14 June 1996

Trial shows clover-rich wheat has less septoria

Andrew Blake

SOWING wheat into an established crop of clover could cut disease levels, notably of Septoria tritici, as well as saving fertiliser costs.

But trials at IACR-Long Ashton highlight the need to keep on top of grass weeds and show the nitrogen input from the clover is hard to assess. The approach looks best suited to whole-crop silage production.

Researchers at the Bristol-based institute believe an understorey of clover can help cut rain splash which disperses septoria inoculum. Recent findings, however, are that basal infection is not the only source of trouble during stem extension. Lesions are often found higher than the emerging leaves. Use of clover should help pinpoint the relative importance of the two, says Darren Lovell.

The trials, examining output both for silage and for grain, show that provided enough white clover is present (25-30% of dry matter), silage gross margins can be nearly double those of conventional whole-crop silage.

But the so-called bi-cropping for grain was disappointing in 1995. Overall yields from five sites were less than half those of conventional crops, notes Dr Bob Clements. Grass weeds were catastrophic at two sites." Burning off with paraquat, which also checks competition from the clover, could solve the problem, he says.

Some better means of estimating the nitrogen available to the wheat in its early growth stages is also required if the savings on bag fertiliser are to be fully exploited, he adds.

Long Ashton researcher Darren Lovell is examining the role of a good clover sward in restricting the spread of septoria in wheat.