Leaf Rust


Leaf rust, also known as brown rust, is a fungal disease caused by Puccinia triticina. Because the disease lowers a wheat plant's photosynthetic capacity, it impacts the crop’s growth and development.

(Image Credit: Thirunarayanan Perumal, Banaras Hindu University, Bugwood.org)

Leaf Rust

Leaf Rust Impact on Wheat

When affected by leaf rust, the energy that the plant would typically allocate for growth and grain production is instead redirected to combat the disease. This energy diversion can result in smaller, less productive plants and a significant reduction in grain yield.

Leaf rust primarily targets the leaves of the wheat plant. The pustules disrupt the photosynthetic tissue, undermining the plant's ability to produce food. This disruption can lead to stunted growth and reduced grain size. In severe cases, the disease can also impact the stems and heads, leading to further yield reduction.

How to Identify Leaf Rust

Leaf rust manifests as small, round to elongated pustules on wheat leaves, stems, and occasionally, the heads. These pustules, filled with reddish-brown spores, lend the disease its name.

To confirm the presence of leaf rust, look for the characteristic pustules on the wheat leaves. Leaf rust typically first appears on the lower leaves and can eventually spread to engulf the entire plant. These small pustules are often surrounded by a yellow halo, particularly in the early stages of the disease. The pustules then darken to a more reddish-brown hue as the disease progresses.

These pustules can rupture the leaf surface, releasing thousands of spores capable of infecting other plants.

(Image Credit: William M. Brown Jr., Bugwood.org)

Leaf Rust

Geographic Reach of Leaf Rust

Leaf rust can strike in any wheat-growing region. However, it tends to be more prevalent in areas with moderate temperatures and high humidity — conditions that favor the growth and spread of the fungus.

Timing of Leaf Rust

The disease typically emerges in late spring or early summer when conditions are most conducive to fungal growth. Nonetheless, it can occur at any time during the growing season if the conditions are favorable.

How to Manage Leaf Rust in Wheat

Most yield loss from leaf rust comes from infection of the flag leaf, so application timing between Feekes 8 and 10 is best as a preventative measure. Our experts recommend GCS Azoxy and GCS Azoxyprop.

Product image of GCS Azoxy 2SC jug


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This content was generated with the assistance of Norm℠, FBN’s artificial intelligence (AI) Ag Advisor, based on a dataset of information containing general industry best practices and research. The AI model did not use specific external sources to generate this content. Our process involves using AI to aid human subject matter experts with the initial drafting and/or refinement of content.

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