develops, but they tend to ripen, the color changing from green to yellow. EccPLANTS (Temperature, 45° to 50° F.; relative humidity, 85 to 90 percent) Eggplants cannot be expected to keep satisfactorily in storage for more than about 10 days. STORAGE OF FRUITS, VEGETABLES, AND FLORISTS’ STOCKS 33. ENDIVE OR ESCAROLE (Temperature, 32° F.; relative humidity, 90 to 95 percent) Endive or escarole is a leafy vegetable and under commercial con- ditions is not adapted to long storage. Even at 32° F., which is con- sidered to be the best storage temperature, it cannot be expected to keep satisfactorily for more than 2 or 3 weeks. The storage require- ments for endive #re practically the same as for lettuce. Like lettuce it should keep somewhat longer than the period just mentioned if it is stored with cracked ice in or around the packages. The relative humidity in rooms where endive is held should be kept at 90 to 95 percent in order to prevent wilting. A certain amount of desirable blanching usually occurs in endive that is held in storage. Gartic (Dry) (Temperature, 32° F.; relative humidity, 70 to 75 percent) Garlic is best stored under the temperature and humidity condi- tions required for onions. If in good condition and well cured when stored, this product should keep at 32° F. for 6 to 8 months. In California, where considerable garlic is grown, it is frequently put in common storage, where it may be held for 3 to 4 months or some- times longer if the building can be kept cool, dry, and well ventilated. Garlic is stored in loose mesh bags, which are piled two layers deep in stacks separated by air spaces. It is essential that garlic be well cured in the field before going into storage. HorsRADISH (Temperature, 32° F.; relative humidity, 95 to 98 percent) Horseradish should keep satisfactorily for 10 to 12 months if stored under the conditions recommended for carrots. JERUSALEM-ARTICHOKE (Temperature, 31° to 32° F.; relative humidity, 90 to 95 percent) Jerusalem-artichokes, if held in storage at a temperature of from 31° to 82° F. in a relative humidity of 90 to 95 percent, may be ex- pected to remain in good condition 2 to 5 months. At low humidities they shrivel badly and are more likely to decay than if kept in a moist atmosphere. They are sometimes stored in barrels or in paper- lined, airtight bags, in which they keep longer, with less wilting and decay than if left in open containers. KoHLRABI (Temperature, 82° F.; relative humidity, 95 to 98 percent) Kohlrabi should keep 2 to 4 weeks if stored under the conditions recommended for carrots. 34 CIRCULAR 278, U. S. DEPARTMENT OF AGRICULTURE LEEKS (GREEN) (Temperature, 32° F.; relative humidity, 85 to 90 percent) Green leeks are crated and stored under conditions similar to those suitable for celery. If properly handled, they should keep satis- factorily for 1 to 3 months in storage. LETTUCE (Temperature, 32° F.; relative humidity, 90 to 95 percent) Lettuce is sometimes put in cold storage when there is a surplus on the market, or in certain sections when the fall crop is threatened by approaching cold weather. If in good condition when stored, it. can be expected to keep for 2 or 3 weeks. When lettuce is held tem- pe out of cold storage crushed ice will greatly aid in keeping it resh. Even when held in cold storage, ice tends to keep this product fresher by preventing drying or wilting. One of the most troublesome diseases of lettuce in transit and stor- age is tipburn of the type that develops in the interior of the head. This injury appears in the field, but in the later stages of the market- ing process it is frequently followed by a slimy bacterial decay, which may result in serious damage. Frequent inspection of stored lots is desirable. MELONS Cold storage is used very little for most kinds of melons. When it is used, the storing is generally done at the terminal markets to avoid temporary adverse market conditions. WATERMELONS (Temperature, 36° to 40° F.; relative humidity, 75 to 85 percent) The ordinary commercial varieties of watermelons cannot usually be expected to keep in storage for more than 2 or 3 weeks. Experimental lots have been held at temperatures of 32° F. and did not develop decay as rapidly as at the recommended temperatures, but there was a tendency for the melons to become pitted or dented and to take on an objectionable flavor after 1 week. MUSKMELONS (CANTALOUPS) (Temperature, 82° to 34° F.; relative humidity, 75 to 78 percent) The common commercial varieties of cantaloups can be expected to keep about 1 week in cold storage at the recommended temperatures after arrival on the market and, under favorable conditions, for a few days longer but not as long as 2 weeks. The riper the melons are on arrival, the shorter the storage period should be. When they are held too long in storage, decay develops so rapidly on removal that they soon become practically worthless. (See 60.) STORAGE OF FRUITS, VEGETABLES, AND FLORISTS’ STOCKS 35 HONEY DEW AND HONEY BALL MELONS (Temperature, 36° to 38° F.; relative humidity, 75 to 85 percent) Honey Dew and Honey Ball melons can usually be kept a little longer in storage than cantaloups. At 36° to 88° F. or shghtly lower, such melons can be expected to keep for 2 to 4 weeks and still reach the consumer in good condition. If held for a longer time at tem- peratures below 36°, low-temperature break-down marked by a watery discoloration of the rind, followed by fungus decay will probably result; at 36° to 38°, decay, which will seriously discolor the rind, may occur. All blemishes show more plainly on these melons because of their light-colored, smooth surfaces. CASABA AND PERSIAN MELONS (Temperature, 36° to 40° F.; relative humidity, 75 to 85 percent) Casaba and Persian melons are relatively good keepers. They will remain in good condition in storage for at least 4 weeks and have been reported to keep as long as 6 weeks. MusHrooMs (CULTIVATED) (Temperature, 32° to 35° F.; relative humidity, 80 to 85 percent) Mushrooms do not keep well in storage and are therefore stored only temporarily for periods of 2 to 3 days or slightly longer. They are easily injured by freezing. | ONIONS AND ONION SETS (Temperature, 32° F.; relative humidity, 70 to 75 percent) Onions are held in either common or cold storage. In the northern onion-growing States, strongly flavored varieties, mostly of the globe type, are generally held in common or dry storage. ‘The principal northern onion-producing States have a sufficiently low average winter temperature so that onions can be successfully held in common storage there during the winter months. About one-fourth of the onion crop of these States, however, is put into cold storage for consumption late in the spring. About the first of March is considered as late as onions should be held in common storage, because after this time there is danger of sprouting. The mild or Bermuda types, such as those pro- duced in Washington, southern California, Texas, and other States, where the climate is not suitable for common storage, are usually con- sumed shortly after being harvested. These onions can be, and limited quantities are, held in cold storage, but usually for much shorter peri- ods than the globe varieties because of their poorer keeping qualities. The Spanish or Valencia type of onions grown in this country are often stored and, if well-matured, are considered capable of storage for practically as long as the globe type. A comparatively low relative humidity (70 to 75 percent) is very desirable for the successful storage of onions. At higher humidities, in which many other vegetables keep best in storage, onions are dis- posed to root growth and decay. The commonest form of the latter 36 _— CIRCULAR 278, U. &. DEPARTMENT OF AGRICULTURE is gray mold rot occurring at the top of the bulb, whence its name “neck rot” ($5). The fungus causing it can develop to some extent even at 32° F’.; hence onions intended for storage should be carefully sorted over to remove all diseased bulbs. A uniform temperature of 82° is found to be sufficiently low to keep onions dormant and reason- ably free from decay provided they are in good sound condition and well-cured when stored. Onions are not perceptibly injured by slight freezing if allowed to thaw out slowly and without rough handling. Im cold storage they are usually held in bags of 50 or 100 pounds each, which are best piled in pairs laid crosswise in stacks five or six sacks high. The stacks should be set a few inches off the floor on 2- by 4-inch strips and the individual stacks separated by a few inches of space to allow for air circulation. When kept in common storage, onions are best stored in slat field crates holding about 1 bushel, rather than in bags. Be- fore being placed in storage onions should be well dried or cured in the field for a period of 4 to 6 weeks, and all decayed specimens or those showing thick or “bottle” necks should be sorted out. Onion sets are usually held in common storage. They require nearly the same conditions as large onions and are best stored in shallow slat-bottom crates or trays not over 4 inches deep and about 5 by 5 feet in some districts or 2 by 3 feet in others. The corner posts of the crates should project about an inch above the side pieces in order to prevent the crates from resting tightly on each other when stacked and to allow air circulation between them. Because of their size, onion sets tend to pack closely in the crates; hence it is essen- tial to allow as much air circulation as possible and to maintain a comparatively low humidity. If good stock is provided and is held under proper storage conditions, it should keep 6 to 8 months. PARSNIPS (Temperature, 32° F.; relative humidity, 90 to 95 percent) Parsnips have nearly the same storage requirements as carrots and should keep for 2 to 4 months. They are not injured by slight freezing while in storage but should be protected from hard freezing and should be very carefully handled while in a frozen condition. Parsnips dry out readily in storage; hence it is essential that the humidity of the storage place be kept relatively high. Parsnips are sometimes stored in sand or clean soil to prevent wilting, but they will keep in good condition when held in barrels or crates if the proper humidity is maintained. Pras (GREEN) (Temperature, 32° F.; relative humidity, 85 to 90 percent) Storage conditions required for green peas are somewhat different from those for beans. Gaece peas tend to lose part of their sugar con- tent, on which much of their flavor depends, unless they are promptly cooled to near 32° F. shortly after being picked. They cannot be ex- pected to keep in salable condition for more than 1 to 2 weeks unless packed in crushed ice, in which condition the storage period may be extended perhaps a week. Peas keep better unshelled than shelled. STORAGE OF FRUITS, VEGETABLES, AND FLORISTS’ STOCKS 37 PEPPERS CHILI PEPPERS (DRY) (Temperature, see text; relative humidity, 70 to 75 percent) Chili peppers are usually picked when ripe and then dried and . allowed to equalize in moisture content in covered piles. Water is usually added to the peppers after drying, and as a result they become less brittle. They are then packed tightly by tamping into sacks holding 200 to 300 pounds and stored in nonrefrigerated warehouses for 6 to 9 months. The temperature of the warehouses depends to some extent on their construction and the way in which they are managed but chiefly on the outside temperature. In southern California, where a large part of the commercial crop of Chili peppers is produced, the outside temperature ranges from 50° to 80° F. during the usual storage eriod. i The moisture content of Chili peppers when stored is generally low enough (10 to 15 percent) to prevent mold growth; the chief storage trouble is insect infestation. Sometimes manufacturers of Chili pepper products hold part of their supply of the raw material in cold storage, but they prefer to grind the peppers as soon as possible and store them in the manufactured form in airtight containers. SWEET PEPPERS (Temperature, 82° F.; relative humidity, 85 to 90 percent) Sweet, bell or bullnose peppers, if in good condition, may readily be kept fresh in storage for a month to 6 weeks at a temperature of 32° F. A relative humidity of 85 to 90 percent is desirable to