RTI Xtreme Gardening 2505 CalCarb Foliar Spray, 6-Ounce (Discontinued by Manufacturer)
Both calcium and carbon are critical to plant development.  Calcium is generally supplied through the soil and carbon enters the plant as carbon dioxide which is necessary for photosynthesis to occur.  CALCARB is a unique form of a simple and very common compound that contains both calcium and carbon.  Calcium carbonate is used in agriculture throughout most of the world to adjust soil pH levels.  CALCARB is an unusual form of calcium carbonate that is highly unstable, converting to calcium oxide and carbon dioxide rapidly when applied to foliage.  This unique phenomena increases calcium avalability to plants through the foliage, but more importantly, the carbon dioxide levels directly outside and inside the stomata can rise threefold, which is near optimum for photosynthesis efficiency.  Forget to water?  Didin't remember to bring that tender houseplant in before the first cold snap?  If it is not too far gone, treat it with CALCARB and you may be able to rescue it.  CALCARB helps in recovery by increasing photosynthesis in the foliage that is not too seriously damaged and by raising the surface pH of damaged foliage which deters airborne pathogens from taking advantage of the weakened cellular tissue.