| Q I
read your comments on rot tendencies in Psychopsis that appeared in
the March 2001 issue of Orchids. I have similar problems with Laelia
anceps, Cattleya trianaei and various dendrobiums. New growths start,
but when they become 1 to 2 inches long, they turn black and die.
Eventually, the plants die because they are unable to sustain new growths.
What organism causes this and can we test the plants to determine the
problem? I have found that Subdue slows down the process for a while but
then it reappears. A Possibly several factors are at work here. I have always found that virused orchids will be susceptible to losing their new growths in the way you have de scribed. Dark, wet and cool conditions all tend to favor common fungi and bacteria, which can also cause the symptoms de scribed. My advice would be to give the problem plants space and even hang them during the critical period when their new growths develop. There is nothing wrong with applying Subdue if the label says it is approved for orchids, but the real cure lies in addressing the problem, not treating the symptoms. - Andy Easton |
Reprinted, with permission, from "Orchids" - The Magazine of the American Orchid Society, May, 2001.