Preharvest Calcium Sprays Do Not Improve Highbush Blueberry (Vaccinium corymbosum L.) Quality

Calcium sprays were applied to `Bluecrop' highbush blueberry bushes between petal fall and fruit harvest. In 1992, bushes received five sprays between 18 June and 16 July that totaled 0, 1.0, 1.9 or 3.8 kg Ca/ha. Calcium was applied as CaCl 2 at spray concentrations of 0.08% to 0.2% Ca. Treatments in 1993 consisted of a control; 12.1 and 24.2 kg Ca/ha as CaCl 2 ; and 12.1 kg Ca/ha as the commercial product Nutrical. Calcium was applied in seven sprays between 4 June and 16 July using spray concentrations of 0.1% to 0.4% Ca. Berry samples were hand-picked, stored for 3 to 20 days, and evaluated. Treatments had no effect on the percentage of soft or rotten berries, berry firmness, or berry Ca concentrations during either year. Calcium applications increased leaf Ca concentrations. Chemical names used: calcium trihydroxyglutarate (Nutrical).