WIN 1 § \ t HIM 105 510 THS A PRELIMNARY STUDY OF HARRENNESS OF GOOSEBERRAES 7N I‘AECHIGAN Thesis for the Degree of M. 5. (31611:: H. Cowles 1937 1‘ — Michigan State College A Preliminary Study of Barrenness of Gooseberries in Michigan A Dissertation Submitted to The Faculty of The Division of Horticulture in Candidacy for the Degree of Master of Science By Glenn Hill Cowles .__“‘ East Lansing, Michigan June 1937 W/wt“ 6,7737 / M 7,2,44. 1‘ big ,3. [in II] nu will: THESIS 1,_()S_)U'7 8 TABLE OF CONTENTS LIST OF TABLESOOOOOOOOOOOOO II. III. IV. VI. VII. INTRODUCTION........ Page 00.00.00... HISTORICAL BACKGROUND........... REVIEW OF LITERATUREOOOCOOOOOOOO DEFINITION OF TYPES............. MATERIALS AND METHODS OF PROCEDUREOOOO00.000000000000000. Oceana County an Ideal Location for Work Field Surveys Attempt to Transmit "Bull" Condition Blossom Counts Were made Collection and Preparation of Histological material PRESENTATION OF RESULTS......... Economic Aspects ANALYSIS OF GROWERS' 11 OBSERVATIONS ll 16 TABLE OF CONTENTS-~CONTINUED VIII. THE BLOSSOM-SET PROBLEM............Pa§g IX. INTERNAL FACTORS................... 34 X. SUMMARY............................ 37 XI. ACKNOWLEDGEMENTS................... 37 XII. LITERATURE CITED................... 38 iii Table I. II. III. IV. V. VI. VII. VIII. II. LIST OF TABLES Contrasting Nermal and Barren Characteristics................. The Total and Average Yields for the Plant Types in Plot III. The Total and Average Yields for the Plant Types in Plot 11.. lonetary Loss in Plots II and IIIOOOOOOOOO0000000000000... An Analysis of the Thirty-Two Plants in Plot II Changing Over to "3.111" TyPeOOOOOOOOOOOOOOOOOO Regrouping the Bushes Which Came Out of the "Bull" conditionOOOOOOOOO000.000.0000.. Remaining Groups in Plot II Where the "Bull" Types Appeared-000000.00000.000.000.00. Appearance and Yields of Grafted Plants in Plot II....... Blossom Counts.................. iv Page 10 17 18 20 22 23 24 28 33 Graph II. LIST OF GRAPHS Showing Precipitation in Oceana County During 1934, 1935. and. 19360000000000.000 Showing the Relation of "Bull" and Normal Yields to Early Summer Precipi- tationOOOOOOOOOOOOOOOOO00000 Page 30 50 INTRODUCTION Owners of gooseberry plantations in various sections of Michigan have from time to time made in- quiry concerning a barren condition of individual bush- es characterized by excessive vigor. The more painstak- ing and prudent growers have attempted to remedy this condition by rogueing out these unprofitable plants or by special fertilizer applications, but barrenness has continued to be a problem. Nevertheless in spite of this and other difficulties, Michigan canners packed 5600 tons of gooseberries in 1934, a year of great drought. At present (1937) there is much renewed inter- est in this fruit as the growers report a good price the past season. Thus, any light that may be cast upon the subject of gooseberry barrenness would seem timely. HISTORICAL BACKGROUND All of the important commercial varieties of gooseberries which have become pOpular in the United States originated directly from North American species. Of the dozen or more varieties to gain prominence, only three are extensively planted at the present time, namely: Downing, most widely grown in the United States; Oregon (Oregon Champion), in Rocky MOuntain and Pacific Coast States; and Poorman, the newest of the three, now on trial in various parts of the United States. Even Downing, the old reliable, is but 80 years old, having been introduced by Charles Downing in 1855 (8). It is recognized of course, that the gooseberry attained its greatest development in England during the latter por- tion of the twentieth century. This, however was with European varieties seldom found in the United States. REVIEW OF LITERATURE A great dearth of material is noted by all who attempt to locate any reference on the subject of goose- berry barrenness. This is due partly to the fact that gooseberries and currants have generally been treated to- gether, and partly because both of these fruits are‘ minor and often neglected. A careful review of the lit- erature since 1900 showed only two references on either gooseberries or currents that could be construed as hav- ing any bearing on the subject. The first is a report by P. Thayer(9) describing a variation in the Downing goose- berry, which is probably identical to the barren type under consideration in this paper. A second is an invest- igation on the American out-lawed species, black currents, by J. Amos (1) at the East Malling Research Station and might possibly be in the nature of a parallel for that species. He reports these "rogue" varieties as having no commercial value. "Rogue" bushes were inarched with normals, others