The following article is dedicated to this theme, which goes into detail about the cleaning and sterilization of vases (plastic and terracotta) and the materials used for the substrates (pumice, lapillus, gravel, etc.) which have been set aside after the last repottings carried out in recent months. (…)

Premise

The recycle of pots and aggregates is common practice. Obviously it is not always possible to recycle everything, but a good part of what has been used for the cultivation of our plants can easily be used for future repotting, as long as the materials are thoroughly cleaned and sterilized. Clearly, broken pots and peat must be eliminated since they have exhausted their “cycle” (the peat has already been exploited and would be of little use), but the first major distinction to make is whether those materials (pots and substrates) have given hospitality to plants in perfect health or if they have hosted plants that have died from rot or are otherwise affected by parasites. Let’s see everything in detail by dividing the two categories: vases and inert materials.

Recycle pots

Recycling pots, especially if you use plastic ones, is a must. First of all, we contribute (in our own small way, clearly) to the reduction of plastic production; secondly, you save money, because plastic vases are very long-lasting and can be washed extremely easily. If you use terracotta vases, recycling also takes on an additional value: you can reuse particular vases, perhaps “valuable” or in any case large and therefore expensive.

 PLASTIC POTS  – If no plant has died in the pot, you can limit yourself to a thorough washing with warm water and a detergent product. Even in these cases, however, adding a little bleach is always useful to eliminate germs and bacteria that may have formed while the vases were stacked waiting to be recycled. For washing, all you need is a sponge with a slightly abrasive side and a little bit of patience. Important: if you use bleach you should wear rubber gloves, the classic gloves for household work!

However, if a plant had died in the pot, you can decide to throw away the old container to eliminate the risk that the new “tenant” could contract the same fungus, or carry out a more in-depth operation. In this second case, rinse the vases well, then place them in a basin containing water and bleach and leave them to soak for a few hours (even a whole night if you want). After this period of time, wash the vases carefully, trying to reach every internal corner, with a slightly abrasive sponge, always with water and bleach. At the end, wash a second time with soap and water and rinse thoroughly. Once the vases are clean it is advisable to leave them in direct sun for at least a day: even intense sun helps to sterilize.

 TERRACOTTA VASES  – Unlike plastic vases, terracotta ones are porous: this is why cleaning is longer and more difficult, since an old terracotta vase may have limescale or greenish stains. If the vase is already clean enough, you can wash it carefully with soap and water and a drop of bleach. If, however, the vase is marked by limescale stains or moss residues, it can be immersed in a basin with water to which we add lemon juice, or bicarbonate or vinegar. We leave the vases to soak for a few hours and give them a vigorous wipe with a sponge, using the same water in which they were soaked. Once the “signs of old age” have been removed, proceed by washing the vase with water and soap and then placing it in direct sunlight for at least a day, to ensure that all the water evaporates from the porous walls.

If a plant has died from rot in the terracotta pot, there are two cases: if the pot is already old, chipped or of negligible value, it can be thrown away. However, if the vase is valuable, large or has a certain value, it can be cleaned thoroughly and then sterilized. The cleaning procedure is the same as described above, while as regards sterilization you can use the old boiling method (obviously if the jar is not huge): you place it in a cooking pot, fill everything with water and turn on the heat, leaving the vessel to “cook” until it boils. Once the water boils, turn it off and leave the jar to soak for at least twenty minutes. Alternatively, you can immerse the terracotta pots in water, adding an “aggressive” sanitizing solution, such as bleach (leaving them to soak for at least an hour). Once the vase has been cleaned and sterilized, it is placed in direct sunlight for at least a day, so that it can dry completely.

The procedures described above are applicable, up to a certain point, also to enamelled pots usually used for bonsai. In this case, they are usually valuable vases, enamelled on the outside and porous on the inside: all the more reason it is a shame to throw them away. A word of caution when dealing with this type of vase: in these cases it is best to avoid boiling (which could ruin the enamel), preferring bathing in water and bleach. Likewise, it is better to avoid abrasive sponges that could scratch or ruin the enamel.

