Methylated Seed Oil Research Articles

Optimizing foliar activity of glyphosate on Bidens frondosa and Panicum maximum with different adjuvant types

The influence of non‐ionic (X‐77) and organosilicone (L‐77) adjuvants and of methylated seed oil (MSO) on the uptake, translocation and efficacy of glyphosate was investigated in Bidens frondosa L. and Panicum maximum Jacq. In addition, the physicochemical properties of adjuvants and adjuvant + glyphosate aqueous solutions were determined. Significantly lower surface tension and contact angle values were obtained with aqueous solutions of L‐77 alone and with glyphosate. Over a 48‐h time course, it was observed that >50% of applied 14C‐glyphosate was absorbed within 15 min in B. frondosa with L‐77. At 6 h and thereafter, 14C glyphosate absorption was significantly higher with MSO compared with X‐77 in B. frondosa. In P. maximum, uptake and translocation of 14C‐glyphosate + adjuvant were increased in general up to 48 h after treatment application, except with L‐77, which showed no improvement in uptake – instead there was a significant reduction compared with no treatment with L‐77. This indicated its antagonistic effect on this grass species. The lower values of 14C‐glyphosate in P. maximum also confirmed that adjuvant effects were species specific. In the efficacy studies, glyphosate formulated with L‐77 achieved significantly higher control of B. frondosa, while there was no control of P. maximum with this treatment. This confirmed antagonism in glyphosate absorption into P. maximum by L‐77. Furthermore, significantly higher control of tested plants was recorded with MSO in comparison to X‐77, which confirms the solubilizing or humectant nature of MSO.

Absorption, fate, and soil activity of quinclorac in field bindweed (Convolvulus arvensis)

Laboratory and greenhouse experiments were conducted to examine the absorption and fate of quinclorac in field bindweed and to assess the importance of quinclorac soil activity for field bindweed control. No foliar absorption of14C-quinclorac occurred when applied alone, but absorption increased to 24% when quinclorac was applied with 2,4-D, 28% urea ammonium nitrate (UAN), and methylated seed oil (MSO). Quinclorac translocation in field bindweed was limited, as < 18% of the total amount of absorbed radiolabeled material translocated out of the treated leaves 168 hours after treatment (HAT). Quinclorac metabolism in the treated leaves was minimal; 95% of the recovered14Cwas intact herbicide 168 HAT. Quinclorac soil activity on field bindweed was demonstrated in preemergence and soil subsurface applications. Preemergence application of 35, 70, 140, or 280 g ha−-1quinclorac reduced field bindweed shoot growth. Field bindweed shoots exhibited auxinic herbicide symptoms at all quinclorac rates. Subsurface layering of quinclorac below the root system at rates of 35 and 280 g ha−-1also reduced shoot and root growth. Both herbicide rates induced malformation in root structure with a proliferation of lateral branching, swollen and fused root tips, and malformed root buds. Shoot growth from surviving roots replanted in untreated media was also reduced in both herbicide treatments. These findings suggest quinclorac soil activity may be important for field bindweed control.

Optimizing foliar activity of isoxaflutole on giant foxtail (Setaria faberi) with various adjuvants

Greenhouse, laboratory, and field studies were conducted to evaluate the potential of nonionic surfactant (NIS), crop oil concentrate (COC), methylated seed oil (MSO), and 28% urea ammonium nitrate (UAN) to enhance whole plant efficacy, absorption, and spray retention of foliar applications of isoxaflutole to giant foxtail. In greenhouse studies, isoxaflutole at 10 g ai ha−1reduced giant foxtail growth 5%, whereas the addition of a spray adjuvant reduced giant foxtail growth at least 75%. The addition of UAN improved giant foxtail growth reduction when used in combination with isoxaflutole plus NIS. Isoxaflutole spray retention on the leaf surface was increased with an adjuvant and a further increase was observed with the addition of UAN. Isoxaflutole applied with NIS, COC, and MSO resulted in 42, 60, and 91%14C absorption, respectively, compared to 21% absorption from isoxaflutole applied alone 24 h after treatment (HAT). Increased14C absorption and entry into the cuticle when an adjuvant was utilized with isoxaflutole resulted in greater translocation of14C from isoxaflutole out of the treated leaf. Significant basipetal movement from foliar applications of14C-isoxaflutole suggests phloem mobility. In field studies, isoxaflutole applied with MSO provided greater giant foxtail growth reduction compared to isoxaflutole applied with NIS and in some cases COC. The addition of UAN to isoxaflutole did not increase whole plant efficacy in field studies. These studies indicate isoxaflutole has excellent potential to be used for control of existing giant foxtail present at the time of corn planting if an adequate adjuvant is utilized.

