Sometimes, the buds on the rose bushes turn black. This disease is called gray rot and it is caused by a fungus that appears on young parts of rose shoots, buds and this year’s leaves. This fungus can be in the soil, last year’s dry leaves and get on plants through seedlings for years. Gray rot spreads in cool, wet weather, with thickened planting, an excess of nitrogen fertilizer, and strong soil compaction.
Excess moisture can be not only as a result of frequent and endless rains, sometimes there are very large dews, after watering, drops of water can remain on the young branches of roses, and the air temperature drops over the course of several days.
Fight against gray rot
It is necessary to immediately cut the affected shoots of roses with a knife or scissors, grabbing a little healthy tissue of the plant. The cut should be treated with garden broth or not cold boiled milk.
First, water the ground under the diseased bush with plain water, then spray it with a fungicide containing copper: copper sulfate, and other analogues. It is necessary to treat roses with fungicides from early spring to late autumn for preventive purposes. From time to time it is necessary to change the drugs among themselves so that addiction does not occur.
Blackening of shoots on a rose bush can be caused by a lack of boron. If the plant does not receive boron, it can easily get sick with various bacterial diseases, because it helps calcium to be assimilated in plants. Roses are very responsive to the lack of this element, the ovary and unbloomed buds begin to fall, and the top of the shoot dies. But if you regularly feed the rose bushes with the necessary trace elements and boron, the plants will thank you with lush blooms.
You can use, as a quick aid, a solution of ordinary pharmacy boric acid. To do this, dilute 1 gram of the drug in 1 liter of warm water. This procedure is carried out when the roses begin to form buds and bloom.