It 
 
 
 U. S. DEPARTMENT OF AGRICUL ttJRE, 
 
 BUR] vr OF PLANT INDUSTRY Cireulai No 
 u i OALLOWAY, i • Bui 
 
 SOME CONDITIONS [NFLUENCING 
 THE YIELD OF HOPS. 
 
 II Y 
 
 W. W. STOCKBERGER, Pharmacognosist, 
 JAMES THOMPSON, Expert, 
 
 DrI O-Pl INT I w ! STIG \ I i' '\-. 
 
 I-. .m; in 
 
 »M-.«iic« : OC 
 
 
 
 ■EPOSITORY 
 
1 fir. 56] 
 2 
 
 Bl REAL OF PLANT INOISTRY. 
 
 Chiif of Bureau, Beverlx T. Galloway. 
 Assistant Chief of Bureau, G. Harold Powell. 
 
 EditO) . .1- E. K' ICK WELL. 
 
 Chief Clerk, James E. .Junes. 
 
I: r . 
 
 SOME CONDITIONS INFLUENCING Till; 
 YIELD OF HOPS. 
 
 INTRODUCTION. 
 
 In certain of the hop-growing sections <>t' the United States the 
 opinion i- frequently expressed thai there has been a progressive de- 
 cline in tin' :i 1 1 n 1 1 ;il average yield per acre extending over ;i term of 
 years. In other sections growers believe thai the yields are ;it least 
 as great now as the} have ever been. Some supporl for each view i- 
 found in Table I. adapted from Bulletin N<>. -"'<i of the Bureau of 
 Statistics, I . S. Department of Agriculture. 
 
 Tabu I i cragi yield of /c;/>n. by States, foi /'" <■ cam /^ s ". 1890, 
 
 and /.'"■". 
 
 
 ■ 
 
 
 
 
 
 
 
 
 
 
 
 
 1.155 
 
 
 
 
 ply Illustrates tin- Importance "f applying exact methods in 
 studying the factors i; • yields. The facts I fortb were 
 
 obtained from a study of the i hops, and they ofTer suggest ioi 
 
 Importani rxower. I rable to emphasize the 
 
 iKiint that the most profitable methods of culture and handling can nol be 
 
 iletermlned bj general observation alone, sin.-.' many details will be over- 
 l which, apparently trifling in thei le of great Importance 
 
 when taken in the the direct loss due n> the ' 
 
 .] nlone may not be appreciated until a survej is made and the percentage 
 ratio determined 
 
 The practlca in tliis publication were developed in connec- 
 
 tion with an extended investigation of American bop growing and handling 
 which Is being m by Dr. W. W. Stockberger, Pharmacognosis 
 
 bj Mi rhompsoi under il ■ - Di R. II. True 
 
 . Plant Investigations, and i r ble to 
 
 make these results immediately avaUable in the form G. H. 
 
 |»'ir 
 
4 SOME CONDITIONS INFLUENCING THE YIELD OF HOPS. 
 
 The Bgures given in this table were taken at ten-year intervals, and 
 in the absence of those for the intervening year.-, they are of little 
 value in determining either an increase or a decrease in the average 
 annual yield. Assuming, however, that the apparent diminution of 
 yield for the State of California as indicated by the table was real, a 
 thorough study of an individual acre in the central part of the State 
 was begun in L909 for the purpose of determining some of the factors 
 which might he responsible for diminished production. 
 
 The results of this study clearly indicate that closer attention to 
 certain cultural details should result in a substantial increase in yield. 
 
 THE METHODS EMPLOYED IN THE INVESTIGATION. 
 
 The acre selected for study represented, as far as inspection 
 alone could determine, the average of conditions existing in several 
 contiguous tields of hops aggregating about 600 acre-. The soil, a 
 rich sandy loam, had been under hops continuously for the last ten 
 years. The rows were 7 feet apart, running from east to west, and 
 the hills were approximately C-i feet apart in the rows. The hops 
 were trained on strings about 18 feet long, depending from the wire-, 
 of the usual type of high-wire trellis.'' 
 
 When the crop was ready for harvesting, a plat was made of the 
 entire acre and a definite number assigned to every hill. The hops 
 were then picked from each hill separately, weighed, and the weight 
 recorded opposite the number assigned to that respective hill. The 
 number of vines to the hill, the occurrence of male, dwarf. " bastard," 
 nonproductive, and missing hills, and the general characteristics of 
 the product of each hill were also recorded. 
 
 EFFECT OF IMPERFECT STAND ON YIELD OF HOPS. 
 
