Nutrient: Postbloom

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



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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 (bitterpit of apples): 2-4lb/A per application. Make 6 to 12 applications from early June to Late August. 5 to 15 lbs of actual Ca per season is recommended which equals 15 to 50 pounds of calcium chloride per acre per season. Calcium in the form of calcium chloride is recommended because of its proven effectiveness and lower cost. See Penn State Extension’s useful calculator for comparing calcium chloride to other sources of calcium, as it is important to make sure you develop a season-long program for applying sufficient total amounts of elemental calcium.
Rate Recomendations Actual Ca lb/A per season
Actual Ca lb/A Expected Results
4-5 This is the lowest rate that should be used. It will give some control of bitter pit and corking, will cause no leaf burning and is not likely to enhance storage.
6-8 Should give good control of preharvest physiological disorders. It should not cause any significant leaf injury and will probably not enhance fruit storage life.
9-11 Should give excellent control of corking and bitter pitting and should be the intermediate rate. It may enhance fruit storage life and shoudl result in almost no leaf injury.
12-14 The highest rate that should be used. Should give outstanding control of corking and bitter pit. May result in some enhanced storage life.
Courtesy Dr. Rob Crassweller, Penn State Extension.
Calcium (cherry fruit firmness and reduced cracking): Six weekly sprays of Ca(NO3)2 or chelated Ca sources (Ca2+ at 0.1-0.15%) between pit hardening and harvest has been shown to increase calcium quantity in fruit and post harvest quality (Wang, 2016). Greater than 0.2% Ca2+ increases risk of leaf burning and reducing fruit size. Fruit applications do not replace, but only augment, good management of soil Ca, irrigation and root health.
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.



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Copper deficiency: Follow manufacturer's label. May be incompatible with calcium chloride. Can cause fruit injury. See text.

Iron (lime-induced chlorosis): Follow manufacturer's label.

Magnesium deficiency: Apply in June. Repeat in July if necessary. Do not apply after August 1. Follow manufacturer's label for labeled product rates.

Nitrogen deficiency: Apply only as needed to apples or cherries. Not effective on pear or other stone fruits and can cause injury. See text.

Potassium: See text. Indiscriminant use of potassium sprays can increase the incidence of bitterpit in apples and cork spot in pears.




Zinc deficiency, bearing trees: 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.