were connected directly by an arrange- ment of tubes, and in all, 103 successful transmissions were made. The normal plants, however, did not show rogue characteristics until the second season. Further, this "unprofitable rogue" has many characteristics quite different from the barrenness under consideration in this paper. DEFINITION OF TYPES Barrenness of one sort or another has vexed the fruit grower since early times. It has been reported in all fruits but as here used deals only with an unfruit- ful condition of the Downing gooseberry. Early in this investigation it was found that grower reports as to the behavior and appearance of these so-called "Bull" or barren type bushes varied con- siderably. Thus, it became imperative to delineate the type or types under consideration. Field surveys were accordingly initiated in four plantations totaling 29 acres. These varying reports were soon found to be due to intermediate or possibly transitional stages. See Figure 4. Often it was difficult if not impossible to differentiate barrenness of the intermediate "Bull" type from barrenness due to various common and well- known causes. These barren types were found to be scat- tered throughout each patch in a hit and miss manner. It is also quite common to find a rather typical barren plant which will have one or more of its branches prod- ucing a normal crop, and with few and small berries throughout the remainder of the bush. However, the typical "Bull" or barren type is easily recognized even at a distance by its large size and extremely vegetative condition. The comparative size of a "Bull" bush and a normal plant of the same age is clearly shown in Fugure 1. Fig. l.--The "Barren" type bush on the left produced four pounds in 1936 while the "Normal" on the right produced over seven pounds. These two plants are the same age, apparently the same variety, and only eight feet apart. Figures 2 and 3 are also photographs made in the same field and show foliage differences as seen at a few feet. -_‘-0 . . r‘ll .- ’ - x " w IFS“ s .-\‘ 322‘ v. ' k ‘. ’5’,“ " Fig. 2.--Normal fruitful bush with a fair crop of berries and wide flat leaves. L *___ A Fig. 3.--"Bull" bush with scattered fruits and narrow puckered leaves. Figure 4 was taken against the sky to show the large size and sparse foliage of the so-called "intermediate" type which so confused the early reports. Fig. 4.--Barren type bush with long shoot growth but scant foliage. (Inter- mediate type). The contrast between typical "Bull" bushes and representative normals with the size of a picking lug is shown in Figures 5 and 6. Fig. 5.--Normal, yielding a good crop of 13 pounds in 1936. Fig. 6.--"Bu11" bush nearly four times as large as the normal in Fig. 5 but yields only 8.i pounds. Representative branches of the two types were cut and photographed, as shown in Figures 7 and 8. Fig. 7.--Representative Fig. 8.--Representative branch from "Bull" bush. branch from a "Normal" bush with a fair crop of berries. Upon close observation it is found that the bar- ren bushes have more deeply cleft leaves which are held in a more upright position and have a more pointed ap- pearance than do the average normal plants. This differ~ ence is more clearly shown if the leaves are removed and ppread out on a flat surface. This was done in Figure 9, 10 which shows all of the leaves from a barren branch on the one hand contrasted with the leaves of a represent- ative normal limb on the other. Fig. 9.--Contrasting nor- mal wide leaves on the one hand with narrow deeply cleft "Bull" bush leaves on the other. These differences are further contrasted in Table I. At harvest time the difference is most apparent as the "Bulls" yield a maximum estimated at 70 per cent of a crop and from this on down to a practically barren con- dition of three to five small berries on one very large limb. TABLE I CONTRASTING NORMAL AND BARREN CHARACTERISTICS 11 TABLE I CONTRASTING NORMAL.AND BARREN CHARACTERISTICS Points of Comparison: Normal "Bull" Leaf Characteristics: Petiole size Angle of petiole Blade size Upper surface Lower surface Length of lobes Length of sinuses Blade shape Blade apex Blade base Blade margins Blade segment- ations medium Normal for Grossularia fl Apparently Terminal equal to lateral Slightly cleft Reniform to deltoid Obtuse to acute Truncate to obtuse Crenate Thinner than normal Less than normal n H I! very similiar '1 fl Terminal longer Deeply cleft Ovate to lanceolate Acute to acuminate Obtuse to acute Serrate or incised Indistinctly palmately lobe4 Distinctly lobed MATERIALS AND METHODS OF PROCEDURE (a) OCEANA COUNTY.AN IDEAL LOCATION FOR WORK As some of the largest commercial gooseberry plantations of the state are located in the Oceana 12 