Determination of yield and herbicide

Four postemergence herbicides were applied during the harvest season to an established asparagus crop. The spears were harvested every alternate day for 3 weeks after treatment, counted, assessed for quality and production, and analysed in the laboratory for presence of herbicide residues. The suggested use rates of clopyralid and dicamba caused little damage to spears and their residues in the spears declined quickly. Amitrole was slightly more damaging and its residues were detectable in spears for up to 7 days after treatment. Glyphosate caused severe damage to the treated spears, but those emerging after the spray application did not show any significant damage and residues in these spears declined below detectable levels within 5 to 7 days after treatment. The suggested use rates of these herbicides did not appear to have any long term effects on the asparagus crop.