Interacting effects of MON 12000 and CGA-152005 with other herbicides in velvetleaf (Abutilon theophrasti)

Greenhouse and laboratory studies were conducted to determine the effects of dicamba, atrazine, and bentazon on efficacy, foliar absorption, and translocation of MON 12000 or CGA-152005 applied to velvetleaf. The efficacy of MON 12000, CGA-152005, and a combination of CGA-152005 plus primisulfuron applied at 4.5 g ai ha−1was similar when applied alone or with 140 g ha−1of dicamba. However, applying these herbicides in combination with 840 or 560 g ha−1of atrazine or bentazon, respectively, reduced velvetleaf control. Increasing the rate of MON 12000, CGA-152005, or the combination of CGA-152005 plus primisulfuron to 9 g ai ha−1or replacing crop oil concentrate (COC) with methylated seed oil (MSO) increased velvetleaf control of the atrazine and bentazon combinations but not to levels equal to these herbicides applied alone. Dicamba had no effect on the foliar absorption and translocation of14C from MON 12000 or CGA-152005. Atrazine had little effect on foliar absorption of14C from MON 12000 or CGA-152005, but bentazon reduced the foliar absorption of14C from MON 12000. Replacing COC with MSO increased the foliar absorption of14C from MON 12000 or CGA-152005 applied alone or with dicamba or atrazine, but not with bentazon. Translocation of14C from MON 12000 or CGA-152005 out of the treated leaves was 11 and 12%, respectively, averaged across adjuvants and sampling times. These values were reduced to an average of 3 to 4% for both MON 12000 and CGA-152005 when applied in combination with atrazine or bentazon. The majority of14C from MON 12000 or CGA-152005 was translocated acropetally. Atrazine and bentazon significantly reduced the acropetal translocation of14C from MON 12000 at 24 and 72 h and for CGA-152005 at 12, 24, and 72 h. The physiological basis for the observed antagonism of MON 12000 and CGA-152005 by atrazine and bentazon appears to be due to reductions in acropetal translocation of MON 12000 and CGA-152005 to velvetleaf meristems.

Adjuvant Combinations with Quizalofop for Wild Oat (Avena fatua) Control in Peppermint (Mentha piperita)

Field experiments were conducted at Kalispell, MT, to determine the optimum adjuvant combination for wild oat control in peppermint with quizalofop. Quizalofop was applied to four- and eight-leaf wild oat plants at 20 and 50 g ai/ha with either a nonionic surfactant (NIS) or methylated seed oil (MSO) alone or in combination with 28% urea ammonium nitrate (UAN) liquid fertilizer. Differences among adjuvants were most apparent when quizalofop was applied at the lowest rate. MSO was more effective than NIS for enhancing quizalofop activity. Quizalofop efficacy with both adjuvants increased when applied with UAN. Greater than 90% wild oat control was obtained with the lowest rate when applied with MSO plus UAN to four-leaf wild oat plants. These results demonstrate the potential to improve the consistency of weed control as well as reduce postemergence herbicide rates when applied with the proper adjuvant combination.

Dicamba Antagonizes Grass Weed Control with Imazethapyr by Reducing Foliar Absorption

Greenhouse and laboratory studies were conducted to determine the effects of tank-mixing the sodium salt of dicamba (Na-dicamba) with imazethapyr on the efficacy and foliar absorption of imazethapyr, applied with non-ionic surfactant (NIS) or methylated seed oil (MSO), by shattercane, giant foxtail, and large crabgrass. The effects of various salt formulations of dicamba and the addition of ammonium sulfate on efficacy,14C-absorption and on foliar spray retention by the same species were also evaluated. Na-dicamba antagonized imazethapyr efficacy by reducing14C-absorption. Using MSO instead of NIS prevented antagonism when Na-dicamba was applied at 70 and 140 g/ha and reduced the severity of the antagonism at greater application rates by greatly increasing14C-absorption compared to NIS. Reductions in14C-absorption and spray retention were due to the salt formulations of dicamba rather than the parent acid. The addition of ammonium sulfate prevented dicamba antagonism of imazethapyr toxicity to grassy weeds by maintaining14C foliar absorption and spray retention at normal levels.

