Symptoms

Yellow Spot is a frequently misdiagnosed disease. There are several basic warning signs that can be easily checked:

1. Is there wheat stubble in the field?

Yellow Spot infection is most serious in continuous wheat cropping systems with stubble retention. Burning, stubble grazing and cultivation can all be effective at reducing the Yellow Spot inoculum.

2. Can black fruiting bodies be seen on the stubble?

The fruiting bodies are responsible for the primary seedling infections. They will be rough to touch when rubbed.

3. Do the lesions have Yellow Spot characteristics?

Look for brown spots with  a yellow border, that gradually elongate, coalesce and turn tan in colour. Lesions will be randomly distributed across a leaf, with the more extensive and larger lesions on the oldest leaves.

Risk factors:

  • Wheat-on-wheat crop sequences
  • Stubble retention
  • Minimum tillage
  • Growing susceptible wheat varieties
  • Extended moist periods of time
  • Temperatures between 15 oC – 28 oC

 If you suspect Yellow Spot infection, consult with your local agronomist.