Slow growing rust discolouration around base of Paph. kolopakingii

[southernbelle]

I have sprayed all my Paphs with spider mite control a few days ago. I will do so again just to make sure.

I think it’s 3 sprays 5-7 days apart but check on it.

 

[Kate Boyce-Miles]

This turned out not to be spider mite. It is some foul fungal pathogen which allowed entry of secondary bacterial infection which finished it off. The kolopakingii has completely succumbed to it despite being under the fan constantly and treated with powerful doses of hydrogen peroxide. I tried sulphur and cinnamon but it did nothing for it. A few more of my plants are also affected now and I am very upset about this. The second image is a stonei x praestans which is affected. Please does anyone have an idea of exactly what the fungus is? The only thing I can think of is southern blight/collar rot.

 

[musa]

No idea what it could be. Years ago I lost a kolo the same way. The stonei x praestans seems to get a new shot if it is quick enough it could make it, my lowii survived that way but it will take time...

 

[GuRu]

Kate, unfortunately I read this thread not before today and in my eyes it's clearly a beginning fungus infestation. I thing SuperPaph was on the right track even a fortnight ago.

Although climes are not similar, I think the way on which fungus develope are similar at all aroud the world. In my experience, and watching the kind of lessions this plant is showing, it looks to be a fungus, a dry fungus, that first kills the stome, and begin to "run" along a "line of cells".

I'm no expert, I only repeat what I read and I just can point on this site about Orchid diseases of the HARK Company, a German orchids propagating laboratory.
One kind of fungus which I would think can cause your problems is COLLETOTRICHUM the other on one is RHIZOCTONIA. Unfortunately you can't not anymore switch the language to English on the HARK site but you can see few photos and the names of the fungi and with that you can start a search in English.
One certain sign of a fungus infestation is......you can smell it if you go with your nose closely to the infested site.
The most important thing is reduce humidity, reduce watering and stop spraying.
I used to use a paste of cinnamon powder steered with some drops of water and one drop of washing-up liquid. This paste I apply with a small paint brush.
Good luck and all the best to your plant.

 

[Kate Boyce-Miles]

Kate, unfortunately I read this thread not before today and in my eyes it's clearly a beginning fungus infestation. I thing SuperPaph was on the right track even a fortnight ago.


I'm no expert, I only repeat what I read and I just can point on this site about Orchid diseases of the HARK Company, a German orchids propagating laboratory.
One kind of fungus which I would think can cause your problems is COLLETOTRICHUM the other on one is RHIZOCTONIA. Unfortunately you can't not anymore switch the language to English on the HARK site but you can see few photos and the names of the fungi and with that you can start a search in English.
One certain sign of a fungus infestation is......you can smell it if you go with your nose closely to the infested site.
The most important thing is reduce humidity, reduce watering and stop spraying.
I used to use a paste of cinnamon powder steered with some drops of water and one drop of washing-up liquid. This paste I apply with a small paint brush.
Good luck and all the best to your plant.

Thank you for your response. Do you know what chemicals are affective against these two you have mentioned?

 

[GuRu]

Kate, I always used with reasonable success my cinnamon paste and since I've stopped spraying when watering the infestations decreased remarkable. On the HARK site they recommend some fungicides, for example (Mancozeb, Metiram, Maneb) but I think on the one hand these are for professional use only and on the other hand they might be named different in UK. I'm not sure but I think you live in UK.

 

[Kate Boyce-Miles]

Kate, I always used with reasonable success my cinnamon paste and since I've stopped spraying when watering the infestations decreased remarkable. On the HARK site they recommend some fungicides, for example (Mancozeb, Metiram, Maneb) but I think on the one hand these are for professional use only and on the other hand they might be named different in UK. I'm not sure but I think you live in UK.

Thank you for the reply. Cinnamon does work perhaps on some of my orchids, just this particular fungus seems really virulent and cinnamon does nothing to control it. I do live in the UK, yes, and it is very frustrating to me that these chemicals exist that could potentially treat this disease yet I cannot get hold of them.

 

[GuRu]

Kate, maybe you can start an internet search and find out the trade names of these fungicides/substances in UK or maybe there is a nursery nearby the place you live which can help you out with a reasonable fungicide?

 

[eds]

If they are available in the EU then we should still be able to order them (for now!) into the UK. You might have to buy them from Germany though!

The range of fungicides is rather lamentable I'm afraid to us domestic growers over here.

 

[Ozpaph]

Those last 2 pictures look like bacterial rot. Lower humidity. More airflow. Try cinnamon. If it gets bigger i would remove those leaves.

 

[Kate Boyce-Miles]

Those last 2 pictures look like bacterial rot. Lower humidity. More airflow. Try cinnamon. If it gets bigger i would remove those leaves.

Yes bacterial rot moved in, but a fungal disease started first. I have done all that and cinnamon actually made it worse. One of these plants is now dead.

 

[werner.freitag]

yes, looks like bacterial rot

 

[Ozpaph]

You have to 'cut it out' very early to win. Maybe try Dragons Blood topically and the cinnamon. Ive not tried H2O2 but some use it.

 

[Justin]

Bacterial rot. I would remove that leaf and treat the plant quickly with Phyton 27.

Roberts has it: Home INDEX

 

[Russ1992]

All of these pictures from different users show Rhizoctonia to me except @Kate Boyce-Miles last two images that do appear to be bacterial. If you go to the Hark Orchideen website the rusted neck looks EXACTLY like Rhizoctonia. This comes from poor air circulation at the roots and being too moist for too long. The above in combo with high humidity and high temps with poor air movement almost ensures problems to take hold. It’s important to note however that the host plant can also infect nearby plants that are strong with good culture. This is a soil born disease which is why it is visible first at the base of leaves, but at that point it has probably already infected the roots. The infection noticeably slows down or stops growth. Lower leaves yellow with brown smears and spots dotting them at the base. In most cases this progresses slowly but in seedlings I have seen them deteriorate rapidly. I have been struggling with these same issues.

I have been told to apply Hydrogen peroxide, and Physan by nursery growers but these treatments seem pretty ineffective.

AOS states that the following can be used:

Thiomyl
Banrot
Clearys 3336
Terraclor
Zyban

Some ST users advocate using

Zerotol
Liquid Copper

In my experience Thiomyl is ineffective when a plant is already infected. Zerotol seems to slow the advance of the infection but doesn’t eradicate it.

Interestingly one user advises that there is just one fungicide that will work for a current Rhizoctonia infection: Rizolex. The active ingredient is Tolclofos-methyl.

I haven’t tried this Rizolex or many of the others but will probably give it a go. Will report back my findings.