Harvest and Storage- Oilseed Rape

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Harvesting
There are several harvesting methods for this crop. The pros and cons are given below.

Method
Advantages
Disadvantages
Direct combining with desiccation.
 This process ensures crop ripens evenly. Shedding losses can be high if conditions are very windy.
A standing crop will ripen sooner than a laid crop. Extra cost of chemical and contractors cost.
Ideal for leaning or lodged crops. Shedding losses from spray application
Ideal for weedy crops.  
Ripening is brought forward,crop is exposed to bad weather for a shorter period.  
   
Direct combining without desiccation.
 Ideal for spring rapes. Not suitable for lodged, weedy or uneven growth crops.
No desiccation cost or swathing costs. Ripening takes longer (10+days) and so crop is exposed to weather conditions longer.
A standing crop will dry faster after rain than a swathed crop. Shedding losses can be high if crop grown on an exposed windy site.
No seed loss from desiccation operation or swathing operation.  
     
Swathing.
 Shedding losses in swath crops are normally less than that of a standing crop in windy conditions. Thin plant stands will make pickup if swathed difficult.
Combining can be faster and easier. High cost of swathing operation (£30/ha).
No seed loss from a desiccation operation. Some shedding losses from swathing operation particularly if done on the late side.
  Drying of swaths can be slow after heavy rain compared with a standing crop.
  Not suitable for severely lodged crops as there will be no suitable standing stubble to place the swathe on.


Dessication with Diquat (Reglone).

Rate - 3.0lt/ha + non-ionic wetter at 100ml/100lt diluted spray.
Water rate - 250-500lt/ha
Cost - £22.50/Ha
Harvest interval - 7 days
Rainfast - 15 minutes.

Timing

  • Top third pods - more than half the seed will be green, firm and pliable with a few early ripening seeds brown to black.
  • Middle third pods - 90% of the seed will be reddish brown to dark brown with a few seeds black. The remaining 10% will be green but must be firm and pliable.
  • Bottom third pods - all seeds will be dark brown to black.

Harvest
Combining can normally take place 7-10 days after spraying. Check moisture content after 5th day after spraying.

Dessication with Glyphosate.

Rate - 3.0lt/ha + ammonium sulphate (2kg/ha)
Water rate - 150lt/ha
Cost - £4.35/ha
Harvest interval - 14 days
Rainfast - 6 hours


Timing.

  • Select an area representative of the whole field and pick 20 pods from the middle raceme of several plants.
  • Open each pod. If a colour change from green to brown is detectable in at least two thirds of the seeds per pod and in at least 15 of the pods, the earliest correct stage for Glyphosate has been reached. Repeat this procedure in other areas of the field.
  • If this criteria is reached then spray within the next 4 days. The window of opportunity will be approximately 7 days in total at the end of which the crop will be entering the timing for Reglone.

Dessication with Glufosinate-ammonium (Harvest)

Rate - 3.0lt/ha
Water rate - 300-400lt/ha
Rain fast - 6 hours

Timing.

  • Apply when most of the pods in the centre third of the main raceme are yellow and the majority of seeds within are reddish to dark brown in colour. This is approximately 14-21 days before harvest.


Swathing.

  • The timing for swathing is very similar to that of glyphosate. Seed in the middle third pods of the main stem start to turn green brown mottled at GS 6

Seed size and quality if saving seed for drilling.
Results from work over the last few seasons on the comparison between small, medium and large seed has indicated that large seed was faster to establish and more vigorous than small seed care needs to be taken at harvest to achieve the required quality. Select a weed free part of the crop from a lower plant density part of the field if possible.

 

RAPE STORAGE.
Grain intended for long storage must be in a state of low metabolic activity achieved by controlling both temperature and moisture. Damp seed needs ventilating or aerating within 6-10 hours to prevent heating. Damage from heating can occur within 24hours. Hot grain will sweat and cause condensation and mould/mite problems. Moisture within the seed bulk causes heating which increases insect and fungal growth. It is necessary to dry rape to 7.7% - 8% moisture content and cooled to 5 degrees C to prevent mite problems.

Storage pests.
Insects in general are not a problem in oilseed rape during storage, apart from mites. Often large numbers of harmless insects are carried into store from the field. These can increase the quantity of admixture if they cannot escape before they die. It is thought that low glucosinolate and erucic acid varieties may be more prone to insect attack from grain beetles and grain weevils.

Mites (Acarus spp, Lepidoglyphus spp) Glycyphagus
Life cycle.
Mites lay eggs in the bulk seed, the larvae and nymph stage feed on the seed before becoming adults. Development and multiplication is very dependent on temperature and moisture.

Damage.
Mites eat out the seed, reducing quality and weight. They leave pools of light brown dust on the surface and can taint the sample.

Prevention.

  • Clean stores out prior to harvest.
  • Store at low temperature and moisture.
  • For minor attacks use Silico-Sec.
  • For major infestations call in a reputable fumigation service.

SILICO-SEC
Silico -Sec offers an alternative to other forms of grain store treatment. It is derived from diatomaceous earth by a special process and consists of highly micronised specific amorphous silica (silicon dioxide), which is highly absorbent due to its biophysical properties. On contact with the product, Silico-Sec damages the external wax layers of target pests resulting in desiccation and eventual death. This product can be used either as a protectant or as a curative treatment. Silico-Sec is a fine white powder. Its dusty nature is essential to its high level of effectiveness. For further information on this material see HGCA topics No 62, No 79.

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