Charcoal rot/root rot of sunflower
C/O: Rhizoctonia bataticola (Macrophomina phaseolina)
Symptoms:
- symptoms after flowering stage.
- The infected plants show droopingof leaves and death occurs in patches.
- The bark of the lower stem and roots shreds and are associated with a large number of sclerotia.
- Dark coloured, minute pycnidiaalso develop on the lower portion of the stem.
Etiology:
- black, round to irregular shaped
- The pycnidia are dark brown to black with an ostiole and contain numerous single celled, thin walled, hyaline and elliptical pycnidiospores.
Disease cycle:
- Seed borne disease
- Surviving structure: sclerotia, pycnidia
- Primary source of inoculum: sclerotia and infected seed
- Secondary inoculum: wind borne conidia
- Transmission: wind, water
Favorable condition/ Epidemiology
- Moisture stress
- High temper
Management:
- whenever the soil becomes dry and the soil temperature rises then irrigation should be provided.
- Seed treatment with Trichoderma virideformulation at 4 g/kg seed.
- In endemicareas long crop rotation should be followed.
- Treat the seeds with Carbendazim or Thiram at 2/kg
- Spot drench with Carbendazim at 500 mg/litre.