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Rhizoctonia root rot

Rhizoctonia root rot

Description

  • Rhizoctonia root rot survives between crops in particles of plant residue in the soil

  • The fungus grows out of this material after autumn rains and spreads rapidly

  • The roots of germinating plants are infected when they grow into the fungus

  • All crop, pasture, and weed species are susceptible

Symptoms

  • Infected plants are normally stunted and purple in colour

  • Severely infected plants have small, discoloured root systems, with characteristic brown 'spear tips'

  • Bare patches may appear in the crop from an early growth stage and form sharply defined areas of stunted plants

Damage

  • Yield penalty can be severe

Control

Control grasses and prevent seed set with selective herbicides by spray topping or cultivation. Control weeds from the first autumn flush. Weeds must be dead for 2 to 3 weeks before sowing. Perform a single deep cultivation (50 mm under the seedbed) in the fortnight prior to sowing.

 

 

Links and Resources

CSIRO - Rhizoctonia root rot

2 Page PDF. Information on rhizoctonia, plants affected, resistant cultivars, symptoms, recovery/losses, and pre-season management. Published 1997.

DEPI VIC - Rhizoctonia root rot

Information on symptoms, survival, hosts, conditions that make an outbreak more likely, and control. Published 1996, updated 2013, reviewed 2013.

GRDC - Rhizoctonia fact sheet

4 page PDF. Key points, why rhizoctonia is still a problem, biology, symptoms, key factors controlling occurrence and severity, management of soil inoculum, management, disease suppressive soils, and frequently asked questions. Published 2012.

Victorian winter crop summary - Rhizoctonia root rot

Table 6: Wheat disease guide. Page 11. Causal organism, symptoms, occurrence, inoculum source, and control. Updated annually.