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Video: Pests On Cacti
How to identify them, and how to deal with them
Cacti, like other indoor plants, are affected by a large set of pests - nematodes, worms, spider mites, aphids, sciarids (mosquitoes), scale insects, false scutes, wood lice, slugs and others. But the most dangerous for this plant are the first three of all named. Therefore, lovers of these beautiful plants need to closely monitor their thorny pets and their condition. For the timely detection of pests, each grower should always have a magnifying glass or magnifying glass at hand. They will help you notice the symptoms of defeat in time. A plant inhabited by any pest should be immediately isolated from healthy specimens, otherwise the entire collection will soon be populated by the pest.
Nematodes are among the most dangerous polyphagous pests of indoor plants, including cacti, which are extremely difficult for flower growers to fight. These are microscopic filamentous white or colorless worms (0.5-1.5 mm in size) armed with a long spear protruding from the mouth. With its help, they pierce the membranes of plant cells and suck out their contents. Nematodes cause serious morphological changes on cacti in the form of thickening on the roots (galls or cysts). Their appearance and active reproduction is favored by the increased moisture content of the soil substrate. Experts distinguish between halo- and cyst-forming nematodes that can harm cacti.
Root gall nematode, penetrating into the roots of the plant and sucking the juices, causes the formation of nodules (galls) by the action of its enzymatic system, by which one can guess about its presence in the soil. Damaged roots stop absorbing water and nutrients from the soil substrate, as a result of which diseased plants lag behind in growth and development, and if severely infested, they die. Over time, the roots die off and are destroyed along with the galls, as a result of which the eggs of the nematode fall into the ground, which serves as a source of further spread of the pest.
Developing in the root system, the cyst nematode destroys the tissues of the epidermis. The body of the female is a cyst sac (about 1 mm in diameter) filled with eggs and larvae. The cysts are brown in color, similar in shape to small lemons, as if hanging from the outside of the root. The flower grower notices the unfavorable condition of the plant only when, as a result of significant damage to the root system, it begins to wither strongly. Cysts of these nematodes are found on the roots and in the root zone.
Nematodes move independently for short distances or are carried by water. If the grower is not careful, they can spread over very long distances with damaged plants, through infected pots, tools, soil, even with the soles of shoes. Due to their biological characteristics, nematodes can multiply very quickly. Under unfavorable conditions, they are able to enter the resting stage, staying in this state for months and even years, waiting for a favorable moment to appear again.
Control measures. To prevent the spread of nematodes, all precautions must be strictly followed. The simplest but effective method is to disinfect containers for flowers and tools before use by scalding them with boiling water. Plastic pots of some designs, in order to avoid their deformation during such processing, are thoroughly disinfected with a solution of bleach, and then washed well with soap and water.
For successful pest control, different methods must be combined. For example, in the fight against rootworm nematode, severely damaged roots with galls are removed during transplantation. As a last resort, all roots are cut and the plant is placed in a new rooting medium. True, this operation does not completely insure against the secondary appearance of nematodes as a result of the reproduction of surviving individuals. To avoid their revival, you can resort to a rather laborious thermal disinfection of the root system.
This method is designed for high sensitivity of nematodes to temperatures of 43 … 45 ° C: the roots painlessly endure immersion in a water bath (for 30 minutes), and the pest dies. The fight against the cactus nematode is quite long due to the presence of cysts in it. Therefore, some hobbyists sometimes resort to heat treatment at a more risky temperature. To do this, cacti in pots are first watered abundantly, pots with affected cacti are placed in a basin, water is poured at a temperature of about 40 ° C until the cactus is completely immersed, and then hot water is added, bringing its temperature to 50 … 55 ° C. At this temperature, cacti are kept in it for 10-15 minutes (the temperature is measured at the bottom of the pelvis), and then the water is gradually cooled to 25 ° C. After processing, cacti are placed in a shaded place, and after two weeks of rest, they can be exposed to the open sun.
Worms (sometimes called "hairy aphids") are also considered very dangerous and quite frequent "guests" in cactus collections. They suck nutritious juices from these plants. These insects (ranging in size from 1 to 3 mm) are clearly distinguishable with the naked eye, having a white waxy coating on the body; under a magnifying glass, they resemble a white woodlouse. The wingless females are armed with proboscis, which they pierce the body of cacti. As a result, plants slow down their development, they become lethargic, and, as a rule, shed their buds. Experts distinguish between mealy and root bugs.
The body of the mealybug is, as it were, covered with a white waxy coating (it seems as if it was sprinkled with flour, which is why the insect got its name). The female forms a white cotton-like discharge as a protective shelter, where she lays eggs. Worms are mobile throughout their life, they reproduce rather quickly. Their sucking activity leads to the weakening and even death of severely affected specimens.
At an early stage (at the first appearance of the pest), it is rather difficult to detect a mealybug, since it prefers to settle on cacti with a cushion-shaped growth (mammillaria, Echinocereus, rebuts, etc.), usually in secluded, inaccessible places for observation. Of course, with a trained eye, you can fix a female when she settles on the tops of cacti (near growth points), on buds and fruits, in areoles (under the protection of thorns and hairs). Experienced cactus growers claim that these pests can also be found on the tops and at the base of the stem of other cactus species. If you do not take urgent measures, then the worms multiply quickly in a dense felt-like cocoon in those places where moisture does not get, and where they are not easy to find; they form large colonies there.
At the first detection and with a weak infestation, the pest can still be removed with a hard brush or a strong stream of water. At the first stage of the fight, you can try to use an aqueous solution of tobacco extract (vegetable insecticide), which is carried out 3-4 sprays (at intervals of a week). After processing, the plants are additionally washed with warm water. If such a remedy does not help, they still resort to the use of chemicals to completely destroy the worms.