 When the observations were tabulated it became evident that the 
 yield had been heavily reduced through the occurrence of a large 
 
 number of nonproductive and missing hills, as will he seen from the 
 following: 
 
 Hills producing Imps 853 
 
 Hills having vines with no hops 4:2 
 
 Missing hills ."it; 
 
 Hills with dwarfed vines 1 
 
 Hills having '^bastard" vines 5 
 
 Hills having only male vines 10 
 
 Total 967 
 
 Deducting the number of male hills, the presence of which i- held to 
 he necessary for the proper development of the crop, there should 
 
 have been on this acre ( .»:>7 productive hills, as against !->">:> hills 
 
 '• See Farmers' Bulletin 304, i>. 14. 
 [Cir. 56] 
 
SOME CONDITIONS INFLUENCING THE YIEU [O] .") 
 
 actually bearing I n »| >-. This gives an absolute reduction of 104 lulls, 
 
 or l". s per cent. Had il ntire number >>f lull- been in bearing 1 1 h- 
 
 yield would have been l-.l per rent greater than thai actuall} ob 
 tained. 
 
 The distribution <>f the hills having \ ines with no ln>|>- and of the 
 missing lull- is shown <>n the accompanying diagram i iiL r . I ). The 
 
 
 
 
 
 
 
 
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 llstrlbntlon <•( nonproductive unci missing bills ..f I 
 lental acre In California. # - Vines bearing no bops; x _ hills. 
 
 «l<>t- indicate the hills having vines bearing no hops, and the crosses 
 
 tln> missing hills. This distribution appears to be entirely one <>f 
 
 chance and not <lin- to variation in the soil, imperfections in the 
 drainage, or other purely local factors, 
 
 [v'lr. ."«; ] 
 
b SO.MK CONDITIONS ENFLUENCING THE YIELD ol EOPS. 
 
 VARIATION IN THE YIELD FROM INDIVIDUAL HILLS. 
 
 A wide variation was observed in the yield from individual hills. 
 This ranged from a few ounces in some cases to as much as 18 
 pounds in others. In making the records the weight of green hop- 
 was taken to the nearest half pound, and the results have been put in 
 tabular form, appearing in Table II. In the columns marked 
 " Yield '" the weight of green hops is given to the nearest half pound, 
 and in the other two columns is given the number of hills, each of 
 which gave the yield opposite these numbers in the adjacent column 
 to the left. 
 
 Table II. — Number of hills giving various yields <// hops <m tin experimental. 
 
 acre in California. 
 
 
 Yield. 
 
 mils. 
 
 Yield. 
 
 mils. 
 
 Pounds. 
 
 Number. 
 
 Pounds. 
 
 Number. 
 
 o. .-, 
 
 18 
 
 9.5 
 
 24 
 
 1.0 
 
 50 
 
 10.0 
 
 31 
 
 1.5 
 
 34 
 
 10.5 
 
 16 
 
 2.0 
 
 39 
 
 11.0 
 
 24 
 
 2. 5 
 
 33 
 
 11.5 
 
 10 
 
 3.0 
 
 32 
 
 12.0 
 
 20 
 
 3.5 
 
 43 
 
 L2.5 
 
 :. 
 
 4.n 
 
 41 
 
 13.0 
 
 7 
 
 4.:, 
 
 35 
 
 13. 5 
 
 i. 
 
 .Vll 
 
 60 
 
 14.0 
 
 11 
 
 5.5 
 
 44 
 
 14.5 
 
 3 
 
 6.0 
 
 44 
 
 15.0 
 
 j 
 
 6.5 
 
 21 
 
 15. -'i 
 
 i 
 
 7.11 
 
 49 
 
 lti.o 
 
 ii 
 
 :..'. 
 
 36 
 
 16.5 
 
 
 
 8.0 
 
 46 
 
 17.1'. 
 
 l 
 
 8.5 
 
 25 
 
 17.5 
 
 l 
 
 9.0 
 
 38 
 
 18.0 
 
 3 
 
 The total yield of this acre was .\207.5 pounds of green hop';, and 
 this divided by 853, the number of bearing hills, a'ives i',.ii)4— pounds 
 as the average production per hill. Of the entire number of hills, 
 47."! were below the average and 380 hills were above the average 
 production. Also, the average production is only one-third of that 
 reached in the case of a few hills. 
 
 According to the quantity of hops produced the hills may be 
 roughly divided into three classes, or groups: (1) Those yielding 
 less than 6 pounds. (2) those yielding from 6 to 12 pounds, and (.3) 
 those yielding more than 12 pounds. The first group consists of 129 
 hills, or 50.1 per cent of the entire number, and these produced only 
 1,380.5 pounds, or 26.5 per cent of the entire yield. The second 
 group has 381 hills, or 45 per cent of the entire number, and the pro- 
 duction was 3,261 pounds, or 62.6 per cent of the entire yield. The 
 third group consists of 40 hills, or 4.7 per cent of the entire number, 
 and i he hop- produced weighed 5GG pounds, being 10.S per cent of 
 
 LCir. 56] 
 
BOME CONDITIONS IMI i ENCING Mil' YIELD OP HOPB. 7 
 
 the entire yield. The accompanying figure (fig. •_' i Bho* graph- 
 ically the relationship between these three groups. 
 
 Figure 2 will serve, also, in forming some conception of type with 
 re i "■<■! to yield from the hills of an entire field. A study of the hills 
 
 of group l shows thai for vslt - reasons thej are less productive 
 
 than those usually regarded a- average or representative hill-. Simi- 
 larly, the hills of group :'■ arc iVw in number and may be considered 
 as exceptional ami their occurrence expected far less -'lien than that 
 
 
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 £<?*'£-*' £//*?/ 7- of- y/£V.O —O.S fOCS/D /='£?? /V/Z/. . 
 
 /2 
 
 
 o.^ 
 
 1 '"- -' '• ■<- the r:i t i.. of the Dumber of hills to the production of bopa in 
 
 H" of low, medium, and high yielding hills. 
 
 of the hills of the other groups, Ii seems, therefore, that among the 
 hills of group 2, where the bulk of the yield was obtained, the typical 
 
 liill- with respect to yield may I spected to occur. Assuming, then, 
 
 that the prevailing type of normal hills with respect to yield lies 
 between those producing 6 and those producing 12 pounds, there is 
 every reason for giving special attention to the hills low in yield for 
 the purpose of bringing them to a higher state of productiveness. 
 
 I'lic fact should not be losl sight of that the average yield for this 
 acre, 6.1 - pounds per hill, lies just above the lower limit of yield in 
 [Or. Oti] 
 
8 SOME CONDITIONS INFLUENCING THE YIELD OF HOPS. 
 
 the second group. I i" through better methods of handling and closer 
 attention to the details of culture the number of bills in the first 
 group can be materially diminished, the average yield for the entire 
 acre will be correspondingly advanced toward the upper limit of 
 yield in the second group, and the total yield thereby substantially 
 increased. In the following pages some suggestions will be given as 
 to how this may he accomplished. 
 
 RELATION OF NUMBER OF VINES PER HILL TO YIELD. 
 
 The records obtained from the acre under observation show, fur- 
 ther, that the number of vines trained from the individual bills 
 varied from one to eight. The distribution of the hills according to 
 the number of vines is shown in the following: 
 
 Hills having one vine 54 
 
 Hills having two vines 113 
 
 Hills having three vines 135 
 
 Hills having four vines 186 
 
 Hills having Ave vines 188 
 
 Hills having six vines 168 
 
 Hills having seven vines 8 
 
 Hills having eight vines 1 
 
 Total sr,:; 
 
 Several explanations of the variation in vines to the hill may be 
 advanced. Among them are the recent replanting of certain hills, 
 in which case they would not have the vigor of older hills: the weak- 
 ening of the roots of some hills by disease or the attacks of Insects; 
 the exhaustion of the vigor of others through long-continued pro- 
 duction; the breaking off of a portion of the vines in cultivation: the 
 destruction of some vines by the wind; or the cutting off of too many 
 vines at the time of training. What seems most probable i> that 
 through the carelessness and negligence of the workmen the proper 
 number of vines was not trained. It i- probable, also, that indi- 
 vidual differences in vigor and productiveness should be taken into 
 account. 
 
 The relation between the number of vines per hill and the yield 
 per hill is shown in Table III. 
 
 [Cir. 56] 
 
SOMI CONDITIONS INFLUENCING I II I VIELD O] UOl'S. 
 
