Maternal water stress reduces sensitivity of offspring to herbicides in Amaranthus palmeri (Palmer amaranth)

AbstractPalmer amaranth (Amaranthus palmeriS. Watson) is the most problematic weed in agronomic crop production fields in the United States. The objective of this study was to determine the effect of degree of water stress on the growth and fecundity ofA. palmeriusing soil moisture sensors under greenhouse conditions. TwoA. palmeribiotypes collected from Nebraska were grown in loam soil maintained at 100%, 75%, 50%, 25%, and 12.5% soil field capacity (FC) corresponding to no, light, moderate, high, and severe water stress levels, respectively. Water was regularly added to pots based on soil moisture levels detected by Watermark or Decagon 5TM sensors to maintain the desired water stress level.Amaranthus palmeriplants maintained at ≤25% FC did not survive more than 35 d after transplanting.Amaranthus palmeriat 100%, 75%, and 50% FC produced similar numbers of leaves (588 to 670 plant−1) based on model estimates; however, plants at 100% FC achieved a maximum height of 178 cm compared with 124 and 88 cm at 75% and 50% FC, respectively. The growth index (1.1×105to 1.4×105cm3plant−1) and total leaf area (571 to 693 cm2plant−1) were also similar at 100%, 75%, and 50% FC.Amaranthus palmeriproduced similar root biomass (2.3 to 3 g plant−1) at 100%, 75%, and 50% FC compared with 0.6 to 0.7 g plant−1at 25% and 12.5% FC, respectively. Seed production was greatest (42,000 seeds plant−1) at 100% FC compared with 75% and 50% FC (14,000 to 19,000 seeds plant−1); however, the cumulative seed germination was similar (38% to 46%) when mother plants were exposed to ≥50% FC. The results of this study show thatA. palmerican survive ≥50% FC continuous water stress conditions and can produce a significant number of seeds with no effect of on seed germination.

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Sex Lability and Dimorphism in Dioecious Palmer Amaranth (Amaranthus palmeri)

10.1101/769935 ◽

2019 ◽

Cited By ~ 3

Author(s):

Mohsen B. Mesgaran ◽

Maor Matzrafi ◽

Sara Ohadi

Keyword(s):

Water Stress ◽

Sex Ratio ◽

Sex Expression ◽

Palmer Amaranth ◽

Amaranthus Palmeri ◽

Dioecious Species ◽

Relative Growth ◽

Male And Female ◽

Secondary Sex Characters

AbstractDioecious weeds (separate sexes) may benefit from a maximized outcrossing and optimal sex-specific resource allocation but there are costs associated with the evolution of this breeding system which can be exploited for long-term management of dioecious weeds. That is, seed production in dioecious species is contingent upon the co-occurrence and co-flowering of the two genders and can be further complicated by biases in sex ratio. We therefore explored the sex ratio and dimorphism in secondary sex characters in three populations of Palmer amaranth (Amaranthus palmeri) from California, Kansas and Texas and tested if water stress can change the sex expression and/or the synchrony of flowering (anthesis) between male and female plants. Sex ratio (proportion of males) was balanced and did not deviate from 1:1 in all experiments and populations (California, Kansas, Texas) when plants received normal watering. Male and female plants of A. palmeri did not differ in timing of emergence, plant height and relative growth rate. While the initiation of flowering (emergence of inflorescence) occurred earlier in males than females, females preceded males in timing of anthesis. Water stress delayed anthesis in males to a larger extent than females giving rise to an anthesis mismatch as large as seven days between the two sexes. Water stress induced a female sex expression in Kansas population giving rise to a female to male ratio of 1.78 which significantly differed from the equal 1:1 sex ratio. Our data provide the first evidence of sex lability and environment sex determination (ESD) in A. palmeri, suggesting manipulation of sex expression and phenological asynchrony as novel tools for ecological management of dioecious weeds.

