1305 AJCS 5(10):1305-1310 (2011) ISSN:1835-2707 Efficacy of sea water in combination with trifloxysulfuron and quinclorac to control weeds in salt tolerant tropical turfgrass Md. Kamal Uddin 3 , Abdul Shukor Juraimi 1* , Mohd. Razi Ismail 3 , Mahfuza Begum 3 Radziah Othman 2 and Anuar Abdul Rahim 2 1 Department of Crop Science, Faculty of Agriculture, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia 2 Department of Land Management, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia 3 Institute of Tropical Agriculture *Corresponding author: ashukor@agri.upm.edu.my Abstract Research was designed to reduce herbicide use by replacing post emergence herbicides with readily available sea water to control weeds in salt tolerant tropical turfgrass. Different concentration of sea water in combination with trifloxysulfuron-sodium and quinclorac were used in this study. Maximum injury of 70-100% occurred at 21 DAT in Sporobolus diander, Cyperus aromaticus, Cyperus rotundus, and Emilia sonchifolia, except E. atrovirens, when treated with ¾ trifloxysulfuron-sodium{N-(4-6-Dimethoxy2- pyrimidinyl)-3-(2,2,2-rifluoroethoxy)-pyridine-2-sulfonamide sodium salt} with sea water, ¾ trifloxysulfuron-sodium with ¾ sea water, trifloxysulfuron-sodium with ½ sea water, ¾ quinclorac (3,7-dichloro-8-quinoline carboxylic acid) with sea water and ¾ quinclorac with ¾ sea water. The trifloxysulfuron-sodium and quinclorac herbicide can be effectively used for weed control in C. dactylon ‘satiri’ and P. vaginatum respectively; and both the herbicides can be used for effective weed control in Z. japonica. Keywords: Sea water, weed, turfgrass, trifloxysulfuron-sodium, quinclorac. Abbreviations: EC-Electrical Conductivity, LSD-Least Significance Difference DAT-Day after treatment. Introduction Weed causes a continuous problem in management of all turfgrass species. There are numerous herbicides available for pre and post weed control in bermudagrass (Cynodon dactylon), seashore paspalum (Paspalum vaginatum) and zoysiagrass (Zoysia japonica) (Blum et al., 2000; Wiecko, 2000; Unruh et al., 2006; Teuton et al., 2004). According to numerous studies, seashore paspalum exhibits exceptional salt tolerance (Kamal Uddin et al., 2009; Carrow and Duncan, 1998; Dudeck and Peacock, 1985; Duncan, 1998; Duncan and Carrow, 2000) and also bermudagrass, is listed as tolerant (Carrow and Duncan, 1998; Marcum and Murdoch, 1994, Marcum and Murdoch 1994; Kamal Uddin et al., 2011). Most herbicides used in warm season turfgrass will not control grasses and sedges. Nonselective use of herbicides, such as glyphosate and glufosinate, provide control but injure desired turf (Hossain et el., 1999; McCarty et al., 1993). Quinclorac is also leveled in turfgrass preemergence and post emergence for control of several weed species including Digitaria sanguinalis, Panicum repens, Trifolium repens, and Hydrocotyle spp (Kelly and Coats, 1999). Trifloxysulfuron- sodium, a sulfonylurea herbicide, has been developed for use in cotton, sugarcane and bermudagrass (Hudtez et al., 2000; Mosdell et al., 2001; Porterfield et al., 2002; Rawls et al., 2000). Trifloxysulfuron-sodium was readily absorbed by shoots and roots and was rapidly translocated in weeds. Growth of susceptible weeds was inhibited by trifloxysulfuron-sodium application with complete mortality within 1 to 2 weeks after application (Hudetz et al., 2000). Several golf courses have the capability to use saltwater for irrigation, and this practice is becoming more common in coastal environments (Duncan and Carrow, 2000; Wiecko, 2003). Many weeds can be suppressed in saline conditions, but salt tolerant weeds will require other means of control. Weeds are a common problem and need to be controlled in order to maintain a high quality turf. Furthermore, many golf courses border environmentally sensitive areas and hence chemical control of weeds is not always feasible. While sea water may control some weed species, salt tolerant weeds would require more innovative approaches for effective control. Sea water integrated with combinations of reduced herbicide rates offer opportunities for improved weed control (Wiecko, 2003). The specific objective of this study was to evaluate the performance of sea water in combination with reduced herbicide rates on to control weed in salt tolerant turfgrass species. Results Effect of combinations of sea water and trifloxysulfuron on turfgrass injury Paspalum vaginatum Significant differences in injury level were observed at 3 days after treatment (DAT) in the different combinations of trifloxysulfuron-sodium herbicide and sea water (Table 3- supplementary data). Applications of fresh water (FW), ½ sea water (½ SW) and ¼ sea water (¼ SW) did not cause any