Brown Rust of Wheat and its Managements

Ahsan Raza*, M Zeeshan, Ayesha Fatima

ISLAMABAD: Wheat is one of the most important staple crops globally, providing essential food products like bread, pasta, and baked goods. It is rich in carbohydrates, proteins and essential minerals. There are several varieties of wheat with distinct characteristics and uses such as hard red wheat, soft red wheat, durum wheat, and soft white wheat. it is grown in a diverse range of climate that is in temperate to tropical regions. Pakistan is the eighth largest producer of the world with annual production of 28.161 million tons.

Wheat is susceptible to a wide range of diseases that include rust, smut, powdery mildew and cause significant yield losses. Wheatrust is one of the most damaging fungal diseases and have three types which includes blackrust, brownrust, and yellowrust. Among these rust, brown rust caused by the fungus Puccinia triticina, is one of the most destructive diseases affecting wheat. It causes 30-50% crop losses in wheat.ECC approves 0.3m wheat import from Russia

Symptoms of brown rust appear as presence of orange-brown pustules on the upper surfaces of leaves, stems, and sometimes even the heads. These pustules are filled with spores, which are released into the air to infect other plants. Initially, the symptoms appear as small, yellow or pale spots on the leaves, which gradually enlarge as the infection progresses. As the disease develops, the affected areas turn a characteristic rusty orange-brown color, giving the plant its name. These pustules often rupture, spilling spores onto surrounding plant tissues, which leads to further infections.

The infection begins when the fungal spores land on the wheat leaves, where they penetrate the tissue and form pustules (lesions) filled with orange-brown spores. These pustules rupture the leaf surface, releasing new spores and infect other plants. as the infection progresses, the affected leaves develop yellowish or orange-brown lesions, which coalesce and lead to extensive tissue damage. The disease reduces photosynthesis by damaging the chlorophyll in the leaves, weakening the plant and limiting its ability to produce energy for growth and grain development. In severe cases, brown rust lead. Rusts spread rapidly under favorable weather conditions and devastate entire fields if not controlled. Under severe conditions this disease infect leaves, ears and stem. Brown rust thrives in warm, moist environments and spreads rapidly through windborne spores and cause significant yield losses if not controlled.

Brown rust thrives under specific environmental conditions that favor its development and spread. The disease is most active in warm temperatures, typically between 15°C and 22°C (59°F to 72°F), which provide the ideal climate for fungal growth and spore germination. High humidity is also crucial, with relative humidity levels above 90% promoting the formation and spread of rust spores. Leaf wetness, caused by rain, dew, or irrigation, plays a significant role, as the spores require moisture to germinate and infect wheat tissues. Additionally, moderatewind helps disperse the fungal spores across large areas, accelerating the spread of the disease.

Managing brown rust in wheat involves a combination of integrated strategies aimed at reducing the impact of the disease and preventing its spread. One of the most effective ways to manage brown rust is through the use of resistant wheat varieties, (these are dilkash-20, ujala-16, fakhare-e-bhakkar, v-14124, hyt 60-5). These varieties help reduce the severity of infection, particularly when environmental conditions are favorable for disease development.

In addition to resistant cultivars, fungicide application is a key component of rust management. These fungicides include azoles, strobilurins, sdhis, pydiflumetofen, tebuconazole, metaconazole, prthioconazole. Timely application of these fungicides control spread of the disease, especially during periods of high humidity and moderate temperatures when rust is most active.

Croprotation is another preventive measure that helps break the disease cycle by reducing the buildup of rust spores in the soil. It’s also important to practice fieldhygiene, including removing infected crop residues, to reduce the source of initial infections. Properspacingandplantingdensity are essential for improving airflow between plants, reducing the humidity around the crop canopy and minimizing the conducive environment for rust.