Articles
Concentration of quinclorac in cranberry plant tissue with repeated annual applications
Article number
1357_27
Pages
185 – 192
Language
English
Abstract
Quinclorac is an effective control for dodder (Cuscuta spp.) and other weed species in cranberry.
Concerns that repeated annual use might increase fruit residues, and anecdotal reports of dodder control in the years after application raised questions about quinclorac persisting in cranberry tissues.
A 2-year tissue-residue study and a 3-year yield-impact study were conducted on established Stevens vines in Massachusetts.
Small plots were treated with two applications (June and July) at 280 g a.i. ha-1 quinclorac in each treatment year.
Treatments for the tissue-residue study were applied two consecutive years in a row, while treatments for the yield-impact study were applications in year (Y) 1 only, Y1 and Y2 only, or Y1, Y2, and Y3. Fruit were collected from each plot annually.
Cranberry leaves and stems were collected annually and separated into current year growth (“new”) and previous seasons growth (“old”). Residues from tissue were extracted and analyzed by LC/MS/MS. After one year of two applications, quinclorac residues were detected in all tissue types.
The lowest concentration of residue was detected in old stems.
Plots treated again in Y2 had similar levels in leaves as those treated in Year 1, but the quinclorac concentration in stems approximately tripled from the previous year.
Fruit collected in 2017 (Y3) were also analyzed for quinclorac residue, and showed no detects for plots treated in Y1 only and left untreated for two years before residue analysis, 25 ppb (mean, n=4) for plots treated in Y1 and Y2 and left untreated for one year before residue analysis, and 657 ppb (mean, n=4) for plots treated in all 3 years (US tolerance = 1500 ppb). Carryover of herbicide in stem tissue may account for weed control observed in the year following application.
Concerns that repeated annual use might increase fruit residues, and anecdotal reports of dodder control in the years after application raised questions about quinclorac persisting in cranberry tissues.
A 2-year tissue-residue study and a 3-year yield-impact study were conducted on established Stevens vines in Massachusetts.
Small plots were treated with two applications (June and July) at 280 g a.i. ha-1 quinclorac in each treatment year.
Treatments for the tissue-residue study were applied two consecutive years in a row, while treatments for the yield-impact study were applications in year (Y) 1 only, Y1 and Y2 only, or Y1, Y2, and Y3. Fruit were collected from each plot annually.
Cranberry leaves and stems were collected annually and separated into current year growth (“new”) and previous seasons growth (“old”). Residues from tissue were extracted and analyzed by LC/MS/MS. After one year of two applications, quinclorac residues were detected in all tissue types.
The lowest concentration of residue was detected in old stems.
Plots treated again in Y2 had similar levels in leaves as those treated in Year 1, but the quinclorac concentration in stems approximately tripled from the previous year.
Fruit collected in 2017 (Y3) were also analyzed for quinclorac residue, and showed no detects for plots treated in Y1 only and left untreated for two years before residue analysis, 25 ppb (mean, n=4) for plots treated in Y1 and Y2 and left untreated for one year before residue analysis, and 657 ppb (mean, n=4) for plots treated in all 3 years (US tolerance = 1500 ppb). Carryover of herbicide in stem tissue may account for weed control observed in the year following application.
Publication
Authors
K.M. Ghantous, H.A. Sandler, D. Cunningham, E. Giro, K. DeMoranville
Keywords
Vaccinium macrocarpon Ait., carryover, fruit residues, yield
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