The choice of vase? Here’s everything you need to know…

Recycle inert

In the cultivation of succulent plants, whether cacti or leafy succulents, many inert materials are used, i.e. materials useful for draining the substrate. The aggregates can be porous or smooth, each one has certain properties and the choice is truly remarkable and it is good to know them to choose the most suitable ones for the mix we want to create. In this article you will find an examination of most of the materials useful for preparing soil for succulents. Having said this, when you dig up the plants and thoroughly clean the roots you will find yourself with entire basins full of the old substrate, which, if done correctly, contains a lot of inert materials. Unlike peat, which becomes depleted over time and with the absorption of nutrients by the plant, aggregates retain their usefulness and this is why (as well as saving money) it is certainly a good thing to recycle them.

As with pots, however, it is important to point out that the substrate in which a plant has died or in which parasites have been found (for example, root cochineal) must be eliminated. The pots, as we have seen, can be washed and sterilized, but in the case of the substrate it is better not to take unnecessary risks: if a plant has rotted in that soil or if we have found parasites in that soil, we throw it away without hesitation.

If, however, the substrate has been recovered from the repotting of perfectly healthy plants (it is essential to carefully check that no parasites nest among the roots) we will be able to recycle it without problems. The first thing to do, once all the old substrate has been collected in buckets or basins, is to sift it, using a fine mesh sieve, so as to separate the actual aggregates from the peat, dust or clay. The fine part, now used, must be eliminated, while the aggregates are deposited in a clean container. Once all the aggregates have been obtained, we move on to sterilization, which is useful even if no plant has died in that substrate.

To sterilize inert materials there are different methods: for example, they can be spread on a cloth and sprayed with a non-aggressive disinfectant (let’s avoid bleach) then letting everything evaporate, or they can be boiled, exactly like terracotta vases. Finally, they can simply be spread out on a nylon sheet and left in direct sunlight for at least a week, allowing the sunlight and air to give a good cleaning to pumice, lapillus, gravel, quartzite, etc. In essence, the sterilization process of the aggregates is mild and rapid since if there were no parasites or bacteria present in the substrate that caused the plant to rot, it can simply be deduced that that soil was and is perfectly “healthy”.

Once the cleaning and sterilization operation has been completed, the aggregates can be put aside or used immediately for the composition of a new substrate, adding fresh peat, earthworm humus or any other element useful to the plant that will be repotted (for example chalk for some cactus genera).

Important note: when taking the plants out of the pot it is essential to thoroughly check their health and check that no parasites are nesting among the roots (here you can find a video on root mealybug). Only in this way can we have reasonable certainty that those aggregates can be recycled without problems. When in doubt, it’s better to throw everything away: it would be a shame to put the plants at risk just to save a handful of pumice or lapillus!

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Correlated articles

• Diseases and pests: all the articles
• Choose the right pot
• Substrates: all the articles
• Inert and materials
• Repotting: all the articles

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L'articolo Pots and inert in the cultivation of succulents: can we recycle them or is it better to throw everything away? proviene da Il fiore tra le spine.

With the beginning of autumn almost all succulent and cacti begin to prepare for the vegetative stasis which will last until February/March. In the winter months, cacti (with some exceptions such as Melocactus, Discocactus and epiphytes such as Epiphyllum) and many succulents (with the exception of those originating from the southern hemisphere or areas such as Madagascar) stop growth and go dormant to recover energies and be able to flourish during the following season. In these months the plants should be kept cold and should not be watered. However, it is useful to carry out some preventive treatments to prevent the formation of mold or fungi during these months, thanks to the winter humidity, which, when the temperature start to rise, triggers rot. Warning: preventive treatments with chemical products can be useful but do not necessarily have to be carried out. It is simply a preventive measure, since the best form of defense is always the spartan cultivation of plants accompanied by a good exchange of air during autumn and winter. There are growers who limit these treatments to the essentials, perhaps favoring products with a low environmental impact (I myself have adopted this decision for years) and growers who abuse chemical products in the hope of thus making their plants invulnerable to animal parasites, fungi and mold.

