The relative sensitivity of various crops and weeds to celery root residue incorporated into soil was determined in greenhouse experiments. A range of concentrations was used to determine the percentage of celery residue needed to cause a 50% reduction in plant growth (I50). The most sensitive weed was spiny amaranth and the least sensitive was common purslane. The most sensitive crop was radish and the least sensitive was celery. Selectivity was calculated as crop I50/weed I50 and varied from a maximum of 13 for celery and spiny amaranth to a low of 0.4 for radish and common purslane. Selective weed suppression might be obtained when celery residue is present.
