Table of contents:
- Bacterial rot
- Bacterial spot, fire blight, vascular bacteriosis
- Treatment of bacteriosis, rot, spotting
- Bacterial plant cancer
- Plant viral diseases
Diseases caused by bacteria and viruses do not always have a clear picture, it is possible that the signs of diseases are mixed, for example, with root rot, oily or glassy spots may appear on the leaves, as in bacterial spot, which then turn brown.
The causative agent is bacteria of the genera Pectobacterium, Erwinia.
The disease manifests itself in the softening and decay of individual areas on the leaves, petioles, roots and fruits of the plant. The bacteria secrete the enzyme pectinase in the leaf tissue, which causes tissue breakdown. Most often, succulent and fleshy parts of plants are affected.
A small, shapeless spot, gray, brown or black, first appears on the leaves, which grows in size. On the bulbs and tubers, simply put, putrefaction (mucus, oily) begins, often accompanied by an unpleasant odor. Under favorable conditions for the pathogen - in a warm and humid climate, the disease spreads very quickly. And the affected part or the whole plant turns into a soggy mass.
The pathogen penetrates through mechanical damage to the plant - even microscopic cracks and wounds. It remains in the soil with plant debris. Therefore, disinfection of the soil is required before planting, and when cutting roots, tubers and bulbs, the cuts must be sprinkled with crushed charcoal. And the instrument should be disinfected with alcohol after each circumcision
The development of the disease is provoked by the introduction of excessive doses of fertilizers, stagnation of water in the soil, dense, caked soil, cooling of moist soil in pots, for example, in a cool room in winter.
Bacterial spot, fire blight, vascular bacteriosis
The causative agent is bacteria of the genus Xanthomonas, Pseudomonas.
The disease often affects young leaves and shoots.
Bacterial spots, depending on the type of pathogen, have different symptoms. The most typical picture is when small watery spots are first formed on the surface of a leaf or stem, which gradually acquire a black or brown color. Most often, spots have an irregular-angular or amoeba-like shape, and are limited to a yellow or light green border, sometimes glassy or oily. The bacterium spreads along the veins or near the wound surface (break, crack of a leaf, stem). Unlike spots caused by fungi, spots of a bacterial nature never form concentric circles or small black dots - spores. The transience is different, sometimes the plant withers for a very long time, sometimes it quickly turns yellow and dies.
Optimal conditions for the development of phytopathogenic bacteria are temperatures of 25-30 ° and high air humidity. The death of bacteria occurs only at temperatures above 56 °. Bacteria of the Xanthomonas genus are resistant to drying out and can tolerate low temperatures for a long time.
A variant of bacterial blight is the so-called fire blight, which is caused by bacteria of the genus Pseudomonas. In this case, not spots appear on the plants, but rather large shapeless areas of blackening, which then dry out. It looks as if this section of the leaf is burnt, charred. If the disease is accompanied by favorable conditions, then it develops very quickly, causing the death of the entire plant. A fire blight begins more often with young leaves, shoots and flowers. Bacteria enter plants through stomata or wounds and begin to multiply in the intercellular spaces of the leaf parenchyma. The incubation period for the development of the disease is 3-6 days, depending on the temperature. The bacteria persist in the soil and on the seeds
Treatment of bacteriosis, rot, spotting
The plant can be saved if the bacteriosis has not yet affected the entire vascular system or is local in nature (for example, the rot started from the tip of the leaf). If the roots are rotten, then you can try to root the top (if this plant is rooted by cuttings). If rotting has affected only part of the roots, and the aerial part looks alive, you need to try to save the plant: free the roots from the ground, cut off all the rotten ones, transplant them into dry prepared soil and pour them with a fungicide with a bactericidal effect:
- abiga peak 50 g per 10 l of water
- acrobat MC 20 g per 5 l of water
- oxyhom 20 g per 10 l of water
- home 40 g per 10 l of water
- alirin-B 2 tablets per 1 liter of water
- vitaros 2 ml per 1 l of water
All working tools and pots must be thoroughly disinfected (spilled with boiling water), the soil must be steamed or heated in the oven.
As a prophylaxis, as well as for the treatment of bacteriosis on vegetables and berry bushes (poisons cannot be used), use the treatment of plants with phytolavin biobactericide or watering and spraying with phytosporin, trichophyte. When planting seedlings and indoor plants, glyocladin tablets can be placed in the ground. At home, on indoor plants, spraying and watering the soil with a solution of trichopolum is successfully used - crush 1 tablet of trichopolum into 2 liters of water.
Preventive agents or biologicals cannot always protect plants from infections. You should not rely on them entirely. Plant health depends, first of all, on the correct care, the selected irrigation regime, soil composition, timeliness, but not excessive fertilization. Sometimes plants are weakened by a completely insignificant (at first glance) detail - unsuitable acidity, excess fluoride in water or chlorine, unsuccessful transplantation with broken roots, contact with cold window glass in winter. All these moments are entirely in the hands of the grower.
