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• 11. [Article] Some factors affecting absorption and translocation of phenoxyalkylcarboxylic acids in plants

  Studies were conducted to determine the influence of formulation and molecular configuration of some chlorinated-phenoxyalkylcarboxylic acid herbicides on their absorption, translocation and metabolism ...

  Citation × Citation Citation Abstract Copy Title: Some factors affecting absorption and translocation of phenoxyalkylcarboxylic acids in plants Author: Norris, Logan A. (Logan Allen) Studies were conducted to determine the influence of formulation and molecular configuration of some chlorinated-phenoxyalkylcarboxylic acid herbicides on their absorption, translocation and metabolism in bigleaf maple, Acer macrophyllum, Pursh. Five to eight year old bigleaf maple seedlings were treated with one percent solutions of carbon 14-labeled herbicids. After three days the treated leaves were washed with alcohol and the plant sectioned into the treated leaves, new growth, stem and roots. A test of the acids, triethanol amine salts and 2-ethylhexyl esters of 2,4-D and 2,4,5-T revealed an inverse relationship between molecular polarity and absorbability within herbicides. The translocation of the various formulations and chemicals were influenced to a large degree by the amount absorbed. The translocatability of the acids and the amine salts were similar while the ester formulations were lower. In terms of actual amounts of chemical translocated to the roots, however, 2,4,5-T ester was most effective A study of the 2-ethylhexyl ester of 2,4-D, 2,4,5-T, 2,4-DP and 2,4,5-TP revealed some trends in absorbability. In general, the alpha-phenoxypropionic herbicides were absorbed to a greater degree than the phenoxyacetic herbicides. Between herbicides of equal side chain length, the dichlorinated member was more readily absorbed than the trichlorinated member. The translocatability of these various herbicides from the treated leaves was not significantly different. However, the movement into the roots differed significantly among chemicals. In terms of actual amounts of herbicide translocated to the roots, the following decreasing order was observed: 2,4-DP, 2,4,5-T, 2,4-D and 2,4,5-TP. It is believed that chemical toxicity to the transport mechanism, absorption by the phloem parenchyma cells and leakage to the xylem influenced herbicide movement to the roots, Studies of the: metabolism of 2,4-D, 2,4,5-T, 2,4-DP and 2,4,5-TP in single detached bigleaf maple leaves revealed that decarboxylation was not an important means of detoxification in this species. Paper chromatograms prepared from alcohol extracts of these leaves showed only limited formation of metabolites. The metabolism of 2,4-D and 2,4,5-T in intact seedlings, however, showed various plant parts have a greater ability to alter the form of the applied chemical than the treated leaves. Differences in the rate of chemical alteration between 2,4-D and 2,4,5-T were also observed in the same plant part. It was shown that 2,4,5-T was more stable than 2,4-D in most plant parts. The stability of 2,4,5-T in the roots was considered of importance in determining the relative effectiveness of these two herbicides on bigleaf maple. Studies of the absorption, translocation and metabolism of 2,4-DB in bigleaf maple were also conducted. It was shown that detached bigleaf maple leaves rapidly decarboxylated 2,4-DB. Absorption and translocation studies revealed slightly reduced absorption compared to the other herbicides tested, but it was markedly superior in translocatability. Gas chromatography was used to establish that the primary product of oxidation of 2,4-DB in bigleaf maple was 2,4-D. These tests also indicated the form of the translocated material was 2,4-DB rather than its oxidation product, 2,4-D. Studies using excised root and stem tissue revealed the roots were capable of rapidly converting 2,4-DB to 2,4-D. The stems had only a limited ability to perform this conversion. It is felt the garnma-phenoxybutyric herbicides may have a valuable place in control of some brush species which have resisted control with