Fusarium in vandas. Diagnosis and management?
 

Hi all,
I got this Vanda online in mid-May in bud. Almost as soon as I got it, it lost about 3 leaves in quick succession from the middle of the stem. And then it stopped losing leaves. Even though there are still a couple of leaves threatening to come off, they've held on for the last month and no obvious progress.
I guessed that this might have been from some trapped water during transport as nothing seems to be spreading too obviously, and also by June the nights were much cooler. The flowers bloomed, the roots seem healthy (though no new growth) and in the last 2 weeks it has started putting out a new leaf.

Now after much reading I've realised this could potentially be Fusarium... But can it affect only the middle of the plant?? If the stem was affected would it still be pushing out this new leaf? I suppose if the roots and core was intact, nutrients can still transfer....

I'm not quite willing yet to cut anything for diagnosis so wanted to see opinions on here. I'm sure it's some sort of rot, which I would hate to spread through the rest of the plant (or worse, to other plants). Should I spray it with something? Any suggestions?!

have you considered contacting the seller?
If it started soon after you bought plant, the disease may have been in the plant when you purchased it.
I have seen fusarium in larger vandas and IF the plant has enough trunk and IF it is a quality flower than it may be worth trimming the rot off the trunk and try to save it, see the link on another forum with similar problem.
BTW other than removing rotted portion of plant with sterilized cutter (Brand new razor blades for each cut until you see clean trunk) I don't think there is a reliable cure for fusarium that does not cost way more than the plant.

broken orchid

Can you post more detailed photos of the symptoms that made you conclude it's fusarium?

Your blooming plant does not have Fusarium. Fusarium is also called Fusarium wilt, and plants with Fusarium often look wilted or scorched (your plant does not show these symptoms).

Fusarium as a diagnosis has become something of a fad on certain YouTube channels. The fad is more common than the actual disease. I also would be reluctant to cut into your plant.

The blackening you see on some leaves could be a fungal problem, it those symptoms persist in new tissue, seek out a broad spectrum fungicide, such as Cleary's.

The plant does look to be in early fusarium stages... have lost a few vandas to the same and that is kinda of what they looked like at first. pls post a picture every couple of weeks and we'll monitor progress and see where it leads... good luck

If it dies it dies. Let it be and see what happens. Chances are you are being paranoid. I never bought into the fusarium hysteria. If a plant dies I just buy a new one; no big deal.

Leaves fall and orchid growths can be ugly as hell but still push on. Relax and put the cutting knife down.

The reason fusarium is a "wilt" is because the fungus tends to colonize the vascular tissue, slowing or preventing fluid flow, so the leaves collapse.

I suppose it's possible that yours is in the beginning stages, as was suggested above, but I've never seen a plant with fusarium not display symptoms over its entirety, and yours might simply need more water!

I do not suspect Fusarium.

I think it may not be watered enough as was mentioned prior.

Vandas not getting enough water will often drop leaves too. They will sometimes drop leaves in no particular order, but it is usually the ones on the bottom that go first.

If it was Fusarium, that'd be mush by now.

How often do you water?

Thanks everyone. Maybe I did jump the gun a bit. I'll keep an eye on it and just make sure I don't share water with my other vandas. As I said the root system looks quite healthy and very much intact, and also that new leaf was definitely not there when I purchased it, so I suspect these are both very positive signs.

It's winter here so I give all the vandas a good soak (5 mins to an hour depending on how distracted I get) every 3 days and mist in between. In summer I try for everyday, missing a day here and there because of work. The other vandas in my collection seem pretty happy (I have about 10).

If there is a bit of a fungal infection between the leaves, can anyone suggest a treatment? (keeping in mind we specific brand names won't help me much being in Australia)

The following site has a lot of information on diagnosing diseases, and chemicals you can use to control them: Orchid Pests and Diseases Refer to the tables with pest and disease controls, available through the link.

You are right, the products we have in the USA may not be the same as in Australia. However, once you have diagnosed a disease (or pest) problem, you can look at the recommended products, research the active chemicals in them, and find products with those chemicals locally.

just a couple of more cents from long time vanda growing in South Florida.... Under watered vandas will ALWAYS start dropping the older leaves (at bottom of plant). Plant will drop leaves to compensate for lack of moisture and will continue to do so until it reaches the balance of water intake and amount of leaves that the reduced water can support. This frequent phenomenon among new vanda growers generates what we call "palm trees". Imagine a 2 foot tall vanda with 3 pairs of leaves at the top, a long bare trunk and roots at the bottom of the plant, roots will be mostly dried and dead. These palm trees got that way because of not enough moisture,

The point being that vanda DO NOT DROP leaves from lack of water from their middle section unless there is a problem in that area.

I don't know...

I'm not so sure it's Fusarium. Fusarium does spread all over, and it does so extremely fast. Since it is showing signs of blackened areas closest to where the leaves connect with the petiole, near the stem, eventually, not only will it cause the leaves to drop, but it will turn that thick stem the Vanda's got into mush. That's how it lives up to its name "wilt".

The thing with Fusarium is that it does exist. It can be a problem, but in the grand scheme of things, it's kind of rare. Most people don't experience it all that often, and when it does, people usually remember what it does to the plant.

I've had it infect a Huntleya wallisii of mine in the past. I had grown it in an area where it was warm, but not too warm, where it had very little light and was humid. Those are perfect conditions for Fusarium to take hold. Come to find out, these conditions did not favor the orchid as well, (it needed to be grown much brighter). This species has a thick rhizome, once the Fusarium infected that rhizome, it turned it into mush and it snapped in half. I could see that characteristic watery purplish-pink ring around where the vascular tissues were. Ive only seen this disease maybe once or twice in my years of growing orchids. The catalyst that starts it is a weakened plant with a weakened immune system.

If deanna wants to take precautions, it is best to use a systemic fungicide. Contact fungicides don't do much if the disease organism has already infected the host.