Glyphosate-resistant smooth-pigweed (Amaranthus hybridus) in Brazil

Foliar applications of14C-bentazon [3-(1-methylethyl)-(1H)-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide] with PPA (polymeric polyhydroxy acid) at 1 or 2% (v/v) or nonoxynol (9.5 POE) [α-(p-nonylpheny1)-ω-hydroxypoly(oxyethylene)] at 1% (v/v) or mixtures of PPA and nonoxynol did not increase absorption or translocation of14C-bentazon in soybeans [Glycine max(L.) Merr. ‘Lee 74′] or common cocklebur (Xanthium strumariumL. # XANST). PPA alone at 1 to 2% (v/v) did not significantly affect absorption or translocation of14C-bentazon in smooth pigweed (Amaranthus hybridusL. # AMACH), but PPA with nonoxynol significantly increased translocation out of the treated leaf. Both PPA and nonoxynol decreased absorption and movement of14C-MSMA [monosodium salt of methylarsonic acid] out of the treated leaf of johnsongrass [Sorghum halepense(L.) Pers. # SORHA]. In greenhouse research, PPA at 0.25 and 0.5% (v/v) did not increase the level of control of common cocklebur obtained following postemergence applications of bentazon at 0.24 and 0.48 kg ai/ha. Similarly, PPA at 0.25 and 0.50% (v/v) did not increase the toxicity of MSMA at 0.3 and 0.6 kg ai/ha to either johnsongrass or common cocklebur.

Download Full-text

Triazine-Resistant Smooth Pigweed (Amaranthus hybridus) Control in Field Corn (Zea maysL.)

Weed Technology ◽

10.1017/s0890037x00027846 ◽

1993 ◽

Vol 7 (2) ◽

pp. 431-436 ◽

Cited By ~ 12

Author(s):

Eric D. Birschbach ◽

Mark G. Myers ◽

R. Gordon Harvey

Keyword(s):

Amaranthus Hybridus ◽

Complete Control ◽

Field Corn ◽

Herbicide Treatments ◽

Smooth Pigweed

Studies were conducted for 3 yr to evaluate herbicides and herbicide combinations for triazine-resistant smooth pigweed (TR-AMACH) control in field corn. Of the PRE treatments, combinations of atrazine plus acetochlor, metolachlor plus dicamba, and atrazine plus alachlor provided the most complete control of this weed (77 to 81%). The best early postemergence (EP) combination was pendimethalin plus atrazine plus dicamba (93% control). Pyridate plus atrazine applied POST provided a four-site average of 98% control. The most effective sequential herbicide treatments consisted of either metolachlor or pendimethalin PRE followed by POST treatments containing either pyridate, thifensulfuron, bromoxynil, or dicamba.

Download Full-text

Identification of Triazine-ResistantAmaranthusspp.

Weed Science ◽

10.1017/s004317450006210x ◽

1981 ◽

Vol 29 (3) ◽

pp. 345-348 ◽

Cited By ~ 17

Author(s):

W. H. Ahrens ◽

L. M. Wax ◽

E. W. Stoller

Keyword(s):

United States ◽

Species Identification ◽

The United States ◽

Seed Source ◽

Amaranthus Hybridus ◽

Redroot Pigweed ◽

Smooth Pigweed

Seed samples of triazine-resistant and susceptible pigweed were received from the four areas of the United States and Canada where resistant pigweed populations have appeared. The reported resistance or susceptibility of all biotypes was verified, and several plants from each seed source were grown to maturity for species identification. Pigweed samples from Maryland and Pennsylvania were smooth pigweed (Amaranthus hybridusL.). One resistant and one susceptible biotype from Washington were also smooth pigweed. All other samples from Washington and the sample from Ontario were Powell amaranth (A. powelliiS. Wats.). None of the triazine-resistant seed samples were redroot pigweed (A. retroflexusL.), despite earlier reports of resistance in this species. Taxonomic characteristics important in the identification of smooth pigweed, Powell amaranth, and redroot pigweed are discussed.

Download Full-text

Phosphorus effects on competitive interactions of smooth pigweed (Amaranthus hybridus) and common purslane (Portulaca oleracea) with lettuce (Lactuca sativa)

Weed Science ◽

10.1017/s0043174500089463 ◽

1998 ◽

Vol 46 (3) ◽

pp. 307-312 ◽

Cited By ~ 17

Author(s):

Bielinski M. Santos ◽

Joan A. Dusky ◽

William M. Stall ◽

Donn G. Shilling ◽

Thomas A. Bewick

Keyword(s):

Competitive Ability ◽

Organic Soils ◽

Weed Species ◽

Population Densities ◽

Replacement Series ◽

Amaranthus Hybridus ◽

Extractable P ◽

Common Purslane ◽

Smooth Pigweed ◽

Water Extractable

Replacement series studies were conducted under controlled conditions to determine the effect of phosphorus (P) rates and population densities on the competitiveness of smooth pigweed and common purslane with lettuce. Densities were 2, 4, and 8 plants per 113 cm2, whereas P rates were 0, 0.4, and 0.8 g PL−1soil. A P-deficient Histosol (0.3 mg water-extractable P L−1soil) was used. High P fertility enhanced the competitive ability of lettuce in smooth pigweed-lettuce mixtures. Smooth pigweed was not responsive to P rates. However, luxurious P consumption by smooth pigweed occurred, reducing the amount of the nutrient available for lettuce absorption. In common purslane-lettuce mixtures, the weed was responsive to P rates, increasing its competitive ability, whereas no increase in lettuce competitive ability was observed. Both weed species were more competitive than lettuce. Competition for P appears to be the main mechanism of common purslane interference on lettuce grown in low-P organic soils. Alternative fertilization strategies (i.e., banded applications) may reduce the effect of smooth pigweed on lettuce.

Download Full-text

Influence of method of phosphorus application on smooth pigweed (Amaranthus hybridus) and common purslane (Portulaca oleracea) interference in lettuce

Weed Science ◽

10.1614/ws-03-069r2 ◽

2004 ◽

Vol 52 (5) ◽

pp. 797-801 ◽

Cited By ~ 4

Author(s):

Bielinski M. Santos ◽

Joan A. Dusky ◽

William M. Stall ◽

Thomas A. Bewick ◽

Donn G. Shilling

Keyword(s):

Portulaca Oleracea ◽

Amaranthus Hybridus ◽

Common Purslane ◽

Phosphorus Application ◽

Smooth Pigweed

Download Full-text

Control of Triazine-Resistant Smooth Pigweed (Amaranthus hybridus) and Common Lambsquarters (Chenopodium album) in No-till Corn (Zea mays)

Weed Technology ◽

10.1017/s0890037x00031481 ◽

1989 ◽

Vol 3 (1) ◽

pp. 136-142 ◽

Cited By ~ 9

Author(s):

Edward S. Hagood

Keyword(s):

Field Experiments ◽

Chenopodium Album ◽

Amaranthus Hybridus ◽

Common Lambsquarters ◽

Crop Tolerance ◽

Resistant Species ◽

No Till ◽

Postemergence Herbicides ◽

Smooth Pigweed ◽

Better Than

Field experiments were established to evaluate preemergence and postemergence herbicides for control of triazine-resistant smooth pigweed and common lambsquarters in no-till corn. When applied preemergence, alachlor in the microencapsulated formulation controlled smooth pigweed better than the emulsifiable concentrate formulation and better than either metolachlor or pendimethalin. These herbicides applied preemergence did not control common lambsquarters consistently. Pendimethalin controlled both triazine-resistant species when applied as a sequential treatment of a preemergence and an early postemergence application. Control of triazine-resistant smooth pigweed and common lambsquarters was excellent when dicamba was applied early postemergence in treatments containing alachlor, metolachlor, or pendimethalin applied preemergence and/or early postemergence. Thiameturon and CGA-131036 controlled triazine-resistant smooth pigweed with acceptable crop tolerance. Thiameturon also controlled common lambsquarters, but control was unacceptable with CGA-131036.

Download Full-text

A Method for Identification of Triazine Resistant and Susceptible Biotypes of Several Weeds

Weed Science ◽

10.1017/s0043174500025856 ◽

1981 ◽

Vol 29 (1) ◽

pp. 70-73 ◽

Cited By ~ 25

Author(s):

J. R. Hensley

Keyword(s):

Chenopodium Album ◽

Quick Method ◽

Amaranthus Hybridus ◽

Senecio Vulgaris ◽

Common Lambsquarters ◽

Leaf Discs ◽

Large Numbers ◽

Common Groundsel ◽

Smooth Pigweed ◽

Phosphate Medium

A simple and quick method is described for identifying biotypes of common groundsel (Senecio vulgarisL.), common lambsquarters (Chenopodium albumL.), and smooth pigweed (Amaranthus hybridusL.) that are resistant or susceptible to triazine herbicides. Leaf discs (3 mm diam) from the tested plants were vacuum infiltrated with a phosphate medium and exposed to a 3-klux light source. When 1.0 × 10−5M and higher levels of atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine) were present, the leaf discs from susceptible biotypes failed to float to the surface, whereas the leaf discs from resistant biotypes floated within 1 h. The urea herbicide, fluometuron [1,1-dimethyl-3-(α,α,α-trifluoro-m-tolyl)urea] inhibited the floating of leaf discs from both the triazine-susceptible and triazine-resistant biotypes. This method can be used to evaluate large numbers of plants to determine if they are resistant or susceptible to triazines without destroying the plants or preventing seed production.

