Infectious burn or cancer stem roses.
Spring on old wood roses may appear brown spots with sunken surface and thickened edges. Spots dry up, bark cracks escape, shoots roses die above the affected places - these are signs of infection burn roses.
The causative agent of infectious burn roses is the fungus Coniothyrium wernsdorffiae. Often, this fungus infects the plant, if it has been overfed with nitrogen. The fungus can get into the fabric roses through wounds on the stems (beware of mechanical damage to the bark of shoots of roses), and during the autumn crop, and then distributed throughout the plant from top to bottom.
Winters fungus Coniothyrium wernsdorffiae in the plant or in the soil. Resistant to infection burn varieties of roses yet. And do not try to treat stem cancer has spread to all shoots shrub roses - seriously sick plant to be burned.
Some authors have suggested with a weak defeat the stem roses to treat cancer patients shoots: to clean (scrape) the lesion garden knife or scalpel, put on them tetracycline eye ointment or paste of garlic, to impose a plantain leaf (or sorrel) and fix plaster. The tool should be disinfected with alcohol (vodka) or a thick solution of potassium permanganate (potassium permanganate).
However, such treatment is justified only if the rose bush stricken with only one or two shoots. Indispensable condition to avoid infection of burns is hiding roses for the winter in dry weather. Autumn, before the shelter roses, you need to cut nevyzrevshie shoots and burn them, to break from the bush leaves.
Fungus pathogen cancer most intensively developed under dark winter shelter, especially at high humidity and high temperature. In the spring, after removing the cover with roses, it is necessary to carefully examine the shoots of bushes - ringed spots cancer shoots should immediately cut (with the capture of a healthy part of the shoot) and burn as a disease-causing fungus is inside the tissue.
For the prevention of cancer stem roses should:
- Avoid pereudobreniya plants with nitrogen;
- Conduct fertilizing roses potash to strengthen the tissues of shoots;
- Timely and ventilate the shelter rose bushes during winter thaws;
- Promptly remove cover roses in the spring;
- Trim and destroy the affected cancer shoots.
After spring pruning roses need to sprinkle the bushes with copper sulfate solution (1%).