aerial application of 2,4-D and 2,4,5-T. Title: Some factors affecting absorption and translocation of phenoxyalkylcarboxylic acids in plants Author: Norris, Logan A. (Logan Allen) Studies were conducted to determine the influence of formulation and molecular configuration of some chlorinated-phenoxyalkylcarboxylic acid herbicides on their absorption, translocation and metabolism in bigleaf maple, Acer macrophyllum, Pursh. Five to eight year old bigleaf maple seedlings were treated with one percent solutions of carbon 14-labeled herbicids. After three days the treated leaves were washed with alcohol and the plant sectioned into the treated leaves, new growth, stem and roots. A test of the acids, triethanol amine salts and 2-ethylhexyl esters of 2,4-D and 2,4,5-T revealed an inverse relationship between molecular polarity and absorbability within herbicides. The translocation of the various formulations and chemicals were influenced to a large degree by the amount absorbed. The translocatability of the acids and the amine salts were similar while the ester formulations were lower. In terms of actual amounts of chemical translocated to the roots, however, 2,4,5-T ester was most effective A study of the 2-ethylhexyl ester of 2,4-D, 2,4,5-T, 2,4-DP and 2,4,5-TP revealed some trends in absorbability. In general, the alpha-phenoxypropionic herbicides were absorbed to a greater degree than the phenoxyacetic herbicides. Between herbicides of equal side chain length, the dichlorinated member was more readily absorbed than the trichlorinated member. The translocatability of these various herbicides from the treated leaves was not significantly different. However, the movement into the roots differed significantly among chemicals. In terms of actual amounts of herbicide translocated to the roots, the following decreasing order was observed: 2,4-DP, 2,4,5-T, 2,4-D and 2,4,5-TP. It is believed that chemical toxicity to the transport mechanism, absorption by the phloem parenchyma cells and leakage to the xylem influenced herbicide movement to the roots, Studies of the: metabolism of 2,4-D, 2,4,5-T, 2,4-DP and 2,4,5-TP in single detached bigleaf maple leaves revealed that decarboxylation was not an important means of detoxification in this species. Paper chromatograms prepared from alcohol extracts of these leaves showed only limited formation of metabolites. The metabolism of 2,4-D and 2,4,5-T in intact seedlings, however, showed various plant parts have a greater ability to alter the form of the applied chemical than the treated leaves. Differences in the rate of chemical alteration between 2,4-D and 2,4,5-T were also observed in the same plant part. It was shown that 2,4,5-T was more stable than 2,4-D in most plant parts. The stability of 2,4,5-T in the roots was considered of importance in determining the relative effectiveness of these two herbicides on bigleaf maple. Studies of the absorption, translocation and metabolism of 2,4-DB in bigleaf maple were also conducted. It was shown that detached bigleaf maple leaves rapidly decarboxylated 2,4-DB. Absorption and translocation studies revealed slightly reduced absorption compared to the other herbicides tested, but it was markedly superior in translocatability. Gas chromatography was used to establish that the primary product of oxidation of 2,4-DB in bigleaf maple was 2,4-D. These tests also indicated the form of the translocated material was 2,4-DB rather than its oxidation product, 2,4-D. Studies using excised root and stem tissue revealed the roots were capable of rapidly converting 2,4-DB to 2,4-D. The stems had only a limited ability to perform this conversion. It is felt the garnma-phenoxybutyric herbicides may have a valuable place in control of some brush species which have resisted control with aerial application of 2,4-D and 2,4,5-T. Close

• 12. [Article] Integrating restoration and ecologically based weed management practices for invasive knotweed control

  Japanese knotweed is an invasive perennial shrub that dominates riparian ecosystems. Effective management techniques are currently limited to repeated annual herbicide applications and there is little ...

