Articles
Comparison of foliar calcium products to reduce bitter pit incidence in western New York
Article number
1432_19
Pages
139 – 144
Language
English
Abstract
Bitter pit (BP) is a physiological disorder of apple fruit and has long been associated with low fruit calcium (Ca) concentration.
Numerous foliar Ca spray products reportedly increase fruit Ca and are marketed to mitigate BP development but vary in concentration of Ca and chemical composition.
A three-year study was performed to understand how four different Ca products: 1) Sysstem©-CAL (0.45 kg ha‑1 Ca from calcium phosphite (CaHPO3)); 2) STOPIT (1.47 kg ha‑1 Ca from a liquid calcium chloride (CaCl2)); 3) Cell Power© Calcium Platinum (1.51 kg ha‑1 Ca from calcium nitrate (Ca(NO3)2)); and 4) Ele-Max© Calcium FL (3.92 kg ha‑1 Ca from calcium carbonate (CaCO3)) could improve fruit nutrient imbalances and reduce BP. Both CaHPO3 and CaCl2 were sprayed each year, while CaCO3 was tested in 2022, and Ca(NO3)2 was tested in 2023. Each product was sprayed weekly each year for 8-12 weeks prior to harvest in an orchard with five training systems.
A mineral analysis method using peel sap was used to measure fruit Ca concentration and potassium/calcium (K/Ca) ratio when the fruit weighed approximately 50 g and BP incidence was calculated at harvest and after 3 months of storage.
Applications of CaCl2 in 2022, increased peel sap Ca and decreased K/Ca compared to the other treatments but not in 2023, which was a year with high Ca concentration in all treatments.
Preliminary results suggest the CaCl2 product can significantly reduce BP at harvest and after storage compared to other calcium products and an UTC. Due to natural year-to-year variation of BP, additional testing of products on fruit nutrient status and BP incidence may identify optimal Ca application rates for growers.
Numerous foliar Ca spray products reportedly increase fruit Ca and are marketed to mitigate BP development but vary in concentration of Ca and chemical composition.
A three-year study was performed to understand how four different Ca products: 1) Sysstem©-CAL (0.45 kg ha‑1 Ca from calcium phosphite (CaHPO3)); 2) STOPIT (1.47 kg ha‑1 Ca from a liquid calcium chloride (CaCl2)); 3) Cell Power© Calcium Platinum (1.51 kg ha‑1 Ca from calcium nitrate (Ca(NO3)2)); and 4) Ele-Max© Calcium FL (3.92 kg ha‑1 Ca from calcium carbonate (CaCO3)) could improve fruit nutrient imbalances and reduce BP. Both CaHPO3 and CaCl2 were sprayed each year, while CaCO3 was tested in 2022, and Ca(NO3)2 was tested in 2023. Each product was sprayed weekly each year for 8-12 weeks prior to harvest in an orchard with five training systems.
A mineral analysis method using peel sap was used to measure fruit Ca concentration and potassium/calcium (K/Ca) ratio when the fruit weighed approximately 50 g and BP incidence was calculated at harvest and after 3 months of storage.
Applications of CaCl2 in 2022, increased peel sap Ca and decreased K/Ca compared to the other treatments but not in 2023, which was a year with high Ca concentration in all treatments.
Preliminary results suggest the CaCl2 product can significantly reduce BP at harvest and after storage compared to other calcium products and an UTC. Due to natural year-to-year variation of BP, additional testing of products on fruit nutrient status and BP incidence may identify optimal Ca application rates for growers.
Authors
B.T. Lawrence, L. Gonzalez Nieto, T. Robinson
Keywords
calcium deficiency, peel sap method, postharvest, ‘Honeycrisp’
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