Brown rust, also known as “leaf rust,” is a fungal disease that affects wheat plants. It causes small, round-oval spots on the leaves, sheath, and stem. These spots are called pustules and are bright orange. The disease spreads quickly in warm and humid conditions and can severely impact the plant’s health.
If the attack is severe, the plant may mature early, have poor root development, and produce light and shriveled grains. Leaf rust is among the most widespread and damaging wheat diseases in many areas. Wheat is a staple food crop that provides a significant portion of the world’s caloric intake. To attain and ensure a high wheat crop yield, it is essential to understand and prevent diseases that can negatively impact its growth and production.
Brown Rust disease management in Wheat
The causal organism of Brown Rust disease
Puccinia recondita tritici is a fungus that causes this brown rust disease of Wheat. Yellow rust disease thrives under conditions of low temperature and heavy humidity. As a result, yellow rust sickness is possible throughout January and February. This illness is more likely to spread in cold and humid climates.
Disease cycle of Brown Rust disease
- Puccinia recondita tritici requires living green plant material to survive.
- It overwinters as dormant mycelium or active sporulating lesions on volunteers or early autumn-sown crops.
- The fungus can survive low temperatures within plant tissue.
- It grows in cool and moist weather in the spring and produces active sporulating lesions.
- Optimal conditions for spore germination, penetration, and new fragment production are 10-15°C and 100% relative humidity.
- Temperatures over 20°C inhibit the fungus, but strains tolerant of high temperatures exist.
- The complete cycle from infection to new fragment production can take as little as seven days in ideal conditions and may be repeated many times in one season.
- Dark teliospores may be produced during late summer, but their function in the disease cycle is unclear.
- Teliospores may contribute to the development of new races through sexual recombination.
Favorable conditions for the spread of Brown Rust disease
- Optimal growth occurs at temperatures between 15-22°C, with free water. Dry and windy conditions can promote the spread of disease, making it difficult to control.
- Late nitrogen applications can also increase the severity of the infection. The fungus is killed at temperatures below five °C and inhibited at temperatures above 25°C, so hot summers and cold winters can reduce its spread.
- The disease has a 7-day optimum cycle in mid to late summer, making it most active during these times. Brown rust is most prevalent in coastal regions with frequent mists, particularly in southern counties.
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Symptoms of Brown Rust disease in Wheat
- At the start of the disease, extremely little (like needle tip) brown or orange pustules (spots) appear on the top surface of the leaves.
- As the disease progresses, these pustules (spots) become thicker and spread as a dark brown hue all over the leaves.
- These pustules (spots) become black in the last stages of the disease, and the sickness stops progressing.
- The disease causes the leaves of the plants to dry up before the harvest ripens.
- The grains of damaged plants become shriveled and tiny.
Percentage of yield loss due to Brown Rust disease in Wheat crop
- Wheat crops as it has a significant impact on both yield and quality. Severe infections can cause significant loss of green leaf area, reducing the photosynthesis rate needed for grain fill.
- It can lead to decreased grain size and weight, reducing yield and lower quality. In addition, the increased rate of transpiration caused by the infection can make the plants more susceptible to drought conditions.
- On average, yield reductions from moderate infections are around 15%, but yield reductions can be as high as 40% in severe cases. It highlights the importance of preventing and controlling brown rust to ensure high-quality wheat crops with maximum yield potential.
Brown Rust disease management in Wheat by Cultural methods
- Mixed Crop cropping with suitable crops.
- Avoid excess doses of nitrogenous fertilizers.
- Plant resistant varieties
- Use 3–4 different kinds of Wheat on each farm at once.
- Avoid late sowing or late maturing varieties.
- Avoid excess irrigation
- Optimum nitrogen and potassium application
Brown Rust disease management in Wheat by Biological methods
- Early sowing refers to planting crops earlier than usual, resulting in increased yield due to more favorable growing conditions and reduced disease incidence.
- Mixed cropping involves planting different crops in the same field, which can help improve soil fertility and reduce pest and disease pressure in brown rust disease.
Brown Rust disease management in Wheat by chemical methods
- High-risk crops with leaf-spray fungicides in early spring.
- Fungicides that can be used to protect crops from brown rust include azoles (DMIs; for example, prothioconazole), SDHIs (for example, bixafen), strobilurins (for example, pyraclostrobin), and spiroketalmines (for example, spiroxamine). These fungicides are often mixed.
- Spray 2.5 kg/ha of Zineb or 0.1% of Propioconazole.
- Spraying Dithane Z 78, Dithane M45 or Tilt are fungicides that can help control brown rust diseases in wheat crops. Applying 2-4 sprays at 0.2% concentration can help prevent crop loss due to disease.
- Comet 200 is a strobilurin fungicide that effectively controls rust diseases in Wheat.
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Brown Rust disease management in WhWheaty natural/organic methods
- Spray 5 liters of sour buttermilk mixed with 200 liters of water on the crop to protect it against rust infestation.
- To prevent rust infection, use amaranth (chaulai or lal bhaji – a popular green leaf vegetable) or Mentha (Pudina) leaf dust as a thin spray (25- 30 gm dry leaf powder per lit of water).
- A foliar spray of Hibiscus rosa-sinensis (China rose) dry leaf extract can also help to avoid rust infestation.
Conclusion
Brown rust disease in whWheatan be managed through a combination of approaches, including monitoring for symptoms, using chemical and biological fungicides, implementing natural and organic control methods, and rotating crops. The best approach depends on the severity of the infestation and local conditions.
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