Diseases of the rose
Diseases of the rose
The rose is one of the plants most affected by more or less serious diseases. In this article we will talk about the most frequent caused by fungi, parasites, viruses or maintenance and care behaviors that are not always correct and the possible remedies.
Main fungus diseases
Gray mold is a disease caused by the attack of a fungus that can infest every part of the plant, creating a layer of gray mold on them; in case of severe infestation, dark colored spots may form on the petals. The ways of transmission of this disease are above all the wounds caused to the plant during normal maintenance operations, it will therefore be advisable, when carried out, to administer specific products.
The black spot is a fungus, Diplocarpon Rosae, which particularly affects the leaves of the rose but can also infest buds and petioles, causing on them the appearance of round dark spots, at first small and then gradually becoming more and more large; the plant that undergoes this attack shows a yellowing of the leaves and the consequent early fall. This fungus proliferates in situations of high humidity, it will therefore be advisable to avoid stagnation of water and promptly eliminate the affected and damaged parts.
The main symptoms of rust, on the other hand, also a fungal disease, are the presence of orange spots and the consequent change in shape of the affected parts such as buds, small ones and leaves. It is very frequent and, very often, it manifests itself during the spring period. A possible and effective remedy will be to eliminate the infested parts and to carry out a preventive treatment with specific products.
Another widespread disease, always caused by a very dangerous fungus, Sphaerotheca pannosa, is white ma, it attacks all parts of the plant by forming a layer similar to white powder on them and causing leaves and flowers to deform and consequently die. The most effective products to defeat this fungus are sulfur based.
Downy mildew is an infection that causes the appearance of dark spots on the upper part of the leaves and mold in the lower one. This fungus can also attack rosebuds, slowing down and, in some cases, stopping their development and causing them to dry out.
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Insect and parasite diseases
Leafhoppers are insects that affect the buds and leaves of roses. The attack manifests itself with the appearance of light-colored spots on the attacked parts that become darker and faded in the veins of the leaves. The remedy consists in administering specific insecticides.
Aphids, also called rose lice, are very annoying insects that attack the plant forming colonies, suck the sugary substances contained in it, giving rise to a honey compound called honeydew. These parasites can be eliminated by using a cotton swab soaked in alcohol or by washing the leaves with soap and water and then rinsing them well. In the event of a very massive attack, administer pesticides.
The spider mite is another parasitic insect that attacks the leaves causing them to turn yellow, causing yellow or darker colored spots on them, the consequent curling and falling. This parasite finds it multiplies in a particular way in dry environments, to fight it therefore it will be advisable to increase the humidity through the intensification of the nebulizations to the leaves, otherwise it will be possible to proceed, as for aphids, with alcohol or washing the leaves with water and soap.
The green agrilo, on the other hand, is a beetle that by depositing its larvae inside the plant causes its progressive deterioration. Another enemy beetle of the rose is the Bark beetle, it infests the plant by digging tunnels inside it and weakening its branches.
The rose can also be the victim of viral attacks, the most widespread and well-known virus is called mosaic of roses; it causes on the leaves, as the name implies, mosaic-like designs of different colors or spots. In case of infestation, the flowers change their shape, show a minor and late flowering. The only remedy may be to uproot the sick roses in order to avoid the possible transmission of the disease to the others.
Then we have the Sore stripe which, as the name itself implies, causes the appearance of yellow stripes on the leaves, slowly bringing them to discoloration.
Diseases of the rose: Natural damage
Finally, there are symptoms that are not referable to any disease caused by parasites, bacteria or viruses, but caused by factors; for example, if our roses begin to lose color between the ribs it will be due to a lack or excessive presence of nutrients in the soil, excessive water intake, temperatures that are too high or too low or the soil is too saline, etc.
There are about 250 botanical species, while the cultivated ones, deriving from various selections and hybridization, are innumerable, given that, every year, hundreds of new varieties are created all over the world.
In general, the old roses, or rather the wild ones, are robust and therefore refractory to various parasites, while those cultivated or hybridized are very sensitive to the environment and relative adversities.
The main reason why almost all the current selections are grafted, is inherent in the fact that the rootstock or wild or rustic foot, then gives the grafted part (cultivated for the flower) greater vigor and resistance in general.
Rosehip is a thorny perennial shruboriginally from Europe and western Asia.
It is 100 - 200 cm high. Has drumswoody hairless, with robust (red) spines, arched, with an elongated base, compressed when young, the stems have a green-brown or red-brown bark, while in adulthood they become dark yellow and streaks appear.
