Diagnosing spring drought in canola

Spring drought refers to plant water stress from insufficient rainfall or stored soil moisture from bud formation to maturity.

 

Dull-coloured plants with dying older leaves and aborted flowers

What to look for

    Paddock

  • Large areas of stressed or dying plants with some better plants in water gaining areas. Areas most affected include:
  • Low water holding soils, such as coarse sands and gravels, very shallow soil over rock or impermeable layer.
  • Heavy clays that retain moisture near the soil surface after light rainfall where it is more liable to evaporate .
  • Areas within the root zone of trees.
  • Double sown areas and more vigourous plants.

    Plant

  • During the vegetative stage leaves turn dark green to purple and tend to stand upright. Older leaves turn yellow and die.
  • During flowering, flowers are aborted, pod set is significantly reduced and plants are stunted.
  • Pod length is reduced and seed development is affected, resulting in shrivelled seed, which may also remain green if the moisture stress is late.

What else could it be

Condition Similarities Differences
Diagnosing nitrogen deficiency in canola Reddish purple more upright older leaves that turn yellow and die However nitrogen deficiency is worse in wetter seasons and on sandier soils
Turnip yellows virus in canola: diagnosis, epidemiology and management Reddish purple more upright older leaves that turn yellow and die However virus affected canola plants often occur in patches or paddock edges, and leaf colours are often intermixed and between leaf veins
Diagnosing heat stress in canola Flower and pod abortion Heat stress can occur when plants have adequate soil water

How can it be monitored?

  • Unless the problem is obviously due to drought, dig a hole and examine the soil profile for:
  • Soil texture
  • Soil pH
  • Presence of restricting layers
Page last updated: Tuesday, 20 January 2015 - 10:50am