The effects of various herbicides on Bryophyllum pinnatum (Lam.) Pers in Nudgee Wetlands Reserve, Queensland

E.C. Sparkes, S. Grace and F.D. Panetta, Alan Fletcher Research Station, Department of Natural Resources and Mines, PO Box 36, Sherwood, Queensland 4075, Australia.


Abstract

Bryophyllum pinnatum (Lam.) Pers is an invasive succulent weed that has often been blamed for stock poisoning, especially in drier seasons when there is limited alternative feed. A trial examining various control options was undertaken in a wetland reserve in Boondall, a suburb of Brisbane. Four herbicides, hand pulling and a standard control were included in this experiment. Since the waxy cuticle of Bryophyllum spp. requires a wetter-spreader adjuvant, the anionic surfactant BS 1000 (alcohol alkoxylate) was added to all spray solutions. 2,4-D (present as dimethylamine salt) at 250 g a.i. and 500 g a.i. 100 L-1 were the most effective treatments, with kill rates in excess of 90% in both cases.

While fluroxypyr as methylheptyl ester at 150 g a.i. and 300 g a.i. 100 L-1 showed comparable efficacy, 2,4-D was the most appropriate herbicide because of its low off target damage and low environmental impact. The higher rate (500 g a.i. 100 L-1) would be appropriate when plants are in a hardened condition, e.g. immediately following winter. Hand pulling would prove far too expensive unless performed by conservation volunteers. Damage to adjacent species indicated that care must be exercised in the application of some herbicides, specifically fluroxypyr, picloram, and triclopyr, as coastal heath vegetation often has well-developed surface root systems that can be damaged by herbicides. This phenomenon, in conjunction with a high water table and sparse vegetation, resulted in severe damage to non-target species such as Casuarina equistifolia L.

 

Plant Protection Quarterly (2002) 17 (2) 77-80.