Competition and control of volunteer Jerusalem artichoke in various crops

A major production constraint in Jerusalem artichoke (Helianthus tuberosus L.) is caused by tubers which are not recovered at harvest. Such lost tubers raise a serious weed problem in the following season. Winter wheat, oat, spring oilseed rape, sugarbeet, maize and ryegrass were grown in a field which had Jerusalem artichoke as the preceding crop in order to obtain information about their cometitive ability and the efficacy of various control measurements against Jerusalem artichoke infestation. The Jerusalem artichoke treatments in these crops were: total control by regular hand weeding (TOC), mechanical/chemical control (MCC), and no control (NOC). Under the NOC treatment, Jerusalem artichoke infestation at harvest was variable among crops, with the number of shoots ranging from 9 to 25 m(-2) in oat in maize stands respectively. The number of Jerusalem artichoke shoots in the MCC plots was reduced by 50 to 99 % in oat and maize, respectively. The highest crop yields in each of the six pecies were realised under the TOC treatment. Insignificant yield reductions were observed in the NOC treatment of wheat, oat, rape and ryegrass. However, under this management yield reductions of 91 and 81 % occurred in sugarbeet and maize respectively. Depending on the preceeding crop, 1 to 9 m(-2) of Jerusalem artichoke were still recorded under the MCC plots in the following season. Consequently, for complete elimination of infestation, volunteers must be controlled in the second and probably in the third year following a Jerusalem artichoke crop.