I have a Cattleya that I bought as a bare root plantlet almost 5 years
ago. It has taken
a long time to get going, but is now growing well and sending its
first flower shoot. It
was probably too dry and underfed in previous years, because it (along
with my phals)
has responded very well to finer bark medium and a heavier feeding
regime. I'm now
using 200 ppm N in a weekly soak with made with a 20-20-20 + trace
elements fertiliser.

One of the Cattleya's leaves is black at the tip and it's
progressing. There is now maybe
15 mm of dry black leaf at the tip and then a band of chlorosis of 3
or 4 mm wide. Can
anyone offer an educated gues on whether this is due to salinity, lack
of Ca, a virus, or
something else? The fertiliser I'm using doesn't contain Ca, but the
water is very hard,
containing an average of 276 ppm of total hardness as CaCO3 according
to the water
company.


Leo