Black Rot - indoors, and freezing outdoors

[Ray]

I suppose we should really separate black rot, itself, from a calcium deficiency.

Most elements can be moved from old parts of the plant to new ones. Calcium is not translocatable in plants, so they need a constant supply while growing.

If it is not provided, new growth will not have enough and will die. That's very commonly seen in cattleya leaf tips, and the tissue is black. Eventually that necrotic tissue will rot, but it is the death of it that is often misdiagnosed as being black rot.

True black rot, caused by pythium and phytophthora, is actually more brown than black in appearance (at least initially), and can-, but does not necessarily start at the leaf tips.


Ray Barkalow
firstrays.com