Corn grey leaf spot

Gray leaf spot Cercospora zeae-maydis 5465607

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Conidiophores of corn gray leaf spot fungus

Disease Cycle Corn Grey Leaf Spot.jpg

Corn grey leaf spot (GLS) is a fungal disease that affects maize (corn) crops. It is caused by the pathogen Cercospora zeae-maydis. This disease is prevalent in many maize-growing regions around the world and can lead to significant yield losses if not properly managed.

Symptoms

The primary symptoms of corn grey leaf spot include the appearance of narrow, rectangular lesions on the leaves of the maize plant. These lesions are typically gray to tan in color and can be surrounded by a yellow halo. As the disease progresses, the lesions can coalesce, leading to large areas of dead tissue on the leaves. This can severely impact the plant's ability to photosynthesize, ultimately reducing yield.

Disease Cycle

The pathogen Cercospora zeae-maydis survives in crop residue left in the field after harvest. In the presence of favorable conditions, such as high humidity and warm temperatures, the fungus produces spores that are dispersed by wind and rain. These spores infect the lower leaves of the maize plant and, as the disease progresses, move upward to infect the upper leaves.

Management

Effective management of corn grey leaf spot involves a combination of cultural practices, resistant hybrids, and fungicide applications. Key strategies include:

• Crop rotation: Rotating maize with non-host crops can reduce the amount of inoculum in the field.
• Tillage: Burying crop residue through tillage can help reduce the survival of the pathogen.
• Resistant hybrids: Planting maize hybrids that are resistant to grey leaf spot can significantly reduce disease incidence.
• Fungicides: Applying fungicides at the appropriate growth stage can help control the disease, especially in fields with a history of severe grey leaf spot outbreaks.

Economic Impact

Corn grey leaf spot can cause significant economic losses due to reduced yield and increased management costs. In severe cases, yield losses can exceed 50%, making it one of the most important diseases affecting maize production.

Research

Ongoing research aims to better understand the biology and epidemiology of Cercospora zeae-maydis, as well as to develop more effective management strategies. Advances in genetic engineering and plant breeding are also being explored to enhance resistance to grey leaf spot in maize.

See also

• Maize
• Fungal diseases of plants
• Plant pathology
• Crop rotation
• Fungicide