Chemical control of thunbergia (Thunbergia grandiflora)

Peter van Haaren and Joseph Vitelli, Tropical Weeds Research Centre, Queensland Department of Natural Resources, PO Box 187, Charters Towers, Queensland 4820, Australia.


Thunbergia is destroying north Queensland tropical lowland rainforests at the rate of about 0.5 hectare per year. Three experiments involving twenty-five herbicides were trialled at various concentrations as high volume foliar applications for the control of thunbergia (Thunbergia grandiflora). Most herbicides produced 100% brown out, but failed to prevent regrowth of underground tubers and allowed complete recovery of treated plants in 3-6 months. Only imazapyr (1.87, 2.5 and 3.75 g L-1) killed both the above-ground growth and the tuberous root system. The three next most effective herbicides, triclopyr/picloram, fluroxypyr and 2,4-D/picloram produced 80-100% foliage reduction and 20-75% regrowth of underground tubers.


Plant Protection Quarterly (1997) 12 (1) 29-32.