Hello,
I purchased a rooted Variegated Monstera Deliciosa cutting on ebay and am very happy with my plant, however I just noticed a slightly sinister looking black area on one of the stems. It measures approx 1"x1.5". When I emailed the seller to ask what it could be, she suggested it was most probably something to do with the old leaf sheath and that it would fall away. However it looks to me to be a 'rot' of some kind as it's in the flesh of the main stem and also in the flesh of the new recently unfurled leaf which has grown from it. Directly on the back side of the blackened stem in is an aerial root (the only one on this cutting).

Please see attached photo. I am based in the UK and the plant will live indoors.

I would be so grateful for any clues as to what this might be please. Also should I worry for the health of my plant and the other plants in my home?

Many thanks
Sacha

Hi Sacha and welcome. I'd be very worried if I saw that on any of my plants. Phytopthora or Pythium both look like that and are very *fast-spreading* black rot fungi. I'd advise you cut out all the black tissue carefully with a very sharp knife or scalpel, and sprinkle the whole area with cinnamon powder (it is a natural fungicide).

But . . I think your grower should refund your money or send you another plant because it's fairly likely that one won't make it. It must have contracted the disease in the greenhouse, before you got it I would think. Doubt very much that either of those organisms would live naturally outdoors in the UK.

dyzzypyxxy said:Hi Sacha and welcome. I'd be very worried if I saw that on any of my plants. Phytopthora or Pythium both look like that and are very *fast-spreading* black rot fungi........ Doubt very much that either of those organisms would live naturally outdoors in the UK.

I agree it's cause for concern but just to additionally note that several species of both phytophthora and pythium do occur naturally outdoors in the UK.

Wow, that's good to know Sue. I thought they mainly grew and thrived in warmth and humidity - like here in Florida where we have (of course) lots of that stuff. It sure does slow down and not occur much in winter here. (edited to add) Our winter weather is pretty similar to what you'd get in the UK in summer, maybe a little warmer and shorter days.

Unfortunately I guess various species of these pathogens are adaptable enough, Elaine. The RHS has been doing some research on them:

https://www.rhs.org.uk/science...

In some parts of Florida I think it gets colder on occasion in winter than it does in at least parts of the UK? I grew up in southern England and the last place we lived was the equivalent of USDA Zone 9 as far as winter was concerned. Yes, very long days in the UK in summer (and very short ones in winter )

dyzzypyxxy said:Hi Sacha and welcome. I'd be very worried if I saw that on any of my plants. Phytopthora or Pythium both look like that and are very *fast-spreading* black rot fungi. I'd advise you cut out all the black tissue carefully with a very sharp knife or scalpel, and sprinkle the whole area with cinnamon powder (it is a natural fungicide).

But . . I think your grower should refund your money or send you another plant because it's fairly likely that one won't make it. It must have contracted the disease in the greenhouse, before you got it I would think. Doubt very much that either of those organisms would live naturally outdoors in the UK.

Thank you for your reply. I have returned the plant for a refund, though I still doubt the seller believes anything is wrong with it.. Shame, as it is apart from the sinister patch a stunning looking plant. I did notice that the two leaves with the black stem patches were seeping tiny droplets of water from their extremities whilst the other seemingly healthy leaves were not. Could this be the plant going into shock of some kind I wonder?

Well, not every person that sells plants is educated or experienced with plant diseases. They really just want to sell the plants that the growers send them.

No idea about the seeping droplets, but if that is a black rot infection, the plant could just collapse and die very suddenly. I'd bet if you go back there in a few days that plant will be nowhere to be found - except maybe in the bin.