It must be said that many diseases affect primarily young and weakened plants, plants for which are not carefully and not properly cared for.
Powdery mildew
The causative agent of fungi of the genus Oidium, Sphaeroteca, Microsphaera, etc. - a common fungal disease. This disease not only weakens and depresses the plant, but often leads to death. It manifests itself in a characteristic white (flour-like) coating on the leaves, mainly on their upper side, then on the stems and buds. Contributes to the disease poorly ventilated room, excessive fertilization and crowding of plants.
Control measures. In diseased plants, remove affected shoots, leaves, buds. If the disease has spread strongly, covered all the leaves, it is easier to cut all the shoots to the root, leaving 5 cm of hemp. After that, be sure to spray everything that remains after pruning with Topaz, also spray the earth and walls of the pot. In addition to topaz, other drugs can be used, for example, fundazol. Dilute fungicides according to the instructions and be sure to re-spray.
Downy mildew
The causative agent of fungi of the genus Peronospora, Plasmoparma, etc. - it is easy to confuse with the previous disease. The difference is that with false powdery mildew, a white fluffy coating of fungal spores covers mainly the underside of the leaf. And on the upper side of the leaves you can see light or purple spots. Downy mildew spreads primarily through wet leaves.
Control measures. Affected shoots, leaves, buds are removed from diseased plants, the plant is treated with a fungicide, and each time it is better to treat the plants with different fungicides in order to exclude the emergence of resistance (addiction) of fungi to the drug. Usually 2-3 treatments are sufficient.
Rose spots
It is rather not one disease, but a group with similar symptoms, pathogens, both fungi and bacteria. At the same time, spots appear on the leaves of the plant, which grow in size with the spread of the disease, merge and affect the entire leaf. Spots can be dry or wet, along the edge or over the entire surface of the sheet. In roses, this disease is more often manifested in the second half of the vegetation, this is facilitated by increased humidity of the air and soil, thickened crown, poor ventilation of the room, dense caked (not loose soil in a pot.
Control measures. Removal of affected leaves and shoots. Spraying with any copper-containing drugs (oxychom, xom, copper sulfate, Bordeaux liquid) or sulfur-containing drugs (colloidal sulfur, thiovit-jet, mankoi, tiram), regulating irrigation and stopping spraying with ordinary water until recovery. Usually 2-3 treatments (including soil surfaces) are required. Note that all fungicides containing copper leave blue or blue stains on the leaves.
Rose rust
With this disease, pustules are formed on the back of the leaf, which can be completely different colors - from red or orange to dark brown, they protrude above the leaf like warts or papylomas, always round. The upperside of the leaf develops brown spots over time.
Control measures. Remove all suspicious leaves as early as possible. Spraying with fungicides designed specifically to control rust fungi, such as topaz. Rose rust contributes to the content in a poorly ventilated room, with high humidity and high air temperature.
Rose pests
Rosanna aphid
A pest that affects both leaves and buds. Shoots and leaves are twisted, covered with sticky aphid secretions, on which sooty fungus settles. It all looks like dandruff or flakes on the plant, flowers and buds are deformed. The damaged parts discolor, the leaves curl, turn yellow and fall off. The plant is severely depressed and stops normal development. Buds do not open, flowers are polluted by secretions. Aphids are especially dangerous in spring, affecting the tips of young shoots. At home, roses can become infected through garden land or with plants from the store.
Control measures. Remove all affected shoots, wash the foliage 2-3 times with soap solution. Then spray and water the bushes with the solution of the actar preparation. If the lesion is very strong, for example, from cuttings cut in a garden where aphids are rampant, then it is better to soak the actellic in a solution (20 drops per 1 liter of water).
Spider mite
Previously, it was believed that the appearance of ticks is facilitated by too dry and warm indoor air, however, this opinion has been debunked by many years of experience: roses are affected by ticks in any climate, with any humidity, they simply have an extremely high susceptibility. But in dry and hot conditions, ticks multiply many times faster than in cool and high humidity, literally in 3 days they can damage a whole rosette bush in a pot. Ticks hide on the underside of the leaf, in the axils of shoots and buds. The surface of the damaged leaves is first covered with pale dots - places where cell juice is sucked out, but later they increase, continuous whitish spots form, the leaves curl and fall.
If you are not sure if there is a tick on the roses, take a magnifying glass and examine the back of the leaf - you can see the skins from the molting of ticks (whitish husks), or the ticks themselves: they can be almost invisible - gray, or yellow-red, brick color or dark brown (variety of many species).
Control measures. Against ticks, drugs of the insectoacaricides or acaricides class are used - actelic, neoron, phytoverm, apollo, vermitek, Etisso Blattlaus-Sticks (stuck in the ground) and others. Since ticks have high resistance (resistance to chemistry with each new generation), drugs need to be changed or alternated. If you buy a rose in a store, bring cuttings from the garden, root a rose from a cut (bouquet), the probability that it has a tick is about 90%, if not more. Therefore, prevention is simply mandatory: spray the leaves very carefully from all sides with phytoverm. Another method of prevention is regular hot showers. Roses tolerate contact with hot water of 53-55 ° C very well. Under strong pressure from the shower, water washes away ticks, eggs, cobwebs. If you carry out 4-5 procedures in a row, you can get rid of ticks without chemistry. Read more about ticks.
Thrips
This pest comes to us, most often, with garden flowers and from bouquets. And high temperature and low humidity contribute to their faster reproduction. At home, trips can harm roses all year round, but especially during the spring and summer period.
Leaves damage thrips, flowers flower buds. As a result of their activity, silvery spots similar to small hatching appear on the upper side of the leaves. With mass damage, the entire surface of the leaf becomes whitish and discolored, and in addition, black shiny pest excrement is visible.
Control measures. The plant should be washed with green or tar soap from the secretions of the pest, remove the most damaged leaves. Then spray and water with a solution of the drug actar or confidor - these systemic drugs are most effective against thrips .