county fruit district, it is an ideal place to pursue an investigation with this fruit, though general obser- vations throughout this district disclosed many planta- tions in such a state of general neglect as to be quite useless. Nevertheless, four were selected as represent- ative, two in Hart Township and two in Shelby Township. (b) FIELD SURVEYS A nine-year old plantation of ten acres was first selected for this field survey work. Two plots of ten rows each with from 76 to 79 bushes in each row were laid out. In addition to these, when frost injurynbecame evident in 1934, two new plantations were selected. These were located on lighter soil but on such a high elevation as to be nearly free from injurious frosts. In all of these plots field surveys were made and the condition of each plant was recorded for 1934, 1935, and 1936. Also, yield records, to be used as corroborative evidence, were secured whenever possible. waever, because of severe droughts, early spring frosts, uncontrolled cut- worm infestations, and severe attacks of mildew depend- able data could be secured for only two plots, one con- taining 759 bushes and the other 233. In these plots accurate tabulations were secured for each bush for the 13 three successive years. From these it is possible to as- certain which are "Bull" bushes, which are normal, and which should be classified as small or inferior. Also, it is possible to determine if there were any changes to- ward or away from the "Bull" or barren type. Notes on flower, leaf, and other plant characteristics were taken from these plants at the prOper time of the sea- 8011. (c) ATTEMPT TO TRANSMIT "BULL" CONDITION Early in the spring of 1934 dormant wood was cut and stored. "Bull" scions were later set on normal bush- es and normal scions on "Bull" bushes. Several scions were placed on each plant. The test plants selected were as typical as possible and scattered throughout Plots I and II. These scions failed to take and Plot I was lost after the drought. Nevertheless, 17 plants re- manied and these were watched very carefully. If it were a virus that caused this barren condition, then these grafts might have transmitted the disease as the cambium layers were brought together. This would seem more probable as four or more scions were set on each bush. (<1) 14 (d) BLOSSOM COUNTS WERE MADE As this study was initiated it was thought pos- sible that the barren bushes failed to differentiate sufficient fruit buds. This was soon disproven the fol- lowing season by a field inspection of the two types of plants during full bloom. In order to secure a numerical sample of this condition blossom counts were taken in Plot I (discon- tinued after drought of 1934) and in Plot II, only in 1935 these were ruined by spring frosts. This was re- peated in 1936 when counts were made and percentage of fruit-set determined ahead of a late spring frost which did considerable damage in the low areas. As more light was thrown on the blossom-set problem the need of investigating the flower mechanism became more and more evident. (e) COLLECTION AND PREPARATION OF HISTOLOGICAL MATERIAL A preliminary sampling of flowers had been taken in 1934. These were subsequently sectioned and stained to show pollen-tube deve10pment. The regular paraffin 15 method was followed except that n-butyl alcohol was sub- stituted for xylol (at the suggestion of Dr. De Zeeuw) as it speeds up the work by combining the dehydrating and clearing processes and also does not harden bud scales. The sections were cut at twelve microns and stained with Safranin "0" on the advice of G. F. Gray who had had exceptionally clear differentiation of pol- len tubes when working with Vaccinium. This first material indicated the need of much more intensive sampling of both types of blossoms (i.e., "Bull" and normal). These were taken at the same time in the hope that a variation could be found in the two types which results in the premature dropping of "Bull" blossoms and in the retention of sufficient flowers by normal plants to insure a full crap of fruit. These samples were later collected and handled as before. The slides from this material not only shed some light upon the problem of blossom fall, but further pointed the way for more Specific investigations of pollen-tube form- ation. Little of a concrete nature could be learned from these samples as we find blossoms of varying ages on a given bush and thus pistils, stigmatic surfaces, and pol- len tubes in varying stages of deve10pment. This clearly indicated the further need of hand- 16 pollination of both types of pistils so that pollen- tube development could be followed and that pre-ferti- lization and post-fertilization stages could be deter- mined at stated