UNIVERSITY OF CALIFORNIA • COLLEGE OF AGRICULTURE AGRICULTURAL EXPERIMENT STATION BERKELEY, CALIFORNIA THE SHASTA, SIERRA, LASSEN, TAHOE, AND DONNER STRAWBERRIES HAROLD E. THOMAS and EARL V. GOLDSMITH BULLETIN 690 February, 1945 UNIVERSITY OF CALIFORNIA ■ BERKELEY, CALIFORNIA CONTENTS PAGE Introduction 3 Shasta 5 Adaptation and origin 5 Characterization 6 Technical description of the fruit of the Shasta variety 7 Sierra * 7 Adaptation and origin 7 Characterization 7 Technical description of the fruit of the Sierra variety 9 Lassen 9 Adaptation and origin 9 Characterization 9 Technical description of the fruit of the Lassen variety 10 Tahoe 10 Adaptation and origin 10 Characterization 10 Technical description of the fruit of the Tahoe variety 10 Donner 11 Adaptation and origin 11 Characterization 11 Technical description of the fruit of the Donner variety 11 Naming of the varieties 11 Summary 12 THE SHASTA, SIERRA, LASSEN, TAHOE, AND DONNER STRAWBERRIES 1 HAROLD E. THOMAS 2 and EAEL V. GOLDSMITH 3 INTRODUCTION The five new strawberry varieties described in this bulletin are being intro- duced for trial in central and northern California as fresh market berries. Their adaptation to southern California conditions has not been adequately determined. All have shown some merit in one or more districts of the central or northern part of the state, but most of the tests have been conducted in the central coast area. Since none has been sufficiently tested to determine the extent or limits of its adaptation, no final recommendations for use can be given here ; nor is it assumed that all five varieties will have enduring value. The berries are the first to be introduced as a result of breeding work car- ried on for several years by the University of California Agricultural Ex- periment Station and initiated at the request of the Central California Berry Growers Association of San Francisco in 1926. At that time the virus disease yellows, or xanthosis, was causing a rapid decline in strawberry production in California. 4 The most logical means of combating the disease appeared to be the development of resistant varieties through breeding. Many years ago Albert Etter of Ettersburg, California, crossed the wild beach straw- berry, Fragaria chiloensis, with various other sorts. Since some of these crosses showed considerable resistance to yellows, the present authors used them as basic material in their early breeding work. To offset partially the low dessert quality normally carried in the F. chiloensis and in the standard variety, Nich Ohmer, it was necessary to cross them with berries of high dessert quality. For this purpose some of the United States Department of Agriculture selections supplied by Dr. George M. Darrow were used. 5 The Nich Ohmer was used for its fall-producing character and proved to be a valuable parent. The nor- mal short life of this plant was offset somewhat by crossing with the longer- lived selections of F. chiloensis parentage. Through a system of recrossing selections and pyramiding desirable characters, there were gradually built up selections possessing a portion of the characters desired by the industry such as resistance to yellows, longevity of plant, good market and shipping quality, and continuous or high fall production. The Marshall-type varieties, including Banner, Marshall, and Oregon Plum, have long been the standard in strawberry production in central and northern California ; yet these varieties offer little help in a breeding program because 1 Received for publication November 20, 1944. 2 Assistant Professor of Plant Pathology and Associate Plant Pathologist in the Ex- periment Station; resigned February 1, 1945. 3 Associate in the Experiment Station; resigned January 1, 1944. 4 Plakidas, A. G. Strawberry xanthosis (yellows), a new insect-borne disease. Jour. Agr. Res. 35:1057-90. 1927. 5 Darrow, George M., George F. Waldo, C. E. Schuster, and B. C. Pickett. Twelve years of strawberry breeding. II. From 170,000 seedlings, seven named varieties: A summary of the crosses made and an evaluation of their effectiveness as breeding material. Jour. Hered. 25:451-62. 1934. [3] 4 California Experiment Station Bulletin 690 of their extreme susceptibility to the virus diseases and their tendency to transmit this character when used in crossing. Eastern varieties in general have not been successful in California and were not valuable as parents except for some specific character. Most of the crossing in recent years has been therefore between selections made and tested under California conditions and exhibiting some of the characters mentioned above. Crossing work by the junior author was begun in 1930, and during the period from 1932 to 1938, when the varieties here described were bred and selected, a total of 55,000 seedlings were fruited. At the outset of the breeding program the seedling testing was carried out at the University of California Deciduous Fruit Field Station located near San Jose. The Station is located in the heart of the central coast strawberry district, where environmental factors are average for the district ; and it was believed that any selection made would likely prove adapted to the entire area. The yellows disease was prevalent ; and if immunity to it could be obtained in a desirable selection, the problem would in a large measure have been solved. It soon became evident, however, that no clone was immune to the yellows disease; that while some were nearly symptomless carriers, there was slow degeneration, with the probability that the selection would sooner or later be discarded. Evidence indicated the improbability of obtaining in the center of any strawberry-growing district any variety that would long remain free of the virus diseases. Immunity to the diseases was apparently very rare if at all possible, and the logical procedure to follow in the breeding program appeared to be the development and holding of all seedlings in an isolated area free of strawberry culture of old varieties. The project was accordingly moved to an area in the Santa Cruz