27 November 1998

Smarter with septoria?

CEREAL growers are still missing tricks when it comes to controlling septoria.

Big differences between varietal susceptibility mean rate cuts, wider spray windows and more effective control are all possible.

Research conducted at IACR Long Ashton shows Septoria can take up to six weeks longer to develop in a moderately resistant variety like Hereward than a more susceptible one like Riband. That is something too few growers take full advantage of, according to researcher Sheila Kendall.

Her claim stems from work to establish an acceptable spray threshold for a diagnostic kit developed in conjunction with fungicide maker Du Pont. The challenge was to identify the level at which a diagnostic response justifies spraying.

The threshold chosen is 1 antigen unit on leaf three, which allows a 10-14 day spray window before the disease becomes too established on susceptible Riband.

But the work also showed that more resistant varieties, like Hereward, can be left unsprayed for six weeks longer, says Dr Kendall. Alternatively significant rate cuts can be made for earlier sprays.

Although the diagnostic kit is unlikely to be available to farmers, results are supplied to consultants so advice can be adjusted during the season.


&#8226 Diagnostic kit indicates best spray timing.

&#8226 Spray windows vary between varieties.

&#8226 Scope for growers to stretch application window or cut rates.