purpleing on cattleya leaf

[lobotomizedgoat]

I got this Rlc. Hawaiian Lightning last June. It bloomed a month or two after I got it, was repotted after that, and has spent the time since growing roots. It was getting less light than my other catt so when some room opened up I moved it closer to one of my grow lights. A few days later I noticed this purple blotch appear, as well as a fainter bit on a leaf further away. Some of the leaves of my other catt receive similar exposure have not changed beyond one lightening a bit.

I angled the plant so the light was less direct and that seemed to halt further discoloration. Over the last few days I feel like the area may have changed in color a bit again. It may be getting some sun at sunrise now, filtered through a screen door, but I haven't been around to check.

Aesthetically, I don't mind the change but I want to double check that it is indeed from light exposure and not disease or undernourishment. Also, if it is from light, how important it is to reduce its exposure?


Culture: 65-75° F, ~60 % RH, med bark, slatted terracotta, flushed with tap water every 5 days, fert ~2/month at ~100ppm N, sometimes misted in between waterings

[Grim Tuesday]

Could it be magnesium deficiency? https://staugorchidsociety.org/PDF/C...ySueBottom.pdf

[Roberta]

It looks to me like it is right on the edge of sunburn or is already scorched. You have to especially careful this time of year as the sun moves higher in the sky - a time of year when I have toasted plenty of leaves. If that leaf is warm to the touch when the light hits it, definitely a likely cause.

If it's getting southern California city water, I would doubt a mineral deficiency... local water has plenty of both calcium and magnesium.

[rbarata]

It looks to me like it is right on the edge of sunburn or is already scorched.

That was my first thought too.

[estación seca]

Yes, that's classic sunburn.

[RoseSD]

In the case of sunburn leaf do you leave it on the plant?

[Roberta]

Originally Posted by RoseSD

In the case of sunburn leaf do you leave it on the plant?

Yes. Might be a bit ugly, but the leaf is still capable of photosynthesis and won't harm the plant. Where cutting would deprive the plant of a food source and possibly introduce pathogens! The plant will shed the leaf naturally when it's no longer useful. Usually within the next year or two, after it has grown some more leaves and new growth.

[Steve83]

It's sunburn, on old growth. Nothing to worry about.