Top Three Ways to Protect Wheat From Leaf Spot Diseases

Ines Marjanovic

Agronomy Expert

Wheat is one of the oldest cultivated crops. It has been and continues to be a popular staple, amongst all foods, for all inhabitants since our earliest history. Today, wheat continues to be one of the most important food grains. FAO (Food and Agriculture Organization) claims that wheat is grown on more land area than any other commercial crop. Not only is wheat a significant part of the human diet, it's also proves valuable as a primary source of animal feed, as well as to industrial products.

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Wheat production and productivity per area have shown a trend increase. However, with rapidly growing population, the demand for wheat is expected to increase by 60%. Since wheat production plays an important role in satisfying future food demands and contrinbuting to hunger crisis solutions, there is an urgent need to further increase wheat production and yields.

Pests and Diseases as an Obstacle to Higher Wheat Production

Scientists claim that pests and diseases cause 20-40% crop yield losses. The exact percentage of yield loss depends on the crop, pest type, and the agroclimatic conditions in which pests occur. The most common wheat insect pests are red and blue cereal leaf beetle and aphids, while diseases that can be present are wheat rust, wheat leaf spot, and kernel mold. Wheat leaf spot diseases have the potential to reduce wheat yields by 50%. They are caused by the fungal pathogens that are distributed in all wheat-growing areas worldwide. The most common leaf spot diseases are Tan spot, Septoria/Stagonospora nodorum blotch, and Septoria tritici blotch.

Tan spot disease is visible in the form of small, oval-shaped spots on the leaves. Eventually, the spots enlarge and become tan, with a yellow border and small dark brown spot in the center. Kernel infection is also possible. In infected kernels the development of a reddish discoloration on the seed coat becomes evident.

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Septoria/Stagonospora nodorum blotch’s (SNB) initial symptoms are visible and show as water-soaked lesions on the lower leaves. Mature lesions are usually lens-shaped. These then develop to become ashen gray with a brown center, with pycnidia also occurring. Pycnidia represents the asexual reproducing of the structure of the fungus, and also serves as the best mean of diagnosing this disease. If wet weather occurs after the flowering stage, lesions can also develop on the glumes.

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Septoria tritici blotch (STB) develops as chlorotic flecks on the lower leaves. These flecks later expand into irregular brown lesions. Sometimes it’s hard to notice the difference between SNB and STB without microscopic observations.

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Preventative Measures as a Practice for Yield Protection

Preventative disease management is the best farm management practice to reduce yield losses due to leaf spot diseases. Disease management measures that every farmer should follow include:

  • Planting of resistant and less susceptible varieties
  • Practicing crop rotation
  • Using pathogen-free, quality seeds
  • Planting of seeds treated with fungicide to reduce the risk of seedling infections
  • Proper crop residue management
  • Regular tracking of weather conditions
  • On-time fungicide application.

 

Among the aforementioned farm practices, three are shown to be best for managing wheat leaf spot diseases:

  1. Planting of resistant varieties; one of the least expensive and most effective management practices
  2. Crop rotation; a practice that reduces the initial inoculum of fungal leaf spot pathogens
  3. Fungicide application; a practice that prevents the disease from spreading onto the flag leaf

 

Along with these preventative measures, farmers also have a wide range of modern farm technologies available to them that are able to assist in reducing the occurrence of insect pests and diseases, with saving the yield being the main goal. Whether they use some type of crop and field sensor, modern machinery, or Agrivi software for comprehensive farm management, farmers can protect their crops from devastating pests and take control of their farm production.

 

Text and image sources: Research Gate || FAO || North Dakota State University || FAO || FAO || North Dakota State University