Tolerance to herbicides of ground cover species for New Zealand orchards

K.C. HarringtonA and A. RahmanB

A Department of Plant Science, Massey University, Palmerston North, New Zealand.

B AgResearch, Ruakura Research Centre, Private Bag 3123, Hamilton, New Zealand.


Summary

A potential strategy for orchard floor management in New Zealand is to grow ground covers which suppress weeds during the growing season, then to apply herbicides to selectively remove any weeds which do establish, spraying only during crop dormancy to minimize the risk of herbicide contamination of fruit.

Herbicide tolerance studies were conducted on eight plant species with potential for ground cover use. Festuca rubra and F. longifolia tolerated a wide range of grass-killing herbicides and could be easily cleared of weeds. Weeds in Trifolium repens could be controlled by haloxyfop, 2,4-D, MCPA and glyphosate, while paraquat, diquat, simazine and haloxyfop could be used in Lotus pedunculatus swards. Dichondra micrantha was sufficiently tolerant of tribenuron, clopyralid, glyphosate, glufosinate and paraquat/diquat to make it a suitable candidate for use in orchards. Hydrocotyle heteromeria and Centella uniflora tolerated several knock-down herbicides and also warrant consideration as ground cover species. However, the range of herbicides tolerated by dryland bent Agrostis castellana would not allow easy removal of grass weeds. The potential for using ground covers in orchards for weed control is discussed.

 

Plant Protection Quarterly (1998) 13 (3) 111-116.