Rose - Rosaceae - How to care for, cultivate and make rose plants bloom
HOW TO GROW AND CARE FOR OUR PLANTS
It is an evergreen plant both indoors and outdoors, very generous in blooms that can become very large, especially if grown outdoors in temperate climate regions.
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There are many parasitic and non-parasitic diseases that can affect the rose therefore in this section we will limit ourselves to describing the most frequent.
DISEASES CAUSED BY MUSHROOMS
The leaves are covered with a characteristic gray mold
This disease is caused by a fungus, also called it gray moldwhich can attack all parts of the plant, in the worst case the flower buds bend. sometimes the petals may have small brown spots.
Remedies: since it is a very frequent fungus in roses that occurs if the appropriate disinfection measures are not carried out when wounds are opened in the plant voluntarily (pruning, etc.) or involuntarily, it is beneficial to preventive treatments as well as agronomic (elimination of the affected parts from rose garden and make sure that water does not stagnate in the plant) based on specificantibotritics such as benzimidazoles or dicarboxymides or with fungicides with a broader spectrum of action such as diclofuanide, tiran and others. After pruning it is advisable to always treat the roses either with the use of mushroom or with the fungicides indicated above.
The leaves of the roses are spotted with black
This disease is caused by a fungus there Diplocarpon rosae said black spot.
As a consequence of the attack, the plant appears defoliated and strongly weakened.The disease manifests itself with numerous spots on the leaves from a few mm to 3 cm, roundish isolated and gradually confluent of a blackish purple color. Affected leaves eventually turn yellow, curl, and drop prematurely. Pathology also manifests itself on the petioles and young shoots. Older leaves are typically less sensitive to the fungus.
Remedies: as always, the fight is both agronomic and chemical: eliminate dead parts of the rose plant and the surrounding soil, avoid water stagnation on the plant and always keep it well ventilated. The chemical fight must be carried out with products such as benzimidazoles, triphorins, chlorothalonil, mancozeb or maneb.It must be remembered that if you do not want to resort to chemicals, the treatment with sodium bicarbonate has a certain efficacy.
The leaves, the petioles, the young buds of the rose appear tinged with an orange color that cause deformation of the affected organs
Surely it is a rust attack, caused by the fungus Phragmidium macronatumThis disease also occurs in almost all rose gardens and must be treated vigorously.It usually occurs in spring on the buds and petioles of roses: small orange-colored pustules that cause deformation of the affected parts. affected parts irregular yellow / reddish spots
Remedies: a first practice of struggle consists in pruning the affected parts promptly and their removal from the plant and the ground. If this is not possible, intervene in winter with copper-based products in an energetic way or with polysulphides.
During the vegetative period or when the rose buds hatch, it is advisable to carry out treatments with Bordeaux mixture or copper oxychlorides (however bearing in mind that copper-based products can stain the buds and burn the petals) or dithiocarbamates. The qualitriforine systemic products and oxycarboxin are also very effective. However, keep in mind that these products must be tested first to verify if the rose cultivar to be treated is not sensitive to these chemical compounds.
The plant becomes covered with a whitish powdery patina and the flowers and leaves appear deformed and necrotize
Surely it is an attack of a fungus that causes the so-called bad whiteor powdery mildew which is one of the most serious diseases of the rose. This disease is caused by a fungus there Sphaerotheca pannosa var. rosae and affects all parts of the plant but prefers the more tender parts. The whitish patina is the mycelium of the fungus
Remedies: in any case it is advisable to intervene with specific sulfur-based products, dinocap, pirazophos, propiconazole.
The leaves have irregular brown-purple-brown leaf spots with a dry consistency in the center and a dark halo on the periphery
It is probably an attack due to Downy mildew spp. also called gray mold, a very well known mushroom. All aerial parts of the rose plant can be attacked
Remedies: the fight against this parasite must be not only chemical but it is also possible to set suitable cultivation techniques that limit its onset. In fact, the fungus develops well with high humidity therefore it is advisable to take all precautions to avoid water stagnation. The chemical fight once preventive with products based on Dithicarbamates and others has evolved with the use of systemic products (which enter the plant's circulation) belonging to the Dimetomorf group of Phenylamides.
DISEASES CAUSED BY INSECTS OR MITES
There are some light spots on the leaves and on the buds, harmonized and faded especially along the veins and in the central part of the leaves and insects that hopping
It could be Typhlocyba rosae L. known as leafhoppers.
Remedies: intervene on roses with specific insecticides based on acefate, pyrethrum or diazinone even if most of the time it is not advisable to treat.
Both on the leaves and on the buds appear small insects that jump and fly. The leaves, the shoots, the flower buds are deformed and do not grow. Presence of honeydew.
If you notice hopping and flying insects on the rose plant, it could be aphids, the so-called rose lice (Macrosiphum rosae L). Look at them with a magnifying glass and compare them with the photo on the side, they are unmistakable, you can't go wrong.
Remedies: treat with specific pesticides readily available from a nurseryman.
The leaves of the roses that begin to turn yellow appear mottled with yellow and brown
If the leaves of the rose begin to turn yellow and after these manifestations crumple, they take on an almost dusty appearance and fall off. Observing carefully they also notice thin cobwebs especially on the lower page of the leaves. With this symptomatology we are most likely in the presence of a red spider mite attack, a very annoying and harmful mite.
Remedies: increase the frequency of nebulizations to the foliage (the lack of humidity favors their proliferation) and possibly, only in the case of particularly serious infestations, use a specific insecticide. If the plant is not particularly large, you can also try cleaning the leaves of the rose plant to mechanically eliminate the parasite using a wet and soapy cotton swab, after which the rose plant should be rinsed very well to remove all the soap.
DISEASES CAUSED DAVIRUS
The leaves have a sort of pattern that looks like a mosaic, chloritic / yellow, annular spots, with lighter veins.
This is a viral attack. The most common virosis of the rose is due to the virus generally known as mosaic roseGenerally the flowers of the rose show no discoloration but malformations, delayed flowering, smaller flower buds than normal.
Remedies: if we are sure that it is a virus (consult the experts), there is no guarantee that it can be done in the open field. It is necessary to remove the affected roses and quickly remove them from other plants.
The younger leaves show some discoloration between the veins
This symptom is very common in our land. It is a matter of iron deficiency or better, iron can also be present in the soil but for various reasons the rose plant cannot assimilate it: little aeration of the soil, excess water, high salinity, excesses of manganese, zinc or phosphates, high or too low temperatures of the ground.
Remedies: Give the roses iron chelates to the leaves or the soil. Repeat the operation over time.
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