intervals. Accordingly, unopened buds were emasculated and covered with manilla bags. Two days later each pistil that appeared normal and healthy was pollinated by touching the stigmatic surfaces with a dehiscent anther from the ammo plant. A mature anther is readily distinguishable with the unaided eye after its appearance has been verified by the hand lens. Samples were then to be taken every 24, 48, 72, and 124 hours. The five-day sample was injured by an unseason- able frost. However, the early samples were made and placed in killing solution in the field to be sure of instant termination of all life processes. These samples were in due time cleared, sect- ioned, and stained as before. Several different stains were tried but Safranin "O" seemed superior for pollen- tube differentiation for Ribes as well as Vaccinium. PRESENTATION OF RESULTS (a) ECONOMIC ASPECTS The field survey material was so plotted for 17 each individual plant that its growth and fruition for 1934, 1935, and 1936 could be read at a glance. From these plottings the bushes were classified as follows: normal, i.e., normal in 1934, normal in 1935, and nor- mal in 1936, or N-N-N; barren or "Bull" as indicated by B-B-B, for the three years as above; X---B, i.e., chang- ing to the "Bull" type; B---X, a barren bush changing to something else, during the three years under consider- ation; and five other groups of lesser importance in this study. These in turn were summarized (with product- ion totals and averages for each type) as shown in Tables II and III. TABLE II THE TOTAL AND AVERAGE YIELDS FOR THE PLANT TYPES IN PLOT III Type of No. in.% of Total Lbs. Berries Av.per 3 Year bush* Plot Total Plant Average 1954 1955 1936 F54 '55 '55 N-N-N 80 34 353 491 370 4 6 5 5 B-B-B 12 5 9 58 67 l 5 6 4 X---B 4 2 10 20 ~16 3 5 4 4 H---X 6 3 11 35 34 2 6 6 5 X-B-X 8 4 ' 34 67 52 4 8 7 6 L's-N's 26 11 177 320 199 7 2 8 9 18 TABLE II (continued) THE TOTAL AND AVERAGE YIELDS FOR THE PLANT TYPES IN PLOT III Type of No. in.% of Total Lbs. BerrieslAv. perIS Year Bush* Plot Total Plant Average 1934 1935 1936 L34'35'36 S---N 49 21 99 174 111 2 4 2 3 Misc. 48 21 65 95 33 l 2 1 1 *For bush types see key. Key For Tables II and III N--Normal Illustrations B--"Bu11" N-N-N--Normal '34, '35, and '36. X--Some other type L--Large S--Small B-B-B--"Bu11" '34, '55, and '36. X-B-X—-"Bu11" in 1935. Misc.--Miscellaneous. TABLE III THE TOTAL AND AVERAGE YIELDS FOR THE PLANT TYPES IN PLOT II Type of No. Plants w of Plot Total Lbs.’ Av. Yield .Bush* N-N-N 259 54 406.8 1.6 B-B-B 72 9.5 52.4 .45 X--~B 51 4.1 B---x 87 11.4 3-193 14 2.0 19 TABLE III (continued) Type of No. Plants % of Plot Total Lbs. Av. Bush* Yield S-N 98 1209 Misc. 199 26.0 By reference to Tables II and III, it will be found that Plot III contained only five per cent typical "Bulls", whereas, Plot II contained nine and one-half per cent three-year consecutively barren bushes. This variance is probably explained by the fact that Plot III was in a plantation which had previously been regularly rogued of its typical "Bull" and suspicious plants for some years. At any convenient time following the pick- ing season the bushes were marked and later removed. Plot II on the other hand had not received such treat- ment and thus contained nearly twice as many barren types. An interesting side light on Plot II is found in the fact that of the 19 "Bull" plants, out of a total of 72, which bore over one-half pound of berries each, 16 were partially dead at picking time. This may be ex- plained by the fact that many woody plants will bear many seeds when they are in such a low state of vigor as to have some or all of their limbs die at the end of the season. In Table IV the loss due to the presence of "Bull" bushes in the plantation is calculated for both plots. TABLE IV MONETARY LOSS IN PLOTS II AND III Plot No. of Pltng. Plts. "Bulls" Av. Lbs. Loss Plts. Dist. per A. per A. per Plt. "N" "B" Lbs. Lbs. @ "B" A. .04 II 760 5'1 8' 1089 103 1.6 .45 1.15 118 $4.72 III 255 6'x 8' 907 45 8.9 5.70 5.20 254 $9.36 Max. Loss 1089 103 8.9 3.70 5.20 536 $21.42 In Plot III, where five per cent were "Bulls" and there were 907 plants per acre, there would, there- fore, br 45 "Bull" plants each of which lost its owner an average of 5.2 pounds per plant, or a monetary loss of $9.36 per acre. This loss was calculated at the rate of four cents per pound which is less than many growers received in 1936. Similiarly, in Plot II with an in- creased number of "Bulls" (9.5 per cent or 103 barren types per acre, as there are 1089 plants per acre in this field) but with very materially decreased yield (due to late weeding and successive early frosts) the loss becomes $4.72 per acre. This, however, is only part of the