prevent shrinkage (38). PoTATOES (Temperature, 36° to 50° F.3 relative humidity, 85 to 90 percent) Potatoes are stored either in cold or common storage, but the greater part of the crop that is stored is held in common storage (SO). Like most other vegetables that can be held for relatively long periods in common storage, potatoes can be successfully kept through the fall and winter months only in those regions where a sufficiently cold winter climate prevails. In either cold or common storage a temperature of 40° F. is as low as table or seed stock need be kept during the first few months after harvest. At tempera- tures below this, there is a tendency for potatoes to become undesir- ably sweet. However, if sweetening occurs, a few days’ exposure to ordinary living-room temperature will partly restore the natural flavor. At 40° potatoes will remain dormant 3 to 5 months after harvest, depending on the variety. If it is desired to keep them longer than this, as is often the case with seed stock, the temperature may be lowered to 86° or 88° F., where they should remain dormant indefinitely. A storage temperature as low as 382° is unnecessary and detrimental. 38 CIRCULAR 278, U. S. DEPARTMENT OF AGRICULTURE Investigations have indicated that potatoes stored at 50° to 60° F. have better texture, color, and flavor when cooked or made into chips than the same stock stored at lower temperatures (54, 104,) although the higher temperatures are not suitable for long-time storage. When potatoes are stored at these higher temperatures, sprouting will occur more quickly. A limited amount of sprouting does not injure potatoes -for food purposes, but it makes the stock difficult to market because usually only dormant potatoes are wanted. If sprouting has started it can be checked by lowering the storage temperature. The relative humidity of a potato-storage house should be 85 to 90 percent, to prevent undue shrinkage through loss of water. In cold storage potatoes are generally kept in sacks holding from 100 to 150 pounds net; in common storage they are usually placed in bins holding from 150 to as much as 1,000 bushels or more. In Maine and northern New York, where the average temperature is sufficiently low, the large-bin storage is used with success, but in the milder climate of States in the latitude of Pennsylvania potatoes should not be stored in such large units. Potatoes are readily injured by even slight freez- ing, which takes place at about 29° F. or slightly below; hence common- - storage buildings should be sufficiently insulated to prevent freezing. Insulation will also prevent the condensation of moisture on the walls and ceilings, and the consequent undesirable wetting of stored stock, which favors the development of decay. Common storages should be provided with sufficient ventilation to take advantage of the cool night air in mild weather; this will aid in removing excess moisture, accumulating especially soon after potatoes are stored in the fall, and will maintain a lower average temperature. Ventilators should never be opened, however, when the outside temperature is higher than that inside the storage house. In addition to damage to potatoes, condensed moisture caused by improper ventilation or inadequate oy. may also cause serious impairment to the building struc- ture (79). ee intended for storage should be handled carefully to avoid bruises and cuts; otherwise they are likely to be damaged by various forms of decay before the end of the storage period. PUMPKINS AND SQUASHES (Temperature, 50° to 55° F.; relative humidity, 70 to 75 percent) In general most varieties of pumpkins will not keep in storage as long as the usual storage varieties of squash. Such varieties as Con- necticut Field and Cushaw are relatively poor keepers and cannot be expected to hold in good condition more than 2 or 3 months. Varieties like Large Cheese and Table Queen will keep 3 to 6 months. Hard-shell squashes, such as the Hubbards, can be successfully stored for 6 months or longer. All stock should be well-matured, carefully handled, and free from injury or decay when put in storage. The best storage temperature appears to be from 50° to 55° F. with a relatively low humidity of about 70 to 75 percent. Investigations have shown that a preliminary curing at 80° to 85° for about 2 weeks is of benefit in ripening immature specimens and in healing mechanical injuries incident to harvesting. STORAGE OF FRUITS, VEGETABLES, AND FLORISTS’ STOCKS 39 RapisHEs (WINTER) (Temperature, 32° F.; relative humidity, 95 to 98 percent) Winter radishes require the same storage conditions as carrots and should keep in good condition for 2 to 4 months. RHUBARB (Temperature, 32° F.; relative humidity, 90 to 95 percent) Rhubarb stalks, if fresh and in good condition, may be stored for 2 to 8 weeks. The bunches slicnld be packed in crates, which are stacked to allow ample air circulation on all sides; otherwise there is danger of heating and mold growth. RUTABAGAS (Temperature, 32° F.; relative humidity, 95 to 98 percent) Rutabagas require the same storage conditions as carrots and should keep satisfactorily under such conditions for 2 to 4 months. Probabl most of the rutabagas that now appear on the market have been waxed. This treatment improves the appearance and is reported to prevent wilting and loss of weight. SALSIFY (Temperature, 32° F.; relative humidity, 95 to 98 percent) Salsify has the same storage requirements as carrots. The roots are not injured by slight freezing but should be carefully handled while frozen. Under the conditions specified, they should keep for 2 to 4 months. SPINACH (Temperature, 82° F.; relative humidity, 90 to 95 percent) Spinach is usually stored for only short periods. It should kee fairly well for a week or two after being cut. If crushed ice is use in the packages, this period can be extended somewhat. SQUASHES See Pumpkins and Squashes. SWEETPOTATOES (Temperature, 55° to 60° F. ; relative humidity, 75 to 80 percent) The requirements for the successful storage of sweetpotatoes differ from those recommended for most other vegetable crops. When freshly dug sweetpotatoes are to be stored for any length of