In this article, which completes what has already been explained in other articles (which you will find thanks to the internal links) we see what is advisable to do in these weeks to protect the plants and limit losses due to rot or parasites as much as possible. (…)

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L'articolo Here comes autumn: what treatments can we do to protect succulents and reduce losses? proviene da Il fiore tra le spine.

Anyone who has been cultivating succulent plants for a long time – whether they are cacti or other succulents such as Crassula, Euphorbia, etc. – knows well what should be done after transplanting, and he certainly knows that these plants should not be watered immediately at the end of this operation. However, there is repotting and repotting: there is the “invasive” one and the one that involves simply moving a plant from one pot to another. There is repotting which involves total cleaning of the roots and that which involves only a superficial cleaning of the old soil. In short, there are many situations and one can proceed in various ways. However, there are some fixed points and they must be respected if we want to avoid the risk that following this operation the plant will go into stress or, in the worst case, die following a rot that started right from the roots.

This is why this article, certainly useful to the novice, can prove equally useful to the long-term grower. In fact, here we will see the various types of possible repotting, the precautions to use and, above all, what to do (not only from the point of view of watering) once the repotting of a succulent is finished. (…)

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L'articolo Repotting a succulent plant: what to do afterwards and how long to wait before wetting the soil proviene da Il fiore tra le spine.

For the avoidance of doubt: the title is ironic and here we are talking about rot, unfortunately. No new Copiapoa has been discovered, neither the one you see in this photo and in the other incredible images within this article. Simply, this is what remains of one of my Copiapoa cinerea that rotted this winter without me even realizing it. What we see now is nothing but the armor of thorns that the plant has left me. The quills are so compact and close together that they perfectly maintain the shape of the plant (complete with a dry flower at the apex). The stem simply no longer exists. It has rotted and “evaporated”, disappeared.

Here is what happened and, above all, here are the exceptional photos of this plant, whose fate, moreover, from time to time also touches the specimens in habitat, as I happened to see in some online photos and once, directly, with a young specimen of Ferocactus during a trip to Mexico. (…)

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L'articolo New cactus species discovered: “Copiapoa invisibilis”! Exceptional photos of a plant… that no longer exists proviene da Il fiore tra le spine.

Unfortunately it is a less rare phenomenon than one might think. The flower itself, the maximum expression of the plant, its instrument for reproducing and safeguarding the species, can transform itself into its executioner. With cacti, plants that require seasonal rest corresponding to the winter months, the flower can sometimes be fatal. It obviously only happens with those species that flower in mid-winter, therefore a small minority compared to all cacti. But it is often precisely from there, from that flower that blooms in November, December or January, that the rot is triggered and which, if neglected or not seen, can lead the specimen to death. This is what happened to two of my Ferocactus latispinus in recent days. Or rather, in the past few weeks, except that the damage has become apparent recently. And now it was too late to intervene and save the plants.

In this article we look into this phenomenon and see what can be done to prevent it or, at least, be able to intervene before the rot passes from the flower to the plant. (…)

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L'articolo Be careful of winter blooms: rot can start from here. Here are the species at risk proviene da Il fiore tra le spine.

Let’s talk about cacti and diseases starting from a simple photo. The plant that inspired this article, and which you see above, is (or rather, was) an Ancistrocactus (=Glandulicactus) mathssonii. I had obtained this specimen with my sowing about ten years ago and fortunately eight or nine other “brothers” of this plant are still in perfect health, growing and flowering regularly. This particular plant, although treated exactly like the other specimens of that sowing and planted in the same type of substrate in which my other mathssonii live (clay, marl and 60% aggregates), a couple of years ago took a fungal pathology and within a few weeks it was dead. I think it was fusarium, but today it doesn’t matter, because the disease has run its course and what remains is… the armor of this cactus, that is a beautiful interweaving of thorns that embraces the void left by the stem which, over time, it dried up until it decomposed and disappeared altogether. The observation of what remains of this plant, which for a couple of years I have kept along a low wall not far from the greenhouse, where I usually move the diseased plants (by diseases, in this case, I mean generically pathogens and parasites) to prevent them from infecting other specimens, led me to some considerations on the cultivation and treatment of plant diseases.

