PJ Phelan: So many reasons to grow winter rape

Winter oilseed rape
Winter oilseed rape
PJ Phelan

PJ Phelan

While this year's harvest is not yet complete, it is time to complete sowing of Winter Oilseed Rape (WOSR) for harvest 2020.

Although there is concern about the possible impact of Brexit on the export of oilseed to the UK, there is no denying that cereals on farms with a breakcrop such as oilseed rape outperform those that do not.

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In 2019 WOSR yielded between 1.6t/ac and 2.4t/ac, with many crops averaging 2t/ac, giving a margin of close €300/ac - which beats 5t/ac of wheat.

Prices for rape have remained remarkably stable over the past seven or eight years at €350/t +/- €20. So while rape growers have not seen bumper prices, neither have they seen very disappointing prices.

Granted, rape must be harvested at close to 9pc moisture and there are serious penalties for crops with high levels of contamination.

The economic reasons for growing oilseed rape are strong and are added to by the fact that it can be used as part of the strategy to control sterile brome, a grass that has become a serious problem in recent years with the increase in the area of winter barley.

The need to delay sowing of winter barley into October with the loss of seed dressings for aphid (BYDV) control and the decreased aphid control with pyrethroids increases workload and weather dependency in that period.

Rape sown now will reduce the pressure. Harvesting of winter rape starts before that of winter wheat or spring cereals and provides a beneficial workload spread in the harvest.

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WOSR must be sown on free-draining soils of medium to heavy texture. Beet or brassicas should not have been sown within the previous four years so as to minimise transmission of soil-borne diseases.

Seedbeds must be fine, firm and level to enable sowing to a depth of half an inch. Seed must be covered to allow the use of pre-emergence weed control. Sowing should be completed by early- to mid-September.

The Department of Agriculture's recommended list has four fully recommended varieties and three provisionally recommended. All their varieties with the exception of Anastasia (open pollinated) are hybrid varieties. Hybrids are generally shorter and have higher vigour than conventional varieties and gave higher yields. Anastasia has performed very well in trials (yielding 102) and on farms in 2019.

Weed control is best achieved with the application of Katamatan Turbo (2-2.5l/ha) or Butisan S/Rapsan 500 (1.5/ha) to moist soil (not a problem this year) within 48 hours of sowing.

If it is necessary to re-sow due to crop failure (poor germination or pest attack) following Katamaran Turbo application you cannot sow cereals for four months; for Rapsan 500 SC it is six months; and after Butisan S you must plough to six inches.

Perhaps the greatest breakthrough in recent years for oilseed rape production has been the introduction of Clearfield (CL) varieties on which the herbicide Cleranda can be used to control charlock, mustard, runch and volunteer oilseed rape.

However, use of that herbicide on varieties other than Clearfield will result in total crop loss. Clearfield varieties do not have the yield potential of other varieties on which Salsa may be used for the control of charlock and its close relations.

Salsa works well on occasion but can be very disappointing and should not be relied on if there are high levels of charlock etc throughout the field. Its use must be on young, actively growing weeds.

Rape will emerge within 7-10 days after sowing and will be at risk from flea beetle until it has established four true leaves. Monitor crops carefully in that period, particularily on days with bright sun when flea beetle is most active.

A one-day attack is enough to wipe out a crop.

Spray with a pyrethroid possibly when damage is seen and weather conditions are bright - best at late evening or at night.

Slugs are the other major risk to establishment and can result in crop failure. Good fine firm seedbeds are half the battle, with greatest risk presented by cloddy seedbeds or where there are high levels of trash.

Any delay in taking straw off land or spreading chopped straw guarantees a slug problem, and slug pellets should be applied at or immediately after sowing. In lower-risk situations place slug baits, under cover, at several locations throughout the field, and if an average of two slugs per bait is found, apply slug pellets.

Given environmental concerns, the need to protect our products from abuse and the risk for penalties on your Basic Payment product, labels must be read and instructions followed carefully in using any pesticide.

PJ Phelan is a tillage advisor based in Tipperary and is a member of the ACA and ITCA

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