Leaf Rot help!

[milan360]

Dear all,

So I have been looking after my dendrobrium well until I noticed the top 2 leaves of one of the pseudobulbs going soft and mushy!

I went into panic mode, sterilised a scissors and snipped those leaves off. The base of it is still mushy and when I press a paper towel, seems a bit 'weepish'.

I don't have cinnamon powder at home, however I improvised by breaking cinnamon sticks which I had to tiny chips and placed a few pieces at the opening (where the soft leaves used to be)

Then I sprayed a little plant safe pesticide over the plant and that's it.

Any advice what I should do and what type of rot is this?

One of the older pseudobulbs is only just sprouting a new cane. Don't want the plant to go down.

[King_of_orchid_growing:)]

This is not a terribly common occurrence with Dendrobiums. It does happen, but rarely if the basics of orchid growing is observed. I'd first look into your cultivation habits and change that habit immediately. One thing that comes to mind is, are you spray misting the leaves and letting the water stand? The way the leaves are positioned, they are allowing the water to funnel towards the crown of the plant. If the plant is grown indoors, that can cause problems with the water not being able to evaporate fast enough to prevent a problem like this. If the plant is grown outdoors, this problem tends to not show up as frequently because the air dries up the water really fast. The same thing can be said if you are watering the plant, but you've allowed the water to settle into the crown.

Without using cinnamon, seal the wound by using a piece of metal and heating up real hot, then brand the affected area thoroughly. Either this or pass a lighter around the open wound. Forgot to mention that you should clean up the affected area by removing dead material and maybe using some isopropyl alcohol (70% or 90% is fine), to disinfect it a little. To be honest with you, I would expect some unaffected tissue to die off, but in the end if the plant is saved, this shouldn't matter.

---------- Post added at 10:33 AM ---------- Previous post was at 10:23 AM ----------

Here's another tidbit that might help you out...

If you are doing the whole foliar feed thing or making sure that the plant is getting the proper humidity levels. Just know that the plant's pores, (aka stomata), are located underneath the plant's leaves, not on top.

The top of the leaf is protected by a layer of wax. That wax prevents dehydration from becoming excessive, is the first line of defense against certain predators and pathogens, and is a clever device for rain water to bead and dribble off the leaves, keeping water away from the orchid's delicate crown.

As for spray misting, I don't advise it. In cultivation, it can cause a multitude of problems. If you want to provide humidity for the plant, I recommend using a humidifier like the ones you can get at your local pharmacy if you are living in the US.

If you are living in Malaysia or Singapore, humidity should not be an issue for you at all.

I would focus on providing better air circulation.

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[bil]

OK, I had a similar problem, possibly caused by moisture getting into the crown from a misting system. The solution is very simple.

I simply got a pair of secateurs and chopped off the top of the cane between the leaf nodes. When I looked at the cut surface I saw there was discolouration, so I cut again, between the next two leaves, and this time there was no discolouration.

So, then I took mancozeb powder. It's an effective fungicide in powder form that you mix with water. I use it as a dry powder to cover the wound. The plant in question is doing fine and throwing a spike at the moment.

Cauterising the wound might work, I just see it as unnecessarily damaging the cane and leaving dead tissue that might be prone to rot. You would effectively be cooking the end of the cane.

Oh yeah. I also moved the nozzle a bit that had been wetting it.

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[estación seca]

Your problem is rainy, warm, humid growing conditions most of the year. This predisposes plants to fungal infections, particularly plants like Den phals whose ancestors come from areas that may get pretty dry in the winter.

I would cut off the cane well down into good tissue as bil suggested. Don't mist your plants when humidity is over 50%. Water the roots and medium but try and keep the tops dry.

Others here have commented that calcium supplementation helps plants become more resistant to fungal infections. I don't know how much calcium is in Singapore water.

[milan360]

Thanks guys for the help.
I have cut down the dead leaves but right in the centre there is still dying tissue. Would this mean i have to snip off a part of the cane(including 2 healthy leaves) because to access the deeper bad parts, thats the only way.

I don't mist the orchid. I suspect I got careless during watering and allowed water to settle. The plant is placed indoors in a south-east facing window. Not as much air circulation as I would like but good sunlight. Yes , humidity here is 70% . Usual good hot weather but last week its been wet weather so no watering.

So... do i have to snip off a part of the cane to access the deeper rotting parts?

Thanks!

[estación seca]

Yes, you need to snip off the stem, and do it fast, before the rot spreads down the stem into the roots.

[milan360]

So I have come home and snipped off the top leaves and mushy parts and the inside of the stem looks like this. (refer to attached)

Help! What should I do? Cut further?

Thank you and best regards,

Milan360

[milan360]

Originally Posted by milan360

So I have come home and snipped off the top leaves and mushy parts and the inside of the stem looks like this. (refer to attached)

Help! What should I do? Cut further?

Thank you and best regards,

Milan360

Updated *

I cut it down further and finally I see pure green. I guess the rot traveled down faster than I imagined. (refer to attached). I don't suppose I need to cut it anymore right?

Can I dab the wound with a little bit of anti-fungal spray?

best regards,

Milan360

[bil]

Originally Posted by milan360

Updated *

I cut it down further and finally I see pure green. I guess the rot traveled down faster than I imagined. (refer to attached). I don't suppose I need to cut it anymore right?

Can I dab the wound with a little bit of anti-fungal spray?

best regards,

Milan360

You have to cut that stuff out like it was cancer. Treat it with anti rot, and keep the wound dry, which is why I like a fungicide powder.

[milan360]

I've cut it down to all green now. That's good enough?

It's in a very airy place right now where it will sit for the night. I used cotton bud dabbed with plant safe fungicide on the wound. Don't have powder with me