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Under pressure: maternal effects promote drought tolerance in progeny seed of Palmer amaranth (Amaranthus palmeri)

Weed Science ◽

10.1017/wsc.2020.75 ◽

2020 ◽

pp. 1-8

Author(s):

Maor Matzrafi ◽

O. Adewale Osipitan ◽

Sara Ohadi ◽

Mohsen B. Mesgaran

Keyword(s):

Water Stress ◽

Water Potential ◽

Maternal Effects ◽

Environmental Conditions ◽

Palmer Amaranth ◽

Amaranthus Palmeri ◽

Hydrotime Model ◽

Base Water Potential ◽

Seed Characteristics ◽

Two Populations

Abstract The environmental conditions under which parental plants are reared can affect the seed characteristics of the progeny. The variation originating from such maternal effects has rarely been incorporated into models of seed germination. Here, using Palmer amaranth (Amaranthus palmeri S. Watson), we examined the effects of water stress during the growth of parental plants on the progeny seed characteristics, including weight, size, final germination, and parameters of a hydrotime germination model. We grew two populations (from California and Kansas) under continuous water-deficit or well-watered conditions. In both A. palmeri populations, progeny seeds originating from water-stressed plants were heavier and larger than those from well-watered plants. Plants exposed to water stress also produced seeds that were ~30% less dormant than seeds from control plants. To test whether the maternal environment affects the parameters of a hydrotime model, progeny seeds were subject to five water potentials (0, −0.2, −0.4, −0.6, and −0.8 MPa) and incubated at 20 and 30 C; germination was monitored daily. The estimated median base water potential (Ψb(50)), that is, the water potential at which 50% of seeds cannot germinate, was consistently lower for seeds from water-stressed plants than for seeds from well-watered plants. Our results showed that A. palmeri plants experiencing drought during their growth produce seeds that are less dormant and can germinate from drier conditions—a maternal response that seems to be adaptive. These findings also call for development of germination models that incorporate the environmental conditions of both the current and past seasons to better describe the variability in germination of weed seeds.

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Safety and efficacy of linuron with or without an adjuvant or S-metolachlor for POST control of Palmer amaranth (Amaranthus palmeri) in sweetpotato

Weed Technology ◽

10.1017/wet.2021.27 ◽

2021 ◽

pp. 1-18

Author(s):

Levi D. Moore ◽

Katherine M. Jennings ◽

David W. Monks ◽

Ramon G. Leon ◽

David L. Jordan ◽

...

Keyword(s):

Nonionic Surfactant ◽

Weed Control ◽

Critical Period ◽

Total Yield ◽

Field Studies ◽

Palmer Amaranth ◽

Amaranthus Palmeri ◽

Foliar Injury ◽

Protoporphyrinogen Oxidase ◽

Safety And Efficacy

Abstract Field studies were conducted to evaluate linuron for POST control of Palmer amaranth in sweetpotato to minimize reliance on protoporphyrinogen oxidase (PPO)-inhibiting herbicides. Treatments were arranged in a two by four factorial where the first factor consisted of two rates of linuron (420 and 700 g ai ha−1), and the second factor consisted of linuron applied alone or in combinations of linuron plus a nonionic surfactant (NIS) (0.5% v/v), linuron plus S-metolachlor (800 g ai ha−1), or linuron plus NIS plus S-metolachlor. In addition, S-metolachlor alone and nontreated weedy and weed-free checks were included for comparison. Treatments were applied to ‘Covington’ sweetpotato 8 d after transplanting (DAP). S-metolachlor alone provided poor Palmer amaranth control because emergence had occurred at applications. All treatments that included linuron resulted in at least 98 and 91% Palmer amaranth control 1 and 2 wk after treatment (WAT), respectively. Including NIS with linuron did not increase Palmer amaranth control compared to linuron alone, but increased sweetpotato injury and subsequently decreased total sweetpotato yield by 25%. Including S-metolachlor with linuron resulted in the greatest Palmer amaranth control 4 WAT, but increased crop foliar injury to 36% 1 WAT compared to 17% foliar injury from linuron alone. Marketable and total sweetpotato yield was similar between linuron alone and linuron plus S-metolachlor or S-metolachlor plus NIS treatments, though all treatments resulted in at least 39% less total yield than the weed-free check resulting from herbicide injury and/or Palmer amaranth competition. Because of the excellent POST Palmer amaranth control from linuron 1 WAT, a system including linuron applied 7 DAP followed by S-metolachlor applied 14 DAP could help to extend residual Palmer amaranth control further into the critical period of weed control while minimizing sweetpotato injury.

