10 August 2001
Beet mildew spray worth it – IACR

By FARMERS WEEKLY staff

AS powdery mildew starts to infect sugar beet, The Institute of Arable Crops Research station at Brooms Barn advises spraying crops with a triazole fungicide.

Even those beet crops destined for early lifting, should receive a full rate (0.625l/ha) of Punch C (carbendazim+flusilazole).

That contrasts with advice from elsewhere, admits British Beet Research Organisations Mike May.

Traditional thinking indicates that sulphur, which costs about half as much, is more appropriate for beet for early harvest.

“Its fairly clear to us that where the target is mildew you should use Punch C, full stop.” He questions the statistical significance of other trials.

In IACR work, the treatment boosted output from late September liftings last year by 9.4t/ha adjusted. “The yield increase is more than enough to pay for it,” says Mr May.

If rust is severe or on irrigated crops or susceptible varieties, such as Duke, Swift, Rebecca and Rosanna, growers should consider switching to full rate Alto (cyproconazole), he says.

Sulphur can be added, at 10kg/ha, to increase mildew control. But Brooms Barn does not advocate reducing rates in mixtures.

Again, this is contrary to advice from other sources. “Despite the cost saving, the effectiveness and persistence of the chemicals is reduced accordingly,” warns Mr May.

ADAS recommends checking crops for both diseases at least once a week and treating early.