Quote:
Originally Posted by NYCorchidman
I think their website has an photo article on calcium deficiency, but I couldn't see any other.
By the way, I do not think the yellowing edge of the phals leaves are due to any deficiency because all the rest do not exhibit this yellow lining.
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When we hashed thru this last Time-we did not have a good answer for the "why" either-i have 3 doing this and since i add Epsoms Salt-they new Leafs are good-i dont think it will go away on the old ones.But whatever the reason-mine do like the extra treatment.
Deficiency
Symptoms: Magnesium deficiency can result in cupped leaves, a reduction in growth and marginal or interveinal chlorosis (yellow along leaf edges or between veins) and usually is exhibited in the middle or older leaves (extracted from Orchid Species Culture by Margaret L. and Charles O. Baker). It can also cause an increase in appearance of anthocyanin (red/purple coloration) in leaves, particularly after exposure to cooler temperatures.
Treatment: Supply extra magnesium when the plant is in active growth. Use a good cal mag fertilizer, add Epsom salts at the rate of 1 teaspoon per gallon to your water each month (you can add 1 tbsp/gallon as a correction to reddened leaves), add 1 tablespoon of dolomitic lime per gallon or top dress with powdered dolomite.
Prevention: Supply extra magnesium via a good cal mag fertilizer, Epsom salts or dolomitic lime. You can also make the magnesium present in our well water more available to the plant by using an acidity generating fertilizer like 20-20-20 or one of the fertilizers available from SAOS.
Read More: Leaf Reddening from Magnesium Deficiency after Exposure to Cold (Dr. Martin Motes)