Question: strange spots
Hi, my cacti are turning orange. I state that since September I have not wetted them and spent the winter at 5/6 degrees, what is the disease and how could I intervene to avoid losing them? thanks
Answer: strange spots
generally the succulent plants take on an orange color due to a fungal disease, which is often called cactaceae rust; keep in mind that usually however the whole plant gradually becomes orange, rather some roundish spots start, which widen up to cover the whole plant. If this is your case, the proliferation of the fungus is generally favored by a high environmental humidity in the winter period, with a cold climate. To cure a plant suffering from rust it is necessary to treat it with a fungicide, and the best way is to buy a systemic fungicide, or rather that it should be given mixed with the water of the plant, so that it absorbs it and enters the circle; one treatment is generally sufficient. The epidermis of a cactacea can change color but also for other reasons; the main one is related to the brightness: there are thousands of species of cacti, and each of them shows different needs with regard to light; if we cultivate many different species of neighboring cactaceae, with the same climatic conditions, we will have some that are fine, others that suffer from low light, and others that are burned due to excessive sunlight. In general, however, it often happens that the spots are due to a lack of direct sunlight, especially during the winter months. Another problem that can change the color of a cactacea is instead linked to an arachnid, more precisely a mite, commonly called red spider, which develops in very dry air conditions; the tiny specimens of this mite pierce the surface of the stem of the cacti, and suck their lymph, leaving orange, yellow or reddish scars. If the spiders are so many, they can even cause the yellowing of an entire plant; around the plant you should in this case notice thin webs, and the epidermis along the stem should have a speckled appearance, caused by the innumerable punctures caused by spiders. In this case, you will need to use a broad spectrum insecticide and acaricide, checking on the product label that it is also suitable for mites. Typically mites, or red spiders, develop in a very dry climate, with little ventilation; therefore usually, with the arrival of spring and the movement of the pints in a more aerated position the spiders tend to decrease in number; in any case, even if you are about to move your plants outdoors, treatment with an acaricide is advisable.