Phal Roots Turning Orange/Dying?

[meterstick29]

Hey guys, I grow my phals in a grow tent, the temperatures inside usually hit 90F/32.2C in the daytime. Last week I decided to fertilize them for the first time, using the MSU reverse osmosis formula at 130ppm N.

However, the bottom roots of one of my phals have since started turning orange. And most of the ones at the very bottom are dead/growing mold.

Last week, this orchid was perfectly fine and was pushing out new root tips. I'm thinking this might be fertilizer burn but I've never seen roots become orange like this. Any help would be greatly appreciated!

Photos: Orchid Photos - Album on Imgur

[estación seca]

I can't load imgur now on my phone so I'll need to come back to this. How much fertilizer ppwder did you put in how much water?

[meterstick29]

I used a bit more than 3/4 teaspoon per gallon. I used Ray's advice about dividing 10 by the %N on the label to get teaspoons per gallon to use for 125 pm N.

[Dalachin]

I would guess it was too dry, with too much fertilizer, in high temps. 90 can stress some phals, depends on its genetics. Do you have an id?

I fertilize at 25 ppm every watering (in summer, 3+ per week) and try to keep my Phal area in the 80s during the summer, although it might hit 90 on occasion.

[estación seca]

Are you sure you used a teaspoon measure, and not a tablespoon? That amount of nitrogen shouldn't damage Phal roots. The aphrodite ancestry hybrid Phals. here are fine into the 100 F range, though not the polychilos ancestry types.

[meterstick29]

Originally Posted by estación seca

Are you sure you used a teaspoon measure, and not a tablespoon?

Haha yes, I'm sure I used 3/4 a teaspoon, not tablespoon.

[Dimples]

My phals. get root death like that, on the bottom of the pot, when the roots are dry and get too hot on the heating mat. The surface of my seedling heating mats can reach over 100°F, and the roots can’t take that heat for very long while dry-dry. What are your plants sitting on?