Once you have made the decision to start growing cacti, it is necessary not only to obtain information about their content, but also about protection. There are not many diseases in cacti, as well as insects that harm these plants, but if a succulent becomes infected, it can be extremely difficult to reanimate it. Treatment of cactus diseases and getting rid of pests is a painstaking process, and in order not to have to resort to it, it is better to take preventive measures right away.
Both beginners and experienced cacti growers have to deal with diseases and pests of cacti in one way or another. Luckily, cacti don’t have that many. The reason for the disease of cacti, especially in novice collectors, is often the weakening of plants caused by improper maintenance. Among such reasons may be a lack of light, improper watering, depleted soil, too high or, conversely, low temperature, etc. Weakened plants are primarily attacked by pests, affected by various types of rot and physiological diseases associated with metabolic disorders in the plant. However, cactus pests can also attack perfectly healthy plants, so it is very important to detect them in time and take appropriate measures.
How to deal with spider mites on cacti
The spider mite, which most often visits collections, settles on cacti, pierces the skin of plants and feeds on their juice. Signs of its appearance are the thinnest, inconspicuous cobwebs on the stems of plants and dry brown spots, which over time can cover the entire stem.
Look at the photo – this pest of cacti weaves a web, which becomes clearly visible in the sun after spraying, when the smallest drops of water settle on it:
With severe damage, the plant is hopelessly damaged. It is believed that Chamaecereus silvestrii, which is the first to be damaged, can serve as one of the reliable indicators of tick attack. However, this is not at all necessary. A tick attack can start from other species. It is important to notice in time the traces of the activity of the tick and the very small arthropod itself (0.4 mm) of a reddish color and prevent it from spreading throughout the collection. The tick goes through several phases of development, from egg to adult. The duration of the phases depends on the season and ranges from several days to two or more weeks.
How to deal with spider mites on cacti with the help of chemicals? Chemical means of combating ticks and other pests are divided into contact and systemic. The former infect pests by direct contact, the latter enter the plant and destroy pests that feed on sap or parts of plants. Of the old means, excellent results in the fight against ticks are obtained by treating the collection with the Keltan acaricide. 2 g of this preparation is diluted in 1 liter of water (to obtain a solution of 0.2% concentration) and the plants are sprayed. If necessary, the treatment is repeated after a week. It is necessary to spray in cloudy weather or at night. It is advisable to carry out preventive treatment of the collection from a tick in spring and autumn.
Of course, it is possible to use other, more modern drugs, in particular Aktellika, a broad-spectrum insecticide. The drug has low toxicity, is used at a concentration of 0.1% for spraying plants and watering the soil from pests. “Fitoverm” is also a broad-spectrum drug.
Its concentration in the working solution, depending on the type of pests, is different: from spider mites 2 ml per 1 liter of water, from aphids – 4.5 ml, from thrips – 5 ml. If the effect of a new drug on cacti is unknown, it is best to first try it on one plant. Some drugs can cause burns to the skin of cacti.
Below is a description of the pests of cacti, worms and nematodes, as well as the measures to combat them.
How to deal with mealybugs and nematodes on cacti
The mealybug is a small (about 5 mm long) insect covered with a whitish wax coating that repels water. In sheltered areas of the stem, the female lays her eggs in waxy cocoons resembling cotton balls. It reproduces extremely quickly. Worms, like ticks, suck the juice from the cactus stem. How to deal with mealybugs on cacti? An effective pest control measure is spraying the collection with contact poisons.
The root bug is a small insect (1-3 mm) that parasitizes the roots of plants. Against the background of the soil, it is clearly visible. Signs of the disease are the cessation of growth and flowering of plants. The root worm is destroyed by contact poisons or by heating in hot water, as when infected with a nematode.
Cactus nematodes are microscopic roundworms. Infection with nematodes usually occurs for two reasons: poor tillage for planting and when placed in a collection of foreign plants without inspection and quarantine. The last reason is most typical for beginner cactus growers.
Due to the lack of experience and the desire to quickly increase the size of their collection, they often acquire any cacti without verification and place them in the collection. Nematodes live on the roots of plants. Two types of nematodes can parasitize on cacti – gall and cactus. Roots affected by the gall nematode have knotty thickenings of various sizes. External signs of infection with a nematode are stunting and wilting of the plant stem. A cactus shaken out of a pot reveals rotten roots of a sloppy look.
The male cactus nematode is about 1 mm long. Lemon-shaped females penetrate half of their body into the root. The development of the nematode proceeds with the formation of a cyst covered with a cornified membrane resistant to poisons. Signs of infection are similar to infection with root-knot nematodes, but swellings do not form on the roots.
To combat nematodes, special drugs can be used, but they are usually too toxic for home use. Good results in the fight against nematodes are obtained by heating the whole plant in water at a temperature of 50-55°C for 15-20 minutes. After that, it is necessary to cut off the damaged roots and dry the cactus for 3-4 days. The cut roots are destroyed along with the soil from the pot, and the pot and tools are thoroughly washed and heated in hot water. The cactus is transplanted into fresh soil and quarantined to make sure the pest is free. The harmful effect of nematodes is exacerbated by fungal infections that penetrate damaged roots and cause them to rot.
Next, you can see photos and learn about the treatment of cactus diseases.
How to cure a cactus from dry and wet rot
A dangerous disease of cacti is rot caused by fungi.
Dry rot of cacti is caused by fungi. It does not manifest itself long enough, spreading inside the stem. In the later stages of rot development, the cactus stalk inside dries out and it dies. The cause of the disease is usually considered too cold wintering. Astophytums, some mammillaria and other species are unstable to this disease.
Wet rot starts from the roots with excessive stagnant moisture, especially in cold weather, as well as with improper transplantation. Sick roots are cut off, the whole plant is warmed up in hot water, dried for several days and transplanted into fresh soil.
As you can see in the photo, if this cactus disease has reached the stem, it is gradually cut from the bottom to healthy tissue, dried and the rest of the stem is rooted:
And how to try to cure a cactus from rot at home? It is necessary to regularly spray the collection with fungicides, for example, the low-toxic “Fundazol”. The same preparation can be watered with the soil of plants to prevent root rot. It is used at a concentration of 0.05-0.1%. Can be used for spraying seedlings from decay.
In the prevention of root rot, one should not forget about such an old proven remedy as potassium permanganate (potassium permanganate). With a light pink solution of this preparation, it is good to make the first watering in the spring and the last watering – when setting up the collection for the winter. An important point in the prevention of cactus rot is also their competent content in the collection.
Fusarium is another fungal disease, its sign is the acquisition of a red-brown color by conducting vessels, which is clearly visible on the cut of the stem. A pink or purple bloom appears on the stem itself. The disease starts from the roots and manifests itself too late. Diseased plants are destroyed.
There are other, much less common diseases of cacti: viruses, physiological diseases associated with improper care of the collection. If necessary, you can find out about the fight against them in the special literature. It should only be added that with proper care of the collection, regular preventive treatment against diseases and pests, strong, well-growing plants will always delight the owner with beautiful stems and abundant flowering.
These photos show how to deal with cactus diseases: