Methyl bromide (MBr) was a widely used fumigant in plasticulture because of its effectiveness against soil-borne pests and weeds in high-value crops; however, it was found to be a class 1 ozone-depleting substance and is no longer available for use in most of the United States. A mixture of 1,3-dichloropropene and chloropicrin (Pic-Clor 60) is an alternative that has been used to control soil-borne pathogens and nematodes, and has marginal control of weeds. Virtually impermeable film (VIF) and totally impermeable film (TIF) retain fumigants in the soil longer than the low- and high-density polyethylene films typically used in plasticulture production systems. The increased retention by these films may result in greater control of recalcitrant weeds such as nutsedge. Four rates of Pic-Clor 60 (112, 168, 224, and 280 kg ai ha⁻¹) used with TIF, 280 kg ai ha⁻¹ of Pic-Clor 60 used with VIF, and one nontreated control with VIF were evaluated for 2 yr to assess control of yellow and purple nutsedge and to determine an efficacious Pic-Clor 60 rate used with TIF. TIF with a lower rate of 224 kg ai ha⁻¹ of Pic-Clor 60 significantly controlled nutsedge populations compared to a high rate of 280 kg ai ha⁻¹ with VIF.

Nomenclature: 1,3-dichloropropene; chloropicrin; totally impermeable film; virtually impermeable film; purple nutsedge, Cyperus rotundus L.; yellow nutsedge, Cyperus esculentus L.