How to treat roses against rust at home

Rust is a dangerous fungal disease that can quickly overwhelm a large rose plantation and is difficult to eradicate. Unfortunately, it is a common disease, ranking second only to powdery mildew in terms of incidence of rose damage.

Causes of rust

The disease is caused by several species of fungi of the genus Phragmidium – P. disciflorum, P. rosae-pimpinellifoliae, P. tuberculatum, the spores of which are spread by wind and insects.

Rust develops most actively on bushes in the spring, when nature provides the best conditions for fungi—warm, windy weather and frequent rainfall. Even without precipitation, the fungus can awaken, triggering heavy dew due to the large difference between day and night temperatures. The disease often affects greenhouse roses.

In summer, with the onset of hot weather, fungal activity ceases, but if the season is rainy, the disease will quickly progress on the bush and spread to neighboring plants. Spores survive the winter well on plant stems, fallen leaves, or in the topsoil.

Symptoms

Typically, the first signs of rust infection are visible on bushes as early as mid-May. Bright orange formations resembling pollen pads appear first on the stems, and later on the undersides of the leaves. These are clusters of aecidospores, which will darken by the end of August, indicating the fungus has entered a dormant stage for overwintering.

The rusty spots enlarge over time, spreading across the leaf, and the layer of plaque thickens—the growths grow upward, taking on a "columnar" shape. The disease can also affect petioles, peduncles, and rose buds, but most spots will appear on the leaves.

Due to fungal activity, the plant's photosynthesis and, consequently, metabolism are disrupted, and intense moisture loss occurs. Tissues in areas affected by rust thicken, and shoots, leaves, and buds become deformed. Leaves dry up and fall off, bushes weaken, lose resistance to adverse factors, and stop blooming. Stems in damaged areas crack, which can lead to the death of the rose.

Rust treatment

If signs of rust are detected on rose bushes, a multi-step treatment will be required, and even if all the required steps are taken, it is not always possible to completely eliminate the fungus.

Treatment regimen:

1. Immediately after the disease is detected, the bush is inspected and all leaves and buds affected by the rusty bloom are removed. Affected shoots are pruned back to healthy tissue, with a margin. This procedure is repeated as new rusty spots appear on the bush until the plant is completely cured. All cut parts of the plant should be burned.
2. After the first pruning, the bushes need to be treated with copper-containing products.
3. During the remaining time until leaf fall, roses should be regularly sprayed with fungicides. Due to the ability of fungi to develop resistance to the active ingredients of these products, it is recommended to use a variety of products.
4. Before wintering, regardless of the condition of the plant, it is necessary to cut all shoots on infected bushes (not only those where rust spots were found) to the level of the third bud from the base.
5. After the leaves have fallen, thoroughly clean the flowerbed, clearing it of plant debris (leaves, weeds, annuals, etc.). If there are still leaves on the bush when you install the winter cover, you should remove them yourself.
6. The top layer of soil under the roses needs to be replaced and a fresh layer of mulch put on top.
7. After removing the covers in the spring and sanitary pruning of the bushes, it is necessary to spray with copper-containing agents.

Folk remedies against rust

In the early stages of the disease, folk remedies should be used. In addition to copper-containing products, treatment with sulfur and highly alkaline soap are useful for treating rust. If the disease does not progress, switch to spraying with milder herbal infusions, which should be continued throughout the season, even if no new spots appear on the rose leaves.

• Copper sulfate solution. Dissolve 50 grams of copper sulfate in a liter of hot water. Dilute the resulting solution with 4 liters of cold water. This is a 1% copper sulfate solution. You can add 50 grams of laundry soap to this amount.