The branches are long and can be erect or curved but almost never assume a climbing posture. The leavesthey are composed of 5-7 oval or elliptical leaflets with toothed margins (simple teeth). THE flowers, they can develop singly or in groups of two or three, they are pinkish, have large petals and have a light and pleasant scent. It blooms in the months of May and June.
THE fruits(rose hips) are species of berries of intense color (scarlet red) inside they are rich in seeds and fluff while on the outside they have a thin rind when they reach maturity (in the late autumn period) they can be eaten, even if they are collected mainly for their various therapeutic properties.
It is mainly used as rootstock of the main hybrid varieties of roses or in gardens as an ornamental plant in isolated or hedged specimens.
There multiplication of the dog rose occurs by cuttings or by seed.
Sowing is done at the beginning of the spring season before being planted, the seeds undergo a stratification treatment in the heat for eight to twenty-four weeks and in the cold for the same time.
Most used is the propagation by cuttings which is carried out in the spring period
Rosehip is very fond of exposure in full sunor in partial shade.
The ideal soil must be soft, light, rich in organic matter and, above all, with excellent drainage.
It also resists well in cold temperatures.
Pruning: the pruning of the bush-grown dog rose involves a renewal of the old and dry branches trying to ventilate the center of the plant, keeping the vegetation on the edges, it is advisable to proceed with a clean cut and done obliquely but not too much and not carry it out too close to the gem.
The suitable period for pruning varies according to the climate. If we are in an area with a cold and humid climate, we will proceed with this operation in early spring, while in the case of hot weather it will be advisable to prune in late autumn or early winter.
Like all roses, canine roses are also very susceptible to attack by diseases and parasites.
As for the insects, those that most infest the dog rose are the aphids and the cochineal.
In the kitchen, fresh fruits are used to prepare delicious jams or dried to make liqueurs, while with the petals you can produce excellent pink honey.
It is widely used for its contents of C vitamin and for its content of bioflavonoids (phytoestrogens).
The active ingredients (in addition to vitamin C, tannins, organic acids, pectins, carotenoids and polyphenols) are used by the pharmaceutical, food and cosmetic industries: flowers and leaves are used in pharmacopoeia, for example, for the preparation of infusions and herbal teas.
The small fruits of Rosa Canina are the most concentrated "natural sources" in Vitamin C, present in quantities up to 50-100 times higher than traditional citrus fruits (oranges and lemons) and therefore able to contribute to strengthening the body's natural defenses. (100 grams of rose hips contain the same amount of vitamin C or ascorbic acid contained in 1 kilo of citrus fruits).
Containing a high quantity of ascorbic acid, rose hips (or rather its false fruits) is indicated to fight infections of the respiratory tract (ears, nose and throat) as it strengthens the body's defenses. It therefore has an immunostimulating action in preventing flu and colds, especially in children.
It also has an anti-inflammatory and anti-allergic action. According to studies conducted by Nobel laureate Linus Pauling and US researchers, rose hips taken in large doses would also prevent cancerous growth.
Rose hips also have astringent properties (thanks to the presence of tannins they are effective in the treatment of diarrhea) and diuretic (stimulate the elimination of toxins through urine).
The treatment with an extract of wild rose berries is used in cases of rheumatic pain and more particularly against arthrosis o in cases of shoulder pain (the trial is underway at the Rizzoli orthopedic institutes in Bologna on 200 patients suffering from severe osteoarthritis identified among those waiting for hip replacement to verify its effectiveness on inflammation and in the control of pain: http://www.aamterranuova.it/article4431.htm)
The use of rose hips is also well known in cosmetic field, in fact, this plant is very rich in beta-carotene and provitamin A very useful against aging, sunburn and the appearance of wrinkles. The petals are used to produce very effective eye drops.
Distilled water produced with the use of rose hips is used to treat reddened and particularly sensitive skin, while with fresh blended fruits a very useful cream is obtained for smoothing and toning the skin through a beauty mask.
About 96% of women's and 46% of men's perfumes contain rose essence.
The famous rose water was invented by Avicenna, a famous Persian doctor, between the 9th and 10th centuries.
This plant owes its canine name to Pliny the Elder, who claimed that a Roman soldier was cured of anger with a decoction of roots.
Legend has it that Bacchus, god of wine, fell in love with a girl, wished to conquer her, but she fled until he stumbled on a bush. Out of gratitude, Bacchus transformed the bush into pink by giving it splendid flowers of the same color as his beloved's cheeks
How to defend yourself from rose scab
This article indicates the use of plant protection products on the market and permitted for the crop in question at the time of online publication. Always check, before using it, that the active ingredient is still registered for this crop.