Mountains, approximately 8 miles away from other strawberry plantings, and continued for a two-year period. At the end of this time it was evident that the virus disease was filtering in and that the area was not free of the disease as had originally been assumed. In 1935 the project was moved again and this time was set up in the Sacramento Valley in an area isolated by 10 or more miles from any strawberry district. The seedlings were fruited there, and selections made. Foundation stock of each selection was then kept in that district, which was assumed to be an area relatively free of virus diseases. Later experience has indicated that this was a desirable practice. Selections made in the Sacramento Valley cannot be assumed to have adapta- tion in coastal areas, and testing to determine adaptation there is necessary and is normally done. Fall production can be ascertained only in the coastal area, and resistance to the yellows disease is best determined there. Though high resistance to yellows is desirable, some selections possessing only mod- erate resistance have succeeded reasonably well. Experience indicates that if such selections are from foundation stock that is free of the virus and are not set out too early in the spring, they escape widespread infection the first growing season and produce good crops even though virus diseases may be present in the district. In this manner selections possessing only moderate resistance can be used successfully. The new varieties represent what appear to be the most promising of the crosses made in 1935 and 1936. They are released to replace the yellows- Shasta, Sierra, Lassen, Tahoe, and Donner Strawberries 5 susceptible Marshall-type varieties and the unvigorous and short-lived Nich Ohmer variety. The five introductions have been under limited acreage production in the central coast area. All have been selected by growers for expanded plantings and by them deemed worthy of continued trial for fresh-market purposes even though some of the characters are not ideal. In dessert quality, when taste, aroma, and flavor are considered, some of the new varieties are much inferior to Banner, long a standard berry in that respect. From the growers' view- point, however, there are compensating characters — fall production in the coastal area, high total production, desirable shipping and market qualities, disease and insect resistance. These offset the objectionable low dessert quality and justify release of the selections for further trial. In a market berry the maintenance of a bright and fresh appearance is imperative. The individual grower, planning for his particular area, must weigh one character against another or a group of others, to determine whether or not the variety is adapt- able to varying local conditions and is acceptable to the trade. The varieties described vary in their resistance to virus diseases. It is prob- able that none possesses sufficient resistance to make it profitable for long if continuously propagated in an area where virus diseases exist, such as the central coast district of California. The experience of growers thus far, how- ever, indicates that if disease-free stock is propagated in an area free of virus diseases and is not planted adjacent to infested fields or set too early in the spring, all varieties here named will succeed in so far as these diseases affect the yield of fruit. If this procedure is not followed, there is some uncertainty whether those varieties that are moderately susceptible to these troubles will yield profitably for more than two years. The five varieties have perfect flowers botanically. None, however, has been grown entirely alone and away from other strawberries, and thus all have had the opportunity for cross-pollination. All apparently produce enough pollen to ensure a good set of berries, though the quantity of pollen will vary with the season. In the coastal area of California, strawberries sometimes vary considerably in fruit characters with the successive crops produced. The descriptions given below may therefore not remain accurate throughout a producing season; variation from the details given may occur at times. SHASTA Adaptation and Origin. — The Shasta variety has shown promise in nearly all test plantings made in the central coast area of California. It was used successfully by commercial growers in the San Jose and Salinas districts dur- ing the 1943 and 1944 producing seasons. In the interior valleys too few trials have been made to determine its adaptation to these districts. Along the coast it produces well in the summer and fall and has merited recognition because of this character. Shasta has been tested under the California number of 403.8. It is the result of a cross made in 1935 and was selected in 1937. One of its parents w r as Cali- fornia 67.5 — a cross between Nich Ohmer and an unnamed United States Department of Agriculture selection numbered 634. The other parent was 6 California Experiment Station Bulletin 690 California 177.21, a cross made between Department of Agriculture selection 543 and California 68.24. The latter was in turn a cross between Department of Agriculture selection 634, mentioned above, and New York (Geneva) Agricultural Experiment Station selection 4626 — a cross of Marshall and Howard 17. A short form is sometimes used to designate this parentage as follows: Cal. 403.8 = Cal. 67.5 (Nich Ohmer x U.S.D.A. 634) x Cal. 177.21 [U.S.D.A. 543 x Cal. 68.24 (U.S.D.A. 634 x N.Y. 4626)]. Characterization. — The Shasta plant, though not large, is reasonably vig- orous. The leaves are dark bluish green ; their characteristic wrinkled surface and downward cupping distinguish the variety from most others. The plants are shorter lived than those of other varieties herein described, but in longevity nevertheless surpass Nich Ohmer, which often produced well for only one V ^ 36 k v ^> 5 Z.4 %\tD $ 4 - — « — 1 1 1 1 1 ■' I ' J ' J ■ 1 5 he s fa — * — * — * — ' J ' J ' I ' 1 ' 1 ■ 1 • 1 ' T -i — | — I — | — i — | — I — S/er*-a - y * Lossen Loss0o — < — • — » — / ■ Tohoe - / ■ Doo/?