31 May 1996

PEST FORECASTS BANG ON TARGET

PEST forecasting schemes accurate enough to predict attacks on individual farms could be on the cards. ADAS hopes a new system will enable growers to target pesticides more effectively and justify their use to increasingly discriminating buyers.

Cutworms, which attack a range of horticultural crops and potatoes, and pea moth, which can damage combining peas for human consumption, are the first two pests to be targeted. It is hoped others will follow.

Although plenty of forecasting schemes exist, their popularity is not what it might be, says Bill Parker, an ADAS entomologist based at Wolverhampton who helped initiate the project.

"There are two main problems with forecasting schemes. Firstly, growers may not consider the information they receive as being useful. More likely, they dont consider it very relevant, due to its regional nature."

It takes several days to plough through the paper output from the 155 weather stations on which ADAS bases its forecasts. To run individual forecasts is possible, but very time consuming on the existing system, he explains.

Many stations are sited in unrepresentative areas, for example on airfields. That compounds the problem of site-specific forecasting, says Steven Anthony, who is developing the computer system behind the scheme. "Information may not be that relevant even a few miles away."

Updated package

Dr Anthonys updated computer package could change all that. It is based on a geographic information system, which allows easy access to "layers" of information stored in the computer, similar to the latest mapping packages finding their way into farm offices. Vast amounts of information from many different sources can now be processed quickly.

That speed is the key to the new pest forecasting system, he explains. Information can be obtained from all of the met stations for a national picture, from groups for a regional view, or singly for a targeted forecast – in seconds, rather than days.

The pea moth forecast, which is being developed with the Processors and Growers Research Organisation, is based on an estimate of adult numbers in the crop and temperature, which governs the speed at which eggs develop. Pheromone trap information indicates when threshold numbers have been breached, and egg laying has started in earnest.

Sprays must be applied at egg hatch – any later, and larvae will enter pods. Using temperature and trap information, the computer model predicts the likely spray date, explains Dr Anthony.

Cutworms are similar in that their speed of development depends on temperature. But rainfall is also important, since it determines survival rates – the pest thrives in dry soils. So the computer calculates a survival index based on recorded rainfall.

Both temperature and rainfall can vary from the forecast. Thanks to computer power, forecasts can be instantly updated to allow for this, says Dr Parker.

The computer checks to see if weather stations are operating correctly. A "quality index" grades each ones information from poor to good, so suspect readings can be filtered out, keeping the forecast accurate.

Thanks to the speed of the system it will be possible to run individual forecasts for growers, using their own data. A thermometer and a rain gauge would suffice, although a simple automatic weather station would be more accurate, says Dr Parker. "At £1500-2000 they are not that expensive."

The information could be telephoned in, and an answer given immediately. Alternatively, computerised growers could E-mail it and receive information back on screen, he explains.

Such site specific information is likely to prove more popular than current schemes, Dr Parker believes. And demand is likely to increase.

"Growers are facing pressure from supermarkets to adopt integrated crop management principles. This system is another piece in the ICM jigsaw. It could help reduce inputs, and it could also justify their use when the need arises," he explains. &#42


&#8226 For cutworms and pea moth.

&#8226 Other pests could follow.

&#8226 Uses powerful geographic information system technology.

&#8226 High speed – data processing in seconds not days.

&#8226 Farm-specific forecasts possible.

&#8226 Will help reduce or justify pesticide use.