  Citation × Citation Citation Abstract Copy Title: Integrating restoration and ecologically based weed management practices for invasive knotweed control Author: Rudenko, Melody Japanese knotweed is an invasive perennial shrub that dominates riparian ecosystems. Effective management techniques are currently limited to repeated annual herbicide applications and there is little science-based information about which control tactics result in the greatest management success. Restoration of invaded sites to a functioning riparian plant community is needed to prevent re-infestation of Japanese knotweed or other invasive weed species. Field and greenhouse experiments were initiated in fall of 2007 to generate this information on Japanese knotweed management. A greenhouse experiment was conducted to evaluate the efficacy of the experimental herbicide aminocyclopyrachlor methyl ester for Japanese knotweed control. Treated plants were unable to produce new shoots from underground rhizomes indicating that aminocyclopyrachlor is an effective control. This level of Japanese knotweed suppression is comparable to imazapyr and surpasses the level of control that glyphosate provided under greenhouse conditions. A field experiment was initiated in the Nehalem River watershed in western Oregon to evaluate the integration of chemical weed management with restoration of the site to a diverse native grass plant community. We documented that native grasses could be established at this site, but the long-term survival of these grasses was poor. This result indicates that methods for simultaneous chemical control of invasive knotweed and restoration of sites need to be investigated further. The most effective chemical treatment in terms of visual injury and reduced Japanese knotweed biomass and cost of application was glyphosate applied at a rate of 4.21 kg ae/ha for a cost of $160/ha. A secondary experiment evaluating herbicide tank mixtures of glyphosate with imazapyr, imazapyr with aminopyralid, and triclopyr with 2,4-D was conducted at the same site. The most effective chemical treatment in terms of Japanese knotweed control and cost of application for the tank mixture experiment was imazapyr with aminopyralid applied at rates of 1.12 kg ae/ha (imazapyr) and 0.12 kg ae/ha (aminopyralid) for a cost of $346/ha. Title: Integrating restoration and ecologically based weed management practices for invasive knotweed control Author: Rudenko, Melody Japanese knotweed is an invasive perennial shrub that dominates riparian ecosystems. Effective management techniques are currently limited to repeated annual herbicide applications and there is little science-based information about which control tactics result in the greatest management success. Restoration of invaded sites to a functioning riparian plant community is needed to prevent re-infestation of Japanese knotweed or other invasive weed species. Field and greenhouse experiments were initiated in fall of 2007 to generate this information on Japanese knotweed management. A greenhouse experiment was conducted to evaluate the efficacy of the experimental herbicide aminocyclopyrachlor methyl ester for Japanese knotweed control. Treated plants were unable to produce new shoots from underground rhizomes indicating that aminocyclopyrachlor is an effective control. This level of Japanese knotweed suppression is comparable to imazapyr and surpasses the level of control that glyphosate provided under greenhouse conditions. A field experiment was initiated in the Nehalem River watershed in western Oregon to evaluate the integration of chemical weed management with restoration of the site to a diverse native grass plant community. We documented that native grasses could be established at this site, but the long-term survival of these grasses was poor. This result indicates that methods for simultaneous chemical control of invasive knotweed and restoration of sites need to be investigated further. The most effective chemical treatment in terms of visual injury and reduced Japanese knotweed biomass and cost of application was glyphosate applied at a rate of 4.21 kg ae/ha for a cost of $160/ha. A secondary experiment evaluating herbicide tank mixtures of glyphosate with imazapyr, imazapyr with aminopyralid, and triclopyr with 2,4-D was conducted at the same site. The most effective chemical treatment in terms of Japanese knotweed control and cost of application for the tank mixture experiment was imazapyr with aminopyralid applied at rates of 1.12 kg ae/ha (imazapyr) and 0.12 kg ae/ha (aminopyralid) for a cost of $346/ha. Close

• 13. [Article] The influence of herbicide placement in soil on toxicity to emerging seedlings

  Previous research has indicated several soil-applied herbicides are more effective by exposure to emerging shoots than from root uptake. Studies were conducted in the greenhouse and growth chamber to investigate ...

