Orchids at La Motte

Aside from making some really great wines, including a firm favourite Sauvignon Blanc, La Motte has several flower-growing initiatives (and an impressive and picturesque lavender field for essential oil). They are most proud of their Disa growing, and if you ask nicely at the tasting room, the horticulturalist at La Motte (Neels van der Linde) will take you on a tour of their facilities.We managed to get on one of these tours whilst staying in Franschhoek recently.

We went through two different growing areas, one under shadecloth with a suspended misting/watering system, and another higher-tech polytunnel greenhouse.

Neels went through the history of La Motte's acquisition of a large Disa collection from Prof. Cywes, which was in serious danger of being repatriated to Japan, highlights of their natural history in the veldt and pollination and hybridisation.

The number of plants there is quite staggering, yet with the flowering period coming to an end Neels apologised for how "empty" the growing houses were!

Neels said that other than the odd fungal problem (which seems to be an inevitable hurdle in Disa culture) they had found culturing these "notoriously difficult" plants fairly easy - but modestly noted that if it were that easy then surely the horticulturists in the Netherlands would have got it by now - so they must be doing something right!

I asked Neels if it was OK to take a few pictures; I didn't know if they would be sensitive to potential "commercial espionage" (aquaculture facilities often go nuts if you pull out a camera!), but he was more than happy to have me wander around in the greenhouse snapping away.

The more sophisticated polytunnel greenhouse was quite amazing (and would cost several million rand to install, apparently); they have build a series of watertight benches which are occasionally flooded with water about half way up the pot from a ~500l tank below each the benches. Overhead, there are large blowers connected to polythene tubes with air holes along them, supplying fresh air, and of course, a large ventilation fan and wet wall to keep things cool, along with overhead misters. Neels pointed out that fungi are often water-borne, so this method of cultivation is not without risks; I immediately wondered if plumbing in some sort of UV steriliser or even using ozone to sterilise the reservoir water for a couple of hours a day might help... But compared to algae, fungal spores are pretty resistant.

Disas like to keep their roots cold and damp, so that system will certainly help - and it allows them to not sit around in water all the time, which is no doubt good for them. I stumbled across a website in America where someone improvised something vaguely similar for his Disas using a chest freezer to keep the water cool!

South Africa's most beautiful indigenous flower next to some Disas.

Disas. Many, Many Disas! Note the irrigation pipe for flooding the growing bench.

Yeah, you guessed it - Disas!

At the back there are all the new potential Disa crosses, neatly labelled with the mother plant's details, along with what was used to pollinate them.

On our way out of the farm, we bought 4 Disas from the shop at La Motte, robustly packaged in thick plastic gift bags, at the reasonable price of R75 each (picture of the last remaining flower to the left). And some extremely delicious baked goods. We've seen La Motte's Disas for sale at Woolworths too, and bought one last year, but the high heat in the car on the way back from PE (and during the shopping) took a toll the plant never really recovered from - and Disa Rot took it out shortly thereafter. :(

La Motte's recommended Disa culture notes are available on their website.

De-flasking a micropropagated Disa

Whilst at Kirstenbosch National Botanic Garden in Cape Town on a boiling hot day, we found a some micropropagated Disas from the Cape Institute of Micropropagation and decided to see if we could manage to get them to grow; we also conveniently found a sphagnum-moss based potting mix there too, so we grabbed that whilst we were there.

Having pretty much outgrown its little flask, the Disa bivalvata was opened on Sunday, had distilled water added up to the top of the label as per the attached instruction leaflet, and after three days like that, it was time to pot up.

I sterilised a smallish (9cm) pot and some spoons in some hot water with Jik (household bleach) and then thoroughly rinsed it. The potting mix was rehydrated with distilled water.

You can see how ready it was to be potted!

I gently removed it from the flask with a teaspoon; the distilled water soaking loosens the agar up quite nicely.

Disa bivalvata unflasked, with some agar still adhering.

Given the rather nutritious agar and the susceptibility of Disas to fungal and bacterial root rots, it's a good idea to make sure all that gel is washed off the plants, roots and tubers. I used a pressurised spray bottle turned to a jet of water with distilled water to gently blast the agar off; this works quite well and is probably kinder to the delicate little plants than trying to remove it with tools or anything else.

Cleaned plantlets. 3 were in the flask.

I then mostly filled their pot with sphagnum-based potting mix, and gently packed a little ball of it around the roots and tubers before putting each plantlet into the pot and then putting more mix between the "root balls" to keep them in place.

Plantlets now in pot.

Old and new home (taken with dead flash batteries, hence the blur...)

Added to the collection!

The plants were then watered with 4g/l Fungi-Nil (captab) solution in Aquelle spring water; the instructions said to water with a "mild fungicide"; this morning I received an email from Hildegard Crous who runs the outfit that does the micropropagation:

The Captab works very well as it is somewhat systemic, otherwise the better known fungicide to use is Dithane, both can be used at the recommended dosage.

This is mentioned in the Grow Disa book, but I will improve it on the instructions label,

I put them into the cut off bottom of a water bottle and topped it up with distilled water as you can see in the picture above. So there we go. Hopefully, the plantlets take to their new home and our version of green-ish fingers! I've just ordered the Grow Disas book from SANBI as my regular online book dealers don't seem to stock it.

We bought Dr. Louis Vogelpoel's Disa book at Exotic Plant Company, but it seems a little dated. Pretty much all the information in it is available almost verbatim online in these culture notes.

Disas.com has a very comprehensive guide to deflasking.

Disa Rot

Apparently the biggest problem with growing Disas is their susceptibility to fungi. How the little blighters ever manage to grow in the wild is a mystery!

One of the Disas we bought at La Motte was stricken with "Disa rot" whilst in our care, where some bacterium or (more commonly) fungus starts chomping away at the roots. Underground. Where you can't see it. The next thing you know, the leaves start turning yellow. We tried two doses of Efekto's Fungi Nil 500 WP (500g/kg Captab [Dicarboximide]) at 4g/l, but the plant looked more and more sad.

Last night, after potting up some flasked, micropropagated Disa bivalvata, I decided to have a look at the orchid underground and see how things were getting on.

I was dismayed to see just how far the rot had gone; pretty much all the above ground plants had rotted clean through where they join up to the roots/tubers - the flowering stem pretty much fell right off when I removed the plant from its pot. I managed to find one tiny shoot and tuber (with no intact roots) that looked like it might make it; everything else was blackened and had rotted right through. :(

Disa Rot: The surface signs

Disa Rot: Noooooo! My Plants!!!! :( You can see the tubers and the shoots and how it rots right through the middle.

Disa Rot: Up close and personal. Yuck!

Sad looking flowers; you'll note that the seed pod was swelling, so our efforts at pollination had worked. :(

All that remains... (the background is kitchen towel, so you can see just how small this was)

After leaving the tiny little plantlet soaking in fungicide for a while, I repotted it into fresh Disa potting mix and watered it with 4g/l Fungi Nil. Hopefully it will make it, but I don't hold out much hope :( Most Disa growers seem to recommend regular "preventative" anti-fungal treatments - looks like they're definitely needed...