time they Hoult be given a preliminary curing treatment to permit the healing of all wounds or abrasions incident to harvesting and han- dling, in order to prevent the entrance of decay organisms. _ The curing and storing are done in the same house so that the 40 CIRCULAR 278, U. 8S. DEPARTMENT OF AGRICULTURE potatoes do not have to be moved after the curing treatment. When commercial lots are handled, the storage house is generally of special construction with sufficient insulation to maintain a uniform tem- perature and some means of ventilation that will insure the desired humidity. Provision should be made for heating the building during the curing process and for holding the proper storage temperature afterward. The curing process ordinarily takes fom 10 to 14 days, during which the house is kept at a temperature of 80° to 85° F., with a relative humidity of 85 to 90 percent. After the curing period the storage temperature is allowed to drop to about 55°, with a humidity of 75 to 80 percent. Short periods of a few hours at temperatures somewhat lower than 50° need not cause alarm, but prolonged periods of low temperature should be avoided because of the danger from cer- tain types of decay, which are more likely to develop at temperatures below the range given (37, 2). Under the recommended conditions, properly cured stock should keep satisfactorily for 4 to 6 months. Only well-matured stock that is practically free from mechanical injury or decay should be used for storage. Sweetpotatoes are usu- ally stored in slat crates of about a bushel capacity or in bushel baskets. Shallow bins are sometimes used. The roots. should be handled as little as possible during storage. ‘TOMATOES (Temperature: ripe, 40° to 50° F.; mature green, 55° to 70°; relative humidity, 85 to 90 percent) Ripe tomatoes are held in storage only temporarily and, except for short storage, should not be stored at temperatures lower than 40° F. At 40° to 50°, if not already soft ripe, they will keep in good condi- tion for a week to 10 days; at temperatures lower than this they some- times show a tendency to break down. Green tomatoes are best kept at a temperature not lower than 55° F. At this temperature ripening progresses slowly but satisfactorily, and mature green tomatoes can be kept for 3 to 5 weeks before becoming overripe. At temperatures much below 55° green tomatoes do not ripen well and if kept there more than about 8 days and then moved to a warmer place usually do not ripen satisfactorily; on the other hand, if they are to be kept for less than 8 days they can be held at 40° or even somewhat lower. If fairly rapid ripening is desired, temperatures from 60° to 70° should be used. At 70° or slightly above, ripening is accelerated, but so also is the development of decay, which will be found difficult to control. At about 80° coloring will be uneven since the development of the red pigment is inhibited at this temperature or above. The relative humidity of tomato-storage or tomato-ripening rooms should be from 80 to 85 percent. (See 88, 103, 105.) TURNIPS (Temperature, 32° F.; relative humidity, 95 to 98 percent) Turnips require the same storage conditions as carrots. They can be expected to keep for 4 to 5 months. FROZEN VEGETABLES For treatment of frozen vegetables see page 25. STORAGE OF FRUITS, VEGETABLES, AND FLORISTS’ STOCKS 41 CUT FLOWERS, FLORISTS’ GREENS, RHIZOMES, TUBERS, CORMS, AND BULBS By T. M. WHITEMAN, assistant horticulturist The recommended temperature, relative humidity, and approximate length of storage Heed for the commercial storage of cut flowers, florists? greens, rhizomes, tubers, corms, and bulbs are given in table 7, Detailed descriptions of these requirements are given in the text. T'ABLE 7.—Recommended temperature, relative humidity, and approximate length of storage period for cut flowers, florists’ greens, rhizomes, tubers, corms, and bulbs Tem- Approximate Tem-| Approximate Commodity pera- | length of stor- Commodity pera- | length of stor- ture age period ture age period Cut flowers: ! one. Cut flowers—Continued. On. Babysbreath ____----- 40 | 3 to 4 days. Primrose, baby__----- 40 | 3 to 4 days. Bouvardia, sweet__--- 40 | 7 to 10 days. Roset Ok vee seen 35-40 | 1 week. Butterflybush, or- 40 | 3 to 4 days. Snapdragon, com- 40 | 3 to 6 days. ange-eye. mon. Calendula (pot mari- 40 | 3 to 6 days. Snowdrop]. s2 32222 33-36 | 1 to 2 weeks. gold). Soules See eee 33-36 Do. Calla, common and 40 | 10 days. Statice (sea lavender) _| 35-40 | 3 to 6 weeks. golden. Sleviae = 2sise = 2s 40 | 3 to 4 days. Candy tilts. ee 40 | 3 to 6 days. Stock, common___-_-_-_- 40 | 3 to 6 days. Carnation: Strawflower_____-.._- 35-40 | 3 to 6 weeks. Full bloom_-_-__-_- 33-40 | 7 to 10 days. Sweet pea___._...__-- 40 | 3 to 4 days. BiWdSesse ne oe 33-40 | 10 to 15 days. FTN pO Sas ea eae 33-36 | 1 to 2 weeks. China-aster______._-_- 40 | 7 to 10 days. Violet, sweet__-_--__- 33-36 | 3 to 6 days. Chrysanthemum._---_-_- 35 | 2 weeks. Florists’ greens: ! @lornkiqgh 2 ae 40 | 3 to 6 days. Asparagus, fern and | 40-45 | 7 to 10 days. Columbine__.......-- 40 | 3 to 4 days. smilax. Cornflower -_---------- 40 | 3 to 6 days. Ferns: @rocuss=8222 ==. 33-36 | 1 to 2 weeks. Common wood- | 32-45 | 2 weeks to 4 ID ahligwees ese eee 40 | 7 to 10 days. fern. months. Daisy, English_.....- 40 | 3 to 6 days. Daggers ike 32-45 Do. Delphinium: Galaxs Sap bb heaaa le! 32-45 Do. Hardy larkspur__-_ 40 Do. Groundpine (Lycopo- | 32-45 Do. Annual larkspur__ 40 | 3 to 4 days. dium sp.). Feverfew_------------ 40 | 3 to 6 days. ero (Ilex opaca 32 | 1 month. Forget-me-not, true___ 40 | 3 to 4 days. Ait.). Foxglove, common 40 Do. Huckleberry ________- 32-40 | 3 to 6 weeks. and common white. Leucothoe, drooping__| 32-40 Do. reesiat.t22ae) eek 33-36 | 1 to 2 weeks. Mountain-laurel eee hath J 32-40 Do. Gaillardia, common 40 | 3 to 6 days Rhizomes, tubers, corms, perennial. and bulbs: 2 Gardenmiga 262222 a2" 45-50 | 1 week. Begonia, tuber_____-_- 45 | 4to 6 months. GieGholbiet 35 | 2 weeks. Caladium, spotted____ 45 Do. ea thie See 40 | 7 to 10 days. Calla, common and 35 | 6 to 8 months. Fy acint nessa neta 33-36 | 1 to 2 weeks. golden. TiS Sette hee ee wee 33 | 1 week. @annae ete ee ae 40-45 | 6 to 7 months. Laceflower, blue_____- 40 | 3 to 6 days. Crocus = eae 55-60 | 4 to 6 months. Lily: Dahliguwes frees wes 40-45 | 6 to 7 months. Hastersass= sees sae 35 | 1 month. Preesige 2222 See 55-60 | 4 to 6 months. Goldband=== 35 Do. Gladiolus! 