Disa aurata

This is from May 2014, but I'm still trying to catch up with my photo editing from this spring/summer.



Disa aurata, on Flickr

I got it from Wally Orchard of Afrodisa this spring. So I can't take a credit of flowering it. But it is still alive at least. His plants are very nice, and he is very helpful (and his price is too good). This is my first year with growing Disa, and I already killed 2x D. uniflora (maybe the night time temp wasn't cold enough, or I didn't give enough water). I need to get more D. uniflora...

I can see why Disa is so addicting, and I enjoyed reading Tenman's article here. I'd love to learn about the culture of stream Disa from other Disa growers!

Thankfully, not for our climate.

The big issue is keeping them cool and damp in the summer. In your case, if you are not growing them under lights in the winter they may not be getting enough light. These plants are active growers all year round. There is only a brief period in May/June where the old growths senese and the young ones emerge. The other big no-no is moderate fertilizer---it seems to kill them. Fertilizers need to be very dilute but constant for good growth. This is why semi-hydroponics seems to work so well for them.

Thank you, Tyrone. I'm growing them under lights, but I wonder if it will get enough light. Also, getting low temp in the winter is a challenge for me once the heater kicks in.

I was trying lower fertilizer for D.uniflora, but it might have been too much (it was around 15ppm N MSU in rain water once a week or so). For the surviving ones (D. aurata and D. tripetaloides), I'm trying to reduce it further. But I'm getting this pale leaves in the newer growth. Do you have any idea what's going on? Disa seems to be completely different from other orchids, so I'm not sure how to deal with it.

I am impressed with anyone who can keep Disas alive for more than a year!

Can you tell us a bit more about your watering and fertilizer. Also, can you provide a close-up of the yellow leaves and a healthy looking green one. What lights are you using?

Table Mountain gets about 200 microEinsteins/m2/s on a winter day---but this will be mostly in the morning. Do you have a lux-meter and can you tell us the name of the lamp you use (we can work out the light in microEinsteins).

Bye

Thank you for the info Tyrone. I thought that they naturally grow at a higher intensity light.

They are under T5HO (ebay plant spectrum with enhanced red+blue) + cheap warm white LED. I just went to measure it, and it is 100 micromole/m^2/s for 13 h/day. With considering the constant light vs natural light, the cumulative amount of light is similar to 150-200 micromole/m^2/s of peak natural light. Some rupicolous laelia (thin leaved kinds) seem to flower well at this relatively low intensity. But the measurement is with a really old Li-Cor quantum sensor, which I scored from ebay, and it needs routine calibration. I feel like that Disa may be happier with more light. For D. uniflora, I was keeping it under direct sun (but not so strong in AK, I guess).

I top-water them every 2 days (or every day) with rain water (10ppm TDS). The media (mostly perlite with some sphag) seems to be wet all the time. Fertilizer used to be 30ppm N (mostly MSU, but other stuff, too) twice or once a week. But after D. uniflora flowered and declined (with no new pups), I reduced to 15ppm N once a week or so (about a month ago).

Here, I blew up the picture of the leaves (around the region where there are yellow and green leaves). Can you tell anything from this?


I think the green part is probably from the growth under Wally's cultivation. If it were some nutrient deficiency, it would be relatively phloem-immobile elements (Ca, Fe, Mn, Cu, B, S etc.) since the older leaves are not so influenced.

SlipperFan said:

I am impressed with anyone who can keep Disas alive for more than a year!

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I agree, I wonder how many more Disa I have to kill to get there!

Nice. Besides being hard to grow, they are also kind of hard to acquire here.

Hello,

I think the light is adequate given the success with the Laelias. Also, the plant lamps are really heavy in the blue and red (where it really counts). 100 uE/m2/s of a plant lamp is possibly just as good as 250 uE/m2/s of a warm white lamp...

Now to state a giant, over blown, fertilizer debate...

The pale leaves with dark veins can be caused by three different nutrient deficiencies:
K
Mn
Zn

To speak of K-deficiency here is some what anathema as of late... But the descriptions matches what we are seeing: "Older leaves may look scorched around the edges and/or wilted. Interveinal chlorosis (yellowing between the leaf veins) develops."

For Mn the symptoms are: "Growth slows. Younger leaves turn pale yellow, often starting between veins. May develop dark or dead spots. Leaves, shoots and fruit diminished in size. Failure to bloom." And for Zn: "Yellowing between veins of new growth. Terminal (end) leaves may form a rosette."

