1985 Proc. West Soc. Weed Sci. 38: 104
No differences in barley height, tilleres m-2, plant biomass, and several yield components were observed among the different wild oat removal stages in 1983. Barley yield and 1000 kernal weight were reduced 33 and 19%, respectively, when compared to wild oat free barley, only when the potential, i.e. total, osmotic, and turgor potential, due to wild oat interference were observed. Treatment comparisons of wild oat free barley and wild oat alone showed that barley had a lower total water potential and turgor potential than did wild oat at the 4-5 tiller stage of both species. Barley also had a lower osmotic potential than wild oat at heading, but his was reversed when measured approximately 10 days after anthesis. Soil moisture content was not limiting throughout the 1983 growing season. Barley growth and yield measurements in 1984 did result in differences due to wild oat interference. Barley height was 8-10% greater from late boot to anthesis in those treatments where wild oats were not removed. After anthesis, barley height for all treatments was the same except in the 2-3 tiller wild oat removal treatment which was 9% shorter. The number of barley tillers m-2 after heading was an average 39% less compared to the wild oat free treatment in the 2 node, heading, and not removed wild oat in 1983, no difference in water potential was observed in the barley among the different wild oat removal times at either the late boot or mild stage of barley growth. Barley yield and components of yield were affected in 1984 by wild oat interference to a greater extent than in 1983. Barley yields in the 2 node, heading, and not removed wild oat removal treatments were all less (35-47%) than the wild oat free barley. Analysis of yield components showed that kernal number m-2 was most affected (41-52%) by the wild oat competition. The earlier onset of wild oat interference on barley growth and yield in 1984 was attributed to the initial soil moisture content and subsequent water availability in 1984 compared to 1983.