Why reds and silvers, wines and blues, greens and blacks if I can be yellow?

These are Dyckia sp Piratini wilderness collected seedlings.
The yellowish is true and not a temporary reaction to a nutritional deficiency
as lack of Nitrogen. The plant is just this way.
Here you may notice some fungi attack. Those dark spots are fungi.
The high Winter humidity in Joinville favors the fungi growth.
We use to keep it at bay by favoring ventilation and spraying the plants with
a fingicide made for home use.
Resin pine made fungicide may be used.