 I v t . i i III ' ■■• •■■ the production o) /<"/^ '" tin hill and tin numbct 
 
 I', tin hill. 
 
 ill.- hill 
 1 II 
 i II 
 
 in -. 
 II 
 II 5 
 13 
 
 II 
 II 5 
 
 r, 5 
 17 
 
 
 
 hill 
 
 
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 in 
 
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 in 
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 14 
 
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 11 
 
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 11 
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 10 
 
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 7 
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 in 
 
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 1 1 
 II 
 21 
 
 
 
 
 
 
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 14 
 
 7 
 
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 16 
 
 
 
 24 
 
 
 
 1 
 
 
 
 In 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1 
 
 1 
 
 
 
 
 11 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 1 
 
 
 
 
 
 
 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 • 
 
 - 
 
 ] 
 
 - 
 
 In th(> first column of the table the yield per lull is given to the 
 Dearest half pound. The figures at the top of the following columns 
 indicate the number of \ ines produced by each hill <m-i-mi ri n^r therein, 
 and the hills in each column are distributed according to their produc- 
 tion to the nearest half pound. For example, from column 1 it will 
 lie seen that ten L-vine lull- produced 0.5 pound each, twenty-three 
 l-vine hill- produced 1 pound each, etc.; from column •_' eight 2-vine 
 hills produced 0.5 pound each, seventeen 2-vine hill- produced 1 
 pound each; from column : '> seven 3-vine hill- produced 1 pound each, 
 four 3-vine hill- produced 1.5 pounds each, mid so on for the entire 
 table. At tin- foot of the table the totals -how the entire number of 
 hill- producing the number of vino- indicated by the figure :it th< 
 of tin' respectn e columns. 
 
 A study of Table III will -how thai the larger numbers in each 
 column occur in groups, but that the position of these groups with 
 respect to the production per hill i- eery different. Thus (from 
 column li 10, 23, and 11 hills produced ,, .">. 1. and 1.5 pound- each, 
 
10 
 
 SOME CONDITIONS INFLUENCING THE FIELD OF HOPS. 
 
 respectively; (from column 3) 15. \-2. and 15 hills produced 2.5, 3, 
 and 3.5 pounds each, respectively; (from column 5) 14. 18, and 18 
 hills produced 7. 7.."). and 8 pounds each, respectively. From column 
 1 it appears that no 1-vine hill produced more than 4 pounds, and 
 from column G that relatively few 6-vine hills produced less than 
 6.5 pounds each. The balance of evidence, therefore, is entirely in 
 favor of a much larger total production when 6 vines to each hill 
 are trained than with a smaller number. 
 
 COMPARISON OF ACTUAL WITH POSSIBLE YIELDS ON 1 ACRE. 
 
 The actual yield of hops on the acre studied was 5,207.5 pounds, 
 and the mean yield per hill (5.104+ pounds. Had there been a full 
 stand of 957 bearing hills, with this same average yield per hill, the 
 production on the acre would have been 5,841.5 pounds. This is an 
 increase of 12.1+ per cent over the actual yield. 
 
 In a similar manner, the possible yield per acre has been calculated 
 for each number of vines trained per hill. For comparison the results 
 have been brought together in Table IV. which follows: 
 
 Table IV. — Possible yield <m I acre of hops, according to the number of vines 
 trained, with the corresponding increase <,r decrease of the possible over the 
 act nut yield. 
 
 Number of vines to the hill. 
 
 Number ol 
 
 hills. 
 
 54 
 113 
 
 135 
 
 lM, 
 
 ISS 
 168 
 
 <-8 
 ••1 
 
 U'ti'nl Average 
 vied >" i " M ' ' 
 
 Pounds. 
 
 Pounds. 
 
 71.5 
 
 1.324 
 
 293.5 
 
 2.597 
 
 
 4.337 
 
 1,168.0 
 
 6. -'79 
 
 i. 188. 5 
 
 7.917 
 
 1.510. 5 
 
 8.991 
 
 81.0 
 
 10. 125 
 
 Average Possible 
 yield to yield to 
 
 the vine. the acre. 
 
 Pounds. 
 1.324 
 1.298 
 1.445 
 1.569 
 1.583 
 1.498 
 1.446 
 
 Increase or 
 decrease of 
 
 possible 
 
 over actual 
 
 yield. 
 
 Pounds. 
 1 . 257. 
 2,485.3 
 4.150.5 
 6.009.0 
 7.570.5 
 8,604.3 
 
 Per cent, 
 a 75. 8+ 
 a 52. 2+ 
 a 20. 2+ 
 6 15.3 + 
 6 45. 4+- 
 6 65. 2+ 
 
 1 )i •crease. 
 
 '■ Ineivas 
 
 Number of hills too small for consideration. 
 
