Postbloom

Nutrient: Postbloom

See General Recommendations for guidelines on table use. Read all product labels carefully.
After bloom and before harvest

table continues below...

Boron deficiency: Apply only if boron deficiency appears during growing season. Apply amount equivalent to 1. 0 pound actual B per acre. See text.

Boron maintenance: Prepink to pink or postharvest timing is preferred. Apply amount equivalent to 0. 5 pound actual B per acre. See text.

Calcium deficiency: Calcium (Ca) is needed for cell wall development and strengthening, thus essential during fruit cell division stage. In Washington, soil deficiencies are rare, however given the limited mobility of Ca within the plant, fruit deficiencies might still be present. Deficiency levels in the soil and leaf can be determined with standard testing, while fruit deficiency is not well predicted with tissue testing.

Calcium (apples): Rate of 2-4 lbs of actual Ca per acre per application, from petal fall to late June. Up to 15 lbs of actual Ca per season

Calcium (cherry fruit firmness and reduced cracking): Ca sprays in cherries can reduce the incidence of rain cracking. Effectiveness has been variable, as it depends on multiple environmental factors. Calcium Cloride CaCl has proven the most effective. Concentration and coverage are key factors for improved efficacy. Application timing is pre harvest during and post rain events. Note that post-harvest dipping has proven most effective for cracking (Winkler and Knoche, 2019)

Calcium (pear alfalfa greening, Anjou cork spot): Apply four applications from early June to August. Dilute sprays are most effective. Can cause fruit injury. See text.

Magnesium deficiency: Magnesium deficiencies are rare in Easter Washington soils, however in Western Washington or sandy soils, Mg can be leached and become deficient. Total Mg demand is low compared to other macronutrients; thus, soil natural levels might be sufficient. Deficiency levels of Mg can be determined in the soil and leaves with standard testing. Most effective management of Mg is done via ground application, as it has medium mobility in soils and is mobile in plants. Foliar Mg sprays can be effective when deficiencies appear, usually in spur leaves with high crop loads. Best timing is during active fruit growth or when leaf deficiencies appear. Apply in June. Repeat in July if necessary. Follow manufacturer's label for labeled product rates.

continued

table continues below...

Copper deficiency: Copper (Cu) deficiencies are rare, given that several pesticides contain Cu. Deficiency levels can be determined in the soil and leaf with standard testing. Symptoms of Cu deficiency include chlorosis, leaf margin necrosis and curling. Given the low mobility of Cu in the plant, frequent applications during the growing season might be needed to overcome deficiencies. Follow manufacturer's label. May be incompatible with calcium chloride. Can cause fruit injury. See text.

Iron deficiency: Iron (Fe) deficiencies are common in calcareous or high pH soils, also in saturated soils with lack of oxygen. Soil or leaf tissue testing are not good indicators of deficiencies, while symptoms of iron chlorosis are very distinct. Given the low mobility of Fe in the plant, frequent applications during the growing season might be needed to overcome deficiencies. Follow manufacturer's label.

Nitrogen deficiency: Nitrogen demand in tree fruit orchards usually surpass soil supply, so generally needs yearly maintenance. We recommend determining maintenance rates based on crop demand (Table 3). Deficiency levels in plant can be determined with standard leaf testing. Application via ground (broadcast or fertigation) is more effective. However, foliar N application in the fall can support build reserves for the following year. Rates for fall foliar application range between 8 – 10 lbs. of actual N, when using Urea (46% N), make sure has less than 0.25% biuret. Not effective on pear or other stone fruits and can cause injury. See text.

Phosphorous: Phosphorous is essential for tree health and fruit quality. Demand is low compared to other macronutrients. Deficiency levels in the soil and leaves can be determined with standard testing, and we recommend P-Olsen for alkaline soils. Deficiencies should be corrected via ground application; incorporate pre planting, broadcast or via fertigation. However, cold soil, extreme pH (< 4.5 or > 8.5), root limiting factors can justify complementing P management with foliar sprays.

Potassium: is essential for tree health, water relations and fruit quality. Total K demand is high in fruit production. Deficiency levels in the soil and leaves can be determined with standard testing. Most effective management of K is done via ground application, as it has medium mobility in soils and is highly mobile in plants. Foliar K sprays have been used to complement soil application, enhance resistance to stress and color development.

continued

Zinc deficiency, bearing trees: Zinc deficiencies are common in stone and pome fruit trees and enhanced in calcareous or high pH soils. Deficiency levels can be determined in the soil and leaves with standard testing; however symptoms are very distinct. Preferred timings are late dormant (stone fruit), silver-tip (apples and pears), and post-harvest (all tree fruits except for apricot). The deficiency rates for Zn sulfate are 14 pounds actual Zn per acre (dormant timing sprays) and 9 pounds actual Zn per acre (postharvest). Given the low mobility of Zn in the plant, frequent applications during the growing season might be needed to overcome deficiencies. Follow manufacturer's label.

Zinc deficiency, nonbearing trees: See precautions in text. Can cause injury, particularly on stone fruits. Follow manufacturer's label for labeled products.

Manganese deficiency: deficiencies are common in calcareous or high pH soils, while saturated soils can enhance Mn availability and lead to toxicity. Deficiency levels can be determined in the soil and leaves with standard testing. Given the low mobility of Mn in the leaves, frequent applications during the growing season might be needed to overcome deficiencies.

Silicon: macronutrient associated to structural integrity in plants, associated to enhance tolerance to heavy metals toxicity and biotic stress. Si while present in large quantity in the soil’s minerals, is highly unstable and reduced availability for plant uptake. Most refences allude to the impact of silicate in disease resistance. There is little evidence of the benefit of Si sprays in tree fruit (Laane, 2018)