|Plant Part and Time:||Youngest fully expanded mature leaves, starting in December to determine the boron (B) level. Then take the next sample at the first vigorous growth in early Spring. Then, sample monthly through the season.|
|Element and Sufficiency Range||Interpretation and Recommendations|
Deficiency due to inadequate or ineffective N fertilization. Generally, application of 60 pounds N per acre prior to planting will maintain N within the sufficiency range until vigorous spring growth begins. When vigorous spring growth begins, apply through the drip irrigation system 0.6 pounds of N per acre per day (4 pounds N per acre per week) for sandy soils, or 0.5 pounds N per acre per day (3.5 pounds N per acre per week) for heavier soils. If N is less than 2.80% at the early spring sampling, increase the application rate through the drip system by 50% for two weeks, then retest.
Deficiency may be due to low soil P, inadequate P fertilization, or poor root development. If P is less than 0.20% and the soil test level is low and no root damage is evident, apply 10-15 pounds P2O5 per acre as phosphoric acid or monopotassium phosphate through the drip irrigation system in a single application.
Deficiency due to low soil K or inadequate K fertilization. If the leaf K level is less than 1.40%, apply 5 pounds K2O per acre per week through the drip irrigation system. Retest in 3 weeks.
Deficiency is rarely detected since the soil test Ca level must be extremely low for a deficiency to occur.
Deficiencies may occur at very low soil test Mg levels. However, Mg is best managed through soil testing and pre-plant application of Mg. If leaf Mg is less than 0.25%, inject magnesium sulfate at a rate of 20 pounds of magnesium sulfate per acre per week or the equivalent amount of other forms of soluble Mg. Retest in 3 weeks.
Sulfur levels are generally within the sufficiency range. If S is less than 15%, inject materials such as potassium thiosulfate, calcium thiosulfate, or magnesium sulfate at a rate of 2 pounds of S per acre per week.
Low levels may occur on sandy soils if pH is high. If the Mn level is less than 30 ppm, apply 1 1/2 pounds of manganese sulfate per acre in a foliar application or apply 1/2 pound of manganese sulfate per acre through the drip irrigation system.
Iron deficiency in strawberries is not common, but can occur if soil pH is too high. Soil testing for proper pH adjustment avoids this problem. If iron is less than 50 ppm, foliar application of chelated iron such as Fe EDTA plus a surfactant may be partially effective.
Low levels may occur on very sandy and low organic matter (<1%) soils. If the B level is less than 25 ppm, soil apply 1/8 pound of actual boron per acre through the drip irrigation system prior to bloom or as needed during the growing season. Usually, one application is sufficient to correct a deficiency for the rest of the growing season. Do not over apply boron.
Low copper levels may occur often in strawberries. If Cu level is less than 5 ppm, apply copper chelate in a foliar application, following manufacturer's directions, or inject no more than 1/2 pound of copper sulfate (1/8 pound of Cu) per acre through the irrigation system.
Low zinc levels may occur on very sandy low organic matter soils. Apply Zn accordingly to soil test preplant. If the Zn level in plant tissue is less than 20 ppm, apply zinc chelate in a foliar application, following manufacturer's directions, or inject no more than 3/8 pound of zinc sulfate (1/8 pound of Zn) per acre or an equivalent amount of another soluble zinc fertilizer per acre through the drip irrigation system.