Fusarium head blight scab

1
Fusarium head blight (scab)

• Pink mold, whiteheads, tombstone scab
• Same Fusarium that causes crown rot
• DON limit 1 ppm

2
Symptoms

• Tan to brown discoloration at the base of the
  head
• Diseased spikelets (partial bleaching of the
  head) or entire head turns white
• Under moist conditions, pink/orange color is seen
  (produced by fungal spores and hyphae) on the
  surface of the glumes
• Infected kernels are shriveled, white, and chalky
  in appearance (tombstones)

3
Scab in barley vs. scab in wheat

• Barley flowers before head emergence spray
  earlier
• 2-row barley less suceptible than 6-row barley
  (head architecture)

4
Fusarium head blight history

• Fusarium graminearum of the grasses
• First described in early 1900s

5
Future Fusarium head blight control
X

• Rotation
• Fungicide application at flowering
• Folicure, what others? Quilt?
• May not be economical
• Use a more resistant variety
• Many resistant varieties from other regions of
  the country are not adapted to MT conditions

6
Fusarium head blight pathogen

• Residue-borne
• Corn wheat residue massively colonized
• Scabby seed blown out of the combine in the
  previous year
• Conidiospores (asexual) splash dispersed,
  Ascospores (sexual) forcibly ejected from asci
• Infection occurs when spores land on susceptible
  heads
• Most susceptible at flowering
• Limited by moisture

7
Scab in barley vs. scab in wheat

• Barley flowers before head emergence spray
  earlier
• 2-row barley less suceptible than 6-row barley
  (head architecture)

8
Future Fusarium head blight control
X

• Rotation
• Stop irrigation before first flowering 10-14
  days
• Fungicide application at flowering
• Folicur (Sec. 18 next year?, Proline or Prosaro
  label 2008?)
• May not be economical
• Folicur 6/A Proline 17.50/A
• Need to combine tolerant varieties with fungicide
  application
• Orient nozzles towards heads, not downwards
  (forward/backward, not just forward)
• Use a more tolerant variety
• Many varieties from other regions of the country
  are not adapted to MT conditions
• No/poor resistance currently available in malt
  barley

9
Variety reactions to Fusarium head blight
2006, Grey and Dyer
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11

• Fusarium head scab in Montana

lt2004
YR2007
YR 2005, 2006
Dyer, 2008
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