Submitted to: Journal of Plant Nutrition
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/17/2005
Publication Date: 3/1/2006
Citation: Raese, J.T., Drake, S.R. Calcium foliar sprays for control of alfalfa greening, cork spot and hard-end in 'Anjou'pears. Journal of Plant Nutrition. 29(3):543-552. 2006. Interpretive Summary: Adequate calcium nutrition is critical for controlling many disorders of 'Anjou' pears. Use of calcium, on both 'Anjou' and 'Bartlett' pears, can cause serious cosmetic blemishes. Calcium formulations and concentrations must be evaluated prior to commercial use to determine disorder control and pear response to calcium application. Three new calcium formulations(Mira-Cal, Cal-Plex 12, Mora-leaf-Ca) were evaluated at equal calcium rates in multiple pear orchards. Fruit exposed to Mira-Cal had the lowest incidence of cork spot with the highest concentration of flesh calcium with acceptable fruit finish. Results using Mora-leaf-Ca were similar to the results determined with Mira-Cal. Fruit exposed to Mora-leaf-Ca had the lowest incidence of the disorders cork spot and alfalfa greening with a high concentration of calcium in both flesh and peel. Multiple applications of calcium produced the best control of cork spot and highest absorption of calcium in the fruit.
Technical Abstract: New calcium spray materials were made available to test for possible improvement over the often used dry form of calcium chloride products. Four orchards of mature Anjou pears, Pyrus communis L., were selected for the experiments. Three calcium materials were used, at equal Ca rates, consisting of a dry Ca material derived from calcium chloride (Mora-leaf-Ca) with and without Sylgard, a liquid Ca material derived from CaCl2 (Cal-Plex12), and a dry Ca material derived from calcium oxide (Mira-Cal) at different concentrations. In one orchard, Mira-Cal Ca at double rate had the lowest incidence of cork spot and the highest concentration of fruit Ca in peel or cortex. In the fourth orchard, Cal-Plex12 Ca produced complete control of cork spot and the highest concentration or fruit Ca in peel or cortex. When comparing commercial spray machine application of 100 gal per acre, control of cork spot and fruit Ca absorption was improved with six calcium applications versus only two spray applications.