I received this Dypsis lutescens (palm) plant as a gift last spring, it had only two leaves and it was potted in nursery soil with sand. Recently I have noticed that the outer leaf started to form a black ring at its insertion on the stem. After new leaves have emerged I removed the outer leaf, but I have noticed that the next one had a small black dot at the insertion point, too.

At the end of the summer the plant became rootbound, so I moved it to a larger pot using general soil from the store to which I added vermiculite. The black dot became a black ring. I have removed this leaf while its lower part remained attached to the stem, becoming the brown-black ringed stump that you see in the pictures.

Now I notice that one of the leaves has a long black area on its stem (as seen on the red rectangle in the pictures). It is clear that my plant has an infectious disease, but I don't know which one.

My questions are:

  1. What is the name of the disease?

  2. Should I apply a fungicide like Topsin or Ridomil just in case I don't find out what disease is causing this?

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  • I was ready to say this looks normal until I saw your leaf...nice pics btw. Since this is newly from a store/nursery...if I were you I'd look up White Mold or Sclerotinia sclerotinorum or something like that. Keep that plant away from your other plants until this is diagnosed. B A D stuff. Fascinating fungus...truly but usually comes from a nursery/store. Why do you add anything to your potting soil? – stormy Feb 18 '17 at 21:42
  • And there is NO TREATMENT at all for this. If this is Sclerotinia you will want to make sure not a bit of soil gets out of that pot in your home and especially in your yard!! You'll find when you do an AUTOPSY huge black bean looking things in the stem of your plant,they are HUGE. Never ever saw anything like this until I had to get rid of all my plants ALL OF THEM by a low burning fire. To send them to the dump would be wrong. Hope I am just being a downer...These are the signs I've seen... – stormy Feb 18 '17 at 21:47
  • was there a laceration there in the past? – J. Musser Feb 19 '17 at 0:29
  • @J. Musser The dark area on the stem was in fact a black dot on a leaf, then it turned into a black ring, then I removed the upper part of the leaf and, after that, the lower part of the leaf (which was green) started to turn brown-black. – Alina Feb 19 '17 at 9:19
  • @stormy There are only two types of potting soil in my area, and those two types come in various packages under different brands. The first one is closer to peat, very light and aerated, difficult to absorb water, the second is black and heavy and retains too much water. I buy the second and add perlite, vermiculite or sand to delay compaction, to improve drainage and to provide lighter, more aerated soil for the roots. – Alina Feb 19 '17 at 9:29

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