Perennial plant mallow, or stem rose, is very interesting from a decorative point of view. Collected in spike-shaped inflorescences, large flowers of various shades adorn both simple front gardens in a peasant style, and the most refined floral arrangements. Mallow is also called mallow (malva), which has more modest flowers. Both plants from the malvaceous family have much in common in the description and are often used by gardeners.
Healthy, well-developed plants bloom profusely until late autumn, gradually opening first the lower buds, then following up the flower arrow. However, specimens weakened by pests or diseases quickly lose their decorative effect. The leaves turn yellow, the buds dry without blooming. To help the plant, you need to understand what caused these problems.
Mallow flower
Causes of mallow diseases
The provocateurs of diseases are bacteria, fungi, viruses, insects and errors in care. An environment with high humidity contributes to the spread of fungal infections, and pests spread in hot and dry conditions. Due to frequent changes in temperature, the disease quickly damages all parts of the plant. To stop the problem, it is important to make an accurate diagnosis on time.
Types of diseases
The lack of comfortable conditions for growth leads to inhibition of plants, while creating a favorable environment for the development of diseases. Fungal and viral diseases cause the most harm to mallow plantings.
Diseases caused by fungi affect the lower leaves, which dry up and die. As a result, the plant becomes weakened, its flowering is delayed, and the stems are exposed.
Viral diseases are considered even more dangerous. They quickly spread to neighboring flowers and it is difficult to cure the plant from them. Ill malva quickly loses its decorative effect.
Additional Information. Sick plants can be treated with drugs that increase immunity - Epin or HB-101. As a result, the production of natural compounds that impede the development of pathogens is enhanced. Plants synthesize substances that can deactivate toxins of pathogenic fungi and bacteria.
Pathologies of the development of mallow can be caused by a violation of the conditions for the life of the plant: light, thermal and soil conditions.
Non-parasitic problems
Creating optimal conditions for growth is a priority for plant protection. Any malva diseases recede before strong immunity, therefore it is so important to ensure proper care. It includes: rare watering, good lighting, fertilizing with mineral fertilizers, timely removal of wilted leaves and flowers.
Non-parasitic diseases include:
- chlorosis, in which light yellow spots form on the leaves;
- falling buds;
- dropping leaves.
Such pathologies appear as a result of improper care and disappear after eliminating the deficiencies.
Bacterial diseases
Phytopathogenic bacteria cause diseases leading to the death of the entire plant or its parts. Due to blockage of the vessels, a general withering of the mallow occurs, and local damage is manifested by necrosis of individual sites. Bacteria penetrate the plant either naturally (through water pores or stomata), or through mechanical damage. Infected flowers are depressed and discard leaves.
The pathogens are adversely affected by the antibiotic Phytolavin. Processing plants is carried out in the form of spraying and watering the root.
Fungal diseases
Under certain conditions, diseases caused by fungi quickly spread and lead to the death of plants. Most often this is due to excess moisture at low temperatures. It is important to recognize the disease in time and help the plant.
On the mallow red spots: what to do
The causative agents of the stem rust rose are several types of parasitic fungi, but the symptoms are always the same. These are convex spots or stripes of brown color on the underside of leaves, petioles and stem. On the upper side of the sheet they are projected with light yellow pimples.
Rust on mallow
Why does mallow have rusty leaves? Dark velvet pads with fungal spores form on them, due to which yellow-brown spots similar to rust appear on the plant.
The rust on the mallow causes increased evaporation of moisture, and eventually the plant dries. A drug like Poliram will help fight mallow rust. This contact fungicide suspends the synthesis of pathogen enzymes. Measures to control rust on the mallow also include cutting sick leaves and spraying the plantings with infusion of garlic.
Powdery mildew
A white velvety coating on the leaves and buds of the mallow indicates the appearance of powdery mildew. This disease, caused by a microscopic fungus, weakens the plant and spoils its appearance. It provokes the development of the disease stagnation of water. It is necessary to treat affected plants with Topaz fungicide.
