Pasture dieback potential causes and management options under investigation

17 July 2018

Pasture dieback is a complex problem and MLA is investigating numerous potential causes and management options.

While the causal agent of pasture dieback is yet to be identified, the following remediation options are either showing promising results in field trials or have the potential to assist in pasture dieback management.

For more information on the treatments used in field trials, please consult the progress update which accompanies the table below or contact MLA to discuss options and register for our regular pasture dieback newsletter.

Contact:
Greg Palmer
Email Greg Palmer

 

Potential cause or contributing factor

Known remediation options*

Cost estimates ($/ha)

Time to impact

Remediation risks and notes

1

Soil-borne disease caused by:

  • Rhizoctonia sp.
  • Fusarium sp.
  • Bipolaris sp.
  • combinations of 1, 2 or 
  • Cultivate, re-plant with pasture1,3 species
  • Cultivate, re-plant with legume2,3 species
  • Cultivate, re-plant with a mix of pasture and legume species.1,2,3
  • Apply the seed dressing EverGol Xtend™ (Bayer) which is registered for pastures and legumes.

 

 

  • $48–280 (incl. labour)4, 5
  • $54–105 (incl. labour) 4, 5
  • See above
  • Supplied direct to seed suppliers
  • 3–6 months for pasture to re-establish to be suitable for grazing, depending on season and species.
  • This seed treatment should provide some protection to germinating seeds from Fusarium and Rhizoctonia.  
  • Re-sown trials are not showing any sign of dieback returning as of June 2018. However, since the cause of pasture dieback has not yet been determined, it’s possible dieback could reappear in re-sown pasture in the future.
  • Refer to the pasture grass dieback update for species mixes, and contact MLA for more information of on seeding rates used in trials. EverGol Xtend™ (Bayer) has not been trialled directly; however, a fungicide from the same group is showing promising results in field trials.
  • Observe the six week withholding period. This means stock cannot be grazed on pasture established from EverGol Xtend™ treated seed for six weeks after sowing. Always read the label and follow instructions.

2

Soil-borne insects/mites

Insecticide seed dressing Poncho™ 3

 

 

 

 

$4.50/kg seed (approx.)

 

Effective against certain mites and soil insects for 4–6 weeks. Refer to the label for details.

 

Poncho™ has a six week withholding period. This means stock cannot be grazed on pasture established from Poncho™ treated seed for six weeks after sowing. Always read the label and follow instructions. 

3

Mealy bugs

Introduce biological control agents (e.g. lacewing larvae and Cryptolaemus (ladybird larvae), parasitic wasps

 

$400+/ha

Individual solutions could be significantly less.

12–24 months

Re-release may be required. There is no trial data available on the effectiveness of predatory insects on mealy bugs on pasture.

4

Poor soil condition/health as a contributing factor

  • Apply nutrients (e.g. N, P, Zn)6
  • Biological supplements (beneficial microbes)
  • Legumes + P (Pasture improvement)

 

  • $78–168+ application
  • $10–150+/ha
  • $135–185 (incl. labour)
  • 1–3 months
  • 6 months–10 years
  • 3–6 months
  • MAP and DAP at 75kg/ha and 150kg/ha have been trialled. These applications have worked best when combined with cultivation and re-sowing.
  • Microbial supplements have NOT been trialled.
  • Legumes plus P has not been specifically trialled. Costings are based on single superphosphate at 100kg/ha + a legume (see table below for seeding rates).

5

Other

Plant-available silicon can stimulate plant disease resistance and potential control of sucking insects.7

$250+ application

6 months+

Silicon is currently being trialled, but no results are available to date. Silicon can be detrimental to health if inhaled. Observe appropriate WHS practices.

*These are the options under investigation and may not be the only options available. MLA welcomes feedback on these options or others not listed in the table.

Progress update

  1. Recent trials indicate re-sowing with pelleted pasture seed (region-specific) has established well with no sign of dieback.
  2. Recent trials indicate re-sowing with legume species (region-specific) has established well with no sign of dieback.
  3. Re-sown pasture and pasture mixes were coated with a seed dressing that included Poncho™ to protect against soil insects and mites. Cattle cannot be grazed on pasture established from Poncho™ treated seed for six weeks after sowing.
  4. Pasture cost estimates depend on sowing rate, application equipment and labour costs e.g. Callide Rhodes plus Lablab, 5kg Rhodes $55, 10kg Lablab $30 + $30 cultivation and sowing = $115/ha).
  5. Poncho™ treatment costs about $4.50/kg of seed. Re-seeding costs include Poncho™ treatment.
  6. Fertiliser applications were more effective when applied in combination cultivation and re-sowing. Refer to the trial update summary for fertiliser rates which have been trialled.

Note: Take precautions during application to avoid breathing in dust. 

Pasture cultivation, fertiliser and re-sowing costs (based on coated seed, treated with Poncho™).

Pasture species

Seed cost ($/kg)

Seeding rate (kg/ha)

Cost ($/ha)*

Application cost ($/ha)

Total cost ($/ha)

Gayndah buffel

9

2-10

18-90

30

48-120

Callide Rhodes

11

2-10

22-110

30

52-140

Reclaimer Rhodes

9

2-10

18-90

30

48-120

Sabi grass

11

2-10

22-110

30

52-140

Bambatsi panic

12

2-10

24-120

30

54-150

Floren bluegrass

25

2-10

50-250

30

80-280

Bisset bluegrass

25

2-10

50-250

30

80-280

 

Legume species

Seed cost ($/kg)

Seeding rate (kg/ha)

Cost ($/ha)

Application cost ($/ha

Total cost ($/ha)

Highworth Lablab

3

20

60

30

90

Butterfly pea

3

8

24

30

54

Marc Desmanthus

25

3

75

30

105

* The lower cost is 2kg/ha and the upper rate is a single species is sown at 10kg/ha for coated pasture seed. This may be lower depending on pasture species, soil type and sowing mixtures.

Fertilisers

($/kg)

Rate (kg/ha)

Cost ($/ha)

Application cost ($/ha

Total cost ($/ha)

DAP

1.05

75

78

Applied with seed

78

DAP

1.05

150

158

Applied with seed

158

Urea

0.8

100

80

Applied with seed

80

Superphosphate

0.8

100

80

Applied with seed

80

Rock phosphate

1.08

100

108

Applied with seed

108

MAP

1.68

100

168

Applied with seed

168

*All fertiliser prices based on 25kg bags; cost will be reduced when buying bulk.

Disclaimer
Any recommendations, suggestions or opinions contained in this publication do not necessarily represent the policy or views of Meat & Livestock Australia (MLA) or associated research providers. No person should act on the basis of the contents of this publication without first obtaining specific, independent professional advice. MLA takes no responsibility, in any way whatsoever, to any person in respect to the document, including any errors or omissions therein, arising through negligence or otherwise however caused.

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