White spots on my dendrobium

[jimkamal]

Hello everyone! about a week ago, i moved all my orchids outside onto a shelving unit that I bought from home depot. I put it in a location that's shady at the back of my house. I wasn't sure if it gets direct sun in the middle of the day so I didn't put any shade cloth over it.

After the first day of being out, I checked the orchid and realized that this dendrobium and another small cattleya had a minor burn. I realized that the sun do hit it between 12:30 PM and 2:30 pm. So i went over the lowes and bought a shade cloth to cover the top and front area of the orchid. Now everytime when the sun comes in, it is dappled and no more direct sunlight hits the orchids.

After the burnt, a few days after, i noticed white spots on my one of my leaves. I wasn't sure what it is so i let it be. Then today, i noticed a few more at different spots on the orchids. I'm not sure if this is caused by the sun burn or it is something else. Please help me! This was a gift from my partner's mum and I do want to save it.

I water this orchid once every 4-6 days depending on the wetness of the medium. It's in a bark medium. It was doing well before. I live in Hawaii where our temperature ranges from 77F/88F and humidity of 44%/65%.

Below are the pictures of the white spots that I mentioned. Please help me!!!

[dendro photo]

Looks like burn to me but water every 4-5 days sounds a lot to me dens like it a little on the dry side

[jimkamal]

Well, thanks. I noticed today that there is the same problem on the upper leaf of my phalaenopsis. It seems shriveled and had that same white spot. Could it be that it is spreading? Please help!!

[silken]

It looks like sunburn and the location of the spots are the highest and most exposed part of the leaf in most cases. It shouldn't spread unless it becomes infected due to the damage caused to the leaf. You could wipe some hydrogen peroxide or brown listerine over the leaves, but the fact that it was in the sun and where it is located looks like sunburn only. Even if they are orchids that require a lot of light, they still have to be introduced to extra light slowly.

[jimkamal]

Okay thanks! so what should I do with the burned leaves? Should I cut it off? I recently bought physan 20 online and still waiting for it to arrive. I was thinking of cutting it after i get it so that I can disinfect the cutting area. Here's some pictures on my phalaenopsis







How do i introduce them slowly to sunlight? I have a shade cloth covering my whole orchid rack. The phalaenopsis is located at the most bottom part of the rack.

[silken]

I would just leave the leaves as is. They are still alive and photosynthesizing which gives the plant energy. Unless they become infected, which is not that likely, you don't need to do anything. They just won't look as nice. Since you added the shade cloth, they may now be fine. Otherwise put them out only for a few hours to start with and gradually lengthen the time that they are on the new shelf.

[jimkamal]

ahhh.. that's a great idea! Thanks for the tip! I will do that for a couple of weeks for both my dendrobiums and phalaenopsis! Thanks so much!!


PS: How do i know if it gets infected though?

[silken]

The burnt parts may dry up since the tissue is killed, but if you get any wet soggy leaf tissue or anything unhealthy looking, it could be infection. I would try not to get excess moisture on those leaves. Your plants will likely be fine