I have been seeing some small green circular fungus(?) on the top of the soil in container grown plants in my greenhouses, what is it and what is the best way to eradicate it? It is becoming unsightly, as it covers most of the soil surface around the plants.
Liverworts are a huge problem in nurseries on the west coast anyway, perhaps everywhere? Have to keep the soil surface dry to avoid it taking over. This is tough in most commercial container situations. Mulches of pumice or similar are being tried here as well. Capillary watering is also helpful, since the surface stays a lot drier than with surface watering. I also pull off the liverwort growth when repotting, and dispose of it, to keep down the amount of new spores hanging around. I believe vinegar is one of the better liverwort-icides, haven't used it myself but I'd consider brushing it onto the soil surface carefully avoiding the desirable plants...as well as spraying any pathways and vacant areas to again cut down on the propagules of the liverworts spreading around. I'd add some detergent to the vinegar by the way, to help it stick and spread over the "leaves" of the pest.
If your using peat based compost (nothing wrong with that) the really dark, almost black peat is very old peat and holds more water than younger peat.......like growest said, try not to over water, and open the greenhouse up on warm days for some good air flow around the plants. The mulching with pumice is also a good idea, on a small scale it wont be too costly......if you can get hold of some fine grade potting bark, that looks good around plants.
I do not think it is a fungus, since most fungi are not green (it really depends upon the type of fungus). Since you are in a relatively dry area (Corona, CA), I wonder how moist your soil is. I like the liverwort idea. I do not have much experience with nurseries or greenhouses, but I have seen liverworts in yards growing in shady moist areas. I actually think liverworts are pretty cool, especially if they produce gametangia.
Thank You For the Identification of the "green stuff" it was very helpful in finding a control method suitable for my conditions.
