Eucalyptus out-perform Landscape species field performance, evaluated other species in salty, May 1982, Napa SURVIVING, ACCEPTABLE flooded soils Eucalyptus species E. bauerana (0) E. bicolor (f) Dean R. Donaldson 0 Janine K. Hasey 0 William B. Davis E. camaldulensis var. rostrata (f) E. cornuta E. cosmophylla Landscape plants are often needed for gallon size, representative of ordinary E. fruticetorum (0) difficult sites. To find plants that would quality nursery stock. All species were E. grossa (0) grow in saline, frequently flooded soils, basin-irrigated and surface-mulched E. incrassata we evaluated 106 species on a nonirri- during the first year. No fertilizers or E. lansdowneana (0) gated floodplain underlain with salt wa- soil amendments were used. E. melliodora (0) ter along the Napa River in northern The seedlings were planted over a E. microtheca E. occidentalis California. The site was one of many three-year period (1972 to 1974) and E. populifolia established throughout the state for grew for eight to ten years until final E. rudis (f) landscape tree evaluation. data collection in May 1982. Weather E. sargentii Our project, which began in 1972, has extremes occurred at the site, including E. spathulata been limited to testing species for sur- the December 1972 freeze, flooding, the E. tetraptera vival and growth. The planted area has 1976-77 drought, and a subsequent rise SURVIVING, BUT a silty clay-loam soil with a salt water in the water table. NOT ACCEPTABLE table at approximately 3 feet. Flooding Of the 55 Eucalyptus species planted, occurs frequently in winter, and water Eucalyptus species 26 remain. Of the 51 other species, only E. aggregata (f) may remain on the surface for up to 16 3 survived. Eucalyptus thus seems bet- E. albens weeks. Measurements indicate that the ter able to tolerate difficult soil condi- E. anceps groundwater table is within 30 inches of tions. E. blakelyi the surface for seven months of the Appearance changed as plants ma- E. burdettiana year. tured. Many species rated acceptable E. eremophila Soil and groundwater samples during during one evaluation were unaccepta- E. falcata the trial showed soil salinity ranging ble during later evaluat'ions; others E. platypus from 1.6 to 46.7 millimhos per centi- changed from unacceptable to accept- E. rugosa meter with consistently high average able form and appearance. (Acceptable Other species soil salinity and brackish groundwater plants were vigorously growing with no Callistemon salignus (0) [see table). By comparison, garden soil visible salt injury, such as twig dieback Pinus brutia Populus euphratica salinity is usually below 3 millimhos and marginal leaf burn; unacceptable per centimeter. The major salts present plants showed severe salt injury and/or ACCEPTABLE UNTIL 1978, were sodium, calcium, and magnesium stunted growth.) Trees grown on this ALL OR MOST PLANTS chlorides. site appear stunted and frequently show DEAD IN 1982 evidence of salt burn when compared Eucalyptus species Average salinity of soil and of ground water at with sister plants on better sites. E. archeri Napa Valley College test site, 1972-1976 After eight to ten years of periodic E. bancroftii Millimhos per centimeter flooding in saline soil and the 1976-77 E. botryoides drought, 17 Eucalyptus species had sur- E. camphora June June E. diversifolia DeDth 1972May 1974 1976 vived as acceptable landscape candi- E. forrestiana (0) Soil salinity: dates (see accompanying list). Sixteen E. goniantha 0-1 ft 3.9 8.5 14.5 Eucalyptus and 13 other species were E. griffithsii ft - 1-2 12.1 13.5 healthy until six or eight years of age E. 2-3ft - 13.1 10.9 gunnii 3-4ft 15.4 12.9 13.5 and then died. A total of 38 species, E. intertexta (0) Ground water including 6 Eucalyptus, died within a