dendrobium and oncidiums not doing so well??

[ARANDO]

Good day everyone

just wondering is someone can perhaps shed light on this problem - I seriously dont know whats wrong, i keep them in a greenhouse with 70% shade, i have a misting system for humidity.

[-k-]

Looks like the Oncidium leaves are sun bleached, but with 70% shade I wouldn't expect that to happen. . . the Dendrobium looks like it could have a fungal problem...

[Fishmom]

It sure looks like sunburn on the onc. leaves--I have a few that look just like that! I had them in a lath house, and I thought that because the sun was moving during the day, the sunny spots would balance out with the shady spots. Not so! I had to put shade cloth over the whole thing to prevent sunburn. Are you sure the shade is 70% without gaps and holes?

[rcb]

I agree, some serious sunburn going on there.

And remember that sunburn is a component of heat so, the same amount of direct sun when its cool may not burn, but will when hot. And as you are entering the height of your summer - that can happen.

I know here, in spring I have to be careful. I'll have plants that are going along just fine, then we will get a day or two of really warm weather, and I haven't moved the plants to their summer spot yet - and I'll get burn. And it happens to me every year, you think I'd have learned by now lol

The amount of sun didn't change from a day or two, the heat did and resulted in burn.

[ARANDO]

ok i have moved the oncidium away from the window - i think the morning sun through the window is the problem - the dendrobium i will treat with rose care today


Thanx so much for the help

[terra_australis]

I had a similar problem when I first set up my greenhouse... too much heat. You need to make sure it is vented above the level of the plants or the heat build-up will simply cook everything. If there is no air movement you'll also create fungal problems using the misting system and it is surprising how quickly that will knock your plants off if they are already heat-stressed.