Brown crud on my Oncidium Tiger Crow 'Golden Girl'

[dougroc]

Hi, my Oncidium Tiger Crow 'Golden Girl' HCC/AOS started getting some brown crud on the bottom of the leaves. If I rub it with a tissue, no color comes off. What do you guys think it is?

I blasted it with alcohol 2 weeks ago and then last week blasted it with Garden Safe Fugicide 3, which allegedly is a fungicide, insecticide, and miticide, but it looks like the only active ingredient is Neem oil, which I didn't think was effective against everything.

[Halloamey]

The damage looks more physical than of any microbial origin, Check for aphids, mites, mealy bugs or any insects. The sap sucking insects leave such marks on leaves. Its good that you already sprayed the plants, it will act as a preventive measure.

[Brutal_Dreamer]

If it is only on that one leaf, remove it and spray the plant again. If it is all over, spray the plant and keep an eye on the new growth to see if it does the same thing.

Cheers,
BD

[dougroc]

Hi guys,

Thanks for your input on this.

Amey, I checked with my lighted magnifier for anything crawling and couldn't
find anything, although maybe they were there and the spray sent them into hiding. There are definitely no mealybugs.

Bruce, the plant is throw up a new rather vigorous shoot, and the lower leaves show some of this rusty crud and the newest upper leaves so very little to none. There are however old leaves that are hardly affected at all. Is spraying once a week OK, and am I using a reasonable product or do you think something else would be better?

[Brutal_Dreamer]

Doug, if the newest growth doesn't have the problem, then things are looking up! Regarding products: Some people on OrchidTalk recommend using physan. I just stick with a regular fungicide available at local box stores. I would add a fan to your grow area to dry off your plant after watering.

Cheers,
BD