E. maculata salinity: year or two after planting and should E. mannifera subsp. maculosa (0) - 40.0 27.0 26.8 not be planted on similar sites. Accept- E. parvifolia (0) able species varied in shape and form E. perriniana The soil was double-disced before from low spreading to tall skyline types, E. robusta E. salmonophloia planting. Sixty of the species, provided from dense to open branching habits, by the University of California at Davis, and from heavy- to fine-textured fo- Other species were selected for uniformity and plant- Betula tianschanica (0) liage. Coprosma 'Brown Sleeves' ed in a replicated design. The rest, do- Coprosma 'Copper Shine' nated by the Saratoga Horticultural Coprosma 'Green Sleeves' Foundation, were planted for observa- Dean A. Donaldson is County Director and Form Advisor, and Janine K. Hasey is Acting Farm Grevillea 'Canberra' (0) tion only. The UC Davis species were Advisor, Napa County; William B. Davis is Special- Grevillea juniperina 'Rosea' (0) actively growing seedlings from 1-gal- ist, Environmental Horticulture, University of Cali- Grevillea tridentifera (0) fornia, Davis. All are with UC Cooperative Exten- Ion stock, planted in hand-dug holes sion. The authors thank Professors A. W. Harris Hakea oleifolia (0) approximately 6 inches deep. They and A. T. Leiser, Department of Environmental Hakea petiolaris (0) were less than 18 inches tall and were Horticulture, UC Davis, and the staff o Saratoga Leptospermum flavescens var. Horticulture Foundation and Nopa Volly College grandiflorum (0) not root-bound. Others were 1- or 3- for their support 20 CALIFORNIA AGRICULTURE, SEPTEMBER-OCTOBER 1983 Leptospermum lanigerum Myoporum parvifolium 'Horshum' Ornithostaphylos oppositifolia (0) NOT ACCEPTABLE UNTIL 1978; ALL OR MOST PLANTS DEAD IN 1982 Eucalyptus species E. exserta E. kitsoniana E. rnegacornuta E. morrissi E. pyriformis E. rhodantha E. stricklandii Other species Artemisia fragrans Olea africana 'Dwarf' (0) Pinus eldarica (0) NO SITE TOLERANCE: DIED WITHIN 1 - 2 YEARS Eucalyptus species E. caesia E. fastigata (0) E. longicornis E. niphophila (0) E. propinqua (0) E. simmondsii (0) Other species Of the 55 Eucalyptus species planted, 26 remain and 17 are rated acceptable. Nine of the Acer laevigatum (0) acceptable species are shown here. Only 3 of the other species planted survived. Acer macrophyllum Acer morrisonense (0) Acer tegmentosum (0) Artemisia reptans (0) Atriplex rhagodioides Jack Kelly Clark Callistemon montanus (0) m Calothamnus validus (0) C Camptotheca acuminata (0) Celtis sinensis var. japonica ii Comarostaphylis polifolia (0) Coprosma pumila Coprosma 'Lofty' Coprosma 'Shiner' Cytisus decumbens Dodonaea ceratocarpa (0) Dodonaea viscosa (0) Gaultheria odorata (0) Genista lydia Ginkgo biloba (0) Grevillea crithmifolia (0) Grevillea victoriae (0) Hakea gibbosa (0) Hakea sericea (0) llex paraguayensis (0) Jacaranda mimosifolia (0) Leptospermum scopariurn (0) Marianthus pictus (0) Nothofagus fusca (0) Nothofagus obliqua (0) Photinia davidsoniae (0) Platanus 'Autumn Glory' (0) Many trees planted on the salty plain seemed to thrive for six or more years before succumb- NOTES ing. This may be an individual trait, not species All planted on salty, flooded soil in spring failure, since others of the same species sur- 1972,1973, or 1974; received one-year ba- vive and are highly acceptable. EuCalyptUS sin irrigation only; no pruning or staking. sargentii(above) adjacent to the dying E. ca- (0)Observation only; plants donated by Saratoga Horticulture Foundation; all others maldulensis (left) continues to grow as a supe- provided by Department of Environmental rior specimen. Horticulture. UC Davis. (f) Survived December 1972 freeze as one- year-old plants. CALIFORNIA AGRICULTURE, SEPTEMBER-OCTOBER 1983 21 .