Interference of feral radish (Raphanus sativus) resistant to AHAS-inhibiting herbicides with oilseed rape, wheat, and sunflower.

Raphanus sativus (feral radish), a cosmopolitan weed, has developed resistance to acetohydroxyacid synthase inhibiting herbicides in several countries of South America. This study reports the effects of season-long interference of feral radish on grain yield and yield components of oilseed rape, wheat, and sunflower as well as on feral radish growth under field conditions. The number of inflorescences per area, seeds per inflorescence, and seed biomass of crops were reduced with increasing feral radish densities. The yields of winter crops were more severely affected than that of sunflower. The rectangular hyperbola model revealed yield losses up to 100% and 74.4% in oilseed rape and wheat, respectively, while only 12.2% in sunflower. Similarly, feral radish plants were substantially larger in competition with winter crops than with sunflower. Feral radish produced a maximum of 31,200 and 4700 seeds m⁻² in winter crops and sunflower, respectively. Season-long feral radish interference can result in serious economic losses, especially in winter crops. Development and implementation of diverse and effective long-term weed management practices are needed. [ABSTRACT FROM AUTHOR]