BULLETIN 404 APRIL, 1927 Apple Pollination Studies In Ohio Freeman S. Howlett OHIO AGRICULTURAL EXPERIMENT STATION Wooster, Ohio OHIO AGRICULTURAL EXPERIMENT STATION BOARD OF CONTROL LAWRENCE E. LAYBOURNE President ••• ·• • • • • • • • • • • • • • · • • • • • • • • • • • • • • • • • • • .. SI!ring:fleld EGBERT H. MACK, Vice President •.•• · · • • · · • • • • · • • · • · • • · · • · • • · · • • · • • • • • • • · • • Sandusky H S ATIUNSON .................. · · .. · · · · • · · .. · · .. • .. • • • · · · · • · • • • · • ..... Columbus HM!RY A. CATON .................... • · · .. · · .. · .. • · · • · • • • · · · · • • · · • · · • · · .. Cosho.cton JOEIN KAISER • , •• , , •... , .••.. • • • · · · · · · • · · • · · · · • • · · • ' • · • · · · · • • · • · · · • · · · • • .Marietta MRs. ROBERT G. PATDBSON •.•.•.•.•.•. ·. · · · • · • · · · · · · · · • · • · • · · · · · • • • ·······.Columbus JULIUS F. STONE .•..••....•••.•.• · · · · • · • • · · · · · · · · • • · • · • · · · · • · · • · •••·•·· ..Columbus CHARLES V. TRUAX, Director of Agricultu1·e . · · · · · · · • · • · · • · • · • • • · · · · • · · • · · · · •. Columbus CARL E. STEEB, Secreta1'1} , ......... · .... · • · · · · · • · · · · · · .. · • · " • • • • • • " • .. · .. Columbus STATION STAFF C. G. WILLIAMS, Director AGRONOMY ENGINEERING (AGE.) R. M. SALTER, M. S., Chief G. W. McCUEN, B. S., Chief (Col.) C. E. THORNE, D. Sc., Consulting Chief C. 0. RIJDD, B. S., AsHociate (Columbus) J. W. AMES, M. S., Associate P. B. POTTER, B. S., Asst. (Columbus) G. W. CoNREY, Ph. D., Associate B. M. S·rAHL, M. S., Asst. (Columbus) L. E. THATCHER, Ph. G., Associate E. A. SILVllR, B. S., A sst. (Columbus) F. A. WELTON, Ph. D., Associate F. E. BEAR, Ph. D., Asso. (Columbus) ENTOMOLOGY J. B. PARK, Ph. D., Asso. (Columbus) J. S. Housren, M. S. A., Chief C. J. WILLAllD, Ph. D., Asso. (Columbus) L. L. HUBilll, Ph. D., Associate H. W. BACHELOR, M. S., Assistant HERBERT OSBORN, D. Sc., ,1sso. (Col.) L. D. BAVER, B. S., Assistant C. R. CUTRIGHT, Ph. D., .Ass·istant MABEL COllllOULD, B. S., Assistant G. A. FILINGDR, M. S., Assistant I. H. CURIE, B. S. Assistant H. L. Gur, M. S., Assistant J. S. OUTLER, M. S., Assistant }j, G. Ii:ELSHEIMcn, M. S., Assistant C. E. DIKE, B. S., Assistant C. R. NEISWANDDR, l'h. D., Assistant F. R. DRDIBELBIS, B. S., Assistant J. B. POLIVKA, M. S., Assistant R. W. GERDEL, M. S., Assistant T. C. GREEN, B. S., Assistant FORESTRY ADRIAN J. HARTZLER, B. S., Assistant J. T. MCCLURil, B. S. A., Assistant EDMUND SoCRDST, B. S., Chief and Asso. V. H. MORRIS, M. A., Assistant Dir. of Sta. (State Forester) M. T. MYERS, M. S., Asst. (Columbus) J. J. CRmiLDY, Ph. D., ilsBO. (Athens) A. H. PASCHALL, B. S., Assistant 0. A. ALD!lR<IIAN, M. F., Assistant 0. A. PATTON, Assistant F. W. DEAN, B. S., A.gsistant C. J. SCHOLLENBERGER, B. A., A ..sistant B. E. LllDTC, M. F., Asst. (Portsmouth) R. H. SIMON, A. M., Assistant L. J. LEFFELMAN, M. F., A ...istant G. H. STRINGFIELD, B. S. A., Assistant,. R. R. PATON, M. F., Assistant ANIMAL INDUSTRY G. BOHSTEDT, Ph. D., Chief HOME ECONOMICS B. H. EDGINGTON, D. V. M., Associate FAITH R. LANMAN, B. S., Chief (Col.) D. C. KENNARD, B. S., Associate HUGillNA