18 December 1998

Linseed leaf spot not worth spraying

SEPTORIA leaf spot can be found quite readily on winter linseed, but treatment is unlikely to be worthwhile at this stage, advises ADAS.

The disease is characterised by circular, grey or blackish spots with just discernible black dots within the lesion.

Although many plants which successfully weathered poor weather in late November are showing infection, spraying is unlikely to pay. In trials last year responses to autumn fungicide were variable, notes ADAS. Where benefits did occur the combination of symptoms on true leaves and mild conditions was probably a key factor, it says.

Unless infections worsen dramatically treatment is not advised until spring. Crops with high levels of leaf infection may then benefit from sprays in March and at mid-flowering. In 1997 such applications gave good yield benefits.