Garden

Roses with parasites


Question: what do my roses have?


how to cure pink with white spots like mold

Roses with parasites: Answer: rose diseases


Dear Anna,
from your explanation it is not easy to decide what parasite is, especially without seeing a photo. There are two parasites that produce white molds on roses: powdery mildew and leafhoppers.
Powdery mildew, also called mal white, is a typical rose disease, it is a fungus, which gives rise to leaves, buds and buds, to a thin white powder, similar to flour to be seen, which actually creates a true felt layer on the affected organs, which dry out over several weeks. This disease seems to develop more in the spring and autumn months, with a cool and wet climate; tends to develop less in summer, with high temperatures, or on plants exposed to direct sunlight; above all because these mushrooms like to develop in the water that remains deposited on the foliage, which generally is not present in the middle of summer, or which in any case tends to dry quickly. Against the oidium generally the preventive struggle is practiced: the plants are watered to level of the ground avoiding to wet the foliage; position the plants so that they enjoy good ventilation; roses and some vegetables are treated with sulfur, but only when the temperatures are around 15-20 ° C, not when they are higher, because sulfur could be toxic to plants. There are also "home" remedies that seem to work even on plants already affected by powdery mildew; the most popular is to add a couple of teaspoons of baking soda to a liter of water, and use the solution to vaporize the leaves attacked by the parasite.
The leafhoppers are insects instead (they are not real cicadas, but since they resemble the cicadas, the most common common name is this, or also metcalfa pruinosa), of minuscule size, which can be noticed especially shaking the plants, because the adults jump everywhere. They tend to develop in late spring and in summer; they feed on the sap by piercing the leaves, leaving almost silvery spots; in addition to this, small heaps of whitish substances can be seen on the plants, especially on the twigs, at the leaf axil: these are often heaps of eggs. They are insects that must be eradicated as soon as they are seen, because, even though they generally do not cause serious damage to crops, they are often vehicles of viruses and bacteria, which instead can cause very serious diseases to plants.
Special insecticides are used against metcalfa and leafhoppers, which you can find in any well-stocked nursery.