Pasture renovation: interactions of vegetation control with slug and insect infestations

SUMMARYIn a field trial at Rukuhia, New Zealand, ryegrass (Lolium perenne L.) and white clover (Trifolium repens L.) seed was direct drilled into pasture (i) without herbicide suppression of the resident sward, (ii) with banded application of glyphosate or paraquat herbicide at drilling to remove 50% of the resident sward and (iii) after complete removal of the grass and weed components of the old sward with glyphosate or paraquat before drilling. These treatments were compared with the untreated old swards. Where the old sward was removed by herbicide before drilling, pests moved onto the drilled seedling rows, but, where herbicide was sprayed in bands over the drill rows, the pests remained in or moved into the residual bands of the old sward. Significant beneficial interactions between herbicide use and in-furrow applications of molluscicides and insecticides resulted in reductions in the numbers of pests on the seedling rows. The influence of vegetation control on the pest burden is discussed in the context of current pasture renovation practices.