BACKGROUND: The allelochemical sorgoleone, a major component of the hydrophobic root exudates of Sorghum bicolor, was formulated as a wettable powder [4.6 WP] and evaluated as a natural herbicide on several weed and crop species under different growth conditions. RESULTS: Formulated sorgoleone [4.6 WP] suppressed germination and shoot growth of weeds, with broadleaf species showing greater susceptibility than grass weed species. Germination and growth of broadleaf weed species were completely suppressed (100%) at 0.2 g a.i. L(-1) sorgoleone in a growth chamber study. Post-emergence applications of the wettable formulation of sorgoleone [4.6 WP] inhibited 20-25% higher growth of weeds than pre-emergence applications under greenhouse conditions. Broadleaf weeds were more susceptible than grass species to both methods of application. In all studies, growth was suppressed in more than 90% of the broadleaf weeds and two species, in particular, Rumex japonicus and Plantago asiatica, were completely suppressed at 0.4 kg a.i. ha(-1) sorgoleone. The crop species, on the other hand, were much more tolerant to sorgoleone, with 30% inhibition, at most, at the highest rate of 0.4 kg a.i. ha(-1) sorgoleone. CONCLUSION: The results of this study reveal that sorgoleone, after formulation as a WP, is more effective in inhibiting weed growth, and crop species are tolerant to it. The strong weed suppressive ability of formulated sorgoleone therefore offers interesting possibilities as an effective natural environment-friendly approach for weed management.
BACKGROUND: The allelochemical sorgoleone, a major component of the hydrophobic root exudates of Sorghum bicolor, was formulated as a wettable powder [4.6 WP] and evaluated as a natural herbicide on several weed and crop species under different growth conditions. RESULTS: Formulated sorgoleone [4.6 WP] suppressed germination and shoot growth of weeds, with broadleaf species showing greater susceptibility than grass weed species. Germination and growth of broadleaf weed species were completely suppressed (100%) at 0.2 g a.i. L(-1) sorgoleone in a growth chamber study. Post-emergence applications of the wettable formulation of sorgoleone [4.6 WP] inhibited 20-25% higher growth of weeds than pre-emergence applications under greenhouse conditions. Broadleaf weeds were more susceptible than grass species to both methods of application. In all studies, growth was suppressed in more than 90% of the broadleaf weeds and two species, in particular, Rumex japonicus and Plantago asiatica, were completely suppressed at 0.4 kg a.i. ha(-1) sorgoleone. The crop species, on the other hand, were much more tolerant to sorgoleone, with 30% inhibition, at most, at the highest rate of 0.4 kg a.i. ha(-1) sorgoleone. CONCLUSION: The results of this study reveal that sorgoleone, after formulation as a WP, is more effective in inhibiting weed growth, and crop species are tolerant to it. The strong weed suppressive ability of formulated sorgoleone therefore offers interesting possibilities as an effective natural environment-friendly approach for weed management.