In my hands, the reason why the sheath yellows or blackens is because a
change in the growing zone. Either I do not water, or water too much or let
water stand on the plants ( called 'sending them to bed with wet feet') or I
forget to turn on the heater and they freeze, or vice versa. So you can see
there is a variety of factors in this senescence.

What most folks do is slit ot tear open the sheath so any moisture trapped
inside the sheath can evaporate an not affect the developing buds (that you
can see inside.) This leads to yet another problem, which is letting water
stand in the sheath. So be careful watering when/if you do this not to get
water inside the sheath, or to cut the sheath down one side so water won't
collect in it. The sheath is still needed to protect the developing buds
from the accidental bump. So don't tear it away completely.

Getting to be more consistent in your culture practices will reduce this
occurance. That isn't always easy to do either, but is is something to
strive for, grasshopper.

K Barrett

"M. A" wrote in message
ink.net...
Hello, What is it called when the bud suddenly turns yellow or black and
does not open even though you can see a potential flower inside. I had
this
happen on several of my Cats. Thanks for any help. M.A