Considerations that I have condensed in the following article an excerpt of which was also published in the British Cactus and Succulent Society newsletter. (…)

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L'articolo Cacti and diseases: stop anxiety, sometimes we can’t help but let Nature take its course proviene da Il fiore tra le spine.

Circumscribed dark spots, yellowish spots, dryness, discoloration of the stems, reddening, small cuts: over time, signs of various kinds and of varying size may appear on the stem of our cacti. In some cases there is nothing to worry about, because they are small wounds caused for example by the thorns of a nearby plant, or because they are simply the signs resulting from the aging of the plant. In other cases, however, it is necessary to intervene immediately, because that spot is perhaps due to some fungal pathology destined to expand until it seriously disfigures or kills the plant. But how to distinguish a harmless thorn prick scar, for example, from dangerous rot? How to understand if that discoloration of the stem is caused by the sudden exposure of the plant to direct sun or by a lack of nutrients, or by the beginning of a fungal attack? And how to intervene to contain the damage or save the plant when the damage has already been confirmed?

This is what we will see in this article, with the help of a series of photographs that portray different situations and different pathologies. Some photos were taken by readers of Il fiore tra le spine and portray their plants: I thank these readers for agreeing to share their photos with me, thus collaborating in the creation of the following article. (…)

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L'articolo Spots on the stem and rot, here’s what you can do to save sick succulents and cacti proviene da Il fiore tra le spine.

Cacti can be capricious plants, expecially because of their roots. It can happen, in fact, that despite all the cares we dedicate to one of our succulent plants, it stops growing, stops producing thorns and flowers and, in the space of a few weeks (or months, in some cases), begins to deteriorate, deflating and turning yellow. At the origin of this phenomenon, not always a pathology exists, as a bacterial attack that can cause the rot. In the same way, the cause may not necessarily be due to a parasitic attack. If you look closely at the plant, for example, you might not find any traces of spider mite or mealybug, the two main pests of succulents. With experience I have learned that when a plant, even apparently healthy (i.e. not affected by parasites or bacteria) and grown in the best conditions (light, air, watering, soil, etc..) begins to deteriorate deflating and yellowing despite watering, it is always better to remove it from the pot and check the health of the root system. More often than we might think, the problem can hide just there, below the collar.

In this article we will see everything we can do to save a cactus or a succulent plant in evident difficulty or when, after having flared it, we realize that it has lost all or part of its roots. (…)

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L'articolo Cactus without roots: how to save the plant and which soil to use to get it back to full health proviene da Il fiore tra le spine.

In the following article, we will see in detail what consists of prevention; which are the pests and diseases that can affect cacti and succulents; such as the symptoms of their action on plants, and how to carry out treatment and care in case of problems. (…)

The importance of air recirculation

The keyword for prevention is air. Air, air and more air. Therefore, airing the environments in which we keep our plants and, consequently, keep humidity rates low. Open greenhouses as much as possible throughout the period from spring to autumn, fans for air recirculation, outdoor cultivation, are all important factors to give our plants the right amount of air. Also, of course, to the use of correct substrates, draining and low humidity, plenty of light and the right fertilization regimes (an excess of nitrogen, for example, forces the growth of succulents and makes them weaker in the face of adversities), proper irrigation and, more generally, cleaning (of soil, pots, tools and instruments, etc.).

Check the plants

A good practice consists, first of all, in observing the plants carefully before their purchase, discarding those suffering, clearly attacked by parasites (such as cochineal, easily recognizable by the naked eye) or deformed at the apex due to the attack of some aphids. Once purchased the plant, it is good to flake it and thoroughly clean the roots (especially if the plant is in peat), checking the condition carefully and repot in suitable soil. Another useful trick is to immediately isolate the plant or plants that we observe in distress or on which we detect the presence of mites (for example the red spider, see below) or parasites such as cochineal. Even more important is to isolate from other plants those subject to fungal attacks: the spores can quickly pass from one specimen to another and cause real disasters. All plants, then, must periodically be checked carefully to identify any problems and isolate the affected specimens to treat them with specific products and avoid that fungi and parasites may affect other plants.

