Growth control vital as osr is already flowering
It is not just forward cereals
that are keeping growers on
their toes this season.
Runaway oilseed rape,
already flowering in places,
may need careful handling as
Andrew Blake discovered
when he visited our southern
IN COMMON with many crops in the south this year, Patrick Godwins 16ha (40 acres) of winter oilseed rape on Weald clay at Wephurst Park Farm, Billings-hurst, West Sussex is approaching spring in rude health.
Frost damage to the near-flowering Apex is a worry and he is keen to get some growth regulator on for the first time as soon as possible.
Mr Godwin reckons the crop is a good seven to 10 days ahead of normal. "I just hope there is no frost in April."
Sown on Aug 20 at 6.7kg/ha (6lb/acre) with a combination drill after ploughed wheat stubble, the crop got away well and kept growing through the mild winter. "The land came up moist and we had a very good seed-bed. Soon afterwards 0.75in of rain meant every seed grew."
The moisture also ensured the Butisan (metazachlor) plus Tre-flan (trifluralin) pre-emergence herbicide (at 1.35 litres and 2.3 litres/ha respectively), applied the day after sowing, did a good job on the key weeds, chickweed and shepherds purse.
Ever wary of pigeon grazing on the heavily wooded farm, 43kg/ha (34.5 units/acre) of nitrogen went on in September as usual to thicken the crop. "The only damage weve got this year is in a corner where there is a bit of rabbit damage which thinned it and let the pigeons in."
Phoma took a good hold in the autumn. But autumn fungicide was used for the first time and cleaned it up well. Punch C (carbendazim + flusilazole) at 0.4 litres/ha in 100 litres/ha of water went on through bubble-jets on Nov 20.
Despite an October to Feb-ruary rainfall of 376mm (14.8in), which in theory left little available nitrogen, ADAS messages that there was still plenty around persuaded him not to adjust his N dressings. Seventy kg/ha (56 units/acre) of good quality prilled ammonium nitrate, bought for £87/t last autumn, went on in the third week of February. The balance to 180kg/ha (144 units/acre) was applied on Mar 9.
The most urgent task now is to try to prevent too rapid stem extension and protect the relatively lush growth against disease and trace element deficiency. Tactics come through discussion with Nigel Trowbridge of Barth-olomews.
"On the first dry day we plan to go through with 0.5 litres/ha of Folicur and 1.5 litres/ha of Cycocel," says Mr Godwin. Folicur (tebuconazole), used for the first time last spring, was very effective in clearing up phoma and light leaf spot. "It was quite a dirty crop."
Cycocel (chlormequat) will do nothing to slow flowering, he admits. "But it should help slow the crops upward progress which might make it a bit less vulnerable. Folicur also has a shortening effect."
Correct timing of the regulator is important, notes Mr Trow-bridge. "Chlormequat is very short lived in the plant." Maximum activity comes from treatment between the start of stem extension and the beginning of flowering. "There is probably about 10 days to get it on."
Pollen beetle infection
Also included will be 1kg/ha of chelated manganese, 2 litres/ha of liquid magnesium and 250ml/ha of cypermethrin insecticide to stop early pollen beetle infection. "Prevention is better than cure with the crop so far forward," says Mr Godwin.
According to Ian Pugh, south-eastern area manager for United Oilseeds, bolting is widespread but not worrying. The resilience of the crop means it should compensate for any frost-hit very advanced plants, he says.
Close inspection suggests most bolters are from the sown crop. "You can tell by the leaf shape and colour. And it is not just one variety. I have seen bolters in hybrids and Apex."
Growth regulation of oilseed rape will be a first for Patrick Godwin this spring. His crop of Apex at Wephurst Park Farm Billingshurst is due for a fungicide/ pgr mix any day.
Flowering rape across the UK shows the forward state of well-grown crops.