Herbicides in Irrigation Water Following Canal-Bank Treatment for Weed Control

Self Cite

Six crop species were irrigated with water that contained up to several times more glyphosate [N-(phosphonomethyl)glycine] than would be expected in irrigation water as a result of spraying ditchbank vegetation. In June or July 1976, sugarbeets (Beta vulgarisL.), alfalfa (Medicago sativaL., ‘Vernal’), grain sorghum [Sorghumbicolor (L.) Moench], field beans (Phaseolus vulgarisL., ‘Pinto’), tomatoes (Lycopersicon esculentumMill., ‘Roza’), and squash [Cucurbita moschata(Duch.) Duch. ex Poir.] were sprinkler-irrigated with water that contained glyphosate at 0, 0.02, 0.22, or 2.2 ppmw. These concentrations were applied continuously for 8 h to make total applications of 0, 0.01, 0.1, and 1.1 kg/ha, respectively. No injury symptoms developed in any of the crop plants. Yields of treated crops were equal to those produced by untreated plants.

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Response of Certain Crops to Glyphosate in Irrigation Water

Comes¹,

Kelley²

1979

Self Cite

“…The concentration and persistence of TCA and several other herbicides have been reported (3,6) in irrigation water after canal banks were treated when water was flowing in canals.…”

Section: Introductionmentioning

confidence: 99%

TCA in Irrigation Water After Bank Treatments for Weed Control

Comes¹,

Frank²,

Demint³

1975

Self Cite

Concentrations of TCA (trichloroacetic acid) were determined in irrigation water after the sodium salt formulation had been applied to the banks of dry canals at 82 kg/ha for weed control. When the canals were refilled about 5 months after treatment, maximum concentrations of TCA detected in the water ranged from 53 to 297 ppb. The concentration was highest during the first hour of waterflow. The maximum concentration increased at a rate of 26 to 30 ppb/km of canal treated, unless surface runoff or reduced flow volumes caused abnormal flows in the canals. With one exception, no TCA was detected in the water after 4 hr of flow.

“…Broadleaf weeds on ditchbanks and Eurasian watermilfoil in impounded water are frequently controlled with 2,4-D (9,11,15). When applied to weeds on ditchbanks, especially those at the water's edge, small quantities of the herbicide usually enter the water (10). In reservoirs, 2,4-D must be applied directly to water to control Eurasian watermilfoil.…”

Section: Introductionmentioning

confidence: 99%

“…Such treated water, when used for irrigation, could trans port 2,4-D to crop plants. Bruns et al (2,3,4,5) reported that none of several crops, including furrow-irrigated Con cord grapes, was injured or contained significant herbicide residues at harvest time when irrigated with water containing quantities of 2,4-D typical of those found in canal water as a result of spraying ditchbanks (10). A maximum of 0.1 ppmw of 2,4-D is permitted in water used to irrigate most crops, but there is no tolerance for 2,4-D in water used to irrigate grapes with sprinklers.…”

Section: Introductionmentioning

confidence: 99%

Response of Concord Grapes (Vitis labrusca) to 2,4-D in Irrigation Water

Comes¹,

Marquis²,

Kelley³

1984

In field studies 0.1 ppmw ae or less 2,4-D [(2,4-dichlorophenoxy)acetic acid] applied by sprinklers in 5.1 cm of water over 8 h did not affect the number or dry weight of leaves or length of canes of 1-yr-old Concord grape plants (Vitis labruscaL.). A second application at 0.01 ppmw or higher to the same plants 1 yr later reduced growth of leaves, canes, and trunk. Combined effects of root pruning (required to position plants for treatment the second year) and 2,4-D probably account for this apparent anomaly. When 2,4-D was applied annually at 1.0 ppmw or less to established plants for three consecutive years, growth, yield, and fruit quality were not affected. No residues of 2,4-D were detected in the fruit at harvest (detection limit 0.05 ppmw). Grapes treated with 1.0 ppmw 2,4-D developed moderate injury symptoms.