Persian darnel control options are limited and unmanaged populations can cause substantial crop yield loss. Integrating crop diversification and higher crop seeding rates into a cropping system might improve Persian darnel management. Field experiments were conducted to determine the effect of different crops and increased crop seeding rates on Persian darnel fecundity. Persian darnel produced up to 2,800 seeds per plant and 53,000 seeds/m2 when grown without competition. Increasing crop density reduced Persian darnel tillers per plant, seed weight, and fecundity. Increasing crop density reduced Persian darnel fecundity 0.4 to 0.2% per spring wheat plant, 0.6 to 0.1% per canola plant, and 16 to 8% per sunflower plant. Persian darnel fecundity was impacted the greatest by reduced weed seedling establishment, which was caused by crop competition and seeding sunflower late in the spring preceded by a nonselective herbicide application. Results indicated delaying the seeding of spring crops or including a late-seeded warm season crop, like sunflower or safflower, in the cropping system is an effective weed management tool for reducing Persian darnel fecundity.
Nomenclature: Glyphosate; Persian darnel, Lolium persicum Boiss. & Hoh. #3 LOLPS; canola, Brassica napus Koch.; spring wheat, Triticum aestivum L.; sunflower, Helianthus annuus L.
Additional index words: Fecundity, preplant herbicide, seedling establishment, seeding date, seeding rate, stale seedbed, weed interference, yield components.
