John Myers
I would like to ask you for information regarding Chinese cabbage and the mostly contained black dotted leaf edges. A standard Chinese cabbage from the supermarket often has small black dots under the first layer of leaves at the ends of the leaves.
I suspect it’s not rot. If you google the facts mentioned, the answers range from incorrect storage to fungal infestation and allergy-causing substances. These are probably guesses rather than laboratory tests. Do you know more?
The leaves of the Chinese cabbage are naturally serrated, with small vascular bundles opening at the tips. There the leaf veins of wood and bast cells end. It happens that individual cells die off or lignify along the pathway or at its end and dry up black. With a very good supply of nitrogen, but also with a scarce supply of potassium, the phenomenon can occur more severely. In technical terms, these areas are referred to as so-called leaf edge necrosis. However, they can also only develop after the harvest during cold storage or later at home if the storage is too warm.
In terms of health, leaf edge necrosis is completely unproblematic, so that the Chinese cabbage can be eaten without hesitation.
The situation is different with brown wet rot, which is caused by bacteria or fungi. Larger parts of the lettuce leaves turn brown and mushy. In this case, the affected areas should be cut away generously with a healthy margin of about 3 cm and the leaves washed well.
