27 March 1998

Use strob fungicides with care to cover costs

STROBILURIN fungicides need using with care to achieve all the benefits required to cover their higher cost, according to work funded by the Home-Grown Cereals Authority R&D levy.

"Overall, the new compounds appear to offer good disease control, coupled with potentially higher yields compared to existing treatments. However, care needs to be taken to ensure that you make the most of these expensive new treatments," says ADAS pathologist Neil Paveley, joint project leader with Bill Clark.

Results from the first two years of the on-going project show disease control is comparable with good triazole-based programmes, but with a broader range of activity and more flexible timing.

The work also shows leaves stay greener, with significantly more yield-building chlorophyll in the upper leaves.

But unlike triazoles, strobilurin fungicides only protect against disease, offering no eradicant activity, the report notes. That makes correct spray timing vitally important.

Well-timed sprays can boost yield beyond existing fungicide programmes, the report notes, with the best benefit from applications starting as leaf three emerges at T1.

Although yield response is closely related to dose, there is more scope for reducing dose where strobilurins are used in mixtures with other fungicides.

&#8226 Strobilurin advice is contained in a new HGCA R&D topic sheet, which is available from the HGCA (0171-5203945). &#42