Bacterial plant cancer
The causative agent is bacteria of the genus Pseudomonas (Pseudomonas syringae, Pseudomonas tumefaciens).
The disease affects fruit trees and shrubs (among garden crops, almost all are susceptible, but more often apples and pears) in indoor floriculture it occurs on fruit exotics (kiwi, avocados, etc.) and citrus fruits. Bacteria - pathogens live in the soil and persist in it for a long time. Therefore, the disease spreads with non-disinfected soil, as well as with contaminated inoculum.
Bacteria infect the vascular system, causing the formation of cracks, blackening, tissue deformation on the roots, stems, trunks, then the development of tumors, which sometimes reach enormous sizes of several kilograms. On fruit-bearing trees on fruits, signs of the disease appear at first in small small rounded spots, at first light, then blackening. Then, in their place, tubercles grow, turning into ugly warts. In citrus fruits, spots and warts do not penetrate and do not grow inside the fruit, but disrupts their ripening and storage
In nature, the spread of the disease is facilitated by low temperatures, strong winds and heavy rains. The saddest thing is that the disease develops slowly and signs of damage can be detected in a few months, even a year after purchasing a seedling or cultivated tree (in rare cases, the disease develops in a couple of weeks). Large doses of nitrogenous fertilizers contribute to the development of the disease.
Bacterial cancer control measures are effective only if the lesion is local and bacteria have not entered the vascular system of the plant. There is no cure for bacterial cancer. The only reasonable recommendation is to destroy the plant, and so as not to contaminate the environment (for example, burn it). As a preventive measure - disinfection of tools (secateurs, knives) with 1% solution of copper sulfate (100 g per 10 liters of water), soaking for 5-10 minutes. When transplanting plants, old pots should not only be washed, but also thoroughly rinsed with boiling water inside and out.
The soil can be disinfected by heating it in the oven - the bacteria dies at temperatures above 50 ° C. When working with a sick or suspicious plant, it is necessary to treat your hands with alcohol so that, when in contact with a healthy plant, you do not infect it. Although insect pests can also be carriers. When transplanting, try not to damage the roots, and if this happens, then sprinkle the damaged area with crushed charcoal, scraps or cuts of wood - with garden pitch to seal the "gate" for infection.
When buying grafted citrus, fruit and berry seedlings and stone fruits, inspect the plants carefully. Fears are caused by those that have cracks in the bark, deformed, as if corrugated leaves and any growths, as well as small specks on the fruits.
If the plant is sick, what to do
Plant viral diseases
Viral diseases do not always have a clear-cut pattern, especially at the onset of the disease; they are easily confused with chlorosis - all viruses cause yellowing. But sometimes a viral disease can be accompanied by signs that put the grower at a standstill, for example, first chlorosis of the leaves begins, then they crumble, and rotting of the trunk is observed. This picture is typical for diseases of psorosis and xyloporosis of citrus fruits - sometimes found in homemade lemons.
It is characterized by spots and stripes of various shapes, white or yellowish on the leaves, light or dark on the flowers, which is caused by the decay of chloroplasts. A mosaic usually has some kind of pattern - concentric circles, rings or stripes arranged in some order or pattern. In addition, mosaicism is often accompanied by deformation of the sheet - wrinkling or curling. Most often, begonias, calla lilies, hydrangeas, pelargoniums, primroses are affected.
Sometimes the leaf virus is called jaundice - some viruses cause severe yellowing of the leaves or the color becomes light green. Individual shoots or the whole plant lags behind in growth, the stems become brittle due to the fact that a lot of starch accumulates in them, the cells are literally clogged with it. At the same time, a mosaic pattern of concentric circles and spots can also be indicated on the leaves. Sometimes jaundice manifests itself not on the whole plant, but on a separate branch - chlorosis of the leaves begins, and new leaves may appear, but small and already chlorotic.
But curly leaves can be caused by fungal pathogens and viruses. With viral curl, numerous small spots 1-2 mm in size also appear on the leaves, which then dry out, the leaves become wrinkled, wrinkle, the flowers are deformed. The disease often affects hydrangeas (hydrangeas), primroses, pelargoniums, poinsettia.
The exact definition of a specific viral disease is very difficult. Direct fight against viruses with chemical agents is impossible. It is much easier and more reliable to prevent the disease by fighting herbivorous insects, which, as a rule, are carriers of pathogens - aphids, thrips, scale insects. But very often the infection is introduced even in the greenhouse, before the plant goes on sale through damaged roots or wounds on the stems and leaves.
All affected parts of the plant must be removed and destroyed. After work, immediately wash your hands thoroughly with soap, and wipe the used equipment with alcohol. Take cuttings only from healthy plants. In dry and hot seasons, shade the plant and spray more often.
Leaf blight, similar to fungal, bacterial or viral, may not be caused by these diseases, but by nematodes.