Help. New den has little black spots. It is not too widespread yet but I can see that happening unless I get right on it. I hate to spray when it is covered in so many flowers and there are still dozens of buds. I could dab something on the spots while there are only a few but what? The q-tips are ready, give me some ideas on what to use pretty please. TIA

Hmm, those spots look more like insect damage than fungus to me, Alice. In your second picture, could that be a scale insect that has left a trail down the stem?

What a lovely flush of bloom you've got going on there! I'd be inclined to spray the spotted areas with plain water and sprinkle some cinnamon on while it's wet so it will stick. Either fungus or insects may be taken care of by this method. Keep an eye on the area though, and if the spots get bigger, or more appear, more drastic measures may be needed.

No insects, the spots are like a mold or mildew. If the plant had been outside in our humidity this week I could understand it but it has been in the house. Spraying with water and sprinkling with cinnamon might work if I can do that without getting cinnamon on the flowers. Maybe I will paint it with cinnamon using a small makeup brush. Heck, I don't use them for makeup.

The first photo looks like Phyllostrictina capitalensis and is common on Dendrobiums. It is generally not a serious problem but causes unsightly spotting of leaves, detracting from the plant's appearance. You can't reverse this fungus but you can slow it down by removing it from the plant and using a thiophanate methyl-based fungicide. You can also use mancozeb or ferbam.

Jim

Well phooey, I was hoping for a home remedy. I'll see what our Lowe's has but I'll probably have to drive 1 1/2 hours each way to get the fungicides. Living in the middle of nowhere has disadvantages.

Alice, try ordering it online. Then you're sure of getting what you need, AND it is delivered to your door. Neither my Home Depot or Lowe's had the Thiomyl fungicide I wanted. I ordered it online and got it in 3 days from Amazon. Btw, the Southern Ag brand of Thiomyl is the same stuff as Cleary's - generic at about 1/3 the price.

Good to know.

I think I am going to try the cinnamon first. I read where you can mix it into a paste with cooking oil or alcohol and dab it on. It is worth a try.

That's always my first try, and often as not it works, too.

I hate using chemicals, but am finally over the top with the black rot casualties in the late summer and fall, so I'm preparing to don my protective gear and spray the whole family with Thiomyl every couple of months as a preventative.

Kind of odd that it's on the stem and not on the leaves. Most fungi that attack orchids like to get hold of the leaves first. That's why I didn't think of Phyllosticta capitalensis before - I've only ever seen it on leaves.

Alice, I'd try making a paste of the cinnamon with water first, to see if it will stick that way. Apply it to the spots with a Q-tip, maybe?

You are right, Elaine, it is mostly on leaves but it can start on pseubobulbs and move about.

Jim

I was reading AOS tips on the 'cides and they mentioned neem for disease, fungus and bugs. They also mentioned mixing cinnamon with vegetable oil. I am thinking of maybe mixing cinnamon with neem instead and dabbing that on.