Winter Oilseed Rape 2014-15


• Allow 4 years between OSR (or other Brassica) crops
• 3 years between beet and OSR
• 2 years between beans and OSR.

Time of Sowing
• Sow ASAP from Mid-August (early sown crops tend to be more successful) up to a latest sowing date of circa 10th September.

Seed Bed Preparation
Aim for a firm, fine seed bed; similar to a grass re-seed.  Avoid compaction.  Traditional plough-till-sow gives more consistent results however wide-row subsoil sowing (saves time and money) can be successful provided the job is done right:
• Perform on stubble ground without prior cultivation
• Good conditions are essential to avoid soil damage
• Open pipes to deliver seed directly behind sub-soiler leg (seed to fall in the crack, depth not N.B.)
• 60 to 70 (tractor) horsepower required for each sub-soiler leg on the machine as the forward speed needs to be 8-10Km/hour to avoid major surface disturbance
• Machine needs to be level to avoid major surface disturbance
• Very important to consolidate the ground quite quickly afterwards (good seed to soil contact vital).  Simba presses or furrow press can do a good job but conventional Cambridge rollers are too light.

Seeding rate
• Sow to achieve an established plant stand rather than by seed weight. The target plant population (in the spring) is in the region of 30-50 plants/m2, evenly spaced across the field.  Avoid sowing too heavily and take account of TGW as big variations can occur between varieties.  Tiger Sulphur pellets are useful for mixing with OSR seed to ensure accurate seeding rates.
• Sow hybrids at 50 seeds/m2 and conventional varieties at 70 seeds/m2 (adjust depending on conditions and sowing date)

Dairygold supports the DAFF recommended list (RL). Varieties on this list have been tried and tested under Irish conditions.  The varieties below are recommended by Dairygold, other varieties available on request.

Highest yielding variety (104 versus controls) on the list that has performed consistently well over the last number of years.  Quite a tall variety and relatively late maturity for a hybrid.

New to DAFF recommended list in 2014.  Good autumn vigour and relatively early maturing plus good lodging resistance.

• The target pH for OSR is 6.5. 
• Apply Phosphorus (P) and Potassium (K) requirements to the seedbed as per soil test results

• Fertiliser applications should not be combined drilled as this may delay germination.
• Include Boron as part of the fertiliser in the seedbed if a deficiency is known. Relatively mild Boron deficiency results in poor seed set and a reduction in seed numbers per pod and seed weight.  These conditions can be induced by severe summer drought.  Boron can be applied as part of the fertiliser in the seedbed or as a foliar spray in the spring e.g. Wolftrax Boron. 
• Nitrogen is not required for establishment if the crop is sown early. Consider applying circa 25 Kg/ha (20 units/ac) N if sowing is delayed into September or conditions are less than ideal. 
• The key to high yield potential is canopy management in mid-February to early April.
* A target canopy (GAI 3.5) at the start of flowering will deliver maximum yield.  Nitrogen has a large influence on the canopy size. 
* Delay nitrogen until early March in crop with a good canopy (> GAI 1.0)
* Forward load nitrogen in defoliated backward crops (< GAI 1.0).  
* Hold back 40-70 kg N/ha in all crops to be spread as near as practically possible to flowering.  This is to prolong green-leaf area during pod-fill.  Leaves are the most efficient part of the rape plant to convert sunlight into oil.
* Fungicides with growth regulation properties can be used to hold back crops with large canopies (and control disease)

GAI = Ground Area Index and is a measure of how much green plant material is in a crop.  It can be measured by weight or by digital photograph.  See for details.

Weed Control

  • Butisan S or Katamaran offer decent broad-spectrum weed control when applied pre-emergence of the weeds.  Katamaran is similar to Butisan S but controls cleavers and is better on Poppy and Pansy.  Apply within 48 hours of sowing. DO NOT apply if heavy rain forecast. If pre-emergence timing missed, apply at the same rates asap after OSR has reached the cotyledon stage
  • Salsa is for specialist control of Charlock with only very limited activity on a narrow range of other weeds. Target the 2-4 leaf stage of the crop (when all charlock plants are emerged but are not too big or shaded by the crop).  ALWAYS use methylated rape oil e.g. Fortune/Super Rapeeze OR a non-ionic wetter e.g. Torpedo.

• Use a specialist graminicides to control volunteer cereals, wild oats and other grass weeds e.g. Aramo or Stratus Ultra. Early application is recommended at the 2-3 leaf stage of the grass weed before the grass weeds are sheltered beneath the OSR canopy.

• In high risk situations apply slug pellets to the seedbed. 
• Monitor crop for flea beetle and slug damage in the cotyledon stage (just after emergence).

• A fungicide programme for the control of the main diseases Phoma and Light Leaf Spot will involve 1-2 fungicide applications.  Apply an autumn fungicide (mid to late October) when 10-20% of plants show symptoms of Phoma Leaf Spot and/or when symptoms of Light Leaf Spot are found in the spring (late March to Early April).  For thick crops use a fungicide with PGR activity i.e. Magnello or Caramba.  For backward crops suitable fungicides include Prosaro or Proline.  It is worth considering including Boron, if deficient, and/or Nutriphite, if crops backward, in tank mixes if spraying for weeds or disease.
• Sclerotinia is a soil borne fungus that is increased by close rotations (rape grown <1 in 4 years or close to beans).  Wet weather at petal-fall (early to mid-May) has a major effect on Sclerotinia levels as the petals stick to the leaves and creates good conditions for the fungus to penetrate the leaves.  Fungicides will have very little effect curatively and must be added preventatively.  If rotations are close, Sclerotinia was evident in previous crops or oilseed rape is grown in the immediate area apply Filan or Galileo at the start of petal fall.

• Use high clearance sprayer machinery to desiccate with glyphosate 21 days before harvest.  To determine the correct timing for desiccation, randomly sample 20 pods from the main stem across several plants in a representative area of the field.  Where two-thirds of the seed in three-quarters of the pods has a colour change of green to brown the crop is ready to be sprayed.


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