  Citation × Citation Citation Abstract Copy Title: The influence of herbicide placement in soil on toxicity to emerging seedlings Author: Nishimoto, R. K. (Roy Katsuto), 1944- Previous research has indicated several soil-applied herbicides are more effective by exposure to emerging shoots than from root uptake. Studies were conducted in the greenhouse and growth chamber to investigate effects of herbicide placement in soil on toxicity to emerging seedlings. In these studies, an inch of treated soil was placed above the seed, below the seed, or both above and below the seed. The seed was placed in the middle of a 1-inch layer of untreated soil. Each soil layer was brought to field capacity separately and the entire container was covered with a plastic bag. The use of this plastic bag avoided the need for irrigation and subsequent herbicide movement. By this method, numerous herbicides were active on oats (Avena sativa) primarily through shoot exposure, with root exposure having little or no effect on foliage growth. These herbicides included EPTC (ethyl N, N-dipropylthiocarbamate), dichlobenil (2, 6-dichlorobenzonitrile), trifluralin (α, α, α-trifluoro-2, 6-dinitro-N, N-dipropyl-p-toluidine), nitralin (2, 6-dinitro-N, N-dipropyl-4-[methylsulphonyl] aniline), propachlor (2-chloro-N-iso-propylacetanilide), DCPA (dimethyl 2, 3, 5, 6-tetrachlorotereph-thalate), and CDEC (2-chloroallyl diethyl dithiocarbamate). Sindone (isomers of 1, 1-dimethyl-4, 6-diisopropylindanyl ethyl ketone) was more effective on sugar beets (Beta vulgaris) and annual rye-grass (Lolium multiflorum) through shoot exposure than root exposure. Some herbicides are more effective on oats through root exposure. These included bromacil (5-bromo-3-sec-butyl-6-methyluracil), R 11913,¹ Nia 11092 (1, 1-dimethyl-3-(3-[N-tert-butylcarbamyloxy] phenyl) urea), pyrazon (5-amino-4-chloro-2-phenyl-3[ 2H]-pyridazinone), diuron (3-[3, 4-dichlorophenyl]-1, 1-dimethylurea), and atrazine (2-chloro-4-ethylamino-6-isopropyl-amino-s-triazine). Dicamba (2-methoxy-3, 6-dichlorobenzoic acid) and 2, 4-D (2, 4-dichlorophenoxyacetic acid) were more effective on cucumber through root exposure than through shoot exposure. Some herbicides appear to be taken up differently by different plant species. R 11913 was more effective through shoot exposure on sugar beets and more effective through root exposure on oats. Atrazine proved more effective on oats through root exposure; however, with green foxtail (Setaria viridis) and annual ryegrass, shoot exposure was more important when an untreated buffer layer was present between the seed and the treated zone. The possibility existed that a reduction in transpiration, caused by the plastic bag could affect the mode of uptake. In studies without the use of the plastic bag, atrazine was still more effective on oats through root exposure and more effective on green foxtail through shoot exposure. Irrigation in this study was accomplished through straws extended into each layer to minimize herbicide movement. We noticed that green foxtail produced secondary roots as early as five days after planting or two days after emergence. This indicated that these newly-formed secondary roots, as well as the emerging shoot, could absorb atrazine placed in the shoot region. When the buffer layer was removed and atrazine-treated soil was placed adjacent to the seed, placement immediately below the seed showed the greatest toxicity to both oats and green foxtail. This indicates the variation in sensitivity of plants by exposure to different parts of the seedling. Studies were conducted on varying placement positions of the herbicide as well as concentrations. From these studies, proximity to the seed was a major factor in increasing toxicity to oat seedlings by atrazine and EPTC, and to annual ryegrass seedlings by diuron. Atrazine was also more effective to green foxtail and annual ryegrass seedlings with increased proximity to the seed. A narrow concentrated layer was more effective than a wider dilute layer with diuron, atrazine, and EPTC when placed either above or below the seed. With atrazine and diuron, placement of the dilute wider layer completely around the seed was just as effective as the concentrated layer adjacent to the seed. With EPTC, a concentrated layer adjacent to the seed was more effective than a dilute layer completely around the seed. The effects of a constant temperature regime (24 C) was compared with a temperature regime with a low night temperature (27 C/ 13 C) in relation to uptake of EPTC, expressed by toxic action on oats. The temperature regime with a low night temperature caused a slight increase in toxicity to oats through shoot exposure, as well as through root exposure. However, the increase in uptake of EPTC through root exposure was considerably greater than through shoot exposure. ¹No chemical name available, an experimental herbicide of Stauffer Chemical Company. Title: The influence of herbicide placement in soil on toxicity to emerging seedlings Author: Nishimoto, R. K. (Roy Katsuto), 1944- Previous research has indicated several soil-applied herbicides are more effective by exposure to emerging shoots than from root uptake. Studies were conducted in the greenhouse and growth chamber to investigate effects of herbicide placement in soil on toxicity to emerging seedlings. In these studies, an inch of treated soil was placed above the seed, below the seed, or both above and below the seed. The seed was placed in the middle of a 1-inch layer of untreated soil. Each soil layer was brought to field capacity separately and the entire container was covered with a plastic bag. The use of this plastic bag avoided the need for irrigation and subsequent herbicide movement. By this method, numerous herbicides were active on oats (Avena sativa) primarily through shoot exposure, with root exposure having little or no effect on foliage growth. These herbicides included EPTC (ethyl N, N-dipropylthiocarbamate), dichlobenil (2, 6-dichlorobenzonitrile), trifluralin (α, α, α-trifluoro-2, 6-dinitro-N, N-dipropyl-p-toluidine), nitralin (2, 6-dinitro-N, N-dipropyl-4-[methylsulphonyl] aniline), propachlor (2-chloro-N-iso-propylacetanilide), DCPA (dimethyl 2, 3, 5, 6-tetrachlorotereph-thalate), and CDEC (2-chloroallyl diethyl dithiocarbamate). Sindone (isomers of 1, 1-dimethyl-4, 6-diisopropylindanyl ethyl ketone) was more effective on sugar beets (Beta vulgaris) and annual rye-grass (Lolium multiflorum) through shoot exposure than root exposure. Some herbicides are more effective on oats through root exposure. These included bromacil (5-bromo-3-sec-butyl-6-methyluracil), R 11913,¹ Nia 11092 (1, 1-dimethyl-3-(3-[N-tert-butylcarbamyloxy] phenyl) urea), pyrazon (5-amino-4-chloro-2-phenyl-3[ 2H]-pyridazinone), diuron (3-[3, 4-dichlorophenyl]-1, 1-dimethylurea), and atrazine (2-chloro-4-ethylamino-6-isopropyl-amino-s-triazine). Dicamba (2-methoxy-3, 6-dichlorobenzoic acid) and 2, 4-D (2, 4-dichlorophenoxyacetic acid) were more effective on cucumber through root exposure than through shoot exposure. Some herbicides appear to be taken up differently by different plant species. R 11913 was more effective through shoot exposure on sugar beets and more effective through root exposure on oats. Atrazine proved more effective on oats through root exposure; however, with green foxtail (Setaria viridis) and annual ryegrass, shoot exposure was more important when an untreated buffer layer was present between the seed and the treated zone. The possibility existed that a reduction in transpiration, caused by the plastic bag could affect the mode of uptake. In studies without the use of the plastic bag, atrazine was still more effective on oats through root exposure and more effective on green foxtail through shoot exposure. Irrigation in this study was accomplished through straws extended into each layer to minimize herbicide movement. We noticed that green foxtail produced secondary roots as early as five days after planting or two days after emergence. This indicated that these newly-formed secondary roots, as well as the emerging shoot, could absorb atrazine placed in the shoot region. When the buffer layer was removed and atrazine-treated soil was placed adjacent to the seed, placement immediately below the seed showed the greatest toxicity to both oats and green foxtail. This indicates the variation in sensitivity of plants by exposure to different parts of the seedling. Studies were conducted on varying placement positions of the herbicide as well as concentrations. From these studies, proximity to the seed was a major factor in increasing toxicity to oat seedlings by atrazine and EPTC, and to annual ryegrass seedlings by diuron. Atrazine was also more effective to green foxtail and annual ryegrass seedlings with increased proximity to the seed. A