10 April 1999

Scope for savings

What savings can be made to this years devalued oilseed rape crop? Lucy Stephenson seeks advice on the winter crop with AICCs Caroline Hayes.

AS the rape price and subsidy plunges, most growers will take cold comfort from the fact that they have already spent most of their winter rape budget.

But theres still a long way for the crop to go. Independent agronomist Caroline Hayes identifies the key areas to make savings in the crop now in the ground – and for next season.

FIRST target for savings is the pollen beetle spray. Only spray when the threshold of five beetles per plant pre flowerbud-open (greenbud) is reached.

Damage is done when the beetles bite their way into closed buds to reach the pollen. "Once the buds are open there is no point in spraying because they just walk in and get it. You see people going through the crop in full flower and its a total waste of money," she says.

Seed weevil is similar. Spraying will only give a yield advantage at the threshold level of two weevils per plant.

And there are of course cost savings to be made when harvesting. "More people should be combining direct – its cheap. Harvest losses are high from swathing, and providing there arent loads of broad-leaved weeds theres £37/ha (£15/acre) to be saved by direct cutting," Mrs Hayes estimates.

Pre-harvest Roundup (glyphosate) costing £5-7/ha is the cheapest harvest aid. Avoid desiccation unless crops are laid and wet, she advises. "Desiccation with Harvest (glufosinate-ammonium) costs £35/ha and £24.50/ha with Reglone (diquat), and there will be losses on the headlands even if the operator is careful."

Be very careful setting up the combine and checking the chaff coming out, she adds, because losses are always big in oilseed rape.

The area payment for oilseed rape will come down over the next three years, so growers will have to find ways of saving all through the growing season. "Its quite easy to farm with a blueprint when theres lots of money in the job; much easier to put on the full rate than to cut it or miss out an application," adds Mrs Hayes.

"Its possible to make savings with careful management. But it does mean that yields will go down," she says. "So farmer expectations will also need to come down." Here are her recommendations for those planning winter oilseed rape in next years cropping.

IT may be tempting to drill high seed rates to moderate the effects of pigeons, slugs and poor germination, but most crops are too thick. Seed rate can be cut to 3kg/ha but lower rates need better seedbeds and may not be practical every year on all soil types.

PRE-EMERGENCE herbicides are cheapest and best. Where broad-leaved weeds are low, Treflan (trifluralin) incorporated in the seedbed prior to drilling is a classic way of getting a clean rape crop off to a good start, says Mrs Hayes. Half-rate Butisan (metazachlor) or Katamaran (metazachlor plus quinmerac) is an alternative where cleavers are a known problem.

"Post-ems are expensive and the results are often unacceptably poor," she cautions. Thick charlock will justify treatment in December, and needs to be sprayed by the end of January. Patch spray mayweed on gappy headlands before flower buds are visible, she advises.

But Mrs Hayes admits defeat with cleavers problems: "There are no legal options that are cheap – Lentagran (pyridate) costs £29/ha and Galtak (benazolin) £39/ha." Otherwise put up with weeds and resign yourself to desiccation, she says.

"DONT economise on a well-timed autumn spray for phoma – its really important," says Mrs Hayes. "The one spray that you do seem to get massive returns from is this one. We used to think that you could spray in spring and get the same result but by then youve blown it."

Use half-rate Folicur (tebuconazole) plus half-rate CCC (chlormequat) if the crop is very thick and in need of growth regulation, she says. Otherwise, in varieties with good standing power, if the crop is clean this mid-season fungicide will have to go.

Another for the chop is the spray for alternaria, which is no longer a problem in Mrs Hayes area. "We havent had an alternaria year for 7-8 years but Rovral (iprodione) and Ronilan (vinclozolin) are often used in the late season spot by habit."

"Sclerotinia sprays need only be MBC (carbendazim), at 0.5 litre/ha, cost about £2.30," she says. "And they should only be applied if theres wet weather before petal fall and in known sclerotinia areas. Its more of an insurance spray, but its cheap enough."

More nitrogen equals more yield in oilseed rape. But with current low prices the point at which cost exceeds gain is also lower this year. "You could trim N rates by 20kg or more; from 225kg N/ha to 200kg N/ha saves £8/ha," Mrs Hayes calculates.