Field assessment of herbicides to aid establishment of manuka (<i>Leptospermum scoparium</i>)

Abstract

Herbicide treatments were assessed in two concurrent experiments for improving the establishment of manuka seedlings (three provenances) transplanted into hillside pastures for honey production Height and trunk diameters 18 months after planting were still significantly reduced by initial poor control of weeds Controlling weeds in a patch of 10 m diameter gave better manuka growth than doing so in a 05 m diameter patch Two of the more effective treatments were a mixture of glyphosate simazine and clopyralid applied before planting and a postplanting application of glyphosate and simazine sprayed while shielding the manuka A mixture of haloxyfop clopyralid and simazine applied in August then again in December following planting in July gave no further improvement in manuka growth than when applied only in August Residues of metsulfuron equivalent to 120 g ai/ha applied just prior to transplanting caused no adverse effects in any of the three provenances of manuka