Nontarget plant damage from picloram and triclopyr used for climbing spindle berry control in regenerating native forests

Abstract

Climbing spindle berry (Celastrus orbiculatus) is a deciduous liane climbing to 12 m It is spreading in Waikato particularly in hedgerows and native forest remnants Control has been by foliar spray with a herbicide mixture containing picloram This study investigated damage to surrounding nontarget native flora where climbing spindle berry was treated with herbicides containing picloram The most abundant native species in the plots included Podocarpus totara Blechnum blechnoides Asplenium bulbiferum Coprosma spathulata Carex sp Adiantum cunninghamii Pittosporum eugenioides Deparia petersenii and Lastreopsis glabella Picloram triclopyr (Tordon Brushkiller 100 g/litre picloram as the amine salt 300 g/litre triclopyr as the butoxyethyl ester) as a foliar spray was compared with picloram gel as a cut stump treatment Both the cut stump and foliar spray resulted in excellent control of climbing spindle berry The cut stump treatment resulted in little damage to adjacent vegetation The foliar spray was damaging to adjacent small nontarget plants especially the ferns The affected nontarget plants recovered within 6 months with no damage apparent on new growth This study coincided with a protracted drought and seedling recruitment was compromised; therefore it was difficult to obtain conclusive results about seedling emergence