Factors affecting clover root weevil (Sitona lepidus) numbers and clover production

Abstract

The impact of a range of simulated pasture management options on damage to white clover resulting from the presence of the clover root weevil was evaluated in a glasshouse experiment. Pasture management options included were irrigation, cutting regime, cultivar, soil fertility (Olsen P) level, and nitrogen application. Two different soil types were used. White clover growth was significantly enhanced by moist soil conditions, as were clover root weevil (CRW) larval numbers recovered per plot. Few (<1%) CRW larvae developed from the eggs (applied at 4000/m2) under dry soil conditions. Dry soil conditions dominated any effect that could be attributed to other treatments. More (c. 10.5%) CRW larvae developed under moist soil conditions, but clover plants tolerated this without significant losses to shoot production, although it did significantly (P = 0.01) affect shoot/ root ratio (on average 50% lower when CRW larvae were present). More clover dry matter was produced on mineral soil (P < 0.05), when nitrogen was applied (P < 0.05) and when the cultivar ‘Challenge’ was used instead of ‘Prop’ (P < 0.001). Cutting regime had a minor influence (P < 0.10) on clover production but the influence of Olsen‐P level was not significant.