Diagnosing white leaf spot in canola
A white-spot forming fungal disease that is mainly a problem in wet weather.
What to look for
- Plants with circular to irregular white lesions that may spread after high rainfall.
- Damage is worse in wetter areas
- Greyish-white to light-brown leaf lesions up to 10mm diameter often with a brown rim.
- Lesion can merge and lead to premature defoliation and spread to upper leaves and less commonly, stems and pods
What else could it be
Where did it come from?
- White leaf spot survives on canola stubble between crops.
- After prolonged wet weather in autumn/winter ,wind-borne spores are produced that cause primary leaf lesions on canola.
- These initial lesions produce new wind and rain-borne spores that cause the rapid spread of the disease throughout the crop.
- The disease is not usually seed-borne but can be spread by infected seeds or infected debris with the seed.
- White leaf spot infection is not usually severe enough to warrant control.
- Crop rotation and isolation from the previous year’s canola stubble will prevent infection from wind-borne spores.
- Control cruciferous weeds and volunteer canola.
- Provide adequate nutrition to reduce crop stress
Where to go for expert help
Page last updated: Friday, 17 April 2015 - 9:11am