Being an amateur orchid grower, one is always faced with many challenges. There is the unpredictably rough weather, the occasional bug, the looks-gorgeous-in-Google-but-does-nothing-in-my-home stubbornness of some species, and of course, nasty rots. Like the one that I’m battling right now.
It’s a leaf spot disease that has devastated most of my young orchids. Here is what I mean:
The infection is worst and most prevalent on my dendrobiums, followed by soft-leaved oncidiums, phalaenopses, and vandas. Paphiopedilums are the least affected. The disease spreads fast and the rain isn’t helping. I had to do something quickly!
When it comes to orchid leaf spots, a fungal pathogen is what first comes to mind. The usual suspects are Phyllosticta, a disease that infects and marks the leaves with black spots, or Anthracnose, a fungal disease that typically creates black rings on leaves. I suspect this could be the latter and a very severe case of it.
Without waiting till the weekend, I proceeded to:
- Sterilise a sharp blade and sacateurs with a lighter,
- Using either of the above, cut away the infected parts, making sure to leave a margin between the damaged spots and clean tissue.
- Discard the infected leaves in a bin (better yet, burn them if you could) including those that have dropped off on their own.
Next, out came the fungicides. In rotation and a week apart, I sprayed my orchids with mancozeb, thiram and thiophanate-methyl, all broad-spectrum fungicides recommended for a variety of fungus diseases (do follow the instructions on the labels carefully).
Then, I waited and observed if the spots stopped.
Much to my dismay, they didn’t. Fresh spots appeared as though the fungicides did nothing! But I’m not giving up.
Not wanting to rule anything out, and with so much to lose, I decided that this might be a bacterial infection and to treat it as such. They don’t sell garden bacteriacides here, so a little improvisation is in order. I do not know if this will work, but I’m prepared to risk it to save my plants.
Here’s what I did:
It has come to the point where it’s the iodine-mouthwash dab or nothing. Hope it works, fingers crossed.
If this ends up with more harm then good, I’m prepared to try the non-chemical route such as cinnamon, or a biological inoculator next, which I’ve read, has given some growers positive results.
Of course, the last thing I could do is to cut losses, toss the plants and start over. That would be drastic.