La roya is a fungal disease A very common disease that affects ornamental and horticultural plants. It is easily identified by the appearance of orange pustules on the underside of the leaves and, over time, darkening to brown or black tones. The affected leaves eventually fall and the plant weakens when its photosynthesis is compromised; new shoots may appear reddish spotsThere are multiple species of fungi responsible, with preferences for different plant families; for example, it is common in roses, and also in the group of alliaceae (garlic, onions, leeks).
In addition to being highly visible, rust is a disease with a complex biological cycle: some species complete the cycle on a single host plant, while others alternate between two different hosts. Under moisture y mild temperatures, the spores germinate rapidly, are dispersed by wind or contact, and colonize neighboring leaves. Although it rarely kills the plant on its own, it significantly reduces the vigor, the flowering and production of fruits, and predisposes to other pests and diseases.
TO PREVENT ITS APPEARANCE:
Remove the parts from the plant that is already there affected for the disease to prevent its spread.
Avoid getting wet the top of the plant during watering.
Respect planting spaces of the plant to avoid accumulations that hinder the correct aeration.
Respect the cultivation calendar and use resistant varieties and appropriate for your area.
Create the greatest possible diversity in the orchard and garden to hinder the appearance of diseases. This can be encouraged by crop association.
Perform preventive fumigations to ecological fungicides that help fight the disease. The same can be used prepared that in the case of powdery mildew and downy mildew. Since the leaves do not cure, it is advisable protect the new growth, flowers and fruits.
PREVENTION AND DETECTION
The most important thing to avoid major damage is the prevention and early detection. As with people's health, prevention is better than cure in the garden. Plan a inspection routine weekly to carefully observe leaves (especially the underside), stems, shoots and fruits, looking for orange pustules, chlorotic spots on the upper surface, spore dust or dark lesions in advanced stages.
The conditions that most favor rust are: persistent humidity on foliage and mild temperatures. Therefore, prioritize the drip irrigation or directed to the ground, waters to first hours so that excess moisture evaporates quickly and avoids wetting the leaves. Ensures ventilation between plants (wide planting frame) and avoids the excess nitrogen which produces more susceptible tender tissues.
Other key cultural measures: cleaning up debris pruning and fallen leaves, especially at the end of the season; disinfection of tools; crop rotation in the garden; select healthy plants when purchasing and checking the transplants very well. The plant diversity reduces the speed of propagation and inoculum pressure.
At the slightest suspicion, remove diseased leaves and do not compost them If you are unsure of reaching temperatures capable of inactivating spores, it is preferable to dispose of them separately.
Rust on plants
Also called rust, rust is a disease caused by fungi that forms circular spots and rust-colored pustules measuring 1 to 3 mm, usually on the underside of leaves. While on the plant, they produce spores that are easily dispersed by wind, splashes, or contact. To strengthen your defenses and learn more, you can check out our article on plagues and diseases in general.
During periods of high humidity, their activity is at its peak. In many areas, the greatest pressure occurs from the beginning of the growing season until the end of the season, coinciding with periods of higher environmental humidity and excessive watering on the foliage. Especially in the Alliaceae family (garlic, onions, leeks), rust is recurrent: first small spots appear; then the leaves become covered with a orange powder which later becomes dark crust and the leaf ends up drying out.
Pustules are often located on the underside of the leaves, but they can also appear on the upper and lower surfaces. stems. In some hosts, yellow, orange, brown or even blackish tones are observed. The affected areas turn yellow or brown and the leaves turn deform and fall off. In heavy infestations, the foliage may become dark in appearance widespread rust.
Despite its aggressiveness, rust is rarely lethal on its own. However, it does reduce the flowering and the performance In crops, it increases vulnerability to other diseases and negatively affects the appearance of plants. The key is in act quickly and combine good cultural practices with treatments.
How to combat rust
Many plants produce natural compounds with some antifungal action, but when there is low diversity or the plants are weakenedThe fungus takes over easily. Therefore, the first step is to strengthen the system: ventilation, proper irrigation, balanced nutrition, and stress management. For additional information, we recommend consulting our section on April sayings containing useful tips.
When infection appears, immediately remove the affected leaves (also those that fall on the ground) to reduce the amount of spores. Disinfects the tools after use and avoid working with plants when they are wet (spores spread more). Keep a planting frame wide so that air can circulate and the aerial part of the plant does not remain wet.
If the infection is localized, cultural measures are sufficient and preventive treatments soft. If it is more widespread, combine sanitation with specific treatments. Whenever you try a new preparation, perform a test on a small area and apply early in the morning or at dusk to avoid unwanted reactions due to sun and heat.
As a general principle of Integrated Management, prioritizes preventative measures, monitors, acts locally, and uses lower-impact treatments first, reserving more specific formulations for higher-pressure scenarios or in high-value plants.
Rust home treatment
A useful homemade mixture is the bicarbonate with oil, which can alter the microenvironment on the leaf surface and hinder fungal development. Mix in a spray bottle 1 liter of water, 1 teaspoon of baking soda y 2 teaspoons olive oil. Optionally, add a few drops of potassium soap to emulsify better. Apply to affected leaves and repeat after 2-3 weeks If necessary.