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Response of Palmer amaranth (Amaranthus palmeri S. Watson) and sugarbeet to desmedipham and phenmedipham

Weed Technology ◽

10.1017/wet.2021.1 ◽

2021 ◽

pp. 1-9

Author(s):

Clint W. Beiermann ◽

Cody F. Creech ◽

Stevan Z. Knezevic ◽

Amit J. Jhala ◽

Robert Harveson ◽

...

Keyword(s):

Mortality Rates ◽

Selectivity Index ◽

Palmer Amaranth ◽

Greenhouse Experiment ◽

Amaranthus Palmeri ◽

True Leaf ◽

Cotyledon Stage ◽

Equivalent Rate ◽

Herbicide Treatments ◽

High Level

Abstract A prepackaged mixture of desmedipham + phenmedipham was previously labeled for control of Amaranthus spp. in sugarbeet. Currently, there are no effective POST herbicide options to control glyphosate-resistant Palmer amaranth in sugarbeet. Sugarbeet growers are interested in using desmedipham + phenmedipham to control escaped Palmer amaranth. In 2019, a greenhouse experiment was initiated near Scottsbluff, NE, to determine the selectivity of desmedipham and phenmedipham between Palmer amaranth and sugarbeet. Three populations of Palmer amaranth and four sugarbeet hybrids were evaluated. Herbicide treatments consisted of desmedipham and phenmedipham applied singly or as mixtures at an equivalent rate. Herbicides were applied when Palmer amaranth and sugarbeet were at the cotyledon stage, or two true-leaf sugarbeet stage and when Palmer amaranth was 7 cm tall. The selectivity indices for desmedipham, phenmedipham, and desmedipham + phenmedipham were 1.61, 2.47, and 3.05, respectively, at the cotyledon stage. At the two true-leaf application stage, the highest rates of desmedipham and phenmedipham were associated with low mortality rates in sugarbeet, resulting in a failed response of death. The highest rates of desmedipham + phenmedipham caused a death response of sugarbeet; the selectivity index was 2.15. Desmedipham treatments resulted in lower LD50 estimates for Palmer amaranth compared to phenmedipham, indicating that desmedipham can provide greater levels of control for Palmer amaranth. However, desmedipham also caused greater injury in sugarbeet, producing lower LD50 estimates compared to phenmedipham. Desmedipham + phenmedipham provided 90% or greater control of cotyledon-size Palmer amaranth at a labeled rate but also caused high levels of sugarbeet injury. Neither desmedipham, phenmedipham, nor desmedipham + phenmedipham was able to control 7-cm tall Palmer amaranth at previously labeled rates. Results indicate that desmedipham + phenmedipham can only control Palmer amaranth if applied at the cotyledon stage and a high level of sugarbeet injury is acceptable.

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Sex dimorphism in dioecious Palmer amaranth (Amaranthus palmeri) in response to water stress

Planta ◽

10.1007/s00425-021-03664-7 ◽

2021 ◽

Vol 254 (1) ◽

Author(s):

Mohsen B. Mesgaran ◽

Maor Matzrafi ◽

Sara Ohadi

Keyword(s):

