Too much water or fertilizer for this CAT

[Dallasgarden]

I just got this plant in the Fall (LC Fire Dance) and it was very root bound so I just moved it to a larger pot with Lava Rock but didn't pull out the roots. I have about 8 new growths, but just noticed this large yellow spotting with subtle deformity. (We had an unusual day of rain yesterday) So what's the problem? Are the roots not drying quick enough/overwatering or am I over-fertilizing that's causing these yellow spots?

I'm pretty sure it's not a virus because this has happened on occassion with some other orchids and then disappeared again...

Notice the older leaves are rich dark green.

Here's the pic.

[clintdawley]

From first glance, my thoughts were "thrip bites"...

They enjoy the softer, new growth and can stiple the leaves like that--check for bugs.

[Dallasgarden]

Where would they be? In the rocks? I check at night with a flash light and never see anything (but an occassional slug). How should I treat?

[clintdawley]

Try a good systemic or maybe some Neem Oil (my favorite).

If it isn't insect damage, then make sure the foliage is dry when the plant gets bright sunlight. Water on leaves can magnify the sun and cause yellow spots as well.

[Dallasgarden]

I'll try some Neem oil. After yesterday's long rain, it did get some bright sunshine so perhaps that is why I didn't notice it until today!

[clintdawley]

That could be it! Be careful to shade the plants for a few days after the application of Neem Oil--it can cause orchids to burn in bright sun!

[Brutal_Dreamer]

It probably is the burns from the light on the oil, but when I first saw the leaf, I thought - SCALE .

I have been battling a terrible outbreak of scale on my cattleyas. The last two weekends I have filled a 32 gallon trash can with malathion and dipped and scrubbed the little @#$@%%# off of my orchids. I literally sunk the orchid for 5 - 10 minutes in the poison and then pealed off all of the fibrous sheath stuff and brushed them with a toothbrush all the way into the roots. I just about cried every time I broke off the new growth or knocked off an eye. I have about 75 plants to go to finish, but we sprayed those and the rest of the greenhouse and the visible stuff looks dead. --sorry about the rant, but I hate scale and it is so quick.

Anyway, scale when hiding under a leaf will make the leaf turn a yellow color like that. But yours if probably from the neem oil.

Cheers,
BD

DEATH to SCALE!

[jkhom]

Looks like bug bites to me also. I had the same symtoms on one of my catts. I couldn't see the bugs without magnifying. Neem worked for me.

[Dallasgarden]

Yes, the neem wasn't on it yet when these symptoms appeared. I did spray with Neem this morning and hopefully it will curb the symptoms because it has so much new growth and I want them to look well.
BD, I've had problem with mites on plants indoors, but for some reason the outdoor plants don't seem to get it. I wonder if all my ants eat those guys. The one thing I'm constantly amazed by is the teeny, teeny, teeny size of bugs on plants and how much damage they can do!

[Lizgeo]

I just ordered 10+ orchids, one of them is catt. maxima, and has scales everywhere. I sprayed it with home made solution I learned years ago from an orchid nursery here. I have used this spray whenever I see scale problem on catts or blcs, sometimes additional Qtip dipping in alcohol for one or two scales I see.

The solution is made of 1 part of rubbing alcohol, 1 part 409, 4 parts of water. It might be 3 parts of water, but I forgot the exact number, so I stay on safe side by using 4 parts of water.