How to know if vanda has fusarium wilt

[Orchid Whisperer]

Hi SouthPark

The Fusarium issue is perpetuated con YouTube, including one common poster regarding orchids that indicated her entire collection needed to be eradicated due to Fusarium (despite many blooming).

[SouthPark]

Originally Posted by Orchid Whisperer

The Fusarium issue is perpetuated on YouTube, including one common poster regarding orchids that indicated her entire collection needed to be eradicated due to Fusarium (despite many blooming).

Hi O.W.! Thanks for mentioning this. After you mentioned it, I checked youtube, and found a youtube video that's very likely to be the one mentioned. The spreading could have been significantly cut down by not dunking the plants, roots etc. in the same tubs of water during potting, dividing etc. I'm thinking that if almost the entire collection is infected, then that would probably be the best time for studying --- as in -- don't purchase any more orchids, and see how long the ones with known infection (purple rings in bulbs) last for. If they just keep going and going, year after year ----- then this kind of study would be extremely useful. If many keep surviving year after year, then that would be fantastic. Otherwise, if most succumb to the fusarium oxysporum, then the result would be significant and beneficial to us growers, even though it would be a case of taking one for the team. The study would certainly not go to waste.

[Orchid Whisperer]

Hi again Southpark.
I had to cut my prior post short to drive to where I catch public transportation to work.

Briefly, the blooming orchids I saw in the video could not have Fusarium. The primary symptoms of Fusarium include severe tissue dehydration because plant tissues are not getting enough water (plant water-conducting tissues fail to function properly due to the disease). Also, the leaves may have yellowed lesions that go along with the dehydration.

Too many people rely solely on looking for the "purple ring" in the cross section of a rhizome that can come with the disease, rather than the primary symptoms. Sometimes you can get purple coloration in plants that are otherwise healthy (often purple coloration can be natural in the plant).

Look for the desiccation first, if you can't explain that due to under-watering, or root loss, or can't improve it with improved watering, you might suspect Fusarium. If you get the yellow lesions, it is another piece of evidence indication Fusarium. Only then should you start cutting, looking for the purple ring.

I agree with your comments regarding good plant hygiene, and ceasing plant acquisitions (time to study) if you suspect a plant pathogen is spreading in a collection.