What should I do if half of the cactus is rotten?

Pit rot

If the rotten part of the cactus is in the shape of a nest, the rotten flesh should be removed in time, and the part that cannot survive should be evenly covered with a low-toxic fungicide with a concentration of about 70%. You can also use agents such as Dicosone that can remove rotten roots, mix it in the soil about 1 cm high in the pot, and finally cover it with fine soil or sand. Keep it completely dry and in a cool place until the disease is cured, then you can resume normal management. At this point, I would like to emphasize that only two or three grams are needed. Never get any flesh remover on yourself, as it is poisonous. If it gets on your body, wash it off immediately. If it gets into your eyes, mouth or nose, go to the hospital immediately.

Multiple rot

If there are many blue parts on the cactus ball, or even it is hollow, if you can ensure that the pith in the middle is not diseased, after removing the rotten flesh, you should use 1% copper sulfate or other agents to repeatedly rinse the rotten parts to disinfect and sterilize. Place the potted plant in a ventilated, dry and cool place. Wait until the skin dries up and then you can repot it.

Strengthen management

After replanting the cactus, it is necessary to strengthen management and water it properly to avoid root rot due to excessive moisture in the pot; fertilize it properly with a low fertilizer concentration, and it is best to dilute it with water before applying. Before the end of the cactus's growth period, fertilize it generally once every half a month or so. Gradually reduce the amount in autumn and stop fertilizing in winter.

Summary of rules

First, you need to clean up the rotten tissue. You can sprinkle quicklime to deal with the areas that need to be cleaned, and then cover and clean them directly. Repeat 2-3 times, and then place them in a ventilated and dry place to dry, and then you can replant them.