Preventive treatments

Preventive treatments can be useful against fungi and parasites, especially in two specific moments: in autumn and just before the beginning of spring. It is at these times of the year, in fact, that the combination of ambient temperature and humidity, in addition to the low activity of the plants, can favour conditions suitable for the proliferation of mites and bacteria. Before the plants go into stasis, at the end of summer/early autumn, two nebulisations at a distance of 15 days from each other with water and copper oxychloride, possibly combined with sulfur, will protect plants from some types of fungi and bacteria during the winter. In the same way, a couple of nebulisations at the beginning of spring, before watering, will contribute to the prevention at a time when temperatures tend to rise and, with them, the humidity rate due to the March/April rains. Against bacteria in the soil and root parasites, it is possible to carry out systemic treatments, i.e. special products mixed with watering water. Even in these cases, a treatment at the end of summer and one in spring, with the first watering, can be useful for preventive purposes. In these cases, it is possible to use systemic fungicides against radical rot (Previcur can be used against collar rot, while Tebuconazole can be used against fusarium and Propamocarb can be used for a wider spectrum defence). If the fusarium has already attacked the plant, it is advisable to throw away everything: plant, pot and earth.

An excellent choice, respectful of the environment and our health, is to focus on products with low environmental impact, like Neem oil, useful against infestations by mites and parasites. Always remember that chemicals, whether pesticides or fungicides, should be treated with great caution, wearing gloves and masks, as they can be harmful to health if inhaled or in contact with skin (in fact the use of many products is regulated by law and for the purchase and use of some of them, specific patents are required). An interesting alternative to chemicals against insects and pests can be to use natural remedies based on garlic and tobacco.

Some treatment, always for preventive purposes, can be done by nebulization or by the systemic way (i.e. through watering, so that the plant absorbs the product, which will go from roots to stem) even during the growing season. However, if the plants are healthy and robust, the treatments at the end of summer and the end of winter will be enough and the plants will become stronger and will be able to face and solve any problems.

Plant parasites

Plants can be attacked by plant parasites or pests. The first group includes fungi, bacteria, viruses and microplasmas. Fungi and bacteria, in particular, proliferate in the soil in conditions of heat and prolonged humidity. These are, probably, the most insidious and difficult adversities to face. This happens mainly because the presence of plant parasites is manifested only through the symptoms of the disease that they cause to the plant. In other words, fungi, viruses and bacteria cannot be seen with the naked eye, but you can see the effect of their harmful action. Unfortunately, when we realise it, it is almost always too late to save the plant.

 Fusarium  – It is the case, for example, of Fusariosis, caused by Fusarium oxysporum, a fungus present in the soil that causes withering, dry rot and the rapid decay of the plant, which first slows down the vegetation and then stains and then literally withers and dies. In the acute form, the Fusarium causes the basal rot of the affected subject, while in the slow form it causes a chronic infection that causes secretion and suberification of the plant, which slowly dies. Against this pathology, there is usually little or nothing to do, except try to deal with specific systemic fungicides (based on the above-mentioned Tebuconazole, for example). Of fundamental importance is to move the affected plant away from the others and, in case it is too late to save it, throw away plant, soil and pot (unless you want to disinfect it with bleach).

 Root and collar rots  – They are caused by fungi in persistent hot/damp conditions and by water stagnations in the soil. They affect the roots of the plants and extend to the collar causing their rot and, consequently, the death of the plant. If taken in time, for example after having noticed a slowing in the growth of the plant and its deterioration, you can intervene by flaking the specimen, removing all the old soil and cutting off all the rotten roots and then let the plant dry for at least a couple of weeks in the air but not in the sun. If the rot has hit the collar, you can try a rescue by cutting the plant to the healthy part (i.e. until the pulp is white and has no dots or brown areas). It is essential to use a sharp cutter by disinfecting the blade with alcohol before each cut, to avoid infecting the healthy part. Also in this case, after this operation, you will have to leave the plant in a shaded but very ventilated place for some weeks, until the cut part is completely dry and scarred. At that point, you can place the plant on pumice to try to promote the rooting of the cutting.

