TOWARDS AN ECONOMIC FRAMEWORK FOR EVALUATING POTENTIAL BENEFITS FROM RESEARCH INTO WEED-CONTROL

A dynamic economic model for estimating benefits from research into al ternative tactics for weed control is developed, by treating weeds as renewable negative resources. Research benefits are evaluated as the c hange in steady-state profit resulting from research-induced changes i n various parameters of the system. The model is illustrated by applic ation to research aimed at the control of wild oats in wheat in Austra lia, whereby it was found that the magnitude of benefits depended not only on the level of research-induced change but also on demographic b ehaviour of the weed. Research leading to reductions in seedling survi val, potential fecundity or recruitment gave higher benefits than the manipulation of weed competitiveness or seed mortality. Reduced seedli ng survival gave the highest benefits in most cases, but achieving suc h improvement by improving herbicide efficacy may have a high marginal cost given that the tactic is already well-researched. Thus it is con cluded that research into reducing potential fecundity could be more w orth while, since it also gave high benefits but is relatively unexplo red.