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ronan

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:mad:

something very bad...but what? i trashed a lot of phal...
thx for helping.

253660IMG27141600x1200.jpg
 

eggshells

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Looks like fungal or bacteria. I saw those black rings before is it called pseudomonas?
 

Roth

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rhizoctonia confirmed... I got that one several times on import, it is not so rare on Asian monopods, and usually shows up on a fresh import. It is indeed very contagious in a nursery, usually targeting soft phal leaves, sometimes new paph leaves, but usually it caters to phals and monopodials.

Against that, only ONE fungicide is efficient, tolclofos methyl. There is none other...

Terraclor/Quintozene is efficient as a preventative, but tolclofos methyl/RIZOLEX saved for me plants that were far more infected than ronan photo...
 

Roth

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I thought rhizoctonia was a group of soil-bourne fungi which attack roots etc?

Have a look in images.google.com for 'rhizoctonia foliar blight'. Hark Orchideen has one picture too, the first one, of rhizoctonia crown rot, which looks similar too, though the symptoms are way less extensive when the humidity is low, or for some specific plants.

Zero tol is not going to help once the infection is there, as the filaments and spores travel everywhere, and are very robust... It can be a preventative however. Only tolclofos methyl can control this on already infected plants. The problem being that the plants can be asymptomatic for months or even a couple of years. In this respect it resemble the equally severe problem of fusarium, but the symptoms are different. I suspect many plants that suddenly 'do not grow well' or 'stop their growth and slowly die' are affected by latent infection of fusarium or rhizoctonia, that progress slowly by steps.
 

SlipperFan

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Doesn't look the same to me. I still say it looks like, when the leaf was still young and folded, something chewed on it.
 
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Have a look in images.google.com for 'rhizoctonia foliar blight'. Hark Orchideen has one picture too, the first one, of rhizoctonia crown rot, which looks similar too, though the symptoms are way less extensive when the humidity is low, or for some specific plants.

Zero tol is not going to help once the infection is there, as the filaments and spores travel everywhere, and are very robust... It can be a preventative however. Only tolclofos methyl can control this on already infected plants. The problem being that the plants can be asymptomatic for months or even a couple of years. In this respect it resemble the equally severe problem of fusarium, but the symptoms are different. I suspect many plants that suddenly 'do not grow well' or 'stop their growth and slowly die' are affected by latent infection of fusarium or rhizoctonia, that progress slowly by steps.
Have you tried other fungicides for Rhizoctonia like:

Cleary 3336
Thiomyl
Zyban

It doesn’t look like Rizolex is approved for orchids/ornamentals
 
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