2 June 1995

GROWTH STAGE SPRAY MESSAGE

An array of Central Science Laboratory work, much of it focusing on forecasting, will be on show at the event to help cereal growers farm more effectively and in harmony with the environment

AT LAST the message on the value of flag leaf sprays for winter cereals seems to be getting through, according to the CSL/ADAS cereal disease surveys.

The exercises, run by Bob Polley and Jean Slough, provide objective data on fungicide use on such crops in relation to:

&#8226 Variety.

&#8226 Sowing date.

&#8226 Previous cropping.

&#8226 Fertiliser use and other

husbandry factors.

&#8226 Final leaf, stem-base and ear

disease levels.

One of the most "interesting trends" is the recent shift towards more winter wheat crops being sprayed at GS39 (flag leaf emergence).

For several years farmers and advisers have been exhorted to put most fungicide resources in-to treating at that stage – the most cost effective timing in terms of disease control and preserving crop yield and quality.

However, protecting the ear by spraying at GS59 (full ear emergence) seems to have been very much the tradition. Fortunately, this seems to be declining in popularity as the importance of protecting the top two leaves is realised, say CSL researchers.

Incidentally, they observe, winter barley growers have sprayed fungicide efficiently on their crops for several years now. The difference is that in winter barley GS31 (first node) is the most important growth stage compared to GS39 in winter wheat.

Advice on applying pesticides is easy to give. "But what about application hazards for the operator?" asks the CSLs Richard Glass. He has some advice and reminders for operators (and possibly bystanders) on how to minimise both general and specific application hazards for all concerned.