• Bordeaux mixture. Prepare a 2% solution of copper sulfate (100 g per 5 liters). In a separate container, dissolve lime in a small amount of water (twice as much as copper sulfate, i.e., 200 g), stir, and add water to bring the solution to 5 liters (that is, to an equal volume with the copper sulfate solution). Then, pour the copper sulfate solution into the lime solution, stirring constantly. This will produce Bordeaux mixture with a concentration of 1%.
• Sulfur solution. To prepare 10 liters of the solution, you will need 30 g of ground sulfur. A mixture of sulfur and slaked lime can also be used. Allow 10 days between sulfur treatments, with a total of three sprays allowed.
• Soapy water. Dissolve 400 g of laundry soap (2 bars) in 10 liters of hot water and let the solution cool. This solution can be used for 1-1.5 months, with 2-3 days between sprays.
• Wormwood infusion. In a plastic or wooden (but not metal) ten-liter container, steep 400 g of chopped green plant parts (the raw material must be fresh). The minimum steeping time is 24 hours. This is sufficient if the infusion is being used for soil treatment, in which case it should be poured onto the rose. To treat a bush, let the infusion sit for 14 days, strain, and use, diluted 50/50 with water.
• Nettle infusion. Prepared in the same way as wormwood infusion, but require a larger amount of nettles (half a bucket of nettles per 10 liters of water), and add hot water. The nettle infusion should be steeped for about 48 hours (longer is possible) and should only be used for spraying.
• Horsetail infusion. 1 kg of chopped fresh horsetail is steeped in 10 liters of water for 24 hours, then boiled for half an hour, cooled, and strained. For spraying rose bushes, dilute the infusion with water at a ratio of 1:10.

Chemicals

If folk remedies do not produce a visible effect and the disease continues to progress, the use of chemical fungicides is required.

Rules for choosing a product:

1. Good copper-based products for treating and preventing rust include Ordan, Abiga Peak, HOM, or Oxyhom.
2. Minor lesions on the bush can be treated locally with Skor or Topsin-M.
3. In advanced cases, you should spray the rose bushes with Propiconazole, Strobi, and Topaz.

Prevention

Fungal spores can be carried long distances by the wind. The health of plants in your garden and neighboring plots is no guarantee that rust won't appear on your rose bushes. Therefore, rust prevention, especially preventing recurrences, should be a crucial part of rose care.

Preventing rust from reappearing

You should begin taking steps to protect your plants from the beginning of spring and continue them until you cover your rose bushes for the winter.

1. Before bud break, spray the plants and the surrounding tree trunks with a 3% ferrous sulfate solution. You can also treat with HOM or Oxychom fungicides.
2. In May, before flowering, another fungicide treatment should be carried out. "Falcon" has proven itself effective for this purpose.
3. If the disease does not appear, spraying is repeated at the end of July or the beginning of August.
4. The final treatment is carried out before installing the shelters, using iron sulfate (3%).

In subsequent years, if rust doesn't recur, you can treat the bushes with wormwood or horsetail infusions. Spraying with herbal remedies should be done more frequently than with chemical solutions, approximately every two weeks, and repeated during periods of precipitation. During rainy periods, copper sulfate is preferred. Iron sulfate is also recommended for the first and last treatments of the season (before and after winter sheltering).

Resistant varieties

Even fungus-resistant rose varieties can be affected by the disease if weather conditions during the current season are favorable for its development. However, the risk of rust affecting these rose varieties is significantly lower:

• Rosarium Uetersen;
• "Jean Cocteau";
• "Elisa";
• Perennial Blue
• Tequila
• "Bel Ange";
• «Virgo»;
• Morena 2002;
• "Sahara";
• "Rosenfee";
• "Santana";
• "Dame de Coeur";
• "Guirlande d'Amour";
• «Isarperle».

General recommendations

To prevent rust:

1. The plant should receive a complete potassium-phosphorus fertilizer, as well as micronutrients, primarily boron, calcium, magnesium, and iron. It's advisable to apply phosphorus foliarly before flowering, as this will enhance the plant's defense against fungus.
2. High-quality hygiene in the flower garden is required: removing fallen leaves in the fall and weeds throughout the season, sanitary pruning, and disinfecting equipment.
3. You can plant garlic, marigolds, yarrow or wormwood between the rose bushes.
4. You should refrain from watering roses using the sprinkler method.

Even if treatment has been successful and all possible overwintering sites for spores (fallen leaves, soil, and affected plant parts) have been eliminated, under favorable conditions the fungus often returns to the garden the following year. Therefore, it is advisable to destroy plants that are highly susceptible to the pathogen and have been affected for several years.