 The average yield to the hill was determined in each case by divid- 
 ing the number of pounds produced by all of the hills having the 
 same number of vines by the number of such hills. The possible 
 yield was then obtained by multiplying the average yield per hill 
 by 957, the number of possible bearing hills to the acre. It will be 
 observed that the possible yield in the case of the hills having 1. 2, 
 and o vines, respectively, is very much less than the actual yield, 
 which was 5,207.5 pounds. Also, in the case of the hills having I. 5, 
 and 6 vines, respectively, the possible yield is far in excess of the 
 actual, being 65.2+ per cent greater for the 6-vine hills. 
 
 [Cir. 56] 
 
Ml I 0ND1 I l<>\- INFLUENCING I III YIELD OP HOPS. 1 1 
 
 Ii should be noted that 1 1 1 « - average yield per vine is fairl} « -» » i • 
 stant, irrespective of the number of vines to the lull. The average 
 yield per vine for the entire acre also i-losch accords with thi 
 figures, being in this case 1.513 pounds per Tine. 
 
 Tile averages given in Table IV tnaj be considered as applying 
 not only in the acre studied, but also in a general waj t<> the entire 
 crop in the section where this work was done. So long as the general 
 conditions remain unchanged there is ;i high degree of probability 
 that these averages will be found to represent fairly well what may 
 be expected in succeeding years. Changed weather conditions, at 
 tacks of lice, mold, and spiders, or other unfavorable influences to 
 which the hop crop is subject, will of course materially affect the 
 chance of these averages being repeated. But thej do -how that a 
 greal increase in yield maj be reasonably anticipated in fields in 
 which there is a full stand and 6 vines arc trained t«> each hill over 
 the entire field when it presents the conditions existing on the acre 
 which has furnished the data for these observations, 
 
 THE SO-CALLED •BASTARD" VINES. 
 
 Iii -nine sections hop vines are occasionally found which hear both 
 -laminate and pistillate flowers. Such plants are known locally as 
 "bastards," "mongrels," or "bull-hops." When they occur they 
 represent a total loss, so far as yield is concerned, since the few hops 
 borne by these vines are inferior and never gathered. On the acre 
 under consideration there were only five of these plants, but they 
 have been observed in much greater proportion in other years and in 
 other localities. 
 
 There is no e\ idence that these vines usually occur n< ar a male vine, 
 as stated by Myrick; neither can an excess of pollen falling upon 
 the pistillate flowers produce this abnormality, as is believed by some 
 to be the case. Plain- of this type frequently occur among seedling 
 hop-, and their presence may he expected in held- where chance seed- 
 lings springing up near the permanent hills have been trained in the 
 usual manner. There are also good reasons for believing thai this 
 undesirable characteristic may be introduced through the root cut- 
 tings used in replanting or in setting out new held-. In L908 a num- 
 ber of cuttings were taken from one of these "bastard" plant- and 
 removed to a locality about In miles distant. The vines from these 
 cuttings came into flower in 1909 and in every case reproduced the 
 malformation of the original plant from which they were taken. In 
 view of this fact care should be taken to prevent the use of cuttings 
 from •• bastard " plant- by promptly digging them out and destroying 
 
 Myri.k. II. The Bop, New Sort, 1889, p. 23. 
 [Cli 
 
12 SOME CONDITIONS INFLUENCING THE YIELD OF HOPS. 
 
 the roots as soon as they arc observed. In this way their perpetuation 
 may be prevented and the loss in yield due to their occurrence avoided. 
 
 SUMMARY. 
 
 A critical study of yield on an acre of hops in California selected 
 as representing the average condition of 600 surrounding acres show- 
 that, owing to the occurrence of a large number of nonproductive and 
 missing hills, the actual yield was only 87.9 per cent of what might 
 be expected with a perfect stand. 
 
 The yield from individual hills was found to vary from 0.5 to 18 
 pounds. Owing to the large number of low-yielding hills the average 
 yield per hill for the entire acre was reduced to G.lO-t-f- pounds. 
 
 The number of vines trained to each hill varied from one to eight. 
 As the number of vines per hill increased, the average yields of the 
 hills having the same number of vines were found to increase in 
 approximately the same ratio. 
 
 Assuming a full stand of 957 hills with G vines trained to each hill, 
 the calculated possible yield is 65.2-f- per cent greater than the actual 
 yield on this acre. 
 
 "Bastard" or "mongrel" hills should be dug out and destroyed, 
 as they are of no value and diminish the total yield. 
 
 Approved : 
 
 James Wilson, 
 
 Secretary of Agriculture. 
 
 Washington, D. C, March 7, 1910. 
 
 [Cir. ■",<;] 
 
 o 
 
N V 
 
 UNIVERSITY OF FLORIDA 
 
 3 1262 08928 9762