 Pythium  – It is a fungus that attacks the seedlings bringing the roots and the collar to rot. If it is not too late to intervene, the plants should be flared, the old soil removed and the seedlings left to dry. Afterwards, it is possible to use a fungicide based on Previcur, both for preventive and curative purposes.

 Powdery mildew  – This is another pathology caused by fungi, commonly called powdery mildew. It develops in conditions of low humidity and temperatures above 20 degrees and spreads through the spores carried by the wind. It reveals with white/greyish pulverulent spots, which lead to the decay of the plant. Against powdery mildew can be useful nebulizations with water mixed with sulfur.

 Sooty Mould  – Also the sooty mould is caused by fungi, a pathology that leads to the production of a dark-coloured crust or to the formation of black powder, often on cacti areoles, at the base of thorns. Are affected by it some cacti, like Ferocactus, which produce honeydew, nectar secreted by the areoles. In case of smoke, it is possible to intervene with copper sulfur, either by spraying or manually, by cleaning the affected areas with a toothbrush or a cotton bud soaked in a solution based on water, sulphur and copper.

 Rust  – This name indicates a pathology, septoria, caused by a fungus called septoria. The symptoms are yellowish spots on the stem, more or less extended depending on the severity of the attack. They are created in conditions of poor ventilation and stagnant humidity. The rust seems to particularly affect Ferocactus latispinus during the winter. It can be controlled by providing the plants with maximum ventilation and low humidity. In case of attack it is good to move the affected plants, give them more air and intervene with copper-based products.

 Botrytis  – Botrytis cinerea, also known as “grey mould”, is caused by a fungus in conditions of persistent humidity and poor aeration. It creates spots initially dark green with yellowish edges. Then the spots are darker until they become brown or black and are covered with grey mould. The best prevention is a good recirculation of air and space between one plant and another. In case of an attack by botrytis, it can intervene with systemic fungicides in association with copper oxychloride. Isolate the affected plant immediately to prevent the spores from passing on to other specimens.

Animal parasites

Even against animal parasites, the best weapon remains prevention, understood as proper cultivation aimed at obtaining robust and healthy specimens. However, some bad encounters between our plants and some parasites (or lice, as they are commonly called) can always happen.

 Cochineal  – These insects are among the main enemies of succulent. They attack plants like the Opuntia, but they do not disdain the other Cactaceae. They can be of three types: waxy cochineal, mealybugs and shield. They usually strike the apex of the plants, but they can nest, also between the roots when the soil remains dry for long periods. In the latter case, the attack is more dangerous, because we only notice it when we repot or if we are very careful if we see that the plant has blocked the growth and is declining without any other apparent causes. The mealybugs suck the sap from the succulents, weakening them, and compromising their growth. The waxy cochineal nestles between the coasts of the Cactaceae or around the areoles, is a couple of millimetres long and secretes a layer of wax. The cotton cochineal, as its name says, produces small white woolly balls. It threatens the apex of the cacti or between the leaves of the succulents and sucks the sap. If the infestation is limited, you can manually remove the mealybugs or crush them with a toothpick. In the case of root cochineal, it is necessary to remove the soil, clean the roots thoroughly, shorten them and, immerse the root system or the whole plant for a few minutes in a contact insecticide and then let to dry for a few days before repotting in the new soil. The cochineal shield is more difficult to remove manually, which also reproduces quickly and, if left to do, can literally cover the plant seriously compromising its growth until it decays. It clings tenaciously to the trunk of the cacti, is white/greyish and has the typical shield shape. They can be removed with a toothbrush, or removed with a nail, but it is not always an easy action. Specific systemic insecticides, or summer mineral oil, can be used against mealybugs. It is also useful alcohol (diluted in water and nebulized), which dissolves the waxy protection produced by these insects and makes them more vulnerable to a subsequent treatment based on specific products. In case of radical cochineal, it is good to immerse the roots (or the entire plant) for a few minutes in a solution based on water and specific anti-cochineal products. When crushed, the cotton cochineals produce a red substance that was used as a textiles dye by Mexican populations.

