Phalaenopsis Orchid leaves turned white and limp!
 

Hi guys,

I'm not sure if this is a disease but it doesn't seem like sunburn either. I recently was gifted an orchid that isn't doing very well. You'll notice some shrivelled roots in the picture, but these were preexisting before I had the plant. Despite these shrivelled roots, I examined some of the other roots in the pot and they seemed fineZ.

I have had the plant for about a week now and it seemed to be doing alright. I have been growing it in bright, indirect sunlight alongside my other orchid (which is perfectly happy). Last night I noticed that all the flowers had died and had fallen off the orchid, but it's leaves looked fine and the typical green colour. Today I came home and the leaves had turned limp and white. Again, my other orchid has been grown in identical light, heat, and watering conditions for months and is fine.

Does anyone know what is causing this? Do I need to get rid of this new orchid?

Any help is appreciated!!!!

That bleaching sure looks to me like sunburn - like a shift in the sun just happened to make a direct hit on that spot. If you haven't already, I'd definite repot. Losing flowers with a change in environment is common (a draft, or just a change - including a sudden change in light level) can do it. Long term, the plant may well be fine. Remember, your other orchids are used to that spot, this one may have grown under lower light and just got unhappy at a sudden change.

Thank you! Would you recommend trimming away the plant's shrivelled roots when I repot, or are these harmless? I've been worried to mess with its roots in case that stresses the plant out even more than it evidently already is.

A gentle tug at the root can determine if it is useful or not. If the coating on the outside of the root is mushy, it'll pull off easily. The stringy inner part of the root, if it doesn't pull off easily, can still wick moisture into the plant, and also help stabilize it in the pot until it grows some new ones. (It's important when repotting that the plant is held in place firmly... wobbling can damage new root tips) So don't be too aggressive. You do want to get soggy media off the roots, wash off the crud under running water, then nice fresh bark will give the roots the air that they have been craving. You can trim the toasted part off the leaf if you wish, but other than being unsightly it does no harm. There does look like some good leaf remaining, you certainly don't want to harm that. One thing to remember... when you pot into bark, you will need to water more often. The plant will love that wet-dry cycle that it will get when you water well, let it sit for several days to dry out, then water again. (How frequently depends on your conditions... use a wood barbecue skewer to find out the moisture level a few inches down... if it comes out wet, hold off... if it comes out dry, then it's bath time.

Looks like sunburn to me as well.

Textbook sunburn. Wait for the burned parts to dry, you can then cut off anything that is not green/living.

Use a very sharp, sterile blade for cutting. For "leaf surgery", I have an all-metal X-acto knife, the blade is flame-sterilized until glowing, then cooled, before and after cutting.

Single-edge razor blades also work great for surgery on orchids (use them on one plant and dispose of them, no chance to transmit disease, very low-cost) A box of 100 from the paint department of your favorite home improvement store costs about $7.

After the dead parts dry, I like to crumble them off with my fingers rather than cut them. This works with Phals and Dendrobiums, but not Cattleyas, which are much stringier.