Canola emergence issues; our BCG experience!

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Last Saturday (28.5.11) BCG inspected the canola variety trial at Corack and found that only the odd canola seedling had emerged.  A number of reasons for the poor emergence came to mind along with the painful thought of re-sowing. Discussions with growers during the week highlighted similar experiences.

Possible reasons for the poor emergence were, lack of rainfall; seed sown too deep; seed that germinated on the initial moisture and exhausted its energy reserves; surface crust too hard to penetrate; cold soil and mice.

Background trial information

Location:              Corack
Sown:                   21.4.11
Soil type:             Sandy clay loam
Seed depth:       5cm sown into the moisture band (sown across standing stubble)
Soil moisture:    Good moisture at seed depth
Rainfall:                20th April              3 mm the day before sowing

  • 2nd May                 0.5 mm                                
  • 13th May                4 mm                                    
  • 21st May               17 mm                 
  • 7.5 mm for the month following sowing

Trial inspections

  • Throughout last week (starting 29.5.11) we monitored the canola closely and counted emerged seedlings per metre of row and then calculated plants per square metre in two locations.
  • Advisors suggested target plant densities for low rainfall environments of 10-25 pl/m2 for hybrids and 15-30 pl/m2 for open pollinated varieties. For medium rainfall environments plants of 25-40 pl/m2 for hybrids and 30-50 pl/m2 for open pollinated varieties.
 

Mon 30.5.11

Wed 1.6.11

Thurs 2.6.11

Sample Row

Plants per 1m row

Plants per m2

Plants per 1m row

Plants per m2

Plants per 1m row

Plants per m2

1

4

13

12

40

16

53

2

3

10

7

23

14

47

Table 1. No of emerged canola seedlings over time at the BCG Main Corack Site
N.B. Row spacing was 30cm (12 inches). To calculate plants per square metre = seedlings per metre of row multiplied by 100 divided by row spacing in centimetres

Inspections showed that seedling numbers were very low on Monday but by Wednesday more seedlings had emerged and on Thursday, one day later adequate plant numbers were counted.

Take home learning

  • Even though this trial was sown on April 21st following the small rainfall event on April 20th, the majority of canola only germinated on the 17mm rain that fell on the 21st May.
  • It took 10-12 days following the 21st May rainfall for adequate seedling numbers to appear.
  • Canola under the ground grows with bent over and yellow cotyledons.
  • What appeared to be a relatively hard/dry soil crust, now, doesn’t seem to be an issue.
  • Baiting has occurred on a number of occasions and mice numbers have been contained.
  • Depth of sowing 4-5cm doesn’t seem to have hindered emergence.
  • Re-sowing is not necessary for the canola variety trial at this point in time. Phew! Rain this weekend would be welcome.

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