Responsible for the scab is a fungus that develops in spots under the epidermis of the leaves causing blackening of the tissues. Here's how to intervene
In regards to infections of rose scab (Marssonina rosae), first of all collect and remove the first stained leaves from the garden to reduce the infecting elements of the fungus. At the appearance of the first infections, or in the periods during which the hours of wetting of the leaves and the temperatures are optimal for the development of infections, carry out a treatment, every 7-10 days, using copper-based preparations such as Bordeaux mixture-20 (bio, irritant or not classified), copper oxychloride-20 (bio, not classified) at the doses indicated on the label.
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The Rose, with its beauty and its colors, is one of the most widespread plants used to adorn gardens, flower beds and balconies. Its simplicity of "cultivation", however, should not be misleading, as roses can be very sensitive to some fungal diseases, such as Rose scab, which can release them by ruining the appearance and aesthetic function of the plant.
One of the most widespread and well-known diseases of the rose is the so-called Punctuation.
This Mycopathy (fungal disease) is very common and can be found in almost all species of roses, whether they are in pots, in the ground, tall stem varieties or dwarf varieties.
The scab of the rose occurs mainly on the foliar apparatus (the leaves) of the roses, through black spots with irregular edges, with very variable dimensions (from a few mm to 1/2 cm). In the most affected plants, the disease can develop further, totally blackening the surface of the leaves, or making it chlorotic (ie yellow).
The Roses affected by Punctuation, they progressively weaken both due to the continuous effort due to re-budding, activated by the lack of leaf surface useful for its development, and precisely due to the lack of leaves to support the growth and maintenance of the rose.
In the most serious cases, this fungal disease causes the total defoliation of the rose, which will lose the ability to develop its flowers and consequently its ornamental usefulness.
How does Rose Scab develop?
There disease it develops in the rainy and humid seasons, usually in spring / summer, with fairly high temperatures, between 20 and 25 degrees centigrade. The spores they are kept on the leaves and on the previously infected branches of the roses, which therefore infect the plant when the climatic conditions allow it.
So how can we fight this fungal disease, which can weaken our roses?
The fight against Punctuation is of the "Price quotation“, And can be implemented both mechanically and chemically.
The first step is to clean the roses from the twigs and from infected leaves, removing from the ground material that has fallen into the ground, which must be disposed of correctly.
After taking action agronomically, we just have to protect the squad through the use of chemical products. The goal of the treatments will be to avoid scab infections by acting in a preventive manner, thus directly hitting the spores before their infectious action, through the use of copper based products, which can also perform aantioid action.
The treatments will be repeated according to the seasonal trend (thus anticipating any rains) with close shifts, even weekly, using a fine jet spray pump, covering with a copper-based fungicide the surface of the leaves and also any protruding branches, so as to minimize the potential infections of Punctuation.
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What are the Argidae
The Argidae they are small hymenoptera similar to wasps belonging to the suborder of Symphites, family Argidae, originating intropical areas.
Among the species that affect roses in our latitudes, the most common are Arge rosea and Arge pagana, easily recognizable by the yellow-rust or greenish color of the abdomen.
The females, during the period of flickering, between April and May, they lay their eggs inside small cracks of young stems dug with their terebra.
Biological cycle of the Argidae
The Argidae they overwinter at the pupal stage and as a mature larva, in the soil at the base of the plants. In spring, the adults make the first flight by laying eggs on the shoots, giving rise to the first larval generation, active until the beginning of summer. This first flicker is followed by another 1 or 2 depending on the species.
From the hatching of the eggs, hairless larvae of a green-yellowish color with an ocher-colored head come out.
The back and the lateral parts of the body have longitudinal rows of showy black tubercles.
The larvae they feed on leaves causing total erosion of the leaf limb, starting from the margins up to the most tender shoots.
Plants attacked by the Argidae
Roses are the favorite plants of these insects both at the adult stage and at the larval stage.
Damage caused by the Argidae
They are generally insects that live in colonies and, therefore, in the event of heavy infestations, they lead to the death of the attacked plant as the latter can no longer carry out photosynthesis due to severe defoliation.
The injured or incised tissues necrotize and deform and, more often than not, if action is not taken in time, fungal cancers form within the lesions. The necrosis extends and causes the branch to dry out.
Fight and treatment against the Argidae
The fight against these pests is chemical. The treatments are carried out against the larvae, in the early stages.
To contain damage and infestations to other roses, it is good practice to promptly prune the shoots attacked by the larvae.