No-Tillage Improves Broomrape Control with Glyphosate in Faba-Bean

Broomrape (Orobanche crenata Forsk.) causes considerable losses in faba-bean (Vicia faba L.) production in the Mediterranean region. The application of an ultra-low glyphosate rate at an early broomrape parasitic phase, i.e., tubercle development, is the most common control system. This study sought to determine the effect of tillage system and glyphosate application on broomrape infestation, faba-bean yield, and yield components. A field experiment was performed over a 3-yr period in Cordoba (Spain) in a rainfed Vertisol. Experimental factors and respective treatments were: tillage system (no-tillage vs. conventional tillage) and glyphosate application (none vs. 0.113 kg a.i. ha–1). Year x tillage system x glyphosate interactions were apparent in the results. Averaging over 3-yr, no-tillage with glyphosate application reduced weed infestation (42 plants m–2) and increased faba-bean seed yield (1.73 Mg ha–1) in comparison with conventional tillage with glyphosate application (10 broomrape plants m–2, and 1.14 Mg ha–1 of seed yield). When glyphosate was not applied, broomrape density varied from 80 to 45 plants m–2 and faba-bean seed yield from 0.50 to 1.24 Mg ha–1 for tillage and no-tillage systems, respectively. Within each tillage system, glyphosate application always reduced broomrape infestation and increased seed yield. Even in the absence of glyphosate application, seed yields were higher under no-tillage than under conventional tillage with herbicide application over 2 yr. Pod m–2 was the yield component most affected by broomrape infestation. No-tillage is an important tool for broomrape control, but the addition of glyphosate application substantially enhances the degree of control.