Adjuvant Effects on Imazethapyr, 2,4-D and Picloram Absorption by Leafy Spurge (Euphorbia esula)

Laboratory experiments were conducted to identify adjuvants that improve absorption of imazethapyr, 2,4-D amine, and picloram by leafy spurge. Adjuvants (0.25% v/v) included crop oil concentrate (COC), methylated seed oil (MSO), nonionic surfactant (NIS), organosilicones (Silwet L-77®, Sylgard® 309, Silwet® 408), 3:1 mixtures of acetylinic diol ethoxylates (ADE40, ADE65, ADE85) with Silwet L-77, ammonium sulfate (2.5 kg ha−1), and 28% urea ammonium nitrate (UAN, 2.5% v/v). Adjuvants were combined with14C-herbicide and commercially formulated herbicide product. Leaves were harvested 2 DAT, rinsed with 10% aqueous methanol to remove surface deposits of herbicide, and dipped in 9:1 hexane:acetone to solubilize cuticular waxes. Imazethapyr absorption increased by 38 to 68% when UAN was combined with COC, NIS, or MSO. Total absorption of imazethapyr plus COC, MSO, or NIS exceeded 86% 2 DAT when UAN was added. Urea ammonium nitrate reduced the amount of imazethapyr associated with the cuticular wax by 2.0%. Imazethapyr absorption was similar on both the abaxial and adaxial leaf surface when UAN was not added; however, 12% more imazethapyr was absorbed from the abaxial leaf surface than from the adaxial leaf surface when UAN was combined with Sylgard 309. Uptake of 2,4-D ranged from 54 to 78% and was greatest with Silwet 408 and 3:1 mixture of ADE40: Silwet L-77. Picloram absorption ranged from 3 to 19%. Buffering picloram treatment solutions to pH 7 and including 2.5 kg ha-1ammonium sulfate increased picloram absorption to 37%.

Emulsifier surfactant-oil combinations with tralkoxydim

Research was conducted at the Brandon Research Station to determine the optimum oil-emulsifier surfactant ratio for each of two oil-emulsifier surfactant pairs for use with tralkoxydim. A series of adjuvants containing 8.5, 17, 34, and 68% emulsifier surfactant (by weight) plus oil were formulated for a petroleum oil (PO)- or methylated seed oil (MSO)-based adjuvant. Tame oats (Avena sativa L.) fresh weight was used to determine percent control as the indicator for phytotoxicity. PO (Sunoco 11 N oil) adjuvants had greater emulsion stability ratings than MSO adjuvants. Emulsion stability was not related to oats control, as MSO adjuvants enhanced tralkoxydim phytotoxicity more than PO adjuvants. Oats control increased as adjuvant volume increased from 0.25 to 2.0% (vol/vol) of the spray solution for either PO- or MSO-based adjuvants. For PO-based adjuvants, the adjuvant containing 34% emulsifier surfactant (by weight) and used at 0.5% (vol/vol) was as effective as the adjuvant containing 17% emulsifier surfactant and used at 1.0%. However, for MSO-based adjuvants, 17% emulsifier surfactant content was as effective as higher emulsifier surfactant content. Oats control did not correlate with the amount of oil in the spray solution. These data indicate that the optimum oil-emulsifier surfactant ratio will vary for each particular oil-emulsifier surfactant pair. Key words: Tralkoxydim, adjuvant, adjuvant volume, methylated seed oil, petroleum oil, surfactant content

Influence of Adjuvants on the Efficacy, Absorption, and Spray Retention of Primisulfuron

The effect of methylated seed oil (MSO), the organosilicone adjuvant DC-X2-5394, and ammonium sulfate on the efficacy, absorption, and spray retention of primisulfuron applied alone or with atrazine, dicamba, and bentazon to shattercane and giant foxtail was evaluated. Primisulfuron efficacy on both species was reduced by the three tank-mix combinations. Atrazine antagonism was not explained by decreases in foliar absorption and/or spray retention. Reductions in primisulfuron absorption and/or foliar spray retention appeared to cause bentazon antagonism on both weeds and dicamba antagonism on shattercane. MSO, DC-X2-5394, and ammonium sulfate completely reversed dicamba and bentazon antagonism on shattercane and partially reversed bentazon antagonism on giant foxtail by increasing foliar absorption and/or spray retention. Compared with non-ionic surfactant, MSO and DC-X2-5394 consistently increased giant foxtail control with primisulfuron by increasing foliar absorption and/or spray retention.

Hairy Nightshade (Solanum sarrachoides) Control in Potatoes (Solanum tuberosum) with Bentazon Plus Additives

Field studies were conducted to examine hairy nightshade control with, and potato tolerance to, bentazon or bentazon plus nonionic surfactant (NIS), petroleum oil concentrate (POC), methylated seed oil (MSO), BCH-815, or urea-ammonium nitrate (UAN). Bentazon treatments were applied early or late POST. Hairy nightshade control with bentazon at 0.56 kg ha–1plus POC, MSO, BCH-815, or UAN was equal to or better than bentazon alone at 1.12 kg ha–1regardless of time of application. Potato injury with bentazon plus additives applied late POST was sometimes greater than with bentazon alone, but use of additives did not reduce potato yield or quality. Yield of US ♯1 tubers was lower when bentazon was applied late POST than when applied early POST in one of two years.