Autumn-winter drought in canola
Early drought may affect germination and early growth. Water stressed seedlings are more severely affected by other constraints and may have induced nutrient deficiencies.
What to look for
- Patchy germination that may vary across the paddock according to seeding depth, or soil type, or other factors that affect soil moisture infiltration and storage.
- Dull or discoloured, smaller or stunted plants.
- Leaves turn dark green to purple and tend to stand upright. Leaf discolouration disappears after rainfall.
- Older leaves wilt, turn yellow and die.
What else could it be
|Diagnosing Group A herbicide damage in canola||Distorted dark green plants||Seen in wet or dry conditions after spraying and is transient.|
|Diagnosing phosphorus deficiency in canola||Older leaves turn purple-green then bronze then die. Worse in acidic and dry topsoils.||In phosphorus deficient cases the plants don't wilt like they would with autumn-winter droughted plants|
|Diagnosing water repellence||Patchy germination, dry soil||Symptoms are restricted to water repellent soils. Plants on other soils will be actively growing.|
- No treatment. Applied nutrients have no effect.
How can it be monitored?
- Unless the problem is obviously due to drought, dig a hole and examine the soil profile for: 1. Water content 2. Soil texture 3. Soil pH 4. Water repellence
Page last updated: Tuesday, 27 May 2014 - 5:03pm