narrow concentrated layer was more effective than a wider dilute layer with diuron, atrazine, and EPTC when placed either above or below the seed. With atrazine and diuron, placement of the dilute wider layer completely around the seed was just as effective as the concentrated layer adjacent to the seed. With EPTC, a concentrated layer adjacent to the seed was more effective than a dilute layer completely around the seed. The effects of a constant temperature regime (24 C) was compared with a temperature regime with a low night temperature (27 C/ 13 C) in relation to uptake of EPTC, expressed by toxic action on oats. The temperature regime with a low night temperature caused a slight increase in toxicity to oats through shoot exposure, as well as through root exposure. However, the increase in uptake of EPTC through root exposure was considerably greater than through shoot exposure. ¹No chemical name available, an experimental herbicide of Stauffer Chemical Company. Close

• 14. [Article] The herbicide HOE 23408; soil persistence, spring wheat cultivar tolerance, and interaction with broadleaf herbicides

  HOE 23408 [ 4-(2' , 4'-dichlorophenoxy)-phenoxy-u-propionic methylester.1 is a promising new compound for control of wild oats and other grass weeds in small grains. Several factors influencing its use ...

  Citation × Citation Citation Abstract Copy Title: The herbicide HOE 23408; soil persistence, spring wheat cultivar tolerance, and interaction with broadleaf herbicides Author: Ivackovich, Branislav D. HOE 23408 [ 4-(2' , 4'-dichlorophenoxy)-phenoxy-u-propionic methylester.1 is a promising new compound for control of wild oats and other grass weeds in small grains. Several factors influencing its use for this purpose were investigated. Greenhouse bioassay studies were conducted in 1975 to determine relative persistence of HOE 23408 in four western Oregon soils following application in the fall and winter. -Wild oats (Avena fatua L.) were used as a test plant. Soil from each of three application timings at all four locations contained measurable amounts of herbicide. Generally, residue levels in soil treated at the same herbicide rate approximately 1, 2, and 4 months before sampling were similar. Possibly less herbicide reached the soil from postemergence treatments, compensating for the longer degradation time of the preemergence treatments. Variation in residue levels among locations occurred. This may be explained by differences in smoothness of seedbeds and amounts of plant residue at the various locations. A study was conducted to determine persistence of HOE 23408 applied to bare soil on April 29, 1975. Wild oats and corn (Zea mays L.) were used as bioassay plants. Evaluation of plants seeded into the plots at intervals showed a gradual reduction in levels of herbicide through the season. At 1 lb/A, neither species planted 9 weeks after application was injured, indicating that no significant carry-over can be expected from this rate applied in spring wheat. Two and 4 lb/A persisted longer, causing injury to test plants seeded 9 weeks after treatment. A field experiment was established to evaluate the effect of combining each of four commercially used broadleaf herbicides with 1 and 2 lb/A of HOE 23408 on control of wild oats and barnyardgrass (Echinochloa crus-galli (L.) Beauv. ) and on yield of Fielder spring wheat. The addition of bromoxynil improved the effect of HOE 23408 on wild oats but reduced its effectiveness on barnyardgrass. Addition of 2,4-D LV ester, MCPA LV ester, or dicamba amine reduced its activity on both wild oats and barnyardgrass. Delaying the application of 2,4-D for 3 or 7 days eliminated the antagonistic effect but a delay of only 1 day was not sufficient. No detrimental effect on yield was observed from any treatment. A tolerance study was conducted in three commercially used spring wheat cultivars (Waldron, Twin, and WS-1). Excellent tolerance to HOE 23408 was observed in all cultivars, even when the rate was increased from 1 lb/A (proposed use rate) to 4 lb/A. Title: The herbicide HOE 23408; soil persistence, spring wheat cultivar tolerance, and interaction with broadleaf herbicides Author: Ivackovich, Branislav D. HOE 23408 [ 4-(2' , 4'-dichlorophenoxy)-phenoxy-u-propionic methylester.1 is a promising new compound for control of wild oats and other grass weeds in small grains. Several factors influencing its use for this