MCKAY, M. A., Asst. (Col.) D. S. BELL, M. S., Assistant ELSIE STiliGER, B. S., Asst. (Columbus) R. M. BETHil:E, Ph. D., Assistant MARY ANNE BROWN, B. S., Asst. (Col.) C. H. HUNT, Ph. D., Assistant L. B. NETTLETON, Assistant HORTICULTURE W. L. ROBISON, M. S., Assistant J. H. GOURLEY, ],f. S., Chief H. L. SASSAMAN, M, S., Assistant F. H. BALLOU, Asso. (Newark) B. L. WARWICK, D. V. M., Ph. D., Asst. JOHN BUSIINDLL, Ph. D., ,1ssistant GEORGE Z!NZALlAN, B. Ch. E., Assistant DoNALD CoMIN, B. S., Assistant :BOTANY AND PLANT PATHOLOGY C. W. ELLENWOOD, rl.•sistant H. 0. YOUNG, Ph. D., Chief F. S. HOWLETT, Ph. D., Assistant R. C. THOMAS, M. A., Associate I. P. LEWIS, B. S., A.ssistant W. G. STOVER, Ph. D., Asso. (Oolu.mbus) RoY MAGRUDER, B. S., Assistant R. B. Wn.cox, M. S., U. S. D. A. J. S. SHODMAKllR, Ph. D., Assistant MRS. R. W. GERDEL, M. S., Assistant CURTIS MAY, M. S., Assistant MISCELLANEOUS A. G. NEWHALL, M. S., Assistant W. H. ALEXANDCR, Climatologist (Col.) H. A. RUNNELS, M. S., Assistant W. K. GREENBANK, Editor J. D. SAYRE, Ph. D., Assistant W. H. KRAMER, Bur.gar PAUL E. TILFORD, M. S., Assistant SARAH PAINTEI<, B. A., Librarian J. D. WILSON, Ph. D., Assistant DAIRY INDUSTRY COUNTY EXPERIMENT C. C. HAYDEN, M. S., Chief DISTRICT AND W. E. KRAUSS. Ph. D., Assistant FARMS C. F. MONROE, M. S., Assistant l\1. A. BACIITELL, B. S., In Charge A. E. PERKINS, M. S., Assistant ECONOMICS (RURAL) C. H. CRAWFORD, B. S., Supt., Trumbull J. I. FALCONER, Ph. D., Chief (Col.) WALTER MAHAN, Supt., Belmont J. F. DOWLER, B. S., Asst. (Columbus) S. C. HARTMAN, M. S., Southeast, Wash. G. F. HENNING, l\1, S., Asst. (Columbus) R. R. HOYT, Supt., Paulding E. K. JACKSON, B. A., Assistant 0. N. RILIJY, Foreman, Wash. Truck Farm C. E. LIVELY, M. A., Asst. (Columbus) R. W. ROGERS, Supt., Madison and Miami C. G. McBRIDE, M. S., Asst. (Columbus) L. W. SHERMAN, Supt., Mahoning H. R. MooRE, B. A., Asst. (Columbus) H. M. WACHTER, Supt., Southwest F. L. MORISON, l\1. S., Asst. (Columbus) W. E. WEAVER, Supt., Hamilton & Clermont E. C. NEWCOMER, Asst. (Columbus) J. T. WILSON, Supt., Northeast CONTENTS Summary and Conclusions . • . 3 Introduction . 7 Definition of Terms . 7 Literature Review . 8 Fruitfulness of Varieties When Self-pollinated . 9 Effectiveness of Varieties as Pollinizers ............................ 17 Fruitfulness of Varieties as Female Parents . 20 Experimental Procedure ............................................... 21 Source and Cultural Treatment of Trees . 21 Weather Conditions During Blooming Seasons . 23 Vigor of Trees and Flowers Selected . 27 Number and Position of Flowers Pollinated . 30 Collection of Pollen . 30 Storage of Pollen . 31 Relation of Emasculation to Time of Pollination . 32 Emasculation of Flowers .......................................... 32 Method of Self-pollination . 33 Germination of Pollen . 33 Methods of Insect Exclusion . 33 Tabulation of Results ............................................. 34 Mode of Expression of Results . 35 Presentation of the Data . 36 Baldwin ........................................................ 36 Delicious . 42 Ensee . ............................... 45 Golden Delicious . 45 Grimes Golden ................................................... 