The high fluoride Source B perlite was used in this crop. The initial concentration of fluoride in leachate from the five sources of perlite used in this study ranged from 0.05 to 0.83 ppm. Soluble fluoride rapidly decreased in subsequent leachings to very low concentrations. If perlite was a cause of fluoride toxicity, the problem would be experienced in the initial weeks of culture. This has not been reported to be the case.
Toxicity is more prevalent in later stages of the crop.
Clearly, fluoride toxicity does not stem from these sources of perlite.