purpose were investigated. Greenhouse bioassay studies were conducted in 1975 to determine relative persistence of HOE 23408 in four western Oregon soils following application in the fall and winter. -Wild oats (Avena fatua L.) were used as a test plant. Soil from each of three application timings at all four locations contained measurable amounts of herbicide. Generally, residue levels in soil treated at the same herbicide rate approximately 1, 2, and 4 months before sampling were similar. Possibly less herbicide reached the soil from postemergence treatments, compensating for the longer degradation time of the preemergence treatments. Variation in residue levels among locations occurred. This may be explained by differences in smoothness of seedbeds and amounts of plant residue at the various locations. A study was conducted to determine persistence of HOE 23408 applied to bare soil on April 29, 1975. Wild oats and corn (Zea mays L.) were used as bioassay plants. Evaluation of plants seeded into the plots at intervals showed a gradual reduction in levels of herbicide through the season. At 1 lb/A, neither species planted 9 weeks after application was injured, indicating that no significant carry-over can be expected from this rate applied in spring wheat. Two and 4 lb/A persisted longer, causing injury to test plants seeded 9 weeks after treatment. A field experiment was established to evaluate the effect of combining each of four commercially used broadleaf herbicides with 1 and 2 lb/A of HOE 23408 on control of wild oats and barnyardgrass (Echinochloa crus-galli (L.) Beauv. ) and on yield of Fielder spring wheat. The addition of bromoxynil improved the effect of HOE 23408 on wild oats but reduced its effectiveness on barnyardgrass. Addition of 2,4-D LV ester, MCPA LV ester, or dicamba amine reduced its activity on both wild oats and barnyardgrass. Delaying the application of 2,4-D for 3 or 7 days eliminated the antagonistic effect but a delay of only 1 day was not sufficient. No detrimental effect on yield was observed from any treatment. A tolerance study was conducted in three commercially used spring wheat cultivars (Waldron, Twin, and WS-1). Excellent tolerance to HOE 23408 was observed in all cultivars, even when the rate was increased from 1 lb/A (proposed use rate) to 4 lb/A. Close

• 15. [Article] Influence of Norbak, Dacagin, and Vistik on spray drift, volatility, adherence, and efficacy of several herbicides

  Norbak, Dacagin, and Vistik, when mixed with a spray solution, each have the unique property of increasing the viscosity of that solution. This property has been used commercially for the reduction of ...

  Citation × Citation Citation Abstract Copy Title: Influence of Norbak, Dacagin, and Vistik on spray drift, volatility, adherence, and efficacy of several herbicides Author: Ekins, Walter Leo Norbak, Dacagin, and Vistik, when mixed with a spray solution, each have the unique property of increasing the viscosity of that solution. This property has been used commercially for the reduction of spray drift. Studies were made of the drift control adjuvants to determine the following: (1) the effect of the adjuvants on the phytotoxicity of selected herbicides to several crops, (2) the effect of the adjuvants on the herbicidal efficacy of paraquat, (3) the effectiveness of the adjuvants in reducing spray drift under field conditions, (4) the effect of the adjuvants in preventing amitrole-T from being washed off plants with simulated rainfall, and (5) the ability of the adjuvants to reduce vapor loss of 2,4-D ethyl ester when applied in combination to plant surfaces. Field experiments in which adjuvants were sprayed in combination with 2,4-D amine on wheat and corn, dicamba on barley, and MCPA on red clover, indicated that only in the case of Vistik applied with MCPA at rates of 1.0 and 1.5 lbs./A. was there a reduction in herbicidal selectivity. This reduction was very slight. The adjuvants were each very effective in reducing spray drift in paraquat field studies. Injury to test plants 50 feet from the spray swath was less than five percent for the paraquat solution containing an adjuvant as compared to 20 percent for the solution without an adjuvant. Studies were conducted to determine whether the adjuvants would substitute for the wetting agent X-77 in paraquat applications under field conditions. Thirty-two plant species were sprayed in each