Application of Calcium Sprays for the Protection of Citrus from Atmospheric Fluorides
Year: 1969
Type: article
Abstract: Bearing ‘Valencia’ orange trees growing in a commercial orchard adjacent to a known source of fluoride air pollution were sprayed periodically over a 3-year period with Ca(OH) 2 and CaCl 2 sprays. These materials in spray and dust forms have been used successfully in the Pacific Northwest to protect gladiolus and peaches from the harmful effects of fluoride-containing atmospheres. It has been postulated that calcium reacts with fluoride gases to produce insoluble and therefore nontoxic CaF 2 . Results of these studies indicated that under conditions of high fluoride air pollution, application of lime sprays may improve citrus fruit production, but the mechanism of protection or improvement was not as simple as previously postulated. Immediately adjacent to the source where fluoride air pollution was at a maximum, applications of both Ca(OH) 2 and CaCl 2 were associated with increased internal fluoride accumulation by ‘Valencia’ orange foliage. With increased distance and therefore diminishing air pollution, an apparent reversal in effect was observed with the calcium sprays resulting in reduced internal accumulation of fluoride. Although the effects of CaCl 2 sprays on fluoride accumulation closely paralleled those obtained with Ca(OH) 2 , fruit production was not improved where CaCl 2 sprays were applied, possibly as a result of induced chloride toxicity.
Institution: University of California, Riverside
Language: English
Topic: Fluoride Effects and Removal
Subfield: Water Science and Technology
Field: Environmental Science
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,500
OpenAlex ID: W99333905