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ARS Home » Southeast Area » Tifton, Georgia » Crop Protection and Management Research » Research » Publications at this Location » Publication #230458
Title: Herbicide dissipation from low density polyethylene mulch

Author
item GREY, T - UNIV OF GA
item VENCILL, W - UNIV OF GA
item Webster, Theodore
item CULPEPPER, A - UNIV OF GA

Submitted to: Weed Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/16/2009
Publication Date: 5/1/2009
Citation: Grey T.L., Vencill W.K., Webster T.M., Culpepper, A.S. 2009. Herbicide dissipation from low density polyethylene mulch. Weed Science. 57(3):351-356.

Interpretive Summary: The use of low density polyethylene (LDPE) mulch for fumigation, weed control, and soil cover has become the standard for production of many vegetables in the southeastern United States. Most LDPE mulch laid for spring vegetable production is followed by a second crop in the autumn and potentially a third crop the following spring. These succeeding vegetable crops can be transplanted directly into the existing LDPE covered beds formed prior to spring fumigation. This allows for multiple crop production using the same beds in order to minimize expenses associated with LDPE mulch and drip tape irrigation by distributing these costs over multiple crops. Weed control in subsequent crops will require herbicide applications, a practices that is not currently widely adapted. Studies were conducted to evaluate the persistence of herbicide residues on mulch with and without irrigation events. The order for half-life as defined as time for 50% dissipation (DT50) varied by herbicide and presence of irrigation treatment. Glyphosate and paraquat dissipation was rapid with irrigation. Glyphosate and paraquat DT50 were 1 hr for wash off, but 84 and 32 hr without irrigation, respectively. Halosulfuron and flumioxazin DT50 were 3 and 6 hr for the wash off, and 18 and 57 h for the dry studies, respectively. Carfentrazone DT50 was similar at 30 h for the dry and 28 h for wash off. This indicated that carfentrazone was adsorbed to the LDPE mulch.

Technical Abstract: Field and laboratory studies were conducted to examine herbicide dissipation when applied to low density polyethylene (LDPE) mulch for dry scenarios vs. washing off with water. In field studies, halosulfuron, paraquat, carfentrazone, glyphosate, and flumioxazin were applied to black 1.25-mil LDPE at normal use- rates. LDPE mulch was harvested one hr after treatment (HAT) then sampled every 24 hr up to five consecutive rain-free days to determine the level of herbicide dissipation. In similar experiments, treated LDPE mulch was harvested 1 HAT, then washed off with sprinkler irrigation, sampled five HAT, then the same wash and sampling procedure repeated every 24 hr for five consecutive days. The order for half-life as defined as time for 50% dissipation (DT50) varied by herbicide and presence of irrigation treatment. Glyphosate and paraquat dissipation was rapid with irrigation. Glyphosate and paraquat DT50 were 1 hr for wash off, but 84 and 32 hr without irrigation, respectively. Halosulfuron and flumioxazin DT50 were 3 and 6 hr for the wash off, and 18 and 57 h for the dry studies, respectively. Carfentrazone DT50 was similar at 30 h for the dry and 28 h for wash off. This indicated that carfentrazone was adsorbed to the LDPE mulch. 14C-herbicide laboratory studies indicated similar results for halosulfuron, glyphosate, paraquat, and flumioxazin.