Integrated control methods for bellyache bush (Jatropha gossypiifolia L.) in northern Queensland: preliminary results

摘要

In northern Queensland, an integrated trial has been established to determine the most cost effective combination of primary and secondary (follow-up) treatments for the control of bellyache bush (Jatropha gossypiifolia L.). This paper reports on theeffectiveness of the primary control techniques that were applied: control, burning, foliar spraying (using metsulfuron (Brush Off~(R))), stickraking (using a D7 Dozer) and slashing (using a tractor-mounted slasher). Measurements undertaken included mortality of juvenile (up to 20 cm height), mature (20-100 cm height) and old (>100 cm height) bellyache bush plants, and post-treatment seedling recruitment and pasture response. Both slashing and the application of herbicide caused 100% mortality, irrespective of the size of plants. Fire was most effective on smaller plants (96% mortality), with efficacy decreasing with increasing size of plants. In contrast, stickraking was most effective on the largest plants (99% mortality). The natural mortality (control) was 38%. For every plant killed by spraying, slashing, stickraking and burning, 20, 97, 74, and 69 plants were recruited from the seed bank, respectively. For every plant that died naturally, 74 were recruited from the seed bank. The impact of primary treatments on pasture yield varied between treatments. Brush Off increased pasture yield 17% when compared with the control whereas slashing, stickraking and burning reduced pasture yield 37%, 24% and 40%, respectively. Results suggest that foliar spraying of bellyache bush with metsulfuron was the best singular control method in terms of kill effectiveness, level of post-treatment seedling recruitment and sustainability of pasture yield.