Cattleya Leaf Discoloration

[sewcrazy64]

I could use some help identifying a problem I found last night on one of my cattleyas. It has 3 new growths and all of them have the same discoloration. Once I zoomed the photo, I could also see tiny white flecks on the darkened areas. Any help is appreciated!

Link to hires pictures of issue

[sewcrazy64]

An image has now been added to the post

[estación seca]

It's a little blurry. Do the white flecks come off with a moist cloth? I can't see the dark areas well. Many Cattleyas develop purplish pigment like this when exposed to strong light. Do the undersides of the leaves look different? What are your growing temperatures, humidity and light?

[sewcrazy64]

The link in my first post shows much clearer, high resolution photos showing the purpling farther down at the base of that leaf and on another of the new growths. Yes, the white flecks did wipe off with a damp tissue.

My plants grow on a 6’ long table in my sunroom. Temperature stays at 70 degrees in cool weather & mid to upper 70’s in warm months. Humidity right now is mid 30%, mid 40’s to 50% in warm months.

There are East and South windows filtered by lace curtains. For cloudy days, I have three 2’ long Barrina full spectrum 24 watt grow lights. They are in a single row running the full length of the table. Originally I hung them 18” above my phals, but some began to purple so I moved them up to the ceiling, about 36-40” above plants. The purpling greatly reduced.

Originally I had only phals but recently I added Cattleyas to this table. After a few days using the lights, purple areas appeared on the new growths of some catts. I assumed the lights did it, but then I saw the white flecks & wondered if it is a pest issue. With these lights so high above, should they be causing purpling, especially on Cattleyas? Are there pests that cause this?

The spectrum representation of these lights shows they give off quite a bit of green light. I heard that green stimulates anthocyanin, producing the purpling. Could it be that this purpling is due to the amount of green light and not the intensity?

A few weeks ago, there was another Catt whose one new growth developed some purple and then died. Is purpling harmful or was this a coincidence?

[Leafmite]

I really cannot tell from the photo what is happening here. If Phals can easily take the light and temperatures, it should not be too bright for most Cattleyas. A friend did tell me that some of the LED grow lights are really powerful. I am really new with LED lights. I still use fluorescent lighting for the majority of my plants and orchids.

I am not certain if it is the same with orchids but, in other plants, purple coloring can often signify too high of light with too cool of temperatures. It can also mean Phosphorus deficiency. Rarely, it can signify an bacterial/fungus issue.

If you have new growths that start out purple and then turn black, this might mean that you need more Calcium.

You might have already seen this but this is a useful document:

https://staugorchidsociety.org/PDF/O...ySueBottom.pdf

[estación seca]

I looked at the higher resolution photos.

Purpling is normal and common in Cattleyas with high light, but it doesn't look like this. The discoloration is limited to the crease of one or two leaves. I suspect there were insects or spider mites in the leaf when it was developing, and they damaged it. Looking at the underside of a leaf I see cobwebbing that looks like spider mite activity. If you have a good magnifying glass inspect the white flecks and the undersurface of the leaf for arthropods that look like mealybugs, scale or spider mites.

I would treat with 70% isopropyl alcohol (rubbing alcohol.) Put it in a spray bottle and spray all surfaces.

Then do some reading here based on which bug you find. Scale and mealy bugs are very hard to eliminate but it is possible to keep them under control. Spider mites are impossible to eliminate because they are outside in your garden, but they, too can be controlled.

Light purpling tends to occur along creases like you are showing but the tissue otherwise looks completely normal. I've been told many Catt species flower better if they aren't kept extremely purple. Phals don't need high light; they do best with around 1,000 foot candles of light. Cattleyas need twice or more that.

[My Green Pets]

I'm going to go out on a limb and say I think they look ok. New growth is juicy and robust.

[estación seca]

I wish I could see it in person. It looks somewhat blackish to me in the photo. If it's just purple that could be normal. But I've seen bugs damage developing leaves just this way. Boisduval scale juvenile forms often start in the crevice of a developing leaf.