47 Jonathan . .................................. 48 Mcintosh . 48 Nero ........................................................... 48 Northern Spy .................................................... 48 Ohio Nonpareil ................................................... 52 Oldenburg . ................................... 53 Rhode Island Greening . 53 Rome Beauty . 53 Stayman Winesap . 55 Wealthy ........................................................ 56 Yellow Transparent . 56 Discussion of the Data . 58 Fruitfulness of Varieties When Self-pollinated ...................... 58 Degree of Self-fruitfulness of Varieties . 58 Classifications in Degree of Self-fruitfulness .................... 58 Variations in Self-fruitfulness in Different Localities .•.......... 60 (1) CONTENTS Methods of Determining Degree of Self-fruitfulness ............. 60 Field Observations in Determining Self-fruitfulness ............. 64 Effectiveness of Varieties as Pollinizers ............................ 65 Effective Pollinating Varieties ................................. 65 Ineffective Pollinating Varieties ............................... 65 Effectiveness of Pollinizer and Its Pollen Germination . 66 Physiological Cross-incompatibility . 66 Cross-sterility . 68 Fruitfulness of Varieties as Female Parents . 68 Cross-sterility . 69 Practical Considerations . 70 Factors Concerned With Choice of Pollinating Varieties ............. 70 Arrangement of Pollinating Varieties for Adequate Cross-pollination .. 76 Agents of Transfer of Apple Pollen . 79 Literature Cited ...................................................... 81 Apple Pollination Studies in Ohio Freeman S. Howlett SUMMARY AND CONCLUSIONS The results obtained from apple pollination studies in Ohio during the years 1924-1926, inclusive, are presented. The larger part of the data are concerned with the fruitfulness of several varieties when self-pollinated, their effectiveness as pollinizers, and their fruitfulness as female parents in varriM~s crosses. These varieties were Baldwin, Delicious, Ensee, Golden Delicious, Grimes Golden, Jonathan, Mcintosh, Nero, Northe1·n Spy, Ohio Nonpareil, Rhode Island Greening, Rome Beauty, Stayman Winesap, and Wealthy. Limited data are given with respect to the effectiveness as pollinizers of Banks (Red Gravenstein), Gallia Beauty, San Jacinto (Wilson Red June), and Yellow Transparent, and to the fruitfulness of Oldenburg and Yellow Transparent as the female parents in various crosses. The trees used in the experiments were growing in the Experi­ ment Station orchards at Wooster and in the Bing ham* orchards at Hamden, Geauga County, Ohio. The results have been obtained not only from hand pollinated flowers subsequently covered with "glassine" bags (1924-1926) but also from flowers left 'uncovered after emasculation and pollination (1926). In 1926 at Wooster a tree each, of the varieties Baldwin and Golden Delicious, was enclosed separately under a muslin frame with a hive of bees. The Baldwin t1··ee was self-pollinated by the bees. Baldwin flowers were placed under the frame with the Golden Delicious tree to provide pollen with which the bees could cross-pollinate