In these discussions I always like coming back to Mulder's Chart:


Mn and K are related. If you have too little of one, you will see symptoms of the lack of the other. MSU is 13-3-15 so even if you are supplying 15 ppm N your plants should be getting enough K so I suspect the issue is Mn. While it is still sunny and warmish outside, I suggest you fertilize with something like Kelpack or Nitrosol or Seagro once or twice a week (you don't want to use Nitrosol & Seagro indoors, it stinks). These have been used to grow Disa's before, used as a foliar feed. (Seagro is what Jim Holmes of Cape Seed and Bulb uses. He mostly grows Disa uniflora hybrids.) These 3 are rich in Mn but relatively light on the K.

All the best with the Disa!

Eric, contact Wally. He had plants for sale. I was going to give it a try but decided to wait until next growing season.

lovely flower

NYEric said:

Nice. Besides being hard to grow, they are also kind of hard to acquire here.

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Well, there's now a source in AK.

Linus_Cello said:

Well, there's now a source in AK.

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I'd like to be able to do from seed to seed of Disa, but it's a long way to get there!

Hmm, so Tyrone, you think it is nutrient deficiency. It could be deficiency caused by excess. Interference is usually the issue when the overall concentration of fertilizer is too high for the species. Well, it could have caused the dehydration of root (burn), and they may be physically damaged. I could check the damage, but I was told that it is better not to disturb the root for this particular species. Everyone says that they don't need much nutrient, and over fertilization is one of the main causes of Disa death.

The difficult decision is whether the deficiency is caused by interference among elements (over fertilization) or lack of it (under fertilization). I could give mancozeb, but I think I should probably take the safer route of reducing fertilizer further more at first.

Linus_Cello said:

Well, there's now a source in AK.

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When I search, AfroDisa there is no price list, or catalog. Are you the source now!?

Eric, his price is really good. I hope it's ok to post it, but the seedlings are $10-15 (but some of these will flower next year). BS is around $15-20. Flask was around $25, I believe, but you need to wait for the next spring. I'm only interested in species, but he does have lots of hybrids, too. Some stuff he listed last time are D. uniflora, D tripetaloides, D Kewensis, D Golden Age, D Yellow Bird, D Michael Gallagher x D uniflora.

Hopefully we can get a catalog/price list. Thanks.

Email Wally and he will tell you what he has and what the prices are.

Naoki, you make a very good point. Some Disa growers have claimed the best growth by simply watering with distilled water. But the largest plants I have been told about were getting dilute Seagro on a weekly basis (or was it daily basis, I forget?). Over fertilization is a killer with these plants and that is how I have dispatched most of mine.

If we take the standard hypothesis here: too much K, then we could get interference of the uptake of Mg and N. A lack of bother would cause chlorosis but the symptom of the latter is small pale leaves, and as N is mobile you would see degeneration of the older leaves. Mg on the other hand presents as normal sized leaves that are pale and the older leaves become chlorotic between the veins, not like we see here with new leaves being chlorotic. Everything points to an immobile nutrient and our options are Mn or Zn.

This is a useful document to have around: http://www.mgofmc.org/docs/nutrientdeficiency.pdf

High Fe can inhibit the uptake of Zn and Mn. Phosphate inhibits the uptake of Zn and Cu that of Mn. Could there be a P or Cu excess? But now we have abandonded Occam Razor and have an explanation more complicated from the simplest one:

Mn deficiency symptoms: "Yellow to white colored leaves, but with green veins. First noted on new growth. May have a typical
"gray speck" symptom. "

Disa tolerate dilute foliar feeds well and the organic based formulas (Kelpak, Seagro/Seagrow etc...) provide ample Mn and relatively little K, P etc... Kelpak contains 8.40g Mn per L compared to 3.6:8.2:7.2 NPK. Mn is needed in only trace amounts so a little foliar feeding with the Kelpak should quickly clear up an Mn shortage while not offering too much NPK. I have used Kelpak on Disa at 1/2 the recommended dosage.

Thanks Tyrone. The document is a nice summary.

I do use kelp product, but I consider it to be more of hormonal than nutritional value (well, it is an expensive way to supplement nutrients). I think you meant 8.4mg per L of Mn in Kelpak (from Ray's number), which I wouldn't call high Mn. Also percent NPK is 0.36:0.82:0.72, right? 1000 ppm = 0.1%

If you use 2 tsp/gallon, Mn concentration of KelpMax is 0.0219 ppm.
With 10ppm N of MSU, Mn concentration is 0.0682 ppm (3 times more than KelpMax). So you are right, that it can increase Mn without increasing the macro-elements. But it does increase the EC (and interfere with root osmotic pressure). When I measured 2TBS/gallon of MaxiCrop (they are more diluted than KelpMax), it gives 335 microS/cm (approx. 190ppm TDS).

Anyway, if it doesn't improve in a couple months, I'll probably try Mancozeb.

Linus_Cello said:

Well, there's now a source in AK.

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Who is the source in AK?

Beautiful flowers!