Prof. Daniel Tan1, Dr Chinaza Onwuchekwa-Henry1,3, Dr Robert Martin2
1The University of Sydney, Sydney, Australia, 2Agricultural Systems Research Co., Ltd., Battambang City, Cambodia, 3Department of Agriculture and Fisheries, Toowoomba, Australia
Biography:
Professor Daniel Tan graduated from the University of Queensland with a BAppSc (Hort Tech) (Hons 1) in 1991 and a PhD in 1999. He is currently the Development Agriculture Theme Leader of the Sydney Institute of Agriculture, Faculty of Science Postgraduate Coursework Program Director, Cambodian Country Coordinator of the Sydney Southeast Asian Centre and Agriculture, Food and Environment Node Leader of the Sydney Vietnam Centre. He is the food safety theme lead for the One CGIAR funded Fruit and Vegetables for Sustainable Healthy Diets (FRESH) initiative.
Abstract:
This paper presents results on the integrated weed management for the lowland rice systems of northwest Cambodia funded by the Australian Centre for International Agricultural Research (ACIAR). The project determined the benefits of improved establishment methods with direct drill seeders and pre-emergence herbicide applications (including oxadiazon, butachlor, pretilachlor and pendimethalin) as alternatives to high seeding rates (e.g. 200 kg/ha) to improve weed suppression in dry seeded rice. All the plots were infested with different weed species such as grasses, sedges and broadleaf. Pendimethalin consistently controlled the grasses compared with other pre-herbicide options. Oxadiazon showed higher efficacy in controlling sedges and grasses, while butachlor mostly controlled broadleaf weeds. Pre-emergence herbicides, oxadiazon and butachlor were effective in suppressing weeds at low seeding rates of 80 kg/ha. Pretilachlor was not as effective in controlling weeds in dry seeding compared with wet seeding conditions. Pendimethalin can effectively control weeds, but crop damage was a risk in poorly prepared Cambodian seedbed. Plants can recover from pendimethalin herbicide toxicity and grain yield can potentially increase by 55% in dry seeding conditions with pendimethalin application. We collaborated with the Cambodian Agriculture Value Chain Program (CAVAC) and the CGIAR Excellence in Agronomy (EiA) to test the efficacy of applying pre-emergence herbicides (e.g. pretilachlor + fenclorim safener) using Unmanned Aerial Vehicle (UAV) drones with a water volume of 14 L/ha at 1 to 3 days after sowing in wet seeded fields. The pre-emergence herbicides applied at the recommended rates (with low water volumes) using UAV effectively suppressed weeds.