Economic return of purple and yellow nutsedge management in vegetable production of southern California

The economic return of a standard low desert crop rotation of spring cantaloupe (Cucumis melo L.)–summer fallow–winter broccoli (Brassica oleracea L.) infested with purple nutsedge (Cyperus rotundus L.) or yellow nutsedge (Cyperus esculentus L.) was compared to alternative rotations that included: cultivation (hand-hoeing), a smother crop of wheat (Triticum aestivum L.) and sudangrass (Sorghum sudanense L.), a smother crop of wheat followed by solarization, and sweet corn (Zea mays L.) with halosulfuron application followed by sudangrass in southern California from 2001 to 2003. After two growing seasons, broccoli was planted without any nutsedge control. Purple and yellow nutsedge tubers increased dramatically in the untreated plots and purple nutsedge reduced crop yield and economic returns. Solarization was the most effective treatment for reducing purple nutsedge populations, but had a negative economic return above variable costs. Multiple hand-hoeing also controlled purple nutsedge effectively and resulted in a net return of $3069/ha. The halosulfuron and the smother crop treatments did not control purple nutsedge and had negative economic returns. Yellow nutsedge did not affect crop yield significantly during the course of the experiment. All methods controlled yellow nutsedge effectively, especially when there were no crops growing in the summer. However, the economic return of the treatments varied significantly. The net return of the cultivation treatment in the yellow nutsedge field was $9219/ha, while the net returns of the halosulfuron and smother crop treatments were negative. When the final broccoli crop was grown without nutsedge control from October 2003 to January 2004, solarization was the only treatment to be profitable in the purple nutsedge field. The cultivation and the solarization treatments had the highest economic return in the yellow nutsedge field, while the only treatment with negative economic return in the yellow nutsedge field was the smother crop treatment. For both purple and yellow nutsedge, planting sudangrass in the summer had the lowest broccoli yield and economic return.