15 June 2001

Taking positive steps to avoid poor yields

By Andrew Swallow

EVERY little bit of yield is likely to be worth chasing in the fight to reach sugar beet quota this year, says Morley Research Centre.

Extra attention to weed control, irrigation and fungicide use could all pay, members heard at a sugar beet open day last week.

"Last year the yield difference between March and May drilling was 25%, and that was in a wet year," says sugar beet specialist Martin Lainsbury.

"If it is a dry summer, we could be facing an even greater yield loss from the late drillings this year."

Weed control from pre-emergence and first post-emergence sprays has generally been good, he notes. But rapidly drying conditions are making subsequent decisions tricky. Gappy crops mean it could be worthwhile building up residual herbicides to prevent late weed flushes.

"As a rule of thumb, one tall weed per square metre will rob 1t/ha of yield. As A and B quota, that is worth a lot of money."

On light soils, the most soluble residual, Goltix (metamitron), should be used, building up to a total 3kg/ha, says Mr Lainsbury.

"That might seem expensive, especially if it stays dry and no more weeds emerge, but as an insurance it could be very worthwhile."

But Goltix will not control black bindweed, so a switch to slightly less soluble chloridazon is advised where that is a problem, he adds.

Venzar (lenacil) is also an option, but as the least soluble residual, it should be used only on the more moisture-retentive, heavy soils.

BBRO-funded work on the FAR system at Morley is already showing the value of a residual such as chloridazon in the programme this year, says Mr Lainsbury.

"With FAR, the weed control has been easy where a pre-emergence was used, but where it hasnt, sporadic weed emergence is making post-emergence timings difficult."

Last year, adding the residual pre-emergence added little but cost (Arable, Feb 16).

With crops struggling to meet A and B quota, the economics of controlling volunteer potatoes, irrigation and fungicides also shifts, he says.

"Growers tend to concentrate irrigation on potatoes, but irrigation this year may be more worthwhile than usual on sugar beet if it is protecting quota."

Triazole fungicides keep crops greener longer than untreated or even sulphur-treated plots, he adds. Provided there is time for resulting extra photosynthesis, yield increases can top 3t/ha.

On Morleys own farm, fungicides are almost certain to feature, because a 25% yield reduction would slash corrected yields from the five-year average of 55t/ha (22.t/acre) to just 41t/ha (17t/acre), says director Jim Orson.

"We will probably use them even if rust and ramularia arent there. The problem is, we only know how much extra yield they give in a wet year." &#42

MRC QUOTA-FILLING TIPS

&#8226 Top-notch weed control.

&#8226 Gappy crops: build residuals.

&#8226 Irrigate where economic.

&#8226 Use triazole fungicides.

Weed control, fungicides and irrigation will all need extra attention this year, sugar beet growers heard at a recent Morley Research Centre open day.

Build up residual herbicides in gappy crops, says Morleys Martin Lainsbury.

Members day

The sugar beet open day was the first in Morleys programme of members days, which, as long as East Anglia remains foot-and-mouth free, are all scheduled to go ahead. "If theres an outbreak in Norfolk or Suffolk, then everything will be cancelled immediately," says director Jim Orson. Footbaths and wheel-washes are in place and members should check www.morley.org.uk or phone 01953-713200 for the latest news. "With rhizomania on the neighbouring farm, the disinfection procedures would be in place anyway," adds Mr Orson.