 Red spider  – This is a small phytophagous mite (Tetranychus urticae), not visible to the naked eye. It proliferates in dry, warm conditions, so it can develop in the hot season if the waterings are very spaced, and the climate is particularly dry. It strikes the apex of the cacti, where the tissues are more tender, and causes secretion on the epidermis which assumes a grey/reddish colour. Growing up, the stem is chapped and aesthetically compromised. At the same time, a massive attack by the red spider can slow the growth of the plant and compromise its proper development. Good prevention against these mites consists in the cultivation of cacti in full sun so that the epidermis hardens and is less subject to the attack of the red spider. At the same time, outdoor cultivation encourages the presence of insects competitors able to contain the development of this mite. A red spider infestation can be countered by systemic and acaricide insecticides such as kelthane, dicofol and sulfur products. It is important not to use the same active ingredient often because the red spider quickly develops acaricide-resistant strains.

 Nematodes  – They look like little worms. They develop in fresh and humid soils and can penetrate inside the roots of the plants blocking the lymphatic flow and leading the plant to growth block, decay and death. They can be easily noticed only in case of repotting: the roots have swellings, nodules a few millimetres in size. As a preventive measure, it is advisable to take a good look at the roots of freshly purchased plants or during each repotting. In the presence of nematodes it is necessary to cut the roots as much as possible and throw the pot and all the old potting soil. Some growers recommend soaking the roots for about twenty minutes in water at 50°. When you notice the presence of these nematodes, often it is too late because they move from one root to another and eradicating them is quite difficult. It is not by chance that several experts advise throwing away the plant in case of an attack by nematodes.

 Aphids  – Fortunately, they do not frequently attack succulents. These are green or black insects that can weaken the affected plants by opening the door to viruses. Specific products (such as Movento) are easily found against aphids, although they can be removed with soapy water (for example, using a Marseille soap diluted in water).

 Metcalfa  – They are small white or pale green insects and appear from the middle of May. They suck the sap of the plants and can facilitate the onset of honeydew and soot. They can be counteracted with specific insecticides, such as those used against cochineal.

 Thrips  – They are very small so that it is almost impossible to see them with the naked eye. They usually attack the flowers, attracted by the pollen, causing dryness, malformation to the petals and favouring the attack by viruses. Against these insects, you can use blue chromotropic traps, or Marseille soap and water or specific insecticides (dimethoate).

 Swarming Fly  – The larvae of these Dipterans are dangerous for seedlings. In fact, they nest in the soil and attack the collar and the roots of the young plants, causing their decay and subsequently their death. The swarming fly is attracted by humid soils rich of organic substance (e.g. peat); for this reason, it can easily attack the seeds, which for the first months must have the soil always humid. The larvae of swarming fly are fought with specific insecticides to be administered together with the waterings.

 Snails and ants  – Among the potential enemies of cacti and succulents there are also snails and ants. Snails can cause considerable damage because they eat the fleshy leaves of succulents and can attack the apical part of cacti, which is more tender. When they are found, they must be immediately removed from the plants, whilst to keep them away, we can resort to the old system of the saucer with some beer, which attracts them and the stuns. There are also specific products in granules to be spread on the surface of the substrate: for snails, they are toxic and eliminate the problem before the molluscs attack the plants.
Ants are not dangerous, but they steal the seeds of succulents and are attracted to the nectar that the glands of some cacti produce (e.g., Ferocactus). They can also carry insect eggs that are harmful to plants. They contrast with specific insecticides, often powdered, to be spread around pots to keep them away.

Wondering what is the right soil for cacti and succulent plants? You can read here…

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L'articolo Diseases and pests of cactus and succulents: how to recognize them and how to prevent their attacks proviene da Il fiore tra le spine.