Effect of winter oilseed rape cropping on the development of the sugar beet cyst nematode, heterodera schachtii, and control of volunteer plants as a trap crop method

Abstract

The integration of oilseed rape (OSR) into sugar beet rotation systems is restricted due to the very good host status of OSR for the beet cyst nematode (BCN) Heterodera schachtii. In contrast to sugar beet, the cultivation of winter OSR covers a longer period, but at a lower soil temperature regime. Thus, presumably one or two generations of BCN may develop during the cultivation of winter OSR, resulting in moderate multiplication rates of 1-2 in the present study. This multiplication rate was year-dependent, but not affected by different sowing times. For the first time, the present study identified volunteer OSR emerging in high densities post-harvest as a major risk for a high multiplication of BCN at optimum temperatures. The emergence of BCN females with offspring was observed very early, resulting in a significant population increase before 350-degree days (>8 ◦C) in inoculation experiments and in field investigations. Conducting treatment trials with glyphosate to control volunteer OSR in micro-plots and field experiments confirmed effective suppression of BCN reproduction when growth of volunteer OSR was interrupted at 250-350-degree days. Thus, data gained from BCN reproduction studies under controlled and field conditions provided a unique basis for the development of a trap crop method. The degree day model has been successfully implemented as part of an open access management tool.