Causal organism: Rhizoctonia solani AG1-IA
- Symptoms on leaf sheaths : oval gray spots that later enlarge; with black brown margins and gray center
Susceptible stage: tillering to heading
- Symptoms on leaves: lesions are irregular, banded with green-brown coloration; center is grayish white; leaf whitens; panicle exertion affected when flag leaf is infected
Susceptible stages: heading and maturity
Disease development and severity are favored by:
- Presence of the pathogen in the soil
- Relative humidity (85-100%) of the crop canopy
- Temperature of 28 32oC
- Frequent rains
- High nitrogen fertilizer application
- High seeding rate or close plant spacing
- Dense canopy
- Low light intensity
- Use of highly-susceptible semi-dwarf varieties
Disease management
1. Efficient use of nitrogen fertilizer
2. Sanitation control weeds in the paddy and on the bunds; plow deeply to bury infected stubble and weeds.
3. Reduce seeding rate or provide wider plant spacing
4. Expose soil to intense sunlight
5. Drain the field at maximum tillering for a few days
Biological control</strong fungal antagonists, such as Trichoderma harzianum and T. viride, and bacterial antagonists, such as Bacillus subtilis, B. cereus, and Pseudomonas fluorescens.