plot and visually evaluated several weeks later for injury. Results showed that the adjuvants were not effective substitutes for X-77. On the other hand, the addition of Dacagin or Vistik to the paraquat solution did not decrease the herbicidal efficacy when X-77 was used. Norbak decreased the herbicidal efficacy of paraquat with or without the addition of X-77. A study to determine the effectiveness of the adjuvants in preventing amitrole-T from being washed off plant surfaces was conducted. Tomato plants were sprayed with an amitrole-T solution containing adjuvant and washed with simulated rainfall at various time intervals following the spraying. The adjuvants proved ineffective in preventing the amitrole-T from being washed off the plants. In another experiment bean plants were sprayed with a 2,4-D ethyl ester solution in which adjuvant was mixed. These plants were placed in a plastic bag enclosure with untreated bean plants to study the effectiveness of these adjuvants in reducing vapor loss of 2,4-D from the treated beans. Results suggested that only Dacagin had properties that reduced vapor loss, and this reduction was slight. Throughout the above experiments Norbak noticeably decreased the efficacy of the herbicides. This decrease is attributed to the reduction in the number of spray droplets per unit area in the spray swath. Title: Influence of Norbak, Dacagin, and Vistik on spray drift, volatility, adherence, and efficacy of several herbicides Author: Ekins, Walter Leo Norbak, Dacagin, and Vistik, when mixed with a spray solution, each have the unique property of increasing the viscosity of that solution. This property has been used commercially for the reduction of spray drift. Studies were made of the drift control adjuvants to determine the following: (1) the effect of the adjuvants on the phytotoxicity of selected herbicides to several crops, (2) the effect of the adjuvants on the herbicidal efficacy of paraquat, (3) the effectiveness of the adjuvants in reducing spray drift under field conditions, (4) the effect of the adjuvants in preventing amitrole-T from being washed off plants with simulated rainfall, and (5) the ability of the adjuvants to reduce vapor loss of 2,4-D ethyl ester when applied in combination to plant surfaces. Field experiments in which adjuvants were sprayed in combination with 2,4-D amine on wheat and corn, dicamba on barley, and MCPA on red clover, indicated that only in the case of Vistik applied with MCPA at rates of 1.0 and 1.5 lbs./A. was there a reduction in herbicidal selectivity. This reduction was very slight. The adjuvants were each very effective in reducing spray drift in paraquat field studies. Injury to test plants 50 feet from the spray swath was less than five percent for the paraquat solution containing an adjuvant as compared to 20 percent for the solution without an adjuvant. Studies were conducted to determine whether the adjuvants would substitute for the wetting agent X-77 in paraquat applications under field conditions. Thirty-two plant species were sprayed in each plot and visually evaluated several weeks later for injury. Results showed that the adjuvants were not effective substitutes for X-77. On the other hand, the addition of Dacagin or Vistik to the paraquat solution did not decrease the herbicidal efficacy when X-77 was used. Norbak decreased the herbicidal efficacy of paraquat with or without the addition of X-77. A study to determine the effectiveness of the adjuvants in preventing amitrole-T from being washed off plant surfaces was conducted. Tomato plants were sprayed with an amitrole-T solution containing adjuvant and washed with simulated rainfall at various time intervals following the spraying. The adjuvants proved ineffective in preventing the amitrole-T from being washed off the plants. In another experiment bean plants were sprayed with a 2,4-D ethyl ester solution in which adjuvant was mixed. These plants were placed in a plastic bag enclosure with untreated bean plants to study the effectiveness of these adjuvants in reducing vapor loss of 2,4-D from the treated beans. Results suggested that only Dacagin had properties that reduced vapor loss, and this reduction was slight. Throughout the above experiments Norbak noticeably decreased the efficacy of the herbicides. This decrease is attributed to the reduction in the number of spray droplets per unit area in the spray swath. Close