Battle is won but slug war still has way to go
EFFORTS to develop a system for forecasting slug damage are bearing fruit. But further research is needed before the troublesome pest can be hit with more precisely-targetted control, admit researchers.
A fine, firm seedbed is the classic way to prevent slug damage, comments David Glenn of Long Ashton Research. But it is often difficult to achieve on heavy land. Integrating a range of other factors is then needed.
But even if all aspects of integrated control are deployed slugs may still attack. Work at Newcastle University aims to refine a decision-making package which will give growers an 18-hour warning of such an onslaught. Slug bait applications could then be made at the best timing.
Optimum slug control starts with establishing the risk. So far there is little understanding of why population variations occur.
"We have to tease out relationships of the different factors involved, so that we can accurately forecast autumn populations," says Andrew Young, of the University of Newcastle, who is well into a three-year MAFF joint venture project.
At the moment risk is best assessed by baiting with layers of mash covered with 116sqcm (18sqin) hardboard covers. Pellets go on when five to six slugs are found at the test sites.
The new system could assess crop type, infestation level, soil and seedbed characteristics, soil moisture, temperature at soil level, the time of year, the amount and type of crop residues and the risk of imminent heavy rain.
It is hoped that the better understanding of slug population dynamics and risk levels will result in an interactive Internet facility which will allow a farmers local information to be worked through on a mainframe computer model.
This will feed back medium term advice on potential risk and short term help with optimum application timing as part of the developing DESSAC decision support system.