232 ss 40-50 | 7 to 8 months. Reg alere sheer Le 35 Do. IEGyacint haes sees 55-60 | 4 to 6 months. Speciosum_______- 35 Do. Lily-of-the-valley__-__ 25-28 | 12 to 17 months. Lily-of-the-valley____- 40 | 1 week. Lily: Wupine=_b2 fis ays 40 | 3 to 6 days. asters eat is 35 | 6 to 8 months. Narcissus: Regalia ees 35 Do. Datodile assess 33-36 | 1 to 2 weeks. Narcissus: Paperwhite______- 33-36 Do. Daffodil______.___- 55-60 | 4 to 6 months. Orchidh wee ss Fares eek 45-50 | 1 week. Paperwhite______- 75-80 | 5 to 7 months. Peony, Chinese and Peony i228 eee ee 40-45 | 6 to 7 months. common: SNOW CLOPees =e 55-60 | 4 to 6 months. Mightabudssa.-2-2 35 | 3 to 4 weeks. S quill eee eee eet 55-60 Do. Loose buds__-___- 35 | 10 to 14 days. MArOreyss_ ets wares 45 Do. Phlox, garden____-___ 40 | 3 to 4 days. Tn berOS@nee eee eee 40-45 | 6 to 8 months. Poinsettia__..._._-__- 50 Do. ialipi ee. FOr Sire es 50-55 | 4 to 6 months. 1 Approximately 80 percent relative humidity. 2 Approximately 75 percent relative humidity; for individual species see text. 42 CIRCULAR 278, U. S. DEPARTMENT OF AGRICULTURE The average freezing points of some flower petals, foliage, bulbs, corms, etc., are given in the following tabulation: Foliage: Temperature (°F.) 1 | Petals—Continued. Temperature (°F.) AIMaTy Wise =e ewe eee SO Daisueashasias 20s ee 29.3 ASPATAPUS Terme = ae ee 24. 2 Delphinium (hardy lark- Aspidistra cos 2 es es = 24. 9 SPuUL) Las Sopa aa DR Es 26. 6 Caladium, spotted________- 30. 6 Gardenias Doe en toot 28. 3 Garnahion 2.) 2. S204 She este 27. 4 Glidieligs. <=" svienato so, b 28. 7 Chrysanthemum_____..-__ 29.6 ies Gh. pat be 5 elon eas 28. 7 Cotumbines 2 2. 6 ee 29. 1 Hemerocallis. —- pe oe 30. 8 Daisy polastaci22ie Sie 30. 0 ayacingh oh ee ae 28. 7 Delphinium (hardy lark- lris;lapanese=. 4 = Shei 30. 5 SPUE) oa es. Lee eget 29. 2 alys Mastercicn wate ygtt—- Tu 2725 DTACRENA 4.8 comes es eet 28. 0 Narcissus (daffodil)________ 30. 1 Hern daigcver =: Yee ee 23. 6 Orchid (Cattleya) _______2_ 30. 8 Giladiolis 2 to Sa a 26. 8 Peony, common___________ 29. 0 Flemerocalhsie ts. SA! oa 30. 0 Poinsetiiat awit eit parses 29. 2 Holly, lex, opaca) 3-26. 3 Ranunculus) 2 2 5 sjjagereraet 28. 6 Tris: Rose, hy brid tea= = as 30. 0 Dutch 29. 0 ulips< Ss ee 28. 0 German? Ging ost 27. 6 Violet, sweet. 2-2 3-2 Sra 28. 5 Japanesees-. Vet seo 28. 7| Bulbs, corms, etc.: dali Wuaster tas dees sot ane 29. 2 allay cab Sere Se eae 210 Pandas eu 42>. 2) aeeeks 30. 4 Dahliael 222! as pee 28. 3 Rubber, variegated ________ 30. 3 Giadiolus®. —) -ttersow) sions 26. 8 Vaolet..Swebba. =e =-5 teers 27. 4 Hyacinth Sb nhe eee 28. 7 Vanea-major == - ee 28. 6 Tatly.. Regalo it =>". — =: eke Qi Petals: Narcissus: AMETRO NE oo ener esa eee 28. 1 Daffodil. bso. oa PAGE Carnation at 28. 4 Raperwhite <= epee 28. 9 Chrysanthemum _-__-___-~-- 28. 4 PulipL. | OF nes. 25. 4 Columbine ges see: eee eS oid 1 Many of these figures are based on previously published work by Wright (/0/) and are subject to revision whenever further investigation makes this necessary. Cut FLOWERS Most cut flowers are benefited by a freshening period of a few hours in water at about 50° F. immediately after being cut. Cold-storage rooms for the holding of cut flowers for short periods are operated mainly by wholesale florists in the large cities. The temperatures given in this section are recommended to insure a reasonably long life for flowers after their removal from storage. Cut flowers in storage should usually be kept with the stems in water, but experiments in which French marigolds and carnations have been stored out of water for comparatively long periods have been reported (50, 51). They should not be crowded in the contain- ers because of the danger of mechanical injury and the decay that may result because of insufficient ventilation. In most cases care should be taken not to spill water on the blooms as these usually discolor rather readily. Damage to several kinds of cut flowers when stored in the same room or even in the same building with apples, oranges, pears, and other fruits should be emphasized. Such damage is evidenced by premature withering or the rapid aging of the blooms and is known to be caused by the ethylene gas given off by the ripening fruit. Roses, carnations, snapdragons, stocks, and daffodils have been shown to be affected in this way by the emanations from ripening fruit (40, 48). Many kinds of pigmented fiowers fade, discolor, or develop an olt- STORAGE OF FRUITS, VEGETABLES, AND FLORISTS’ STOCKS 43 color appearance during storage, especially under dark storage con- ditions. The use of artificial light to retard this color change has been demonstrated experimentally (49). Chrysanthemums (Chrysanthemum hortorwn Hort.) and gladi- oluses (Gladiolus spp.) may be stored at 35° F. for 2 weeks and usually remain very salable. Longer storage is possible, though frequently not practicable. These flowers are usually tied in bunches of 12 and 25, respectively, but are not wrapped when placed in storage. Pom- pons, however, are sold in bunches of various sizes. As a rule the proper cutting stage for the large-flowering types of chrysanthemums is just after the green color in the center of the flower has disappeared. No general rule can be given for pompons, since several varieties, especially some of those in the anemone group, need more development on the plant than the single varieties. Gladioluses should be cut when three or four of the lower buds are partly opened. For distant shipments before storage the flowers should show color but should be in the tight-bud stage. Easter lily (Lilium longiflorum Thunb.), Speciosum lily (L. speci- osum Thunb.), Regal lly (ZL. regale Wils.), goldband lly (ZL. auratum Lindl.), common peony (Paeonia officinalis L.), and Chinese peony (P. albiflora Pall.) can be held at 35° F. for comparatively long periods, although 380 days is usually the maximum storage