| The effects safflower and planting date have on controlling jointed goatgrass were studied. Jointed goatgrass populations were similar in all treatments prior to planting safflower in 1997, and were higher in safflower prior to planting, and reduced in October planted wheat compared to September-planted wheat in 1998. Wheat yielded 25%--35% higher when planted early. Crop contamination was four times higher in early vs late planted wheat. Jointed goatgrass populations in safflower were reduced 97%. In 1998, jointed goatgrass populations were 55 and 75% less in fallow following safflower than following September- and October-planted wheat, respectively. Soil seedbank concentrations were ten times higher in October-planted wheat than safflower and September-planted wheat at 0--5 cm. Safflower reduced jointed goatgrass populations and reproduction. September-planted wheat yielded higher with less contamination. Delaying planting, to allow additional tillage, proved ineffective in controlling jointed goatgrass, as yield losses far outweighed any benefits gained by delaying wheat planting. |
