Content
Gray rot on roses is a fairly common phenomenon that both experienced and novice gardeners encounter. It leads to a decrease in the decorative value of the shrub, weakening its immunity to unfavorable external factors, which can cause the plant to freeze in winter. Therefore, it is important to be able to recognize the disease at the initial stage in order to take timely measures to treat it.
Gray rot can affect not only roses, but also other garden crops
Signs of gray rot on roses
The causative agent of this disease is the fungus Botrytis cinerea. Pathogens persist on plant debris and soil. It is extremely difficult to confuse gray rot with other rose diseases, since it is characterized by specific symptoms. Initially it affects the buds. Subsequently, the disease spreads to the peduncle, leaves, shoots and ultimately spreads to the root, which already leads to the death of the bush.
A characteristic sign of gray rot are brown spots, which increase significantly in size every day. A week after their appearance, a gray fluff-like coating appears on the affected areas, which indicates sporulation of the fungus. And after this, black sclerotia of an oval shape are formed, inside which the pathogens of gray rot overwinter.Moreover, they can remain on the bushes or get into the top layer of soil.
Affected leaves and shoots gradually dry out. When gray rot develops, the buds die without opening. Because the mycelium covers them completely, which leads to their mummification. If flowers are damaged, whitish spots first appear on the petals, which subsequently darken. As a result, they are completely covered with an unsightly coating, turn yellow, become deformed and rot.
Causes
The causative agent of the disease is activated by a combination of high humidity and sudden temperature changes. Basically, the disease on roses begins to develop at the end of summer, when rains and heavy dew begin and the temperature drops at night.
Main provoking factors:
- dense plantings of shrubs, which leads to insufficient ventilation;
- lack of nutritional components in the soil due to lack of fertilizing;
- violation of the integrity of shoots and leaves due to poor quality pruning and treatment of open wounds.
Excess nitrogen in the soil can also provoke the development of gray rot.
How to deal with gray mold on roses
Every gardener should understand that saving roses from gray rot is possible only at the initial stage of development of the disease. In the future, all applied methods of struggle will not bring the desired result.
Initially, it is necessary to cut off all affected areas to healthy tissue. After this, they must be taken outside the site and burned. Next, you need to treat the roses with Previkur Energy or Fundazol. Moreover, it is recommended not only to spray the bushes, but also to water them to ensure maximum destruction of fungal spores.The procedure must be repeated 2-3 times every 5-7 days.
Prevention measures
Having studied the signs and methods of treating gray rot on roses, you also need to familiarize yourself with preventive measures. They are unable to completely eliminate the likelihood of damage to bushes, but they reduce this likelihood to a minimum.
Roses should not be planted next to grapes, cabbage, strawberries, or tomatoes.
Among them:
- Correct landing. Roses should have the opportunity not only to fully develop, but also to be well ventilated. Therefore, it is recommended to plant them at a distance of 50 cm from each other.
- Choosing a suitable location. For roses, a sunny, open area where moisture does not stagnate in the soil is suitable. In addition, the place must be protected from cold gusts of wind, and the groundwater level must be at least 1 m.
- Timely feeding. Only strong, healthy bushes can resist pathogens. Therefore, it is important to fertilize taking into account the stage of development of roses. At the beginning of the growing season, you can use fertilizers with a high nitrogen content, and during the summer and autumn, plants need more potassium, phosphorus and magnesium.
- Loosening the soil. The causative agents of gray rot lose activity in well-drained soil. Therefore, it is recommended to loosen the soil at the base of the bushes after each watering or rain to ensure air access to the roots. It is also necessary to promptly remove weeds to improve ventilation.
- Pruning roses. To prevent gray rot, it is necessary to promptly prune dried shoots and wilted flower stalks.
- Proper watering. Roses should not be irrigated with cold water.For irrigation, you can use settled water at a temperature of +20-23 °C. In this case, moistening should be carried out at the root, avoiding moisture on the leaves and shoots of roses.
Resistant varieties
There is an opinion that white varieties of roses are more susceptible to gray rot. However, this disease also spreads to shrubs with other shades of flowers. But among the many varieties, there are some that have increased resistance to the causative agent of gray rot.
These include:
- Eliza. Hybrid tea rose with elongated ovoid buds. The flowers are double, bright pink, their diameter when fully opened reaches 9-11 cm. The height of the bush is 100 cm and the width is about 60 cm. Young shoots grow well.
Eliza is also resistant to powdery mildew and black spot
- Fortune. A rose belonging to the floribunda category. Characterized by lush flowering. The buds are resistant to rain. The flowers are single, with salmon-pink petals and a white center. The height of the bushes reaches 50 cm. Flowering is almost continuous throughout the season.
Rose Fortuna is suitable for flower beds and mass plantings
- Hercules. A German scrub variety that was bred in 2007. Characterized by branched bushes with arched, drooping shoots. The flowers are densely double, lavender in color with a rich aroma. In humid weather, the buds do not open completely.
Hercules is distinguished by abundant flowering
- New Dawn. Belongs to the category of the most popular climbing roses all over the world. The variety was developed in the USA in 1930. Flowering occurs in clusters, which consist of silver-pink buds.The height of the bushes is 2 m, but under favorable conditions the shoots can reach five meters in length.
The New Down variety tolerates depleted soil and partial shade
- Topolina. This miniature rose was bred at the end of the last century in Germany. Characterized by compact, dense bushes with glossy dark green foliage. The flowers are simple. Open, pink with a yellow center. This rose has increased winter hardiness.
The Topolina variety self-cleans well
Conclusion
Gray rot on roses appears when there are favorable conditions for the propagation of the pathogen. Therefore, by organizing proper care, you can prevent its occurrence. However, it is worth considering that even resistant varieties after the age of five become susceptible to the fungal pathogen, since the pathogen adapts over time.
