Fusarium oxysporum on Catasetum

[Lars Kurth]

Hi,

I just have lost a nice Catasetum which I bough this spring at the RHS orchid show. The plant was imported from South America and grew on really well. Suddenly over a period of 3-4 weeks it deterioted very quickly. I didn't notice earlier and when I saw the plant this morning, I knew that this was probably the end of it. Maybe some parts could be saved through major surgery.

I thought I'd share some of the pictures. It may help somebody in the future. I am pretty sure the plant had Fusarium oxysporum - probably already when I bought it - and the onset of winter triggered a rapid demise or secondary infection with Erwinia.

It looks as if the disease spread from the rhizome to pseudobulb 3 (the latest growth and thus the most suscteptible and from there to the older bulbs 2 & 1).

The two tips of the older pseudobulbs were still firm and had no colouring,so it may still be possible to save a bit of the plant. But it is unlikely.

In any case: I was surprised about the speed of the demise and the lack of any warning signs. It just shows that one has to be extra careful with imported plants at this time of the year.

I don't think that I overwatered: if anything I kept my Catasinae too dry. I stopped watering nearly a month ago after the plant flowered for a second time this year.

Regards
Lars

[Eyebabe]

I have not seen fusarium wilt but only described in books with pictures.
Your plant is quite like the examples I have seen.
Troubling is how you might have seen it prior to purchase without actually cutting a piece of the plant?
Are there particular species of orchid that are more susceptible to fusarium?

[catasetum-ian]

i know how that feels, the infection are rapid...i almost lost my ctsm trulla and another ctsm hybrid to it. for the trulla is a back bulb i swap with a friend, lost about 1/3 of the base, manage to salvage the top, till now still in dormant phase but at least not rotting further up and had been stable there for about a month and half.
as for the ctsm hybrid, quite similar to your case, came in a pot of three bulbs, flowering when purchased, but as soon as all the flower sheds, something just ain't right about the plant, started to dig everything up, found that the roots beginning to rot, the two back pseudobulbs started to turn color, manage to save almost one entire bulb (have to trimmed slighly further up than usual) and luckily still dormant phase till now, sitting in the platform there for about a month, no signs of further rotting.
i cut off infected area till i see clean healthy tissue then treat the fresh cut area with a dip into Dithane 30 powder, helps to dry the area out quickly but damages the local tissue slightly. good luck....though the tip left in your case is very little,,,,but worth to try. who knows,,,you might have a tough survivor there

[isurus79]

Yep, that's how I lose most of my Catasetinae. Never knew the name for it though. It usually starts for me with a wound to the p-bulb or roots, whether it be mechanical damage or sunburn, and then spreads to the rest of the plant. Its very common in these guys and maybe Ramon can chime in with how to stop/prevent this from happening because I have yet to do it without major plant surgery.

[DavidCampen]

Thiomyl(Cleary's 3336, thiophanate-methyl) is listed as effective for Fusarium and it is a systemic. Does anyone use systemic fungicides routinely for prophylaxis?

[glengary54]

Originally Posted by DavidCampen

Thiomyl(Cleary's 3336, thiophanate-methyl) is listed as effective for Fusarium and it is a systemic. Does anyone use systemic fungicides routinely for prophylaxis?

I grow in Central Florida, I start a preventative fungicide regimen in early spring by the summer rainy season I am spraying every 7-10 days. I have not had rot issues in years.

[cday2inflorida]

Don't know a thing about growing Catasetums. But....I would try Banrot + Thiomyl for fusarium. 1 1/2 tsps per gallon of each.

I rotate a regime of the above two...plus Diathane M45 and Physan. Every two weeks.

[Shirley]

Thanks for your excellent photos Lars. That will help me know what to look out for in future. Good luck with saving your plant.

[Lars Kurth]

It did not survive (-:

[DavidCampen]

Sorry to hear that you lost the plant.

Thanks for the photos.