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Strawberries (Western Oregon--west of Cascades) FG 14 Reprinted January 2000 J. Hart, T. Righetti, A. Sheets, and L.W. Martin Do you want to print a copy? We recommend downloading the print version (64 K). First download the free Adobe Reader, if you don't already have it. Contents Nitrogen (N) Phosphorus (P) Potassium (K) Sulfur (S) Magnesium (Mg) Boron (B) Lime Fertilizer recommendations in this guide are based on the use of well-adapted varieties and disease-free plants, selection of suitable soils, disease and insect control, weed control, and proper irrigation. Application of these management practices is essential to realize optimum fertilizer response. Strawberries respond to generous amounts of soil organic matter. Incorporation of straw or a green manure crop prior to planting is advisable. Fertilize established fields after harvest. Fertilization should be based on a soil test performed after harvest or before the establishment of a new planting. Follow recommended soil sampling procedures to ensure a satisfactory fertilizer recommendation. The Oregon State University Extension Service agent in your county can provide you with instructions on correct soil sampling procedures and a list of laboratories providing soil testing services. Nitrogen (N) New plantings Apply 30 to 40 lb N/a at planting time. One application may be adequate, particularly if the planting follows a row crop such as beans, where more than 80 lb N/a has been applied and a small amount of crop residue is incorporated. If a sod crop or cereal straw has been turned under, use 50 to 60 lb N/a. Apply another 20 to 30 lb N/a in mid-July to mid-August of the planting year unless irrigation is not available. See item 2 under "Established plantings." Established plantings Apply 25 to 50 lb N/a about August 1 followed by irrigation. Shuksan, Olympus, and Totem can utilize higher rates than Hood or Benton. Delay the N application until about September 15 if no irrigation is available. Spring applications of N are recommended only when plants are stressed by winter injury, soil insects, or disease (root rot), or when plants are being grown on sandy soils. Apply 15 to 20 lb N/a. Foliar sprays of urea can be used. Do not apply more than 10 lb of N/a per application. Apply foliar sprays when foliage is dry. The Benton variety has a tendency to produce excess foliage. Reducing the N level by 25 percent may be advisable with this variety. Also, grower experience indicates there may be an association between malformed berries and excess N. top Phosphorus (P) Strawberries have shown a marked response to P on some soils. Apply P according to Table 1. P fertilizer should be banded on both sides of the row. Bands should be 3 to 4 inches from the plants and 4 to 6 inches deep at planting time, or at the edge of the row when rows are trimmed following harvest. P fertilizers are used with greater efficiency when placed below the soil surface. Table 1.--P fertilization rates for strawberries. If the soil test for P is (ppm) 0 to 15 15 to 45 over 45 Apply this amount of phosphate (P2O5) (lb/a) 100 to 120 60 to 10 0 to 60 Potassium (K) For new plantings, rates of 60 lb K2O/a or less can be banded with N and P after planting. Rates above 60 lb K2O/a should be broadcast before planting. See Table 2. Table 2.---K fertilization rates for strawberries. If the soil test for K is (ppm) under 75 75 to 175 over 175 Apply this amount of potash (K2O) (lb/a) 100 to 120 80 to 100 0 to 80 top Sulfur (S) The fertilizer program should include an annual application of at least 15 to 20 lb S/a. S is contained in some fertilizer materials used to supply other nutrients and in fungicides such as sulfur sprays or dusts. Magnesium (Mg) Applications of Mg are suggested when Mg soil test values are below 1 meq of Mg. Mg can be banded similar to P using such materials as potassium magnesium sulfate or magnesium sulfate (epsom salts) to supply 20 to 30 lb Mg/a. Mg also can be supplied in dolomite, which is a liming material. Dolomite reduces soil acidity to about the same degree as ground limestone. top Boron (B) B should be broadcast and worked into the soil prior to planting. B can be very toxic to strawberries if applied in excess of recommended rates; therefore, never band B or borated fertilizer. With a soil test value below 1 ppm B, an annual maintenance application of 1 lb actual B/a should be broadcast or applied as foliar sprays. top Lime Strawberries are fairly tolerant of soil acidity and have a comparatively low lime requirement. If the soil pH is below 5.4 or calcium (Ca) is less than 5 meq, an application of 1 to 1.5 t/a lime or dolomite lime may be desirable. Dolomite is preferred if magnesium (Mg) is needed (see above). For pH to change before planting, apply lime or dolomite lime and work it into the soil at least 3 months before planting. If lime or dolomite applications are made within 1 month prior to planting, increase the K application by 60 to 90 lb K2O/a. top Revised by John Hart, Extension soil scientist; Tim Righetti, professor of horticulture; Arden Sheets, Extension agent emeritus, Washington County; and L.W. Martin, former superintendent, North Willamette Experiment Station; Oregon State University. Revised January 1988. Reprinted January 2000.

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