period. The hlies in this group should be cut for storage when the corolla is about one-half opened or just befcre the tips begin to reflex. Lilies forced at relatively high temperatures should be kept at a temperature of about 50° for a preliminary period of about 24 hours before being put at 35°. Peonies showing color in the tight-bud stage may be stored at 35° for 3 to 4 weeks, but they seldom give satisfaction for decorative purposes without special handling; in the loose-bud stage they may be held satisfactorily for 10 to 14 days. The cut blooms of common and golden callas (Zantedeschia aethi- opica (L.) Spreng. and Z. elliottiana (Knight) Engl.) may be stored when fresh for as long as 10 days at 40° F. and will be in good condi- tion upon removal. Calla blooms should be gathered just before the spathe shows signs of curling downward. Callas that have been sub- jected to hard forcing should be held for about 24 hours at a tempera- ture of 50° previous to storage at 40°. When the blooms are gathered they should be pulled, not cut, otherwise the stems will spht at the cut ends and curl after a few days in storage. The pulling method separates the stem from the rhizome, leaving no useless appendage. Although the blooms are sometimes removed from the plant by cutting, the stub left on the plant will probably rot and thus may serve as a place of entrance for disease organisms. Pulling, however, is much easier with potted callas than with those planted in beds or benches. Callas intended for storage should be tied at the bottom and also loosely tied below the blooms. They are usually put up in lots of one dozen. Lupine (Lupinus), clarkia (Clarkia sp.), common stocks (Mathiola encana R. Br.), candytuft (Zberis), delphinium or hardy or perennial larkspur (D. formosum Boiss. and Huet. and hybrids), cornflower (Centaurea cyanus L.), feverfew (Chrysanthemum parthenium Pers.), common snapdragon (Antirrhinum majus L.), blue laceflower (Trachymene caerulea R. Grah.), English daisy (Bellis perennis L.), 44 CIRCULAR 278, U. S. DEPARTMENT OF AGRICULTURE calendula or pot marigold (Calendula officinalis L.), and common perennial gaillardia (Gaillardia aristata Pursh.) should not be held at temperatures lower than 40° F., and cannot be stored with good results for more than a 3- to 6-day period. Sweet violets are usually made up in bunches of 100, supported underneath by a few galax leaves and wrapped with a light waxed paper, and should be stored at 33° to 36°. Columbine (Aquzlegia sp.), stevia (Pigueria trinervia Cav.) , babys- breath (Gypsophila paniculata L.), annual larkspur, baby primrose (Primula forbesiit Franch.), sweet pea (Lathyrus odoratus L.), true forget-me-not (MZyosotis scorpioides L.), and orange-eye butterfly- bush (Buddleia davidii Franch.) all have flowers whose petals shed quickly, almost regardless of temperature. They cannot be held much lower than 40° F., nor for longer than 3 to 4 days, without impairing the keeping quality after removal. Forced Buddleia is sold by the dozen. The others mentioned are bunched in lots of 25. It is not customary to wrap any of these for storage. Orchids and gardenias (Gardenia augusta (l.) Merrill, G. veitchi Hort., and G@. fortwnet Hort.) are not customarily stored for long periods. However, they may be kept in storage in good condition for about a week at a temperature of 45° to 50° F. They keep best when cut just after they have reached a salable condition. Carnations (Dianthus caryophyllus L.) cut in full bloom may be held at 33° to 40° F. for 7 to 10 days. If cut in the bud stage they may be stored at 33° te 40° for 10 to 15 days. Several varieties of carnations, although it is not known how many, will develop satis- factorily when cut in the bud stage, viz, when one or two petals have unfolded from the bud, and will last considerably longer than if cut at a more advanced stage of maturity (40). Roses for nearby markets should be cut in the loose-bud stage; if they are to be shipped to distant markets they should be cut in as tight a condition as is permissible with the variety In question. In the loose-bud stage they may be held at 35° to 40° for 1 week; if stored at lower temperatures the subsequent keeping quality is often impaired (49). Dahlias (Dahlia sp.), China-asters (Callistephus chinensis (U.) Nees), sweet bouvardia (Bowvardia humboldtii Bailey), and heath (EHrica sp.) may be held 7 to 10 days at 40° F. They usually are handled in.lots of one dozen, tied, but not wrapped. Statice, including bigleaf and‘ notchleaf sea-lavender (Limonium latifolitum (Sm.) Kuntze and ZL. sinwatum (L.) Mill., respectively), and strawflower (Helichrysum bracteatum (Vent.) Willd.) may be kept at 35° to 40° F. for 3 to 6 weeks. They may be dried and will retain their original color and shape; strawflowers are usually dried instead of being stored to retain their freshness. Common foxglove (Digitalis purpurea L.), common white foxglove (D. purpurea var. alba Bailey), and garden phlox (Phlox paniculata L.), are not usually satisfactory for storage but may be held for 3 or 4 days at 40° F. The various forced irises, especially the so-called Dutch irises, may be held for 1 week at 33° F. (92). Cut poinsettias (Huphorbia pulcherrima Willd.) sold during the Christmas season usually need not be stored for the few days between STORAGE OF FRUITS, VEGETABLES, AND FLORISTS’ STOCKS 45 their arrival at the wholesale house and the day of sale. If holding 1s necessary, storage at about 50° F. is recommended. Any change of environment, such as improper storage, will increase the apparently inherent tendency of poinsettias to shed their foliage. They should be cut when showing sufficient color to be salable. Searing the cut ends with boiling water is a practice usually followed to prevent undue loss of sap previous to or during storage. Cut lhies-of-the-valley (Convallaria majalis L.) are kept satisfac- torily at 40° F. and may be held for 1 week at this temperature; if they are kept longer the lower bells often become watery in appearance (91). The proper cutting stage is just after the terminal bell has lost its deep-green color. It should be of a yellow-green appearance, the lower 