Evaluation of Steam Application for Weed Management in Citrus

Abstract

Abstract. In this study, a weed steamer was developed, and several steam treatments were utilized to maintain and control the growth of weeds in a citrus grove. Two factors affecting the steam treatment were studied: (i) tractor speed (low, 1.2 km/h; and high, 1.7 km/h); and (ii) steam flow rate (low, 15 L/h; and high 53 L/h). The weed control treatments included various combinations of steam flows and tractor driving speeds, a post-emergent herbicide (paraquat) treatment, and an untreated check for comparison purposes. Randomized experiments were conducted to evaluate the efficacy of each application. It was found that steam applications at high flow rate provided 93%-97% burndown damage of the weed foliage within 3 days after application. Weed re-growth was observed in steam applications, especially with low flow-rate applications. The combination of low tractor speed and high steam flow-rate was the most effective of the steam treatments tested (84% total weed burndown at 12 days after application). This treatment was found effective in controlling weeds like goatweed and sedges. Florida pusley was the least affected by steam due to its prostrate growth nature that prevents an adequate coverage of steam on the entire plant. Based on the observations from this study, the steam application has the potential to be a non-chemical and sustainable strategy for weed management in citrus tree rows. Keywords: Citrus production, Herbicide, Steam application, Weed control.