Möglichkeiten und Grenzen der Nutzung von Temperatursummen für die Terminierung von Aussaat und Umbruch einer Winterzwischenfrucht zur Kontrolle von Meloidogyne hapla im Ökologischen Landbau

Leguminous plants are good hosts for plant-parasitic nematodes, such as the root-knotnematode Meloidogyne hapla. Meloidogyne hapla can cause massive problems particularlyunder long time organic cultivation and especially in vegetable crops (carrot, onion).Nematode damage occurs as a result of too many host plants within a given crop rotation,insufficient weed control and short times of fallow. Since legumes play a significant role for nitrogen fixation in organic farming, field studies were conducted to evaluate, wheather legumes can be grown in a way that M. hapla will not be multiplied. Legumes were grown as an overwintering green manure crop and then incorporated in spring before the nematode has completed its life cycle. The timing for incorporation was calculated based on the temperature sum requried by M. hapla to complete its cycle, i.e. 450°C (>8°C). The results indicated that in general the temperature sum can be used to predict the time of incorporation; however, adjustments need to be considering winter conditions.