Model Answer
0 min readIntroduction
Plant diseases pose a significant threat to global food security, causing substantial yield losses in various crops. Okra and wheat, being economically important crops in India, are susceptible to several diseases. Yellow Vein Mosaic (YVM) of Okra and Tundu disease of wheat are two prominent examples that impact productivity. Understanding the etiology, symptoms, and effective control measures of these diseases is crucial for farmers and agricultural scientists to mitigate their effects and ensure sustainable crop production. This answer will detail the causal agents, symptoms, and control measures for each disease.
Yellow Vein Mosaic of Okra
Yellow Vein Mosaic (YVM) is a widespread viral disease affecting okra (Abelmoschus esculentus) cultivation in India and other tropical and subtropical regions.
Causal Agent
YVM is caused by Okra Yellow Vein Mosaic Virus (OYVMV), a member of the Begomovirus group. It is a single-stranded DNA virus transmitted by the whitefly (Bemisia tabaci) in a persistent manner.
Symptoms
- Yellow mosaic patterns: Distinct yellow patterns appear on the leaves, varying in intensity depending on the okra variety and virus strain.
- Leaf distortion: Leaves become distorted, curled, and reduced in size.
- Stunted growth: Infected plants exhibit stunted growth and reduced vigor.
- Pod deformation: Pods may be deformed, shrunken, and unmarketable.
- Reduced yield: Significant yield losses can occur due to the combined effects of these symptoms.
Control Measures
- Whitefly control: Managing the whitefly vector is crucial. This can be achieved through:
- Insecticides: Application of systemic insecticides like Imidacloprid or Acetamiprid.
- Yellow sticky traps: Deploying yellow sticky traps to monitor and capture whiteflies.
- Biological control: Utilizing natural enemies of whiteflies, such as parasitic wasps (Encarsia formosa).
- Resistant varieties: Cultivating okra varieties resistant to YVMV. Several resistant cultivars have been developed and released by agricultural universities.
- Rouging: Removing and destroying infected plants early in the growing season to prevent further spread of the virus.
- Crop rotation: Rotating okra with non-host crops can help reduce the whitefly population.
- Intercropping: Intercropping okra with repellent plants can also help manage whitefly populations.
Tundu Disease of Wheat
Tundu disease is a devastating physiological disorder of wheat (Triticum aestivum) prevalent in India, Pakistan, and Afghanistan. It is not caused by a pathogen but by a complex interaction between the plant, environment, and certain soil-borne organisms.
Causal Agent
Tundu disease is a physiological disorder, not caused by a single pathogen. It is associated with the presence of a soil-borne fungus, Fusarium oxysporum f. sp. tritici, and is exacerbated by factors like high temperatures, low soil moisture, and imbalanced nutrient levels, particularly zinc deficiency.
Symptoms
- Early symptoms: Initially, the lower leaves show pale green or yellow streaks.
- Sheath discoloration: The leaf sheaths develop reddish-brown discoloration.
- Grain sterility: The most characteristic symptom is the complete or partial sterility of the grains, resulting in empty or shriveled grains.
- Reduced grain filling: Affected grains fail to fill properly, leading to reduced grain weight and yield.
- Reddish-brown discoloration of internodes: Internodes also exhibit reddish-brown discoloration.
Control Measures
- Balanced fertilization: Ensuring adequate and balanced nutrient supply, particularly zinc, is crucial. Zinc sulfate application can alleviate the symptoms.
- Irrigation management: Maintaining adequate soil moisture, especially during the grain filling stage, is essential.
- Temperature management: Avoiding sowing wheat during periods of high temperatures can reduce the incidence of Tundu disease.
- Seed treatment: Treating seeds with fungicides like Carbendazim or Thiram can help suppress the growth of Fusarium.
- Resistant varieties: Cultivating wheat varieties resistant or tolerant to Tundu disease.
- Deep ploughing: Deep ploughing can help reduce the inoculum of Fusarium in the soil.
| Feature | Yellow Vein Mosaic (Okra) | Tundu Disease (Wheat) |
|---|---|---|
| Causal Agent | Okra Yellow Vein Mosaic Virus (OYVMV) | Physiological disorder associated with Fusarium oxysporum f. sp. tritici |
| Type of Disease | Viral | Physiological |
| Vector | Whitefly (Bemisia tabaci) | None (Soil-borne fungus plays a role) |
| Primary Symptom | Yellow mosaic patterns on leaves | Grain sterility |
Conclusion
Both Yellow Vein Mosaic of Okra and Tundu disease of wheat represent significant challenges to crop production. While YVM is a viral disease requiring vector management and resistant varieties, Tundu disease is a physiological disorder influenced by environmental and nutritional factors. Integrated disease management strategies, including the use of resistant varieties, balanced fertilization, appropriate irrigation, and vector control, are essential for minimizing yield losses and ensuring sustainable agricultural practices. Continued research and development of improved cultivars are crucial for long-term disease control.
Answer Length
This is a comprehensive model answer for learning purposes and may exceed the word limit. In the exam, always adhere to the prescribed word count.