Pests and Illnesses

Coryphantha spp. are quite resistant to pests and are rarely the first cacti to be attacked in a greenhouse.

One should be aware of mealybugs, since they can hide very well in the woolly apex and axils of the plants. Mealybugs on the roots and larvae of Sciara flies can be a threat, especially for young seedlings. Therefore, it is important to control seedlings regularly.

Some of the species are favoured by the red spider mite, which leave ugly traces of their damage on new sprouts of the plants. As the plants grow slowly, the damage is visible for a long time.

A treacherous enemy are the nematodes. Excessive watering transfers them from pot to pot and they propagate in the fleshy and tuberous roots where they prosper. They damage the roots with poisonous products of their metabolism and block the vessels, leading to the death of the whole plant. In spring, if a plant does not fill out and start to grow similarly to all the others, this may be a very suspicious sign for nematodes. In this case, repotting the plant is indicated. Infected roots should be cut off completely, the plant disinfected, left to dry (2-3 weeks) and repotted in fresh soil.

Coryphantha spp. are quite resistant to fungus diseases as long as the air around them is kept circulating. On the other hand, all species with nectary glands normally have black fungus, the so-called sooty mould, mainly around the glands. This fungus does not harm the plants and is only an aesthetic problem. If wasps and ants are allowed to collect the nectar from the glands or if the plants are watered regularly from above, the problem will be diminished.

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