story as Plot II has been rogued in prev- 21 iious years and Plot II is in a very unthrifty condition. Thus, if we were to compute the loss on the basis of the rogued patch (i.e., 9.5 per cent "Bulls") and take as the yield the production of the well-cared-for plot, we find that the value of that loss to be $21.42. As previously stated, of the 72 "Bull" plants in Plot II, 16 partially dead plants produced most of the fruit for this group. In fact, 21 of the 32 pounds were produced by the 16 dying plants. This leaves only 11 pounds for the remaining 56 "Bulls" or two-tenths pounds per plant. This low yield is of course important to the grower as it costs him as much to fertilize and cultivate the "Bull" types as it does for a productive bush and even more to prune and spray it because of its comparative large size. The picking cost need not be considered, as this is always specified as a per cent of the pounds picked and is therefore levied against the crop irrespective of variable yields per plant. All this points directly to the value of rogue- ing as a remedy for the "Bull" bush variety in gooseberry plantations as the loss was reduced from a possible $21.42 to an actual $9.55 or $4.72. Even in this illus- tration rogueing had been discontinued for recent years under new management. In Tables III and IV are found several groups of apparently transition types of partial barrenness all of which showed one or two years barren out of three under survey. An analysis of these 193 plants, all lo- cated in Plot II (760 plants), is shown in Tables V, VI, _and VII. TABLE V AN ANALYSIS OF THE THIRTY-TWO PLANTS IN PLOT II CHANGING OVER TO "BULL" TYPE Survey Types 1 No. of Plants Totals 1934 1935 1936 Nor. Bull Bull (Dying) 7 " Weak "1 " 2 9 "" Bull Bull 6 Miscellaneous 2 8 Nor. Nor. Bull 7 Small " " 3 Miscellaneoup _ 5 15 4.2 % Total f A 32 Table V shows that 4.2 per cent of the total bushes changed over to barren types during the period under consideration, i.e., 1934, 1935, and 1936. While this per cent is low, nevertheless a continuous change 23 of this sort during two or three decades in the life of a plantation would accumulate a greatly lessoned yield although an almost imperceptable annual change. Also, it has been a question whether or not "Bull" bushes become weaker and later died. And it was found that nine of 31 had portions dead in 1936. No other trend is noticeable except the fact that 20 plants changed abruptly from one type to another. TABLE VI REGROUPING THE BUSHES WHICH CAME OUT OF THE "BULL" CONDITION Types as Recorded in Number of Totals Field Work Plants 1934 1935 1936 Bull Bull Nor. 25 " Wk. " " 8 " " " Weak 6 Miscellaneous 4 43 Bull] Nor. Nor. 32 Miscellaneous 12 44 11.4 $ Total 87 In Table VI are classified the "Bulls" located in 1934 which had changed over to some other type by 1936. From this it will be seen that 11 per cent of the 24 total plants in Plot 11 had been cured or partially cured by normal handling of a large commercial planta- tion, even though no rogueing had been practiced. It is further shown that 57 of the 87 bushes made this tran- sition in one season and with no intermediate stage or stages. It is also shown in Table VI that 11 per cent came out of the "Bull" stage while in Table V only four .per cent entered. This would indicate that this barren condition would be eliminated at the rate of about seven per cent per year. H0wever, field observations show that there are more "Bulls" in an old patch than in a young one, which, in turn would indicate that many of those plants apparently cured in 1936 will again revert to a "Bull" form. This also agrees with growers' opinions. TABLE VII REMAINING GROUPS IN PLOT II WHERE THE "BULL" TYPES APPEAR ED 1 Survey Types No. Bushes Totals 1934 1935 1936 Nor. Bull Nor. 30 " Wk. " " 22 Miscellaneous 7 59 TABLE VII (continued) REMAINING GROUPS IN PLOT II WHERE THE "BULL" TYPES APPEARED Ag L Survey Types No. Bushes Totals 1934 1935 1936 Bull .Nor. Bull Dying 6 " " Bull 4 Miscellaneous 4 14 7.9 f Total 73 In Table VII are shown these remaining bushes which exhibited the barren type but did not fall in any of the previous classifications. This represented near- ly 10 per cent of the plot, and of the 73 plants concern- ed, 14 or two per cent changed from "Bull" in 1934 to another type in 1935 and back again to a "Bull" in 1936. (It is possible that this two per cent indicates a por- tion of those plants that might be in a state of bienni- al bearing found in tree fruits). From Tables VI, VII, and VIII it may be calcu- lated that 165 plants change to, or away from, the "Bull" type from one season to the next. These sudden switches would indicate a definite need to test the food relationships of these bushes, and such work is to go on in 1937. 