mottled leaves on a cattleya

[calvin_orchidL]

I have observed something similar in one of my catts which I now suspect is nutrient deficiency. RE: becca, mine are blotches as well, which is uncharacteristic of sun damage. However, it could be as everyone is saying, a result of sun as well

[King_of_orchid_growing:)]

Nutrient deficiency can do it too.

[sevilliana]

To the King's questions - None of my plants had this mottling 12 to 18 months ago. We haven't been able to control exacthumidity until recently - I'd say we are at 70 - 75%.

My plants have been moved a great deal but always within my greenhouse which is approxiamately 20 x 40 feet

[sevilliana]

The mottling does not look like other sun burns I have had but I have never heard of this concept of bleaching. To the nutrient question - there was an extended period without fertilizer 6- 8 months -however, the plants have been amply fertilized for 6 months since then and there has been no sign of recovery.

[sevilliana]

One thought - last year at this time - we ran out of propane for a couple of days and some of my plants froze to death or were greatly weakened could that have done something.

[nancy]

You might try a dose of magnesium, as a deficiency in this often shows up as a whitish, rather than yellowish, coloration of leaves. And it is not a nutrient that's included in many fertilizers.
A tablespoon of epsom salt/gallon water is the typical dosage. I generally (try to) use ES on my orchids and tropicals each spring, as it not only greens them up but makes the plants somewhat more sun- and heat-tolerant.
It isn't sun damage, I think. And I have roasted pretty much everything, so should know...
Regards - Nancy

[Becca]

Originally Posted by calvin_orchidL

I have observed something similar in one of my catts which I now suspect is nutrient deficiency. RE: becca, mine are blotches as well, which is uncharacteristic of sun damage. However, it could be as everyone is saying, a result of sun as well

That's an interesting thought! I use MSU type fertilizer once a week so I figured I would be safe from lack nutrients. I'm thinking it might be something to do with lighting as well. I grow under lights...but I'm usually moving the orchids around always trying to figure out the perfect fit the cram everything into the space I have...maybe it is from the light levels varying because I am always adjusting them. I first noticed this on some seedlings I just got this year...I don't recall them arriving this way...and looking around I noticed another more mature cattleya doing this as well. Must be the light!

[calvin_orchidL]

The period of no fertilizer might explain it. I watered some of my plants with purely RO water for 3-4 months, no fertilizer...mainly because I underestimated the solvent properties of RO. Not sure if recovery of existing foliage occurs but observe the new growth and see if anything improves. I have re-added fertilizer to my watering schedule and now I see all sorts of moss growing and the plants look better. Magnesium is a good idea and reminds me that I need to go get some epsom salts for my plants!

[Donald]

Had the same thing happen to one of my cats after I had moved it to a sunnier location and had it again after moving a phal.

[Gin]

I noticed some of the mottling awhile back started rotating Fert . MSU. and a couple of others seemed to do the trick ..