Help. Sudden Miltoniopsis Leaf Yellowing with Dark Outline

[realoldbeachbum]

I have had this Miltoniopsis Bert Field Crimson Glow for 4 months. It was mail order and came with almost no roots, but has thrived in low light, plenty of hydration, aeriation, and Kelp. Suddenly, on the largest leaf an elongated yellow swatch appeared from about 1/4 way up from base to about 1/4 down from tip of leaf. It does not go all the way to the base or to the tip. It has yellow center with thin dark edge. All other growths look healthy. It has had no overhead watering and is inside on grow shelf with a shop light about 3 feet up which is on about 6 hours a day.

I searched the web for pics of what it might be, but cannot find one that matches this (St Augustine has the best info!)

Do any of you have an idea as to what this might be? I have isolated the plant and plan to snip off the growth. Thanks sooo much, OB. You are my Orchid ER!!

[estación seca]

My first guess would be heat damage... how close to the lights? What kind of light? These are cool-growing plants that are easy to damage when they get too hot.

[realoldbeachbum]

Originally Posted by estación seca

My first guess would be heat damage... how close to the lights? What kind of light? These are cool-growing plants that are easy to damage when they get too hot.

Thanks, ES!

The temp in the grow space does get hot and humid in this Alabama heat - high 80's to low 90's, but I have a fan running during the heat of the day. Will assume for now that heat is the problem; however would heat affect only one leaf? (No other leaves are impacted.) The light above it is a 'shop' grow light that is really far away, so no heat comes from it.

I will bring it inside the house where the AC will keep it cooler. Appreciate your expertise very much.

[JScott]

My first thought was also heat/sun damage. Listen to ES. He knows stuff. And sometimes heat damage appears in odd places, and you think, "how did that happen there?" but that's just how it is sometimes.

[estación seca]

Upper 80s-90s F / 30-33C and I'm surprised it doesn't look worse. That is the part of the leaf that probably faces the lights. Miltoniopsis like to be very cool, very humid, very well-watered and have very good air circulation.

[realoldbeachbum]

Originally Posted by estación seca

Upper 80s-90s F / 30-33C and I'm surprised it doesn't look worse. That is the part of the leaf that probably faces the lights. Miltoniopsis like to be very cool, very humid, very well-watered and have very good air circulation.

Thanks ES and JScott. I will do just as you say. (I am relieved that both of you did not mention virus or bacteria!!!)

[SouthPark]

ROBB - was this plant growing under the conditions it was growing in (under those same lights) for approximately 4 months?

If that is the case, then some consideration would need to be made about the reason for the abrupt development of that damage on that leaf there.

ES could be onto it about temperature and/or light level. If some particular hot day came up, then it could affect the plant. Not sure about why that particular leaf though.

Could also see if there's any attacking bugs.

[realoldbeachbum]

Originally Posted by estación seca

Upper 80s-90s F / 30-33C and I'm surprised it doesn't look worse. That is the part of the leaf that probably faces the lights. Miltoniopsis like to be very cool, very humid, very well-watered and have very good air circulation.

Originally Posted by SouthPark

ROBB - was this plant growing under the conditions it was growing in (under those same lights) for approximately 4 months?

If that is the case, then some consideration would need to be made about the reason for the abrupt development of that damage on that leaf there.

ES could be onto it about temperature and/or light level. If some particular hot day came up, then it could affect the plant. Not sure about why that particular leaf though.

Could also see if there's any attacking bugs.

Hello SouthPark. Yes the plant was in same location for 4 months. No change in lights/water/humidity. The temp did rise significantly in those 4 months when Summer blazed in about 6 weeks ago! I looked for bugs, but nothing there.

I moved it to North Window in living space where we keep AC around 75 F. Only problem now is humidity. I understand Milts love humidity, which is only 40-50% in our living space. Thinking about a humidity tray with dome . . .

If another leaf becomes infected, I will use one of my expensive Agdia ImmunioStrips to test for virus. (I only use them when all else has been ruled out.)

Thanks so much for your guidance. As I said before - the OB is my Orchid ER!!! Stay Healthy.