Calcium Foliar Sprays for Control of Alfalfa Greening, Cork Spot, and Hard End in ‘Anjou’ Pears

ABSTRACT

New calcium (Ca) spray materials were made available to test for their 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 Ca 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-Plex-12); and a dry Ca material derived from calcium oxide (Mira-Cal) at different concentrations. In one orchard, Mira-Cal Ca at the double rate had the lowest incidence of cork spot and hard end with the highest concentration of cortex Ca and acceptable fruit finish, closely followed by the standard rate of Mora-Leaf-Ca. In a second orchard, Mora-Leaf-Ca plus Sylgard 309 had the lowest incidence of cork spot and alfalfa greening. In the third orchard, Mora-Leaf-Ca had the lowest incidence of cork spot and the highest concentration of fruit Ca in peel and cortex. In the fourth orchard, Cal-Plex-12 Ca produced nearly complete control of cork spot and the highest concentration of fruit Ca in peel and cortex. When comparing commercial spray-machine application of 935 L ha⁻¹, control of cork spot and fruit Ca absorption was improved with six calcium applications versus only two spray applications.

Keywords:

• calcium sprays
• pear fruit disorders
• fruit quality

ACKNOWLEDGMENTS

The authors acknowledge the support of the Northcentral Washington Fieldmen's Association, the Scott, Tall and Ward orchardists, and R. Gix and F. Smith, fieldmen. Brand names are necessary to report factually on available data; however, USDA neither guarantees nor warrants the standard of the product, and the use of the name by USDA implies no approval of the product to the exclusion of others that may also be suitable.

Notes

^z Mean separation within columns by Duncan's multiple range test (P ≤ 0.05).

^zMean separation within columns by Duncan's multiple range test (P ≤ 0.05).