28 May 1999

Digital disease forecasting

A NEW disease forecasting service designed to help cereal growers time fungicide sprays more effectively is to be launched at Cereals 99 and should be available next spring.

Rhìne-Poulencs Positif computer-based model has been used in France for four years, where it has helped boost margins in 35 field trials by £25/ha (£10/acre), says UK technical services manager Ian Cockram.

Two years of trials this side of the Channel suggest it could offer similar benefits, he says. "This year, for example, it predicted the need for an eyespot spray two to three weeks ahead of advice from the field."

Intended as a subscription internet service, sold through selected distributors, the program is the first in a planned series of decision support tools. Additions will include systems for potato blight and sclerotinia in oilseed rape.

Covering all the main foliar diseases of wheat and barley, it uses information on rainfall, temperature, variety and emergence date to forecast how each disease develops and gives an idea of when treatment thresholds are likely to be reached.

It is rare for any single disease to dominate, so Positifs predictions need interpreting where several may be attacking the crop simultaneously, says arable marketing manager David James. "It is not prescriptive and is not intended to replace crop advisers. It doesnt tell you what to do."

In that respect it is unlike the HGCA-funded DESSAC system, which is unlikely to be in farm-ers hands before autumn 2000 at the earliest, says Mr Cockram.

DESSAC is PC-based software, he adds. "As such it needs regular updating and a lot of support. By offering Positif through a website, and updating the information daily, we intend to keep those sorts of difficult aspects away from end-users."

Data updates will come from 40 UK sites with disease tracking for the main sensitive and resistant varieties of wheat and barley emerging at different timings.

Positif, a French acronym, is not product orientated, he stresses. "We were determined to steer away from product recommendations. It is a stand-alone tool."

An on-farm study is in progress to determine its price in the UK.

Although the cold April and dry early May checked septoria progress, Positif shows development of the disease at Wittering, S Lincs is already running ahead of last year, which itself was the worst for Septoria for a decade. &#42