What's going on with my Phal?

[PhalOz]

Hi There,

I'm new to the forum and am hoping for some help. I've got about 10 phal orchids but have lost a couple to a suspected fungal disease. I've sprayed the rest with a copper based anti-fungal but now there is something else happening to a few of them. I'll post the photos but can anyone give me some ideas on how to treat?

It's mainly on the leaves but one orchid has now developed this "rusty" colour on a flower stem. Any ideas???

I'm thinking that its two different diseases but I'm not sure.

[RosieC]

I've not seen it on Phals, but it reminds me of the mite damage I had on some Dendrobiums. Not sure, if you look very closely is there any sign of mites (they are very very tiny).

[PhalOz]

Hi Rosie, would you be able to elaborate on 'mites'. How would I get rid of them most importantly as the 'rusty' discolouration has spread to my other plants....

[RosieC]

If it is mites then a miticide is needed. They are tiny tiny tiny creatures which suck the sap and I've seen red discolouration associated with them. There are different types I've had spider mites which also leave webs under leaves.

Some insecticides also work on mites, that's what I found.

However not sure that's what it is, it's just what came to mind. I could see the tiny mites on mine when I looked very closely. (Like grains of dust).

[Discus]

That also looks like it might be mites to me too. You'll need a specific acaricide as most insecticides don't work on them. A "Phalaenopsis mite" may be responsible, but there are several others that will cause damage like this too.
phalaenopsis mite - Tenuipalpus pacificus Baker

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Some suggested controls are listed at http://www.aos.org/Default.aspx?id=131

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I've personally used Vertimec on orchids and other plants; it seems to work.

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Ludwig’s Rose Spider Mite seemed less effective.

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Incidentally, red spider mites will discolour a damp white cloth or paper towel that is wiped along the bottom of an infected leaf with reddish-brown stains, which can be a reasonable test if you can't see the little buggers; I'm not sure if other mite species have the same indicator.

[RosieC]

Also try and keep the affected plants away from the others if possible to stop them spreading.

[sweetjblue]

Phaloz, From the looks of your pics you have a really bad infestation of spider mites. If you take a dampen paper towel and wipe the leaves you will see a discoloration on the towel. Sure sign. Looking under a magnifying glass or 10X loupe you would see them crawling on the leaf.

What you need now to treat would be a Miticide/ Ovicide such as Tetrasan. Not sure if you would have it available in OZ under that name. Throughly spray the plants and then treat in the same manner in 7-10 days to catch any newly hatched eggs. The first treatment will prohibit the adults from laying new eggs as it makes them sterile. Treat ALL your plants not just your orchids.

Mites multiply rapidly in a dry, stagnant enviroment so you may want to increase the humidity in your grow area and use a fan to provide air movement if you don't already do so.



Judi

FWIW. In your last pic the flower stem looks like it is just dried up. If that is the case you can just cut it off close to the plant. That will give the mites less places to hide.