What is causing my leaves to die off prematurely

[emydura]

I am pulling my hair trying to work out what to do with this problem. It is causing havoc with my collection. Below is a leaf of one of my roths. On the bottom side of the leaf, there are all circular marks on the leaves. The result is the leaves die back prematurely as you can see from the second photo. This leaf will die back rapidly from here. The leaf in question is not the oldest leaf either. The leaves often get rot along the way.

I thought it was spider mites. But I had an experienced orchid grower look at it and she thought it was a fungal problem. I am a little bit unsure what to do.

 

[abax]

I hope more knowledgable growers answer your question. I'd find a good fungicide and start there. Perhaps one
that is both a spray and a run through.

 

[GuRu]

David, I would also think primary of a fungal infection, secundary of a bacterial infection mor than think of spider mites. Have you had a look at the leafs with a magnifying glass ? You would see mites or their remains with a magnifying glass. I don't know whether you know this site orchid diseases ? There are some more links there and maybe you will find a solution ?

 

[emydura]

David, I would also think primary of a fungal infection, secundary of a bacterial infection mor than think of spider mites. Have you had a look at the leafs with a magnifying glass ? You would see mites or their remains with a magnifying glass. I don't know whether you know this site orchid diseases ? There are some more links there and maybe you will find a solution ?

Thanks Rudolf for the website. Towards the bottom of that site, there were some fungal options that might be the cause, but I am not confident I could accurately identify it. The brown spots only occur on the underneath side of the leaves not the top, although after a while you start to see the damage from the top. I would have thought that fungal problems would occur on both sides of the leaves, but I could be wrong. That brown pitting can be there for a while before the leaf starts to die dies back. I think the leaf dieback is a secondary infection that takes hold after the leaf is initially damaged by the fungus/mites? I will have to get a magnifying glass. I can't actually see any mites myself.

 

[Ozpaph]

David, if you wipe the unerside of the leaves with a damp, white tissue do you get any mites (with magifying glass)?
What fungicide have you tried?
Could be 'mite/insect damage with secondary bacterial/fungal infection.

 

[emydura]

David, if you wipe the unerside of the leaves with a damp, white tissue do you get any mites (with magifying glass)?
What fungicide have you tried?
Could be 'mite/insect damage with secondary bacterial/fungal infection.

I am going to have to get a magnifying glass first. Fungicides - physan, Yates copper fungicide, mancozeb. I have sprayed miticides as well. Once you get those spots on the undersides of the leaves, it is only a matter of time before the bacterial/fungal infections take hold and the whole leaf collapses. It only impacts that leaf though. Never spreads to other leaves. This only seems to be a problem with the Paphs. Other orchids are never affected. I have also noticed that plants on the bottom benches where it is shadier and has less air movement never seem to be impacted. It is primarily plants on the top benches.

It is pretty heartbreaking watching all these plants you have been growing up for years just going backwards. I feel pretty helpless. Until I can work out the primary cause, it is hard to be confident about a solution.

 

[Ozpaph]

what miticide?
I would use a systemic fungicide.

 

[big923cattleya]

You need to take a step back and slow things down.
You can’t just keep treating for this and for that. Time is needed to assess the effectiveness of each treatment. Roth’s are not particularly susceptible to mite damage. However fungal issues due to overwatering, poor air movement are far more common.
I use Neem Oil for many of my problems. It is an effective miticide, insecticide, fungicide and bacteriacide all rolled into one. Nowadays it is available in a spray bottle formulation. Just follow the directions, don’t spray repeatedly. The damage will not disappear or heal. Concentrate on the new growth from this point on. If they are clean, that is a good sign

 

[emydura]

what miticide?
I would use a systemic fungicide.

I use the miticide Azamax, which is what ray recommends. What fungicide do you use?

 

[emydura]

You need to take a step back and slow things down.
You can’t just keep treating for this and for that. Time is needed to assess the effectiveness of each treatment. Roth’s are not particularly susceptible to mite damage. However fungal issues due to overwatering, poor air movement are far more common.
I use Neem Oil for many of my problems. It is an effective miticide, insecticide, fungicide and bacteriacide all rolled into one. Nowadays it is available in a spray bottle formulation. Just follow the directions, don’t spray repeatedly. The damage will not disappear or heal. Concentrate on the new growth from this point on. If they are clean, that is a good sign

Thanks for your input. I have had this problem for a couple of years now, so I have been trialing things but I haven't been making much progress. But your recommendation of regularly spraying with Neem Oil is a good one and one I will look to implement.

 

[Ray]

I use the miticide Azamax, which is what ray recommends. What fungicide do you use?

Azamax is a concentrated azadirachtin product, which is the active ingredient in neem oil, and is a very broad-spectrum pesticide.

 

[Russ1992]

Have you checked it for a virus?