I'm in South Florida (Zone 9-10) where we had more than useual night rainfall several weeks ago; very little sunshine and less than a gentle breeze for well over a 2-week period. All my Catts are under 50% shade in a lath house along with Bc. Maikai and a few ferns... and about three weeks ago I started noticing leaves dropping over night at a very fast rate that I've never noticed in the six years the orchids have been hanging. Most everything I grow is bare-root and in wooden cedar baskets (and doing what they're supposed to be doing year-after-year) and I've never had an insect problem to really speak of nor any other fungal problem... and, though I've seen Black Rot before, I've never seen it being so 'selective' where it's only attacking new growth. I apply the proper material to help control the problem... and the rate at which the fungus originally hit had dropped down to where it's somewhat acceptable
-- considering what could have happened if I had not noticed it as soon as I did. I've been cutting away, deeply into the rhizome where needed, and doing everything possible (even isolate) to help stop the spread and I think I've reached control even though I had to discard approx 10% of my pants, but my question is: why is it only attacking my bifoliates and not the unifoliate stock (both are hanging intermingled)?
Any help would be greatly appreciated.
BTW, I also grow Bc. Maikai in full west sun (except for July/Aug where I drop them down a bit), and though they are somewhat sunburned at times
-- along with not even a trace of showing dark green leaves... they flower like there's no tomorrow. They do darken up a bit over winter and not the first sight of any fungus is ever noticed. I fert everything weekly as well.
Thanks, and enjoy your growing.
John