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Punctuation is a cryptogamic disease, caused on ornamental plants by fungi belonging to the genus diplocarpon or marssonina and on fruit plants from mushrooms belonging to the genus venturia; it develops above all in the presence of a particularly humid climate and in the absence (total or partial) of an adequate recycling of air; therefore the attacks by the ticking occur particularly in autumn or during particularly cool and rainy springs. The most affected plant species are the fruit rosaceae, in particular the apple tree and the pear tree and the roses; tall trees such as poplar and willow are also affected. The disease particularly affects the leaves, but often also stems and fruits.
The leaves are the first parts of the plant to be affected and from which the type of disease can be immediately understood. More precisely, the leaves gradually cover themselves with dark spots, which at the beginning are small and isolated but which then gradually become thicker, until they almost completely "cover" the leaf. Around the spots, black or dark purple, the leaf tends to discolor to yellow.
The scab, which initially affects the upper page of the leaf, also propagates quickly to the lower page of the same and then passes to the more slender and young branches, then to the bearing branches and finally contaminate the fruit.
If the attack is particularly serious, it is possible to arrive at the premature defoliation of the plant and the plant can weaken to such a point as to reduce its vegetative development and flowering.
This fungus spreads rapidly from one plant to another, so it is good to intervene quickly as soon as the symptoms are seen; in addition to copper-based products, Mancozeb, Dithane and Propiconazole (systemic) products also perform an excellent curative action.
To avoid the persistence of the disease near the plant it is good to destroy the infected leaves.
If you want to use organic products, horsetail based products are recommended.
The fungus survives winter like spores, in the leaves that fall to the ground. The best cure against scab is prevention, which is carried out first of all with adequate pruning, designed to make the air circulate well between the branches and the branches, and also with adequate irrigation and planting, implemented in such a way as to avoid water stagnation in the soil. During the period of vegetative rest a good prevention is also practiced through treatments with Bordeaux mixture or other products based on copper, which give excellent results even in the case of symptoms already present.Punctuation in shortCommon name Black stain of roses or scabScientific name Diplocarpon rosae (in some texts Actionema rosae)Plants affected Almost exclusively roses but also trees and shrubsMain symptoms Black or brown spots on the leaves, confluent, yellowing and defoliation. If severe they can also appear on the branchesCause Of fungal originPeriod of appearance Spring or late summerPredisposing factors Environmental humidity, wet leaves, temperatures between 24 ° and 26 ° C, genetics of the specific rosebushPrevention Avoid wetting the leaves, distribution in the spring and autumn of copper-based estimatesCare Specific coverage or systemic anti-cryptogamicMore suggestions Intervene eliminating the leaves at the first appearance, at the arrival of winter remove all the leaves from the foot of the plants and distribute an fungicide both on the trunk and on the groundDescription and symptoms
Rose scab is a plant disease caused by the fungus Diplocarpon rosae. With oidium, it is probably the most common affection on this type of plant and, once established in the garden, it becomes difficult to control if time is not devoted to cleaning and good and constant disinfection.
It is generally the main cause of defoliation. These in themselves would not be a serious problem. However, if they are repeated, year after year, they can cause a serious loss of vitality in the rose, reducing in particular the ability to bloom. Moreover this weakness opens the door to the attack of various insects and the specimen becomes more sensitive both to the heat and to the cold of winter.
It is stressed that the problem can have a really negative impact especially when going towards the autumn. The most important defoliation takes place at the end of spring and lasts through the summer. The lack of leaves terribly weakens the plant which is unlikely to produce an important second autumn bloom (the main advantage of modern roses over old ones).
Symptoms The infected bushes initially develop small black spots on the underside of the leaves, usually in late spring. Some of these spots can widen and take serrated margins, even reaching a centimeter in diameter. In some cases they are also surrounded by a more or less large yellow halo. In the severely affected specimens there is a general yellowing of all the leaves and then a more or less complete defoliation.
In extreme cases the fungus can also attack the branches that will present brown-purple spots especially on the vintage growth.
The cycle of disease
The disease cycle starts classically from the infected leaves or branches of the previous season. Spores tend to overwinter on them and easily return to the plant due to lack of cleanliness and habit of using leaves or branches as mulch. They are awakened by rain, humidity from the air or abundant irrigation from above.
It should be noted that the spores must remain moist for several hours before becoming active again. The first symptoms are visible more or less 72 hours after the infection, especially in a hot and humid climate. Secondary infections begin to develop within ten days of primary infection.
This mushroom unfortunately tolerates a wide range of temperatures very well. Symptoms can continue to develop during all seasons, especially if temperatures and humidity are adequate. This unfortunately causes many problems, especially in the central and southern regions where at times the predisposing conditions are present until late autumn and there is a moment of rest only for three or four weeks in the middle of winter.