26 ANALYSIS OF GROWERS OBSERVATIONS Plantation owners have various theories concern- ing the occurrence of the "Bull" bushes in their goose- berry patches. Nest of them had observed the condition and some had practiced a system of rogueing. Some even insist that they can spot those bushes which are about to become barren, and others believe that a plant may be barren one year, productive the next, and so on, accord- ing to favorable or unfavorable environment. Various causes for this condition have been sug- gested by growers, field men, and others. Some of these causes are: (1) mixture of varieties, (2) development and propagation of unfruitful (but excessively vegeta- tive) bud-sports; parenthetically, it should be noted that this vigorous type would be the one selected for. propagation before the "Bull" type became so well- known, (3) a disease of one sort or another (4) favor- able or unfavorable moisture relationship, and (5) variations in nutritional relations. ' Undesirable varieties or unproductive bud-sports are entirely improbable in this ease as several of the plantations have been subjected to systematic rogue- ing, which, if continued long enough would eliminate these sorts. Also, an inferior variety or a bud-sport 27 would not account for the fact that "Bull" bushes often have one or more branches which bear normal crops when the remainder of the bush is nearly, if not entirely, barren. The third point, disease, was to have been test- ed by grafting the "Bull" type on normal and visa-verse. However, this point is not fully clear as the great drought of 1934 so nearly killed many of the plants in Plot I as to render them useless and also caused the desiccation and resultant death of the scions set on the test bushes of Plot II. This was again attempted in 1935, but again with little success, partly because the genus Ribes seems very difficult to graft and possibly because the scions, although stored under refrigeration, were injured by too heavy a coating of very hot wax. There is a good possibility, however, that since the cambium lay- ers touched together, there may have been a transfer of any possible disease or virus. This would seem probale as many grafts were set on each of the 17 plants shown in Table VIII. 28 TABLE VIII APPEARANCE AND YIELDS OF GRAFTED PLANTS IN PLOT II Plant No. Grafted With Appearance [Yields in 1934 1935 1936' '36 in Lbs. 75-2(N) 74-39(B) Nor. Nor. Nor. 3.5 75-3 74-39 " Bull " 5.5 75-5 74-39 " Nor. " .75 78-44(N) 76-40(B) " Bull Bull Dying Trace 78-44(N) 76-40(B) " Nor. Nor. .75 78-15(N) 73-7(B) " " " 1.50 76-3(B)v 75-13(N) Bull Bull Nor. 4.5 76-4(B) 75-13 " Wk. " 3.75 76-5(B) 75-13 " Nor. Bull .25 73-7(B) 72-17(N) " Bull Bull Dying 1.00 76-10(B) 72-17 " Wk. " " " 1.25 73-35(B) 71-3(N) " " " Bull Trace 71-12(5) 71-5 " Bull " .5 71.20(B) 71-3 " " " .5 76-40(B) 78-44(N0 " " Nor. 6.0 76-28(B) 78-31(N) " Wk." Bull Dying .5 73-7(B) 78-15(N) " Bull " " 1.0 29 TABLE VIII (continued) Plot II Average normal yield I 1.5 Ii " Bull " I .45 This of course, is a small number of test bushes from which to draw conclusions bu the table is interest- ing if nothing more. Of the six normal plants on which "Bull" scions were set one has definitely and clearly changed over to the barren type and two others have such low yields as compared to the average normal and to the yields of neighboring bushes as to be indicative of a definite trend away from the normal. On the other hand, three of the 11 "Bull" bushes produced a normal yield in 1936 and also were normal in appearance. This is in line with a previous finding in which barren plants became normal and produced normal yields. 4 As to moisture relationships, the records of the Hart Weather Bureau sub-station were consulted and are shown in Graphs I and II. 3O /{' Lgend I ' r—u .. u- m I754! n _ f: g 175.;- I n» [ZZZ] IZJL . g .. ‘3 ~ hifin‘f‘H c-e ., , / I 7 7 A” 44 Kt , dim. Fit. me A]... ”:7 .75». 54:7. {7. soft (9.5-M... .17.... Graph 1. Showing precipitation in Oceana county during 1934, 1935, and 1936. A rare/{ayfo/J I'n Ivor/045, 0 I Y J" ‘ 7 5 9 [g # O-hJ I . :3 Karma / «es/7 . /’ j Rflvif :18 f0" "By/l” 39:6 :22: ‘l ‘fi If J ”35: j W 17.04“. 0’ / 1 .3 if '1” 4’ 7 as .7 n9 .7 (a 7535/;mnge¢w¢afikw .flfimwfl/937CE/w/Fho. Graph 2. Showing the relation of "Bull" and normal yields to early summer precip- itation. 