Sorghum leaf blight is a fungal disease that causes substantial mortality in tropical and subtropical areas. It is a major sorghum disease in India and other nations. In the past, the disease has resulted in substantial yield declines in sorghum. It remains a significant danger. To avoid and control this disease, sorghum producers must comprehend the disease cycle, its interaction with the environment, and risk factors.
Cultural techniques such as crop rotation, thorough plowing, and the use of disease-resistant cultivars, as well as chemical treatments, are used to control the disease. This article will summarize sorghum leaf blight, including symptoms, biology, and control.
Leaf Blight Disease Management in Sorghum
The Causal Organism of Sorghum Leaf Blight Disease
- Exserohilum turcicum, previously known as Helminthosporium turcicum, an obligate plant pathogen, causes leaf blight disease in sorghum. It will develop mycelium that is limited to the infected lesions.
- Conidiophores arise via stomata and are simple in structure, olive green, septate, or compartmentalized and geniculate.
- Conidia are olive green or brown, containing 3-8 septa, and are thick-walled.
- The pathogen is also capable of causing seed rot and seedling blight in sorghum.
The Disease Cycle of Sorghum Leaf Blight Disease
- The fungus begins as microscopic spores that propagate via breeze and water. When spores settle on a sorghum plant, they germinate and penetrate it via the stomata (leaf openings).
- The fungus colonizes the plant, creating a mycelium and developing inside the leaf tissues.
- This mycelium creates toxins that cause the disease’s signs, such as yellow-brown lesions on the leaves and stalks.
- The lesions become darker as the illness advances and can extend to other areas of the plant.
- The fungi also create fruiting bodies, which discharge spores back into the environment, thus continuing the infection cycle.
Mode of Spread and Survival of the Pathogen in Sorghum Crop
- Wind-borne ascospores spread the disease and can survive in the atmosphere for several weeks.
- Seed-borne conidia, responsible for the seedling infection, are the main means of disease transmission.
- Secondary disease spread occurs via wind-borne conidia, and the pathogen that survives in contaminated plant residues is another cause of disease spread.
Causes/Conditions Favorable for Sorghum Leaf Blight Disease Spread in the Field.
- High Rainfall & Humidity – In the atmosphere, approximately 90% humidity and high rainfalls can spread the disease.
- Weather – Cool and moist weather will increase the intensity of the disease incidence.
Symptoms of Sorghum Leaf Blight Disease
- Leaf chlorosis, early defoliation, and stalk rots are symptoms of the disease.
- The disease is distinguished by tiny, brown spots on the foliage encircled by a yellow halo, after which the leaves turn yellow and die out.
- In its early stages, the infection appears as slight, extended, thin patches that eventually spread throughout the base of the leaves.
- On mature plants, the clinical signs are massively elongated diseased patches with darkened edges that are straw-colored in the middle.
- Once the spores are released, the straw-colored area turns black.
- Many patches that form and merge on the foliage could destroy significant portions of fresh leaves, leaving the plant with a burned impression.
Percentage of Yield Loss Due to Sorghum Leaf Blight Disease in Sorghum Crop
- Overall, the percentage of yield loss due to sorghum leaf blight disease can vary greatly depending on environmental conditions, crop management practices, and the implementation of control measures.
- In severe cases, yield losses can reach up to 50% of the crop planted. <