Crop loss elasticity in relation to weed density and control

Relationships between yield loss in crops and weed density are analysed using an elasticity function ($\text{(}\text{d}\text{L}\text{L}\text{)}\text{(}\text{d}\text{W}\text{W}\text{)}$). In general, loss in crops production caused per weed is higher in low density weed populations than in higher density weed populations. Therefore low density weed populations which are widespread could cause significant crop loss.Control of low density weed infestations will often not be economic by chemical and mechanical methods because of fixed control costs per unit area. In contrast, a control method with costs largely independent of area, such as classical biological control, could provide economic control in these situations of widespread low density weed infestations.