Hot summers are helpful to block the spread of the disease a little. In fact, above 30 ° C (but often 27 ° are sufficient) the fungus is strongly arrested in its development. It may be a good opportunity to intervene and carefully clean our roses.
The strategies for the prevention of this disease can be multiple and to get good results it is certainly good to try to match them as much as possible.
Choice of plants One of the approaches that gave excellent results was to choose and implant varieties that are proven to be resistant to this fungus. On the market you can find countless very beautiful cultivars that have passed very tough tests of resistance to this and other diseases (powdery mildew, anthracosis, rust, downy mildew).
They are commonly used for flower beds and public areas and are able to give beauty and long blooms without forcing continuous treatments, which are expensive for the community and make the bush less attractive. They are now available in many different bearings and colors. They can therefore satisfy everyone's needs, especially for people who want a well-kept and pleasant garden at almost any time of the year, but which does not become a pressing commitment.
" title="Good cultural practices In winter ">Good cultural practices In winter
For the more susceptible varieties, on the other hand, a precise timetable must be followed to prevent the spread and possibly minimize the impact of this fungus.
The best time to start is autumn. We must first of all collect all the fallen leaves (and also those still present on the branches, if struck). Under no circumstances should these be used for compost production. Instead, they will have to be taken to the municipal reference centers for the collection of the greenery. An even better approach, if allowed by the municipal regulations of one's city, would be to burn them. In this way you are sure to eliminate most of the wintering spores.
It should also be noted that there are no compromised branches. In that case they must also be removed and eliminated in the same way.
Once this preliminary cleaning has been carried out, various strategies can be implemented. First of all it is important to vaporize a good eradicating product on the ground. It may, however, also be sufficient to have a Portiglia Bordolese or in any case a cupico.
If the condition was severe, we can also spray the mixture on all the branches, especially where there is cracked bark. For an even deeper action we can add water to the Bordeaux mixture until it has reached a creamy consistency and then brush it on the branches. In this way the product will penetrate deeper and remain there for longer.
Good cultivation practices during the vegetative period
With the arrival of the warm season we must try to avoid that the leaves remain wet or damp for a long time. Of course the rains cannot be avoided. We must however try never to water our roses from above, wetting the whole hair. We also avoid watering too abundantly: this causes serious water stagnations that predispose in an important way to the onset of the disease.
From spring to autumn it is good to activate by spraying the plants and their base with copper-based products at least every 15 days. The treatment should be repeated immediately after precipitation, especially if it is in a period with temperatures ranging from 18 ° to 25 ° C. The best time to carry out vaporisations is in the morning: the pesticide will dry quickly on the leaf, but the light will not be strong enough to cause damage.
However, the treatments must be interrupted during the hottest months of the summer because during that period the fungus can hardly be active. Furthermore, the presence of copper or other compounds on the leaves in conjunction with strong light and heat could cause damage, in particular burns.
Should the scab appear
It may happen that, despite all our efforts, the problem occurs anyway. In this case you will have to intervene in the shortest possible time eliminating all the leaves (and possibly the branches) compromised. Also in this case it will be absolutely necessary to avoid using them for the production of compost: they will be burned or taken to the specially prepared ecological areas (or placed in the green collection).
Later, a healing and eradicating product must be distributed with the utmost care. These, compared to roofing products such as cupric (which have only preventive purpose), are able to kill the fungus and can also penetrate inside the leaves and the plant acting in depth. It is good, however, not to abuse or use them only in the case of diseases already present to avoid the emergence of resistance.
Some good products that are commonly found on the market are based on mancozeb, myclobutanil, penconazole, zineb, ziram, ferbam, maneb, captano.
Punctuation fungus: Some varieties of roses resistant to scab
Knock-out landscaping, Double Knockout, Pink Knock Out, Pink Double Knock Out, Sunny Knock Out, meidiland sunrise, sturdy, sea foam, the fairy, La sevillana, Bonica, Candia Meidiland
Cayenne hybrid tea and multiflora tea, Mr. Lincoln, Pascali, Tropicana, Queen Elizabeth, Line Renaud, Pretty Woman, Panthìre rose, Acappella, Alexander, Caprice de Meilland, Honoré de Balzac, Nostalgie, Sebastian Kneipp.Pastella, Souvenir de Baden Baden, Bengali,
Rugosa are practically all immune and usually do not require treatments for fungal problems. Some hybrids can be infected instead.
The roses usually most affected by this problem are the modern ones, in particular those with a yellow flower. The sensitivity derives from the Rosa foetida 'Persiana' rose, which has become part of the genetic heritage of many.
Apple scab is a disease caused by the fungus called venturia inaequalis, and also affects plants
visit: apple scab
Like many other plants described in other articles, the rose also has many species and varieties that draw
visit: rose leaves