INTERNATIONAL JOURNAL OF AGRICULTURE & BIOLOGY 1560–8530/2005/07–5–719–723 http://www.ijab.org Development of Suitable Strategies for the Economical Control of Avena fatua and Phalaris minor in Wheat MUHAMMAD JAMIL 1 , ZAHID ATA† AND ABDUL KHALIQ† National Agricultural Research Center, Islamabad–Pakistan †Department of Agronomy, University of Agriculture, Faisalabad–38040, Pakistan 1 Corresponding author’s e-mail: jamil_narc@yahoo.com ABSTRACT A field experiment was conducted by using sorgaab along with lower rates of organic herbicides to find out some suitable ways for the control of Avena fatua and Phalaris minor in wheat under Faisalabad. Concentrated sorgaab (Sorghum bicolor water extracts) was combined with reduced doses of organic herbicides i.e. 2, 4-D, benzoic acid and sulfosulfuron. For comparison the recommended doses of these chemicals were used and a weedy check was maintained. Sorgaab @ 6 or 12 L ha -1 in combination with lower rate of sulfosulfuron @ 15 g a. i. ha -1 at 30 DAS significantly reduced Avena fatua density (78- 92%) and dry weight (72-98%) and was statistically on par with full dose of sulfosulfuron @ 35 g ha -1 at 30 DAS (T 11 ) which reduced Avena fatua density by 89-96% and dry weight by 99%. One spray of conc. sorgaab @ 12 L ha -1 combined with lower rate of sulfosulfuron @ 15 g a. i. ha -1 at 30 DAS (T 8 ) suppressed Phalaris minor density by 82-91% and dry weight by 86-87%. One spray of standard dose of sulfosulfuron @ 35 g a. i. ha -1 at 30 DAS (T 11 ) reduced Phalaris minor density by 91- 95% and dry weight by 97-100%. Although maximum increase in grain yield was obtained in plots which were applied standard dose of sulfosulfuron @ 35 g a. i. ha -1 but statistically similar yield was also resulted by one spray of conc. sorgaab @ 12 L ha -1 with sulfosulfuron @ 15 g a. i. ha -1 at 30 DAS. Key Words: Avena fatua; Phalaris minor; Wheat; Sorghum water extract; herbicide INTRODUCTION Weed losses are encountered nearly everywhere in agriculture. The introduction of high yielding wheat varieties having high inputs requirements has resulted in tremendous increase in weed population in wheat fields. The extent of losses in wheat caused by weeds is alarming. The weed spectrum of wheat in Pakistan consists of a number of weeds among which Phalaris minor L. (Canary grass) and Avena fatua L. (Wild oat) are most serious weeds. Phalaris minor in rice-wheat areas of Punjab is a serious problem resulting in significantly yield losses (Byerlee et al., 1986). Avena fatua and Phalaris minor had a major share of the total nutrient uptake by weeds. Cheema and Nazir (1995) pointed out that different wild oat densities showed highly negative correlation between grain yield and yield components such as fertile tillers, number of grains per spike and 1000-grain weight. Wheat yield reduction by wild oat was more pronounced in unfertilized plots, whereas the magnitude of yield losses reduced with successive increase in nitrogen rates. Menan et al. (2003) reported that economic threshold for wild oat was between 11.77 and 14.70 plants/m 2 and for black grass between 15.70 and 32.56 plants/m 2 . Donovan (1998) pointed out that as wild oat density increased, competition from the weed, and consequently crop losses, increased. The timely control of these weeds is very essential for better wheat production. The organic chemical compounds having herbicidal properties which are relatively less toxic and cheaper, may be combined with allelopathic water extracts at lower rates. This on one side may improve the efficiency of allelopathic extracts and on other side may provide the opportunities of reducing the herbicidal rates and hence the cost of weed control could be lowered with relatively a more environmentally safe approach. Inhibition of Avena fatua by mixture application is in line with findings of Rice et al. (1981) and Einhelling et al. (1982) who concluded that combinations of chemicals have synergistic effects. The allelochemicals present in conc. sorgaab may work synergistically with lower rates of these organic compounds to decrease Avena fatua and Phalaris minor density and dry weight. The present study was therefore, designed to develop a suitable strategy to control these weeds in wheat. MATERIALS AND METHODS A field experiment was conducted at the Agronomic Research Area, University of Agriculture, Faisalabad for two years. The experiments were laid out in a randomized complete block design with three replications in 7m x 2m plot size. Wheat cultivar (Punjab-96) was sown in the first week of November, in the respective year, using the standard procedure. A basal dose of 110 kg N, 55 kg P and 60 kg K ha -1 was applied. The whole of phosphorous and potassium and half of nitrogen was applied at the time of sowing. The remaining half nitrogen was applied with