One important nuance will immediately make it clear whether such fruits are safe to eat.
Many plums are covered with a white coating. This is especially true for the varieties "Stanley" or "Joyo", which have a clearly visible white coating.
This is a natural feature of the plant that helps protect the fruit from pests, diseases and environmental influences.
This coating is harmless to humans, but plums must be washed thoroughly before consumption.
There are situations when a white coating on plums should be a warning sign. There are cases when such fruits pose a health hazard.
The harmless coating is easily washed off. If the white layer is not removed even by water, then this indicates possible fungal diseases.
In addition, indelible stains indicate that chemicals were used during cultivation. For example, against pests. The tree was probably sprayed shortly before harvesting.