Improving nursery crop weed control by assessing herbicide movement through organic mulch

摘要

Experiments were conducted in 2018 to assess herbicide movement through organic mulch materials including pinebark, pinestraw, and hardwood. Weed species evaluated were crabgrass (Digitaria sanguinalis), garden spurge {Euphorbia hirta), and eclipta {Eclipla prostrata). Liquid formulations of prodiamine, dimethenamid-P + pendime-thalin, and indaziflam were evaluated in combination with mulch materials applied at a depth of 5.1 cm (2 in.). Quantification of these herbicides was performed using biological and chemical assays from the soil samples collected from below the mulch layers. Results showed that only 67% eclipta control was observed in pots originally mulched with hardwood, which indicates thatindaziflam was more tightly bound to this mulch. Crabgrass data showed that pinebark (65% control) was the only mulch type that caused a significant reduction in prodiamine efficacy. Dimethenamid-P + pendimethalin efficacy on garden spurge was reduced inpots originally mulched with hardwood or pinebark, but all treatments provided >94% control. Chemical assays showed that approximately 20% of pendimethalin, prodiamine, and indaziflam that was applied reached the soil surface when mulch was present during the application. More dimethenamid-P reached the soil surface than any other herbicide, with 69% being retained by the pinebark mulch.