Cuban Oregano dying, black spots?

Coos Bay, OR(Zone 9a)

My Cuban Oregano (Plectranthus amboinicus) has been in distress for about a year now. After I accidentally burnt it in the sun outside while trying to acclimate it for last summer, it just hasn't been as vigorous. Leaves have been dropping and none have grown to replace them. The only new leaves are at the tips. Under all of these leaves are tiny black specks that don't move, but seem suspect. Some portions of the stem are also darkened, but are not mushy or soft. I haven't inspected the roots yet, although I may soon if I decide to start from (cleaned) cuttings again.

Any ideas what might be up? It has been living on a bright window sill with afternoon sun. I'd very much like to prevent whatever this is from happening again!

Thumbnail by SincereDeer Thumbnail by SincereDeer Thumbnail by SincereDeer
Contra Costa County, CA(Zone 9b)

Not sure what it is, but you might be able to remove the black spots with a q-tip and rubbing alcohol.
Do you have any other plants nearby? Do they also have black spots? If so, treat all the plants at one time so they do not spread the black things back to a treated plant.

Coos Bay, OR(Zone 9a)

Decided to take some cuttings today of what's left and toss the rest. Small circular things were huddled around where the drainage hole was (first picture). Nearly all of the roots were dead and there was a lot of white-blue stuff that reminded me of mycelium but was more likely mold (second picture, badly taken).

Even if the black specks were something, I have a feeling the mold was the primary issue... will q-tip and rubbing alcohol them off anyway though, just to be safe.

I'll definitely keep a closer eye on the roots next time!

Edit: Nothing near this plant has any similar issues.

This message was edited May 15, 2014 1:54 PM

Thumbnail by SincereDeer Thumbnail by SincereDeer
Contra Costa County, CA(Zone 9b)

I am letting mine get pretty dry between watering. This will minimize the growth of most fungi. Obviously you need to keep the cuttings damp, but as soon as they can be potted up start backing off on the water.

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