Efficacy of a 1,3-Dichloropropene and Chloropicrin Mixture Used with Totally Impermeable Film for Nutsedge Control

Methyl Bromide (MBr) was a widely used fumigant in plasticulture due to its effectiveness against soil-borne pests and weeds in high value crops such as tomato, watermelon, and strawberry. However, it was found to be a class 1 ozone-depleting substance and was phased out under the Montreal Protocol in 2005 and only small amounts are available under a critical use exemption process. Alternatives to MBr must be implemented, but finding a comparable substitute to MBr has been challenging. A mixture of 1,3-dichloropropene and  chloropicrin (1,3-D:Pic) is an alternative that has been used to control soil-borne pathogens and nematodes but has marginal efficacy on 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 reduced rates of fumigant emission may results in greater control of recalcitrant weeds such as nutsedge. Four rates of 1,3-D:Pic (112, 168, 224, and 280 kg/ha) used with TIF, 280 kg/ha of 1,3-D:Pic used with VIF, and one non-treated control with VIF were evaluated during Fall 2014 for control of yellow nutsedge (Cyperus esculentus) and purple nutsedge (Cyperus rotundus). Initial results show that using TIF increases the retention of fumigant compared to VIF. Implementing TIF with 224 kg/ha of 1,3-D:Pic significantly improved nutsedge control compared to a higher rate of 280 kg/ha with VIF.