Their experts still advise using them for greater safety net in order to destroy the offspring of the worm formed in secluded places. For better adhesion of the insecticide, practitioners are advised to inject dishwashing detergent (4-5 ml / 10 L) into its solution. It is very important to thoroughly wet the damaged areas. Some amateurs consider it necessary to pre-spray insects with a solution of low concentration alcohol (1 part alcohol to 4 parts water) or denatured alcohol (to destroy their wax shell). But this option is not suitable for cacti with a waxy epidermis (although it is partially acceptable only in small damaged areas, mainly on green cacti, devoid of wax plaque). This solution is more suitable for spraying infected plants with dense leathery leaves (monstera, oleander, palms, etc.).
Root worm- no less dangerous pest of cacti, living on the roots and underground parts of the stem. It is often found on the root collar of plants that have not received enough moisture. Its activity becomes noticeable only when the damaged plant takes on a painful appearance, ceases to form new shoots, and often it soon dies. Often such a plant is easily infected with a fungal infection, which aggravates the condition of the cactus and accelerates its death. The root bug in appearance resembles a mealybug (due to a whitish, cotton-like discharge), but, unlike a mealybug, it prefers a dry soil substrate. Very low soil moisture, which, however, is characteristic of the successful (especially winter) keeping of cacti, contributes to the very rapid reproduction of the root worm.It can be easily identified by the white clusters of young larvae when rinsing the roots.
Control measures. It is much more difficult to deal with root worms, since it leads a soil existence, and to destroy it, the plant must be removed from the soil. According to experienced cactus growers, the most effective method for combating root worms is the thermal method, in which the cactus roots are kept in hot (45 ° C) water for 30 minutes. As a chemical agent, it is possible to recommend impregnation of the soil substrate with a 0.15% solution of actellik (you can simply place the pot with the plant in a large container with a solution for 25-30 minutes), after which the excess liquid is drained. If necessary, the treatment is repeated several times (with an interval of 2 weeks). After any treatment, it is recommended to keep the plants for 2-3 days in partial shade. By the way, in spring and autumn, experienced cactus growers carry out preventive treatment of plants of their entire collection.
Just for the detection of difficult to distinguish due to its microscopic size (only 0.25 mm) and a little mobile common spider miteand a magnifying glass will come in handy. It belongs to the group of herbivorous mites and feeds on the contents of the cells of cacti and many other plants, especially often inhabiting the upper parts and the youngest shoots. The sucked out plant cells are filled with air, while the processes of photosynthesis are disrupted, assimilation activity decreases. A characteristic symptom of damage to a plant by a spider mite is the appearance of brownish spots of plant tissue, which spread in small zones throughout the plant (with the help of a magnifying glass, it is noticeable that these tissues are dead). When there are many such "air" cells, at the first stage the leaf acquires a kind of silvery ("marbling").
The damaged tissue is no longer restored, and only the growth of healthy tissue can make the damaged areas invisible.For example, in spherical cacti, damage begins mainly from the crown. According to the observations of cactus breeders, more often than other cacti are damaged by the mite mammillaria, rebutia, lobivia, chamecereus, aporocactus. The skin of the plant already damaged by the mite will not recover, only after a considerable time has elapsed, the damaged areas are somewhat masked due to new growth and become less noticeable. In spider mites, unlike insects, the cephalothorax and abdomen are fused, there are no antennae and wings. Their adults have four pairs of legs, while the larvae have three.
Therefore, they are usually perceived as brown, red or glassy inactive dots. On deciduous plants, it is usually located on the underside of the leaf blade. Only with the help of a magnifying glass can you see in more detail the structure of their bodies. Damage by a spider mite is guessed by yellow specks and a delicate light (barely noticeable) cobweb, with which it braids the damaged parts of plants. This pest, as a rule, settles in large colonies, and low soil moisture and high dryness of the surrounding air contribute to its reproduction. In such conditions, multiplying continuously, it is able to give up to 20 generations a year. It belongs to sucking pests, with the help of a piercing-sucking apparatus, the mite pierces the epidermis, sucks out the plant cell sap.
As a rule, the tick is carried in the summer by the wind from gardens and vegetable gardens where cucumbers, zucchini, beans, hops, fruit and flower crops, as well as from bouquets of cut flowers from greenhouses and greenhouses grow. It is believed that if trees do not shed their foliage for a long time in autumn, then it should be expected that next spring the spread and colonization of plants by the tick will be especially strong, and warm and dry May favors its summer reproduction. According to these signs, one can focus on active settlement and penetration of the pest on indoor plants, including cacti.
Control measures.Frequent finely dispersed spraying with water during dry hot periods inhibits the colonization of plants with a tick. Special preparations are used against the tick - acaricides, while during the treatment all cracks and secluded places are sprayed, for example, with an aqueous solution of actellik ke (20 ml / 10 l) or fufanon ke (10 ml / 10 l). In order to prevent the appearance of mite forms in the offspring that are resistant to a particular drug, experts strongly recommend alternating them. These drugs act mainly on adults and larvae, but not on eggs, therefore it is recommended to carry out 2-3 treatments at intervals of several days to wait until the next generation of larvae hatches from the eggs. Also, do not confuse the common spider mite with the useful red mite, which is somewhat larger (1-2 mm) and more mobile. These predatory mites hunt for spider mites,protecting plants from it. Therefore, it must be remembered that when spraying flower crops with acaricides, beneficial mites also die.
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