Download Full-text

Preemergence Weed Control in Gladiolus Cormels

Weed Science ◽

10.1017/s004317450006817x ◽

1986 ◽

Vol 34 (6) ◽

pp. 957-960 ◽

Cited By ~ 2

Author(s):

James P. Gilreath

Keyword(s):

Plant Growth ◽

Weed Control ◽

Minimal Effect ◽

Amaranthus Hybridus ◽

Eleusine Indica ◽

Preemergence Herbicides ◽

Smooth Pigweed ◽

Gladiolus Plant

Multiple applications of several preemergence herbicides were evaluated for weed control and for phytotoxicity to gladiolus (Gladiolus X hortulanus L.) grown from cormels in 1984 and 1985. Oryzalin [4-(dipropylamino)-3,5-dinitrobenzenesulfonamide] consistently provided acceptable control of southern crabgrass [Digitaria ciliaris (Retz.) Koel. # DIGSP], goosegrass [Eleusine indica (L.) Gaertn. # ELEIN], and smooth pigweed (Amaranthus hybridus L. # AMACH) and had minimal effect on gladiolus plant growth even after four applications. Pronamide [3,5-dichloro (N-1,1-dimethyl-2-propynyl)benzamide], alachlor [2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)acetamide], and metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide] provided erratic weed control and reduced yields of gladiolus corms.

Download Full-text

Competition, Growth Rate, and CO2Fixation in Triazine-Susceptible and -Resistant Smooth Pigweed (Amaranthus hybridus)

Weed Science ◽

10.1017/s0043174500069356 ◽

1983 ◽

Vol 31 (4) ◽

pp. 438-444 ◽

Cited By ~ 50

Author(s):

William H. Ahrens ◽

E. W. Stoller

Keyword(s):

Growth Rate ◽

Dry Weight ◽

Dry Matter Accumulation ◽

Lower Growth ◽

Amaranthus Hybridus ◽

Relative Growth ◽

Lower Growth Rate ◽

Net Assimilation ◽

Synthetic Capacity ◽

Smooth Pigweed

Triazine-susceptible (S) and -resistant (R) biotypes of smooth pigweed (Amaranthus hybridusL.) were grown in the field under competitive conditions at varying initial proportions of S and R plants. R plants were less competitive than S plants as measured by accumulation of total above-ground dry weight and seed dry weight. S and R plants were also grown in the field under non-competitive conditions at 100, 40, and 10% light. Growth rate at 10% light did not differ between S and R plants. At the two higher light intensities, dry-matter accumulation 11 weeks after seeding was about 40% less in the R plants. At 100% light, relative growth rate and net assimilation rate were lower in the R plants by about 3.5 and 19%, respectively. The light- and CO2-saturated rates of CO2fixation in intact leaves of glasshouse-grown R plants were 20% less than those in S plants. An apparent 10 and 20% greater number of chlorophyll molecules per photosystem II reaction center in R plants (as compared with S plants) grown in the field at 40 and 100% light, respectively, did not explain differences between the S and R biotypes in photo synthetic capacity. The S and R plants did not differ in specific leaf weight or chlorophyll content on a leaf-area basis. Lower growth rate of R plants may be responsible for inferior competitive ability of R biotypes and could be the result of an impaired photosynthetic capacity.

Download Full-text

Control of Yellow Nutsedge (Cyperus esculentus) and Smooth Pigweed (Amaranthus hybridus) in Summer Squash with Halosulfuron

Weed Technology ◽

10.1614/wt-08-016.1 ◽

2008 ◽

Vol 22 (4) ◽

pp. 660-665 ◽

Cited By ~ 5

Author(s):

Brian W. Trader ◽

Henry P. Wilson ◽

Thomas E. Hines

Keyword(s):

Field Study ◽

Field Experiments ◽

Cyperus Esculentus ◽

Weed Species ◽

Amaranthus Hybridus ◽

Yellow Nutsedge ◽

Application Method ◽

Summer Squash ◽

Smooth Pigweed

Field experiments were conducted in 1999, 2000, and 2001 to investigate PRE and POST applications of halosulfuron-methyl in combination with clomazone plus ethalfluralin for control of sedge and smooth pigweed in summer squash. Halosulfuron was applied PRE or POST to summer squash at 9, 18, or 27 g ai/ha in combination with a PRE application of clomazone at 175 g ai/ha plus ethalfluralin at 630 g ai/ha. Smooth pigweed control by addition of halosulfuron at 18 and 27 g/ha in combination with clomazone plus ethalfluralin PRE was greater than 89% independent of application method. Yellow nutsedge control was greater than 83% with POST applications of halosulfuron at 18 and 27 g/ha in combination with clomazone plus ethalfluralin PRE. Yellow nutsedge control was greater than 60% from all POST halosulfuron applications at 9, 18, or 27 g/ha in the greenhouse. In a separate field study without ethalfluralin PRE, rice flatsedge control was more than 85% from halosulfuron applied POST at 18 and 27 g/ha. Yellow summer squash and zucchini squash were injured as much as 52 and 47%, respectively, from inclusion of halosulfuron PRE or POST at 27 g/ha in treatments. Summer squash yields were generally not affected by halosulfuron rate, and were comparable to or higher than summer squash treated by only the mixture of clomazone plus ethalfluralin. In these studies, summer squash were injured by halosulfuron applied at 9 to 27 g/ha PRE or POST, yet rapidly recovered, making this herbicide acceptable for use in combination with clomazone and ethalfluralin for controlling several common weed species.

Download Full-text