3 or 4 bells at this time being well opened. They are usually tied with foliage in bunches of 25 and are better wrapped loosely in heavy waxed paper, leaving the tops and bottoms of the bunches open. Hyacinth (Hyacinthus orientalis L.), tulip (94), narcissus (daffodil and paperwhite), freesias (/’reesza refracta var. alba Baker), squiils, snowdrops (Galanthus nivalis L.), and crocuses can usually be held satisfactorily for 1 to 2 weeks at 33° to 36° F. Spikes, such as snapdragon, should be cut just after the lower five or six flowers have fully opened; umbels, such as blue laceflower, should be cut just after they develop to a salable condition; flowers formed in heads usually should be cut after the outermost petals are fully de- veloped and just before stamens appear in the center of typically single heads or after the center has become closed with petals in double sorts; corymbs, such as candytuft, are usually best when cut after three-fourths of the lower flowers are opened; those described as thyrses or corymbose cymes, such as the lilac, should be cut when about two-thirds of the determinate branches are developed; cymose clusters, such as babysbreath, should be cut after a few of the terminal flowers have developed. Frorists’ GREENS ~ Fern asparagus (Asparagus plumosus Baker) and smilax asparagus (A. asparagoides (L.) W. F. Wight) are usually shipped in crates. The turn-over of these greens is rapid and shipments are arranged so that storage for longer than 3 or 4 days is usually unnecessary, but they may be kept in the case for 7 to 10 days at 40° to 45° F. The sprays of A. plumosus are tied in bunches of various sizes. Smilax is packed in the crates in various lengths or “strings.” The commercial popularity of A. sprengert Regel has declined to a point where it is produced and used chiefly by small retail growers. Drooping leucothoe (Leucothoe catesbaei (Walt.) A. Gray), huckle- berry, and mountain-laurel (alma latifolia L.) sprays may be held in good condition at 32° to 40° F. for 3 to 6 weeks. They are usually tied in bunches and kept standing in water. Galax (Galax aphylla L.), groundpine (Lycopodium sp.), dagger ferns, common woodferns, ak various species including Dryopteris intermedia (Muhl.) A. Gray, packed in crates, may be held at 32° to 45° F., depending on the length of time it is desired to keep them. At 32° they may be expected to keep 1 to 4 months, whereas at 45° they may be kept for but 2 to 3 weeks in good condition. They are not put in water, but if stored loose they are kept moist by occasional 46 CIRCULAR 278, U. S. DEPARTMENT OF AGRICULTURE sprinklings. If held in wooden cases or packed in such a way as to prevent excessive drying out by direct air currents, no sprinkling is necessary. Galax is usually tied in bunches of 25; the ferns are tied in lots of 50; but both are customarily seld by the hundred. Those who make a business of gathering the greens in this group sometimes store them in coldframes, covering them with about 6 inches of some material such as sphagnum moss or leaves, and shading or using sash as the weather demands. Handled in this way, shipments can be made at any time. Others who might be termed “brokers” have many em- ployees gathering galax and ferns and store their entire holdings in cold-storage warehouses; this is the method commonly employed for storage, and it usually gives satisfaction. Holly (Jlea opaca) sprays or wreaths can usually be held satisfac- torily for approximately 1 month at a temperature of 32° F. and a relative humidity of about 80 percent. These should be left in the packing cases to prevent the circulation of air immediately around them (106). RHIZOMES, TUBERS, AND CorMsS Lily-of-the-valley pips or crowns may be held in cold-storage ware- houses at a temperature range of 25° to 28° F. (97) up to 17 months, although after about 12 months increasing deterioration in quality becomes noticeable. The pips are tied in bundles of 25 with string or willow ties and are packed with sphagnum moss in wooden cases cf various sizes containing from 250 to 2,500 pips. Taro (Colocasia esculenta (L.) Schott), spotted caladium (C. neo- guineensis André), and tuber begonias (Begonia tuberhybrida Voss) may be held at 45° F. and a relative humidity of 75 to 80 percent for 4to6months. They should be packed in dry sawdust, sand, or peat. Cauna (Canna indica L.), dahlia (Dahlia sp.) (3), and peony (Paeonia sp.) may be stored at 40° to 45° F. over a period of 6 to 7 months with a relative humidity of 70 to 80 percent. They are usually packed in dry soil, sand, sawdust, or peat moss. Gladiolus sp. (mostly hybrids) may be stored at 40° to 50° F. with a relative humidity of 70 to 75 percent for 7 to 8 months. A tempera- ture of 40° will hold these corms dormant during the normal storage season. whereas at 50° sprouting will occur after 4 to 6 months’ storage. They should be stored dry in shallow trays with ample ventilation but only after a curing period of 3 to 6 weeks in an open or well-ventilated shed. , Common and golden callas (Zantedeschia aethiopica and Z. elli- ottiana) stored at 35° F. and at a relative humidity of 70 to 75 percent in dry soil, sand, or peat will keep for many months if it is necessary to store them. The normal rest period in the forcing cycle is during May, June, and July. Unless water is withheld during this period complete dormancy will not exist. Therefore, storage in a dry con- dition is essential, with sufficient humidity to prevent undue shriveling. Buss Most varieties of daffodils (Varcissus sp.), hyacinths, freesias, squills (Sez/a sp.), snowdrops (Galanthus nivalis l.), Crocus sp., and similar bulbs may be held at 55° to 60° F. for 4 to 6 months, STORAGE OF FRUITS, VEGETABLES, AND FLORISTS’ STOCKS 47 However, these as well as tulips (Z'ulipa sp.) are usually not stored because better results are obtained by planting them as soon as the are received. Paperwhite narcissus (93) may be stored at 75° to 80° for 5 to 7 months from digging time. Tulips are usually not stored in any packing material, although the use of such material may be advantageous for long storage. Tem- peratures of 36° to 38° F., except for short