The beach strawberry, an important natural resource Royce S. Bringhurst W James F. Hancock H Victor Voth

narrow strip of the western coast- erosion has progressed, clones of particu- taining considerably more organic matter A line has furnished California with a lar interest still thrive. and surface litter. Their roots are num- rare, unique source of wild plant germ- erous, fibrous, and relatively shallow; plasm that has helped the strawberry Desirable traits frequently their leaves are thinner and industry to flourish. less glossy and the plants are more erect. Ironically, the agricultural wealth Among the many desirable traits of this beach strawberry species has helped great commercial value to be found in Development of cultivars to generate is contemporaneous with selected California beach strawberries forces driving the plant itself toward ex- are: tolerance to drought; high tolerance F. chiloensis is fully compatible tinction in many areas. Subdivisions, to salinity; low requirement for fertilizer; with cultivated strawberries; both are commercial development, and people low chilling requirement; and resistance octoploid with eight times the minimum have intruded into the niche the berry to the two most important root diseases functional number in the genus (2 n = had carved for its balanced existence of strawberries, Red Stele (Phytophthora 8 x 7 = 56 chromosomes); consequently beside the salty Pacific Ocean. root rot) and Verticillium wilt. In a recent the hybrids are fully fertile. In breeding, The beach strawberry of California screening of 59 representative clones of the large fruit size and other commercial- (Fragaria chiloensis [L.] Duch.) may very California F. chiloensis for Verticillium ly important characters of cultivated well be the most useful of all the re- wilt resistance, most proved highly resis- strawberries are easily recovered, along maining (octoploid) strawberry germ- tant, about 16 percent were partially with the new traits provided by the wild plasm in the world. The species ranges resistant,and only 15 percent were highly strawberry, after as few as three gener- northward intermittently as far as the susceptible. ations of backcrossing to appropriate Oregon border, from Oso Flaco Lake Where the clones come from makes cultivars. near Santa Maria in Santa Barbara Coun- a great deal of difference for most traits. Undesirable linkages have been ty. In the fragile, very vulnerable ‘‘oasis- Some plants grow in pure beach sand few and heritabilities for Verticillium like” environment at its southerly limit, within a few feet of the sea but seedlings wilt resistance and even the most com- it is surrounded by shifting sand dunes, germinate and normally develop what plex traits, including yield, have been and a few scattered colonies only tenu- closely resembles a tap system, with one relatively high with F. chiloensis. ously survive. Fortunately, at its northern to several roots penetrating relatively All the existing California straw- boundaries the plant is much more abun- deeply. These plants have thick, leathery berry cultivars have California Fragaria dant. Overall, the narrow coastal corridor leaves with a glossy, heavily cutinized chiloensis ancestory and this has con- occupied by the species extends inland surface, typical of certain moisture-con- tributed much to the high adaptation of only a few miles at most, being confined serving species. They are very prostrate these varieties that has resulted in the to the heavier fog belt. and normally few other species compete highest strawberry yields in the world; Much of the area once occupied by with them. a state average of about 20 tons per acre. F. chiloensis has been built over or con- At the opposite extreme, some of As breeding efforts focus more finely on verted to uses incompatible with the the beach strawberries grow some dis- specific traits, the species will be used survival of the Fragaria species. Recent- tance from the sea among the grasses, even more extensively. For example, it ly, for example, in the expansion of the herbs, and chaparral in heavier soil con- should be possible to breed varieties city of Pacifica, most of the important with extremely high tolerance to salinity, colonies we have studied there for many a very serious problem in drought-stric- years were destroyed completely. Our ken California right now. modest collection at Davis of some of the Unfortunately, the California F. most valuable stock is all that remains. chiloensis with the greatest breeding Laaen Other colonies we have studied at / potentiality are those colonies native to various coastal locations for many years 55 23 1 the most vulnerable southern habitats, include those of particular clones which 60 51 8 haFlaco and appropriate steps should be taken to we can readily identify at Point St. F chhnsio preserve them. 52 16 15 ~ /6522031\ George, Bodega Bay, Point Reyes, Pigeon / Tioga 68.69-602 (C2) ~ ‘ Point, Point Sur, and Oso Flaco Lake. \ Royce S. Bringhurst is Professor of They survive very well at a given site if ‘Sequoia Pomology and Pomologist in the Exper- the natural habitat is not completely iment Station, James F. Hancock is Re- destroyed or paved over as is the case search Assistant, and Victor Voth is too frequently. Photographs taken at 10 Pomologist in the Experiment Station. year intervals of the very eroded Point Pedigree chart of a potential cultivar derived All are of the Department of Pomology, St. George colony site show that although from Fragaria chiloensis by backcrossing. University of California, Davis.

10 CAlIFORNIAAGRICULTUE. SEPTEMBER 1977