Powdery mildew
Viruses
Viral diseases lead to a change in shape and discoloration of the leaves. Brightened areas, spots and strips of different intensities appear on the plant. The foliage of the affected flower is deformed, and its growth is suspended. Disease carriers can be aphids and thrips. Affected plants need to be removed, and instead of them, varieties resistant to viruses should be acquired.
Pests
The main enemies of the mallow are aphids, spider mites and slugs. Sometimes the plant is attacked by leaf beetles and nematodes. Pests occupy the plantings of mallow and suck the juice of the plant. It is the presence of pests that is often the answer to the question of why mallow leaves turn yellow. In addition, parasites contribute to the entry of pathogenic microorganisms onto the flower, which leads to the development of diseases.
Chemical pesticides are used to control pests, but you must first determine exactly who eats the mallow. There are drugs that help cope with only one type of insect. For example, Nissoran acaricide is extremely effective against various types of ticks, but is useless in the fight against thrips.
Attention! There are drugs that are universal insectoacaricides. These include Fitoverm, which has no toxic effect on plants, and Oberon, effective at all stages of the development of the pest.
Aphid
The size of adult aphids is about 2.5 mm. Under favorable conditions, the insect multiplies rapidly, and by the end of the season the entire aerial part of the mallow can be covered with aphids. Pests suck juice from the tops of shoots, petioles, leaves. Affected leaves curl, turn yellow and fall.
Aphid on a leaf
Options for getting rid of aphids:
- Chemical etching. Actara has a contact-intestinal effect. It is applied under the root, and the upper part of the plant is treated by spraying. Insects die in 4-6 hours.
- Soap solution. In one liter of warm water, 10 g of tar soap is diluted.
- Spraying with a solution of soda and salt. For 1 liter of water, take one tablespoon of funds.
Spider mite
Putin mites are found almost everywhere. These tiny insects of green and reddish color are extremely prolific. One female lays up to 150 yellowish eggs on the underside of the leaf, and can grow up to 10 generations during the summer. Dry air contributes to the spread of ticks. Damaged plants quickly lose their attractive appearance. The lower sides of the leaves are pulled by a thin gray web, under which pests live and multiply.
Control measures:
- The use of chemicals is the most effective way. A popular tool for combating arachnids is Anticlesch. This acaricide with a wide spectrum of action does not lose effectiveness at high temperatures and quickly inhibits the vital activity of pests.
- The use of folk remedies. It has been observed that onion volatile is toxic to the spider mite. To get rid of the tick, a two-day infusion of onions is used (20 g of onion husks per 1 liter of water). Three times spraying destroys the pest.
Nematodes
There are three types of nematodes: leaf, stem and root. These small, colorless worms penetrate plant tissue. The shape of the damaged mallow changes, in some places swellings form. Tissues gradually die. Flowers do not develop well or do not form at all.
It is difficult to get rid of nematodes. Apply drugs such as Karbofos (contact poison) or universal nematocide Nemagon. Thickened parts of the plants are cut and destroyed.
Slug
Often, slugs annoy plantings of mallow. They can be assembled manually or set traps - containers with beer for bait. Attracted by the smell of a hoppy drink, slugs crawl into jars. It remains to collect and destroy them in the morning.
Leaf beetles
Adult leaf beetle bugs gnaw holes in mallow leaves, feeding on plant sap. Larvae are able to eat the entire terrestrial part of the plant. When a gardener discovers mallow leaves in holes, what to process, the first question arises. Vinegar repels pests. 500 ml is diluted in a bucket of water and sprayed with a planting solution. With a large number of parasites, the drug Confidor is used.
Traces of the leaf beetle
How to protect a plant from diseases
A properly organized system of plant protection against pests and diseases includes not only effective methods of treatment, but also preventive measures. It is necessary to regularly inspect the plants, before planting, sterilize the soil with potassium permanganate or boiling water, remove dried parts of the plant. These simple actions prevent pests and eliminate sources of infection.
The mallow plant is more often than other garden flowers susceptible to various diseases. Pests love to attack him. To reduce the frequency of occurrence of problems and reduce damage from them, it is necessary to maintain the necessary conditions for the healthy development of the flower and regularly carry out the prevention of diseases.