storage, are considered rather low for tulips shipped from the West in which the buds are already formed. The best storage temperature for shipped tulips is between 50° and 55°, at which temperature range they may be kept for 4 to 6 months. Tuberoses (Polianthes tuberosa lL.) stored at a temperature of 40° to 45° may be expected to keep satisfactorily for 6 to 8 months. Bulbs of the genus Léliwm, of which there are approximately 50 species, are like most other bulbs in giving best results 1f planted when received. However, as Easter lilies are forced during the entire year, it becomes necessary to provide cold-storage conditions suitable for satisfactory holding until they are wanted for planting. The bulbs should be packed in boxes in thoroughly dry soil if rooting and desic- cation are to be prevented. A temperature of 35° F., with a relative humidity of 75 to 80 percent is recommended; under these conditions they may be held for 6 to 8 months. The procedure of storing certain bulbs for a time previous to plant- ing at a temperature that will subsequently hasten flowering 1s.in con- siderable use commercially. Bulbs so handled are said to be “pre- cooled” (7, 27, 28). LITERATURE CITED (1) ALLEN, F. W. 1932. POSSIBILITIES AND LIMITATIONS OF COLD STORAGE FOR STONE FRUITS. Ice and Refrig. 82: 424. and PENTzER, W. T. 1936. STUDIES ON THE EFFECT OF HUMIDITY IN THE COLD STORAGE OF FRUITS. Amer. Soc. Hort. Sci. Proc. (19385) 33: 215-2238, illus. (3) ALten, R. C. 1938. TEMPERATURE AND HUMIDITY REQUIREMENTS’ FOR THE STORAGE OF DAHLIA ROOTS. Amer. Soe. Hort. Sci. Proce. (1937) 35: 770-773. (4) Bain, H. F., BEraman, H. F., and Witcox, R. B. 1942. HARVESTING AND HANDLING CULTIVATED CRANBERRIES. U. S. Dept. Agr. Farmers’ Bul. 1882, 24 pp., illus. (5) Barcrer, W. R. | 1933. EXPERIMENTS WITH CALIFORNIA DATES IN STORAGE. Date Growers, Inst., Ann. Rpt. 10: 3-5. (2) (6) 1941. EFFECT OF COLD STORAGE CONDITIONS ON THE KEEPING OF DRIED FRUIT. Ice and Refrig. 100: 235-237, illus. (7) Biaauw, A. H., VERsLuys, M. C., LuyvTen, I., Joustra, G., and MULDER, R. 1925-26. THE RESULTS OF THE TEMPERATURE TREATMENT IN SUMMER FOR DARWIN TULIPS. K. Akad. van Wetensch. te Amsterdam, Afd. Natuurk. Proc., Sect. Sci. 28: 717-731, illus., 1925; 29 [113] 126, [199]-220, illus., 1926. (8) Brooks, C., Cootry, J. S., and FisHer, D. F. _ 1923. APPLE SCALD AND ITS conTRoL. U. S. Dept. Agr. Farmers’ Bul. 1380, 17 pp., illus. CooLry, J. S., and FISHER, D. F. 1930. DISEASES OF APPLES IN STORAGE. U. 8S. Dept. Agr. Farmers’ Bul. 1160, 20 pp., illus. (Revised.) (9) (12) (13) (14) (15) (16) (17) (18) (19) (20) (21) (22) (23) (24) (25) (26) (27) (28) (29) CIRCULAR 278, U. S. DEPARTMENT OF AGRICULTURE Brooks, C., and HARLEY, C. P. 1934. SOFT SCALD AND SOGGY BREAK-DOWN OF APPLES. Jour. Agr. Res. 49: 55-69, illus. and McCo.ttiocH, L. P. 1936. SOME STORAGE DISEASES OF GRAPEFRUIT. Jour. Agr. Res. 52: 319- 351, illus. and McCottocy, L. P. 1937. SOME EFFECTS OF STORAGE CONDITIONS UPON LEMONS. Jour. Agr. Res. 55: 795-809, illus. Camp, A. F., Gappum, L. W., and STant, A. L. 1933. COLD STORAGE STUDIES ON CITRUS FRUITS. Fla. Agr. Expt. Sta. Ann. Rpt. 1932-33: 104-109. CaARRICK, D. B. 1930. SOME COLD STORAGE AND FREEZING STUDIES ON THE FRUIT OF THE VINIFERA GRAPE. N. Y. (Cornell) Agr. Expt. Sta. Mem. 131, 37 pp., illus. CooLEy, J. S., and CRENSHAW, J. H. 1931. CONTROL OF BOTRYTIS ROT OF PEARS WITH CHEMICALLY TREATED WRAPPERS U.S. Dept. Agr. Cir. 177, 10 pp., illus. Denny, F. E. 1924. EFFECT OF ETHYLENE UPON THE RESPIRATION OF LEMONS. Bot. Gaz. 77: 322-329, illus. DIEHL, H. C. 1940. QUICK FREEZING FRUITS [AND] QUICK FREEZING VEGETABLES. Amer. Soe. Refrig. Engin., Refrig. Data Book 2: 19-380, illus. MAGNESS, J. R., Gross, C. R., and BonNEY, V. B. 1930. THE FROZEN-PACK METHOD OF PRESERVING BERRIES IN THE PACIFIC NORTHWEST. U.S. Dept. Agr. Tech. Bul. 148, 38 pp., illus. EnGAr, A. D. : 1938. STUDIES OF POTATO STORAGE HOUSES IN MAINE. U. S. Dept. Agr. Tech. Bul. 615, 47 pp., illus. FRANKLIN, H. J. 1940. CRANBERRY GROWING IN MASSACHUSETTS. Mass. Agr. Expt. Sta. Bul. 371, 44 pp., illus. FRIEND, W. H., and BAcH, W. J. 1932. STORAGE EXPERIMENTS WITH TEXAS CITRUS FRUIT. Tex. Agr. Expt. Sta. Bul. 446, 40 pp., illus. Fruit DISPATCH COMPANY, HQUIPMENT DEPARTMENT. 1933. BANANA RIPENING MANUAL, Fruit Dispatch Co., Equipment Dept. Cir. 14, 15 pp., illus. GERHARDT, FISK, and EzELL, B. D. 1941. PHYSIOLOGICAL INVESTIGATIONS ON FALL AND WINTER PEARS IN STOR- ASE IN THE PACIFIC NORTHWEST. U. S. Dept. Agr. Tech. Bul. 759, 66 pp., illus. and RYALL, A. LLoyD. 1939. THE STORAGE OF SWEET CHERRIES AS INFLUENCED BY CARBON DIOXIDE AND VOLATILE FUNGICIDES. U.S. Dept. Agr. Tech. Bul. 631, 20 pp. Gorn, H. C. 1911. STUDIES ON FRUIT RESPIRATION. I. THE EFFECT OF TEMPERATURE ON THE RESPIRATION OF FRUITS. Il. THE EFFECT OF PICKING ON THE RATE OF EVOLUTION OF CARBON DIOXIDE BY PEACHES. III. THE RATE OF ACCUMULATION OF HEAT IN THE RESPIRATION OF FRUIT UNDER ADIABATIC CONDITIONS. U.S. Bur. Chem. Bul. 142, 40 pp., illus. GREEN, W. P., HUKILL, W. V., and Ross, D. H. 1941. CALORIMETRIC MEASUREMENTS OF THE HEAT OF RESPIRATION OF FRUITS AND VEGETABLES. U.S. Dept. Agr. Tech. Bul. 771, 22 pp., illus. GRIFFITHS, DAVID. 1936. SPEEDING UP FLOWERING IN THE DAFFODIL AND BULBOUS IRIS. U. S. Dept. Agr. Cir. 367, 18 pp., illus. 1936. TULIPS. U.S. Dept. Agr. Cir. 372, 64 pp., illus. HALLER, M. H., and HArpINne, P. L. 1939. EFFECT OF STORAGE TEMPERATURE ON PEACHES. U. S. Dept. Agr. Tech. Bul. 680, 32 pp., illus. (30) (31) (32) (43) (44) (45) (46) (47) (48) STORAGE OF FRUITS, VEGETABLES, AND FLORISTS’ STOCKS 49 HALLER, M. H., HARDING, P. L., LUTZ, J. M., and Ross, D. H. 1932. THE RESPIRATION OF SOME FRUITS IN RELATION TO TEMPERATURE. Amer. Soe. Hort. Sci. Proc. (1931) 28: 583-589. HARDING, P. L. 1935. PHYSIOLOGICAL BEHAVIOR OF GRIMES GOLDEN APPLES IN STORAGE. Iowa Agr. Expt. Sta. Res. Bul. 182: 313-352, illus. and Hauer, M. H. 1933. THE INFLUENCE OF STORAGE TEMPERATURES ON THE DESSERT AND KEEPING QUALITY OF PEACHES. Amer. Soc. Hort. Sci. Proc. (1932) 29 : 277-281, illus. and HAtieEr, M. H. 1935. PEACH STORAGE WITH SPECIAL REFERENCE TO BREAKDOWN. Amer. Soe. Hort. Sci. 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