What could this be? - Oncidium with white veins and curled leaves

[rbarata]

Hello, my friends

First of all, let me sugest a way to see the previous photos, if you want to. Right-click on the photobucket thing and open the photo.

So, after a 2 week vacation period I finally ordered 100 gr of Magnesium sulfate (Epson salt) to try to solve this issue, or at least to see if this is Mg deficiency.
What is the concentration that you recommend and what's the application frequency?

One more question...I need a control, i.e., which genera has a similar Mg requirement as Oncidiums?

In the meanwhile, I decided to put it outside. Summer day time here is extremely dry (usually < 20%) but night time reaches 80%. So, I water it daily at lunch time and leave it out to appreciate the high HR and cooler temps.
These were two backbulbs potted two years ago and in spite of the bad looking of its leaves, it has strong root grow and a surprise.

[estación seca]

It looks good. Maybe 2-3 grams per liter to start?

What sizes of measuring spoons do you have in your kitchen?

[Dollythehun]

Very nice and the leaves don't look so bad. I used cal-mag according to the label once a month and then dropped down to quarter strength once a month. That's not precise but, it seemed to work well. Hope your vacation was great and you are feeling well.

[rbarata]

It looks good. Maybe 2-3 grams per liter to start?

And the frequency? I've read something to avoid using it with regular fertilizer.

What sizes of measuring spoons do you have in your kitchen?

I have 5, 10 and 15 ml spoons.

There are different densities, depending on the sulfate form.
I was given two of them, in cristals or powder.
I asked the powder form which I believe has a certain water content (assuming crystalization occurrs when water is removed slowly).
So, the density I'll use might not be correct (hopefully the label will tell me which form I'm using).

MgSO4 density = 2,66 g/cm^3.

1 cm^3=1ml => 2,66 g/cm^3

2,66 is roughly somewhere between 2 and 3 grams so I'll use it as reference.

So I'll dilute the contents of a 5 ml spoon in 5 liters of water.
Considering the atomic weights, only for the molecule MgSO4, Mb is approx. 20% of the total weight so it will give me something like 500 mg/liter in the case of anhydrous form (which is not common, except in an industrial context).
For the monohydrate form (density=2,45 g/cm^3) the resulting concentration would be 430 mg/liter.
For the most common form used in "regular" comerce and probably the one I've ordered, the heptahydrate (density=1,68 g/cm^3), the resulting concentration would be 166 mg/liter.

I think my calculations are correct.
So, it's crucial to know which form I'll be using.

BTW, about my tap water, for the first quarter 2017, the Min/max values for Mg (mg/l) - 1,33/3,98.
I have not a clue if this is enough or too much.

Hope your vacation was great and you are feeling well.

My vacation should be longer.
And I'm feeling good, thank you!

[rbarata]

Already have my salts. They are in the heptahydrate form (MgSO4·7H2O).

As previously calculated, for a 5 ml spoon in 5 liters of water the resulting concentration would be 166 mg/liter, which is 166 ppm.

Is this concentration ok or is it too much?
If there's someone who can or have the patience to review my calculations, that would be nice.

As a side note, I've read that a concentration less than 24 ppm is not enough for orchids. If my tap water has a max of 3,98, then it is really low.
My fertilizer has 3MgO which gives me, roughly, 0,009 mg/l or 9 ppm using the recommended dosage.
So, I must take this into account and reduce my sulfate concentration.

[rbarata]

I've found this video

[Dollythehun]

Thank you. Quite interesting and explains s lot.

[rbarata]

My twinkle also starts to show a similar pattern like the one in the video (the yellowing and spots), despite its 3 new spikes.
I believe heat also plays a major influence.

[Dollythehun]

Yes, and the burnt looking leaf tips. Very interesting.

[rbarata]

In the meanwhile, and although it is almost blooming, does anyone have an idea of what kind of oncidium could this be?

With flash



Natural light (low)