31 This shows the monthly precipitation for three years. The bar graph shows the total rainfall for the three-month period of April, May, and June. It also shows the average yields of "Bulls" compared with nor- mals for Plot III. The precipitaion reached extreme lows in February and July of 1934. The first low prob- ably greatly reduced the current season's yield (to five and .61 pounds for normal average plants) and re- duced the yields of the "Bullss to almost nothing (.78 pounds). The second low probably had a very pronounced effect upon the fruit-bud differentiation as growth was entirely stopped in Plot II. Many fruit buds must have been formed at that time as we find the 1935 yields at over nine pounds for normals and about four and one- half pounds for "Bulls". Also, this yield was produced in spite of the comparatively low April, May, and June rainfall of that year. To continue this study into 1936 shows that the normal yields are only 1.6 pounds more than the "Bulls". This would indicate that environment- al factors have a pronounced effect upon the yield of "Bull" types. This result is based upon 12 "Bulls", 106 normals, and 233 total bushes in Plot III. Something as to the nutritional variation be- tween the four plots is known but nothing as to the variation between individual bushes. Plot II, located 32 upon heavy clay soil, is usually cultivated from five to seven times per season, sprayed two or three times, and usually receives no fertilizer of any kind. On the other hand, Plot III is on a good strong sandy silt loam. An average year's schedule for this would include about the following: plowed twice in early spring, heavily fertil' lized with barnyard manure, sprayed once if necessary, and cultivated three to six times. The effect of these treatments is clearly shown by comparing the average yield of normal plants in Plot II and III, which are 1.06 pounds and 5.06 pounds respectively in 1936. In addition to the external conditions suggested by growers, Gardner4 mentions the following as being as- soiated with unfruitfulness: (a) pruning, (b) grafting, (c) locality, (d) season, (0) temperature, (f) light, (3) rain at blossom time, (h) wind, (1) spraying at blossom time,-(j) age of plants. Inasmuch as the barren plants are scattered throughout each patch and since both "Bull" and normal are equally subject to and affected by all of the above conditions excepting the last (which is taken up under the problem of blossom- set) it seems reasonable to pass over these factors as being extremely unlikely causes of gooseberry barrenness. Thus completing the study of external factors, we shall look further to the internal factors as affecting un- 33 fruitfulness which are considered.under a later heading. THE BLOSSOM-SET PROBLEM Field inspection of gooseberries in blossom soon established the fact that "Bulls" blossom about as full as normals or at least bear far more blossoms than would be needed for a heavy crop. There seemed to be little difference in the appearance of the blossoms as they first open, possibly the "Bull" blossoms are slightly more pale than the normals. In a few days there is no question about this pallor and the blossoms shower from the bushes whenever a branch is touched. The blossoms continue to fall until less than one-fourth of the crop remains. Sometimes only a handful of berries will be matured on a branch or even on an entire bush standing from four feet high and spreading over an area of six or seven feet each way, TABLE IX BLOSSOM COUNTS (Two Ten-year 01d Plants) Plant N0. BICBsoms Set 3 76-6(B) 7,944 58 .5 76-8(N) ~ 9,785 1100 11 34 TABLE IX(continued) (Two Five-year 01d Plants) Plant No. Blossoms Set fi Large 52-5(B) 5,011 517 12.5 Small 28-5(N) 4,097 , 989 24.1 Table X shows that although only four plants were counted they bore nearly 28,000 blossoms with only .5 per cent blossom-set in a ten-year old "Bull" up to 24 per cent in a six-year old normal. Further, it will be noted that the blossom-set was very much greater in the young plants than in the older plants. Inasmuch as these plants are on similiar exposures (northern slopes), and also have similiar elevations, some import- ance may be attached to these findings and also, as these plants were seemingly fairly representative and only further confirm field observations. INTERNAL FACTORS This leads us directly to a consideration of those internal factors that are associated with un- fruitfulness which Gardner5 lists as follows: imper- fect flowers, dichogamy, degenerating or abortive pistil or ovules, and impotence of pollen. By an in- spection of the blossoms, perfect flowers with equal 35 pistils and stamens are found in both "Bull" and normal plants. See Plate I. Also, it is well to note that the bushes from which the sample flowers were secured have been typical for the type for three successive years. The second point, dichogamy, could be of little import- ance in this case as so many bees were present at the time of blooming as to insure wide distribution of p01- len throughout the patch. Further, there is great var- iation