Black spots on underside of my dendrobium leaves
I have a dendrobium that has black spots that start out on the underside of the leaves. The spots spread slowly, and eventually penetrate the leaf.
Its enjoying semi-water-culture for over 3 months now. It was sitting in a southern veranda in bright indirect sunlight up until a month ago, but on noticing the increase in spots- I moved it indoors to separate it from my other orchids. The weather is pretty hot these days (88° F [31° C] at 11:00 PM today. Note: sun sets at around 6:45PM) with above 55% humidity.
I am aware that it had spider mite infestation. At present, it is clean, but the spots are still progressing. What is causing this? What should I do to stop it from spreading more?
Photos for reference:
Leaf 1: Underside
Leaf 1: Upper side
Leaf 2: Underside
Leaf 2: Upper side
Top view:
Comments (6)
shavedmonkey (Harvey in South Fl.)Z10b
6 years agolast modified: 6 years agosnoozy_bd (Z11) thanked shavedmonkey (Harvey in South Fl.)Z10bRelated Discussions
Black Spots on underside of leaves
Comments (2)Hey Claire, This happened to one of my catt hybrid types...if it's what I have, the spots spread slowly, and eventually penetrate the leaf. I sprayed with H2O2 to no avail. Eventually resorted to phyton27 and the spots stopped and dried up. I suspect fungus but who knows. If you can spare it, and from the photo it seems it is only affecting part of the leaf, chop the part with the spots off and dust the cut with cinnamon. -Cal...See MoreWhite spots on undersides of leaves [Pics Included]
Comments (1)If they are going down in the leaf they are scars from something like a slug biting it. If they are slightly raised, they are scale, a variety that is particularly hard to get rid of....See MoreWhite spots on underside of leaves
Comments (4)I urge you to contact your extension office for help on this. Do you know where your county office is? I'd suggest that you call the office and ask if you can email your images directly to the university diagnostic clinic. With Extension budgets slashed over the years, you never know who might be on call to answer questions. I suspect that these are calcium oxalate crystals, reported in literature for peppers....See Moreorangs spots on the underside of some leaves
Comments (2)Thanks Bill for your advice...Do you think that I am contributing to the spread by spraying them off every few days? I thought they would like the humidity as well as keeping down the mites...Should I hold off on spraying them down? It is in the low 90's here at the beach with a few afternoon showers... not much rain to really soak my plants...but enough to wet them down often... Thanks for your advice!!! Laura...See Moresnoozy_bd (Z11)
6 years agoshavedmonkey (Harvey in South Fl.)Z10b
6 years agolast modified: 6 years agosnoozy_bd (Z11) thanked shavedmonkey (Harvey in South Fl.)Z10bsnoozy_bd (Z11)
6 years ago
jane__ny