Water Stress ◽

Weed Management ◽

Amaranthus Palmeri ◽

Ecological Management ◽

State University ◽

Dioecious Species ◽

Seed Output ◽

Flowering Asynchrony ◽

Secondary Sex Characters ◽

Response To Water

Abstract Main conclusion Phenological isolation can potentially reduce seed output and may be exploited as a novel tool for ecological management of dioecious weeds. Abstract Dioecious plants may benefit from a maximized outcrossing and optimal sex-specific resource allocation; however, this breeding system may also be exploited for weed management. Seed production in dioecious species is contingent upon the co-occurrence and co-flowering of the two genders and can be further disturbed by flowering asynchrony. We explored dimorphism in secondary sex characters in Amaranthus palmeri, and tested if reproductive synchrony can be affected by water stress. We have used seeds of A. palmeri from California, Kansas and Texas, and studied secondary sex characters under natural conditions and in response to water stress. Seeds of A. palmeri from California (CA) and Kansas (KS) were cordially provided by Dr. Anil Shrestha (California State University, Fresno, California) and Dr. Dallas E. Peterson (Kansas State University, Manhattan, Kansas), respectively. Seeds of a third population were collected from mature plants (about 30 plants) from a set-aside field in College Station, Texas. A. palmeri showed no sexual dimorphism with regard to the timing of emergence, plant height, and relative growth rate. While the initiation of flowering occurred earlier in males than females, females preceded males in timing of anthesis. Water stress delayed anthesis in males to a greater extent than females increasing the anthesis mismatch between the two sexes by seven days. Our data provide the first evidence of environment-controlled flowering asynchrony in A. palmeri. From a practical point of view, phenological isolation can potentially reduce seed output and may be exploited as a novel tool for ecological management of dioecious weeds.

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Impact of Palmer Amaranth (Amaranthus palmeri) on Corn (Zea mays) Grain Yield and Yield and Quality of Forage1

Weed Technology ◽

10.1614/0890-037x(2002)016[0532:iopaap]2.0.co;2 ◽

2002 ◽

Vol 16 (3) ◽

pp. 532-536 ◽

Cited By ~ 12

Author(s):

RAFAEL A. MASSINGA ◽

RANDALL S. CURRIE

Keyword(s):

Zea Mays ◽

Grain Yield ◽

Palmer Amaranth ◽

Amaranthus Palmeri ◽

Yield And Quality

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Influence of Selected Fungicides on Efficacy of Clethodim and 2,4-DB

Peanut Science ◽

10.3146/ps11-14.1 ◽

2012 ◽

Vol 39 (2) ◽

pp. 121-126 ◽

Cited By ~ 1

Author(s):

Gurinderbir S. Chahal ◽

David L. Jordan ◽

Barbara B. Shew ◽

Rick L. Brandenburg ◽

James D. Burton ◽

...

Keyword(s):

North Carolina ◽

Sampling Interval ◽

Palmer Amaranth ◽

Amaranthus Palmeri ◽

Solution Ph ◽

Affect Control ◽

Solution Preparation ◽

Positive Correlations ◽

Sampling Times ◽

Large Crabgrass

Abstract A range of fungicides and herbicides can be applied to control pests and optimize peanut yield. Experiments were conducted in North Carolina to define biological and physicochemical interactions when clethodim and 2,4-DB were applied alone or with selected fungicides. Pyraclostrobin consistently reduced large crabgrass [Digitaria sanguinalis (L.) Scop.] control by clethodim. Chlorothalonil and tebuconazole plus trifloxystrobin reduced large crabgrass control by clethodim in two of four experiments while prothioconazole plus tebuconazole and flutriafol did not affect control. Palmer amaranth [Amaranthus palmeri S. Wats] control by 2,4-DB was not affected by these fungicides. Although differences in spray solution pH were noted among mixtures of clethodim plus crop oil concentrate or 2,4-DB and fungicides, the range of pH was 4.40 to 4.92 and 6.72 to 7.20, respectively, across sampling times of 0, 6, 24, and 72 h after solution preparation. Permanent precipitates were formed when clethodim, crop oil concentrate, and chlorothalonil were co-applied at each sampling interval. Permanent precipitates were not observed when clethodim and crop oil concentrate were included with other fungicides or when 2,4-DB was mixed with fungicides. Significant positive correlations were noted for Palmer amaranth control by 2,4-DB and solution pH but not for clethodim and solution pH.

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