Rust ecological treatment
The most widespread ecological way to control rust is to use Bordeaux mixture or others copper authorized. They have action of preventive barrier and help limit new infections; they do not heal already damaged tissue, so they must be applied to protect new growth, flowers, and fruits. To delve deeper into ecological options, consulting natural technologies can be very helpful when planning your protection.
Other interesting ecological resources are: vegetable extracts such as nettle slurry and Horse tail, which strengthen the plant and improve its response. Regular preventive application can help contain fungal pressure. To enhance their effectiveness, also check out our article on what to do about pests and diseases.
Whatever product you choose, alternate modes of action whenever possible and avoid repeating the same active ingredient too many times in a row, to reduce the risk of resistance.
Synthetic treatments: when to consider them
In severe infections or in high value plants, it may be necessary to resort to synthetic fungicides authorized for rust in the crop and ornamental species in question. There are formulations with action preventive and stop on early infections. The key is to start treatment as soon as the terms whether favorable or when observing first symptoms, and cover the front and back of the leaves well.
Always read the label and follow the instructions: crops and species that can be treated, dosage, frequency, safety period for edibles, compatibility, and personal safety measures. For more information, also see our article on .
Rose rust (Phragmidium spp.)
Rose rust is specific to roses. Appear starry spots between yellowish brown and black on the upper surface, and orange pustules on the underside (often of 0,5 to 1 mm), which can converge. With progress, it produces premature defoliation, even completely stripping the plant in severe cases. The stems can also become infected, with lesions that compromise flowering.
La moisture greatly favors its spread. The pathogen winter in leaves and tissue remains of the rose bush itself, so the hygiene At the end of the season, it is critical to remove and discard fallen leaves and prevent them from spending the winter under the plant.
Recommended measures: avoid wetting the foliage when watering, improve the ventilation By pruning and planting frame, remove diseased leaves immediately, and protect the new growth with preventative fungicides (organic or authorized synthetic). Consider rose varieties with tolerance to rust if your area is prone.
Characteristic symptoms and reading of the plant
The most distinctive signs to quickly recognize rust are: orange pustules on the underside, spots chlorotic on the upper surface and, in advanced stages, dark pustules. In roses, the pustules on the underside may coalesce; in geraniums, tan pustules are observed below and yellow circular spots above; in hydrangeas, areas coppery on the beam and pustules orange-reddish on the back. The premature fall Foliage loss is common as the infection progresses, reducing photosynthetic capacity and severely weakening the plant.
Rust in lilies and alliums (garlic, onions, leeks)
In these vegetables, rust follows a typical pattern: small spots in leaves at first, which evolve into a covering of orange powder and finally, dark scabs with the leaf drying up. The loss of leaf surface affects the fattening of bulbs and their quality. To prevent their proliferation, you can also consult the information at How to prevent fungus in plants.
What exactly is rust?
An endoparasite easy to identify. Its ability to persist lies in its spores, which can remain viable for weeks and travel long distances transported by the aireOnce the spore is deposited on a moist leaf, it germinates and penetrates through the cuticle and epidermis, developing internal structures that extract nutrients and produce new spore-filled pustules. For a full analysis, check out our article on what's wrong with your plant.
How does it affect the plant (symptoms)?
It mainly attacks the leaves, although it may affect stems and tender shoots. Symptoms include small, brown bumps reddish, yellowish or orange, chlorotic spots on the upper surface and, as the disease progresses, dark lesions appear. In severe attacks, the plant may suffer premature defoliation from the lower leaves upwards, and the general weakening compromises flowering and harvest.
How to treat it?
Beyond cultural measures, other measures can be applied: fungicides authorized for rust in each crop. In organic gardening, the most notable are copper and fortifying extracts; in severe scenarios, synthetic products are used, following the instructions to the letter. labelSome growers use specific commercial formulations (for example, products like Beltasur in certain contexts), always respecting approved uses, doses, safety intervals and current regulations.
Rust on cannabis plants
Rust can also affect cannabis, especially during rainy periods in spring or autumn. The strategy is the same: prevention (ventilation, watering without wetting the leaves, removing affected leaves) and, if necessary, use of fungicides registered for cultivation and the legal environment in your area. Since floral tissue is sensitive and intended for consumption, take extreme caution with the products and safety deadlines It is essential. Many growers prioritize options ecological and rigorous sanitation, reserving other tools for early vegetative stages when appropriate and the label allows.
Quick practical tips
- Irrigation: Prioritize drip or foot irrigation; avoid wetting leaves. If you do water, do it early.
- Health: Remove diseased leaves and debris from the soil; do not compost them if you don't reach adequate temperatures.
- Spacing: respect planting and pruning frames to improve ventilation.
- Monitor: Check the underside of the leaves weekly; at the first orange spots, act.
Effective rust management combines early detection, hygiene, ventilation, adequate irrigation and, when necessary, preventive or shock treatments. By understanding their favorable conditions and cycle, you can cut the progression before it compromises flowering, garden vigor, or harvest.