Black Tips on Phiaus Thankerville

[kaarthiik]

Hi,

Please help me in diagnosing reason for the black tips on Phiaus Thankerville.

Its very hot here, is it the reason or any other?

Thanks,
Kaarthiik

[Fairorchids]

Many orchids get leaftip damage from build-up of salts in the potting material. Try running a lot of water through the pit every 2nd or 3rd watering.

[kaarthiik]

Thank you.. Would do that !!

[james mickelso]

I would say it looks like antracnose to me. Go to staugorchidsociety.org. Look up anthracnose and it will give you the remedy. Salt build up is brownish and mottled. And the levels of salt will be very high to get this much damage.

[NYCorchidman]

I would say no on antracnose, which almost always have yellow advancing margin as the disease progresses.

I would say burn of some kind.

How much light are you giving? direct sun?
Have you been fertilizing a lot? or chemical or oil spray??

[King_of_orchid_growing:)]

I don't think it's mineral build up that's causing this.

It might be some other thing.

Why do I say this?

Phaius tankervilleae comes from tropical Southeast Asia, particularly places such as Laos, Cambodia, and Thailand.

What do these areas generally have high amounts of?

You guessed it, most of the areas in these places are chock full of limestone deposits. Yeah, sure, occasionally there are a few granite outcrops and other materials, but most of them are limestone.

Yeah, they grow in pockets of top soil/leaf litter, but the surrounding material are limestone boulders or rocks.

What is the plant being grown in?

It may be getting too wet down in the root areas, or the roots may not be getting enough air circulation, and these reasons are what might be causing the roots to possibly start rotting. This symptom is generally more indicative of root damage, in which high mineral build up in the potting medium is one of the causal factors in certain orchids.

I also wouldn't rule out the heat as being a possible problem. You don't mention the exact day temperatures the orchid is sitting under, so I don't really know how warm it's getting. If it is over 100 F, try growing it in an area that is a little cooler, (maybe closer to 95 F).

[james mickelso]

Have a look at the staugorchidsociety.org disease page, go down to anthracnose, click on more pics of anthracnose, and there you will see a good representation of your leaves. Your leaves don't look burned to me and anthracnose isn't always preceded by yellowing. Mineral damage would be all over the leaves as would heat damage. Anthracnose starts on the leaf surface and proceeds down the leaf until it reaches the base where it starts damaging the rizome. It is fungal and can be stopped by systemic or topical remedies.

[NYCorchidman]

No, fertilizer burn ( not necessarily the same as mineral damage as it sounds too general) shows up from the tip.

Philip- The fact that certain plants are coming from area rich in limestone does not mean they are adapted to high salt content, nor higher pH.
Limestone does not melt like sugar in water.
Many paphs in that same region grow mainly on rock that are limestone with some moss or dirt, and often roots directly touching the rock itself.
However, these plants do not tolerate high salt content in the root zone. Also, pH is not that high at all.