Nutsedge control is challenging in commercial vegetable production in the absence of methyl bromide, and therefore, an effective alternative is needed. This study investigated allyl isothiocyanate (ITC) as a methyl bromide alternative for purple nutsedge control under polyethylene-mulch. Greenhouse experiments were conducted to compare the retention of allyl ITC in treated soil (3,000 nmol g⁻¹) under low-density polyethylene (LDPE) and virtually impermeable film (VIF) mulches. Field experiments were conducted to evaluate the effectiveness of allyl ITC (6 rates: 0, 15, 75, 150, 750, 1500 kg ai ha⁻¹) under VIF mulch against purple nutsedge. Additionally, a standard treatment of methyl bromide chloropicrin (67 : 33%) at 390 kg ai ha⁻¹ under LDPE mulch was included for comparison. In the greenhouse experiment, the predicted half-life of allyl ITC under LDPE and VIF mulch was 0.15 and 0.59 d, respectively. In the field experiment, it was predicted that allyl ITC at 1,240 and 1,097 kg ha⁻¹ under VIF mulch is required to control purple nutsedge shoot and tubers equivalent to methyl bromide chloropicrin at 4 wk after treatment (WAT). It is concluded that allyl ITC under VIF mulch would need to be applied at 2.8 to 3.2 times the standard treatment of methyl bromide chloropicrin under LDPE mulch for commercially acceptable purple nutsedge control.

Nomenclature: Allyl isothiocyanate; purple nutsedge; Cyperus rotundus L. CYPRO.

El control de Cyperus rotundus es un reto en la producción comercial de vegetales en ausencia de methyl bromide, y por esto se necesita una alternativa efectiva. Este estudio investigó el uso de allyl isothiocyanate (ITC) como alternativa al methyl bromide para el control de C. rotundus bajo cobertura de polyethylene. Se realizaron experimentos de invernadero para comparar la retención de allyl ITC en suelos tratados (3,000 nmol g⁻¹) bajo coberturas de polyethylene de baja densidad (LDPE) y de láminas virtualmente impermeables (VIF). Se realizaron experimentos de campo para evaluar la efectividad contra C. rotundus de allyl ITC (6 dosis: 0, 15, 75, 150, 1500 kg ai ha⁻¹) bajo cobertura VIF. Adicionalmente, se incluyó un tratamiento estándar de methyl bromide chloropicrin (67:33%) a 390 kg ai ha⁻¹ bajo cobertura LDPE para fines de comparación. En el experimento de invernadero, la vida media predicha de allyl ITC bajo coberturas de LDPE y VIF fue 0.15 y 0.59 d, respectivamente. En el experimento de campo, se predijo que se requiere allyl ITC a 1,240 y 1,097 kg ha⁻¹ bajo cobertura VIF para controlar la parte aérea y los tubérculos de C. rotundus a niveles equivalentes a methyl bromide chloropicrin a 4 semanas después del tratamiento (WAT). Se concluyó que allyl ITC bajo cobertura VIF debería ser aplicado de 2.8 a 3.2 veces el tratamiento estándar de methyl bromide chloropicrin bajo cobertura LDPE para controlar C. rotundus a niveles comercialmente aceptables.