Question
Grammathophyllum leave
Hi Wyne King,
How are you?
My Grammathophyllum leaves has yellow & black spot as shown in pic.
Why does it happen? I've cut down all these leaves. In future, how to prevent it from being like this?
I've noticed cymbidium leaves also happen like this before.
Thanks,
Nwe Lay
AnswerThere are a couple of most-likely explanations. One is that the plant may be virused. There are means of testing for this but there are many types of virus and most tests will not detect all possible virus infections. Apart from the spotting and streaking symptoms of the virus, in the long run, if it is a virus, the virus will weaken the plant and new growth will be less robust. While it is helpful to have the proper diagnosis of a viral infection to be able to isolate the plant and prevent transmission to nearby plants. As of yet, there is no treatment for a viral infection. Insects that feed on an infected plant and move to another plant can transmit the virus from plant to plant.
In your picture, it appears that you have some mealy bugs on your plant. Check your plant carefully as these can hide in crevases and under leaf sheaths and lead to some of the damage you have seen. Mealys are excellent transmitters of virus as they are sucking insects and reproduce rapidly.
Either of these pathologies can result in adventitious fungal infection. This can occur whenever leaf tissue is damaged in some way. You could treat the latter with a weekly spraying of a copper salt fungicide.
