Some type of rot

[papheteer]

Saw this on one of my weak plants tonight and took this leaf off right away. It's not wet but it's not dried up either. Do you guys know what it is? Is it airborne? Should I destroy the plant right away? It's very small and weak but it's an uncommon cross. Paph. Todd Hasegawa x Norito Hasegawa bought from Orchid Inn early 2010 I think, has been struggling since. LOL

 

[gonewild]

Was the leaf turning yellow before the base decayed?

 

[papheteer]

Yes the leaf was yellow already.

 

[ALToronto]

Sounds like an opportunistic infection on a weak leaf.

I've had good success with drug store hydrogen peroxide drying up rot very quickly. I'd spray the plant with H2O2 and isolate it to see if it recovers first.

 

[NYEric]

If you have either Dragon's blood/lime powder, I'd try those.

 

[gonewild]

Should I destroy the plant right away?

No

 

[Paphman910]

Does the black part of leaf have a funny smell to it?

If it does, chances are that it has rot and should be treated with fungicide/bactericide.

 

[papheteer]

Wayne, i didnt really smell it. Went to the garbage bin right away.

 

[gonewild]

This is a similar to the problem Orchid Boy posted recently Rot????.

In both his case and yours the plants are weak but this condition happens to strong plants also. I think it relates to environmental problems and that includes nutrition also.

It is my opinion that this happens to some plants and not others because of genetics. Some plants have more tolerance or resistance to less than perfect conditions than others.There is a very good possibility that this problem is a result of......potassium excess.... or other nutrient imbalances as discussed within the K-lite threads.

 

[Trithor]

I have seen this problem when you pull off a dead leaf too early. If the old brown leaf does not come away without any tugging, it leaves a wound on the leaf base of the leaf above it (I suspect) and a few days later a patch of brown starts, spreading up the leaf. Although I try not to remove old leaves too early, sometimes it is impossible to stop myself, bit like picking a scab

 

[Rick]

Was a new root or growth starting at the base of this leaf axial?

 

[lepetitmartien]

The necrotic zone could be:
- anthracnose,, for the record, but I like the other possibilities better
- too much salts/fertilizer
- lack of calcium
in complement of the other hypothesis.

 

[Trithor]

The necrotic zone could be:
- anthracnose,, for the record, but I like the other possibilities better
- too much salts/fertilizer
- lack of calcium
in complement of the other hypothesis.

When have you seen excess salts manifest in the leaf axil as opposed to leaf tip?

 

[papheteer]

Was a new root or growth starting at the base of this leaf axial?

2 new roots came out of one side of the base of the plant.

 

[Paphman910]

2 new roots came out of one side of the base of the plant.

That is a good sign!

When roots break through the leaf, sometimes under not ideal conditon, the leaf gets rot.

 

[NYEric]

How many/ how large are the remaining leaves?

 

[papheteer]

How many/ how large are the remaining leaves?

Eric, a stunted one that stopped growing at 2/3 inch and there's a new one emerging.

 

[Trithor]

Sounds like whatever the problem was, it was self limiting and the plant is fine?

 

[Rick]

That is a good sign!

When roots break through the leaf, sometimes under not ideal conditon, the leaf gets rot.

Found this out from a plant pathologist concerning Erwinia infections. When new roots or shoots are trying to come through, the plant produces an enzyme that starts degrading/digesting the cells in the old leaf in the path of the new growth. This self imposed decay can be taken advantage of as a food source for opportunistic pathogens. Loosing the old leaf is pretty normal. If the rest of the plant is weak or imbalanced, the pathogens can go beyond the bounds of the lysed area and attack the whole plant.

 

[lepetitmartien]

When have you seen excess salts manifest in the leaf axil as opposed to leaf tip?

This is the axil? If so, nevermind.

On the odour tip :
- if it smells bad, think bacteria
- if it smells mushroom, think fungus

Stupid and simple but working for some situations.