in the maturing of the blossoms on various parts of the bush and bushes in various locations on the plant- ation. It is possible of course, to find degenerating pistils on both normal and barren bushes, but the great majority in both cases are apparently normal in every way. Lastly, the pollen seemed normal as many of the pol- len grains had grown pollen tubes as shown by cross and longitudinal sections of the stigmatic surfaces and long- itudinal sections of styles from both types of flowers. Included under genetic factors (6) are hybridity and incompatibility. One of the well-established charac- teristics of the unfruitful type is its ability to change from time to time and that would hardly be true of a hybrid. Unfortunately, in this investigation no artificial pollen germination was attempted but as pointed out many pollen tubes enter the stigma and start downward through stylar tissue. A comparison of 36 the ovules of each type disclosed a normal embryo sac and associated tissues in the younger blossoms. Then, since the ovules are not fertilized in time to set fruit, a clear case of incompatibility is indicated. Those causes of unfruitfulness due to physiolog- ical influences include, according to Gardner, et a1., (7) slow growth of pollen tube, premature or delayed p01- lination, and variations in the nutritive conditions with- in the plant. The continuous growth of the pollen tubes was not determined but the early growth in hand-pollinated blos- some is readily compared in the longitudinal sections, and little difference is noted between normals and "Bulls". That pollination was complete and immediate was evinced by the presence of many pollinizers in the plantation at the time of full bloom, (which occurred during several days of clear warm weather). Further, the "Bulls" are scattered throughout the patch and would have neither, better nor poorer opportunities for pollination than nor- mal neighbors in adjoining rows. It is a well-known fact that nutritive conditions of the plant greatly affect the growth of the pollen tube through the stylar tissue. The rate of growth may be greatly retarded if the plant fails to have a certain balance between various nutritive substances in its system. We are, therefore, forced again 37 to the conclusion that nutritive conditions are in some way tied up with barrenness of these so-called "Bull" bushes. SUMMARY 1. Unproductive types are known to occur in the Downing gooseberry. 2. Field surveys show that five per cent to nine and one-half per cent are of this type. 3. Rogueing 0f the barren types may reduce a possible loss of $21.42 to an actual $4.72. 4. Fbur and one-half per cent of the bhshes changed over to barren types during 1934, 1935, and 1936. 5. "Bulls" do not get weaker or die out as sup- posed by some. 6. Abrupt changes toward or away from the barren types were noted in one year. 7. Eleven per cent of the bushes changed back to normal by 1936. 8. Environmental factors may have a pronounced effect upon both normal and "Bull" yields. 9. External factors could not be direct causes of barrenness as both types of plants are equally affect- ed. 10. Blossoms occur in about-equal numbers on both 38 types of plants. 11. Blossoms on "Bull" bushes turn pale and fall leaving as little as five per cent set in some cases. 12. Barren plants apparently have perfect flowers. l3. Pollen tubes penetrate the stigmatic surfaces. 14. Incompatibility seems to be the cause of the small fruit-set. l5. Incompatibility seems to be related in some way with the nutritional conditions within the plant it- self. 1 ACKNOWLEDGEMENTS The writer wishes to express his appreciation of the services rendered him in his work: To V. R. Gardner for his assistance and many constructive suggestions; to F. C. Bradford for trans- lating of French and German literature and a kindly in- terest in the progress of the work, and to G.F. Gray for his suggestions and criticisms of the procedure in the histological studies. LITERATURE CITED (1) Amos, J. Annual Report. East Malling. II: Supple- ment A 7. Apr. 1931, Pp. 28-30. (2) Campbell, Carlos. Director Divi of Statistics. (3) (4) (5) (6) (7) (8) (9) (10) 39 Nat Can. Assoc. 1934 Fruit Pack. Darrow & Ditweiler. U. S. D. A. Farmers Bul. 1398 Revision 1934. P. 31. Gardner, Bradford, and Hooker. Fundamentals of Fruit Prod. Pp. 509-520. Ibid. Pp. 489-498. Ibid. Pp. 498-502. Ibid. Pp. 502-508. Hedrick, U. S. Evolution of Cultivated Gooseberries. P. Thayer. Journal of Heredity. Waldo, Geo. F. Bureau of Plant Industry. Cornwallis, Ore., Personal Letter. Plate 1.--Showing Cross-section of the Flower of Downing Gooseberry Rep- resenting Both Normal and "Bull" Types. hf“ WACENVOORD 6: CO. mn' 1.. -- 0., A: "iii Wu (1W TWAIN“