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William T Haller - One of the best experts on this subject based on the ideXlab platform.

  • cross resistance in Fluridone resistant hydrilla to other bleaching herbicides
    Weed Science, 2009
    Co-Authors: Atul Puri, William T Haller, Michael D. Netherland
    Abstract:

    Abstract The development of Fluridone resistance by hydrilla has significantly impacted hydrilla management, and research is ongoing to develop alternate herbicides for effective hydrilla control. We determined the potential cross-resistance in Fluridone-resistant hydrilla to other bleaching herbicides norflurazon, mesotrione, and topramezone-methyl. Phytoene, β-carotene, and chlorophyll contents as a function of hydrilla biotype and herbicide treatment were evaluated. Hydrilla shoot tips were collected from Fluridone-susceptible (S) and -resistant (R) biotypes and exposed to 5, 25, 50, 75, and 100 µg L−1 of herbicide. The susceptible biotype showed an increase in phytoene and a decrease in β-carotene and chlorophyll contents when treated with 5 µg L−1 Fluridone, whereas higher doses of Fluridone were required to affect these pigments in the resistant biotype. There was no difference in response by S and R biotypes to mesotrione and topramezone-methyl, with both biotypes showing significant affects on pig...

  • growth and reproductive physiology of Fluridone susceptible and resistant hydrilla hydrilla verticillata biotypes
    Weed Science, 2007
    Co-Authors: Atul Puri, William T Haller, Gregory E Macdonald, Megh Singh
    Abstract:

    Abstract Hydrilla is one of the most serious aquatic weed problems in the United States, and Fluridone is the only U.S. Environment Protection Agency (USEPA)–approved herbicide that provides relatively long-term systemic control. Recently, hydrilla biotypes with varying levels of Fluridone resistance have been documented in Florida. Several biotypes of hydrilla varying in resistance levels were maintained in 950-L tanks under ambient sunlight and day-length conditions from September 2004 to September 2005 in absence of Fluridone. Phenotypic measurements were performed during this 1-yr period to monitor differences in growth and reproductive physiology. All Fluridone-resistant biotypes (except R3) were growing at the same rate or greater than the susceptible hydrilla. These data suggested that there are no deleterious effects on growth and reproductive physiology because of development of Fluridone resistance. Aggressive spread of Fluridone-resistant dioecious hydrilla in aquatic ecosystems can severely af...

  • mutations in phytoene desaturase gene in Fluridone resistant hydrilla hydrilla verticillata biotypes in florida
    Weed Science, 2007
    Co-Authors: Atul Puri, Gregory E Macdonald, Fredy Altpeter, William T Haller
    Abstract:

    Abstract Hydrilla is one of the most serious aquatic weed problems in the United States, and Fluridone is the only U.S. Environment Protection Agency (USEPA)–approved herbicide that provides relatively long-term systemic control. Recently, hydrilla biotypes with varying levels of Fluridone resistance have been documented in Florida. One susceptible and five Fluridone-resistant biotypes of hydrilla varying in resistance levels were maintained in 950-L tanks under ambient sunlight and day-length conditions from September 2004 to September 2005 in absence of Fluridone. Because Fluridone is an inhibitor of the enzyme phytoene desaturase (PDS), the gene for PDS (pds) was cloned from Fluridone-susceptible and -resistant hydrilla biotypes. Somatic mutations in amino acid 304 of hydrilla PDS are known to confer herbicide resistance. We determined pds sequence from these hydrilla biotypes at planting and 12-mo after planting. Two independent mutations at the arginine 304 codon of pds were found in the resistant hy...

  • stability of Fluridone resistant hydrilla hydrilla verticillata biotypes over time
    Weed Science, 2007
    Co-Authors: Atul Puri, Gregory E Macdonald, William T Haller
    Abstract:

    Abstract Hydrilla is one of the most serious aquatic weed problems in the United States, and Fluridone is the only herbicide approved by the U.S. Environment Protection Agency that provides systemic control. Recently, hydrilla biotypes with varying levels of Fluridone resistance have been documented in Florida. Hydrilla biotypes of varying Fluridone resistance levels were maintained in 900-L tanks under natural atmospheric conditions from September 2004 to September 2005 in the absence of Fluridone. Hydrilla shoot tips were collected from each biotype during September 2004 (at planting), December 2004 (3 mo after planting [MAP]), March 2005 (6 MAP), June 2005 (9 MAP), and September 2005 (12 MAP) and exposed to 5, 10, 15, 20, 30, and 50 µg L−1 Fluridone to assess changes in susceptibility to this herbicide over time. Nonlinear regression analysis was used to calculate EC50 values for phytoene and β-carotene (effective Fluridone concentration to increase/decrease the phytoene/β-carotene content in hydrilla ...

  • phytoene and β carotene response of Fluridone susceptible and resistant hydrilla hydrilla verticillata biotypes to Fluridone
    Weed Science, 2006
    Co-Authors: Atul Puri, William T Haller, Gregory E Macdonald, Megh Singh
    Abstract:

    Abstract Fluridone has been widely used for control of the submersed aquatic weed hydrilla in Florida for over 25 years. Recently, some hydrilla biotypes were suspected of having developed resistance to Fluridone. Laboratory studies were conducted to monitor changes in phytoene and β-carotene contents as a function of suspected susceptible and resistant hydrilla biotypes to Fluridone treatment. Hydrilla shoot tips from each biotype were exposed to 5, 10, 15, 20, 30, and 50 μg L−1 Fluridone. Higher β-carotene and lower phytoene content was observed in all resistant hydrilla biotypes compared with the susceptible. The susceptible biotype showed an increase in phytoene or a decrease in β-carotene content when treated with as little as 5 μg L−1 of Fluridone, whereas much higher doses were needed for the resistant biotypes. EC50 β-carotene values of 9 and 63 μg L−1 Fluridone were found in the susceptible and the most resistant biotype, respectively. Consistent levels of hydrilla injury occurred at phytoene/β c...

Michael D. Netherland - One of the best experts on this subject based on the ideXlab platform.

  • development of a rapid assay to detect reduced Fluridone sensitivity in invasive watermilfoils
    Weed Technology, 2015
    Co-Authors: Sarah T Berger, Michael D. Netherland, Gregory E Macdonald
    Abstract:

    Abstract Fluridone has been used to successfully manage Eurasian watermilfoil since the late 1980s. However, recent documentation of hybrid watermilfoils and the resulting potential for reduced herbicide sensitivity necessitate the need for an assay to determine individual population response to Fluridone. A known Fluridone-resistant hybrid watermilfoil population from Townline Lake in Michigan was compared to 11 Eurasian and hybrid watermilfoil populations in laboratory experiments to develop a method for determining response to Fluridone. Apical shoot tips were exposed to increasing concentrations of Fluridone (0 to 48 μg L−1) for 3, 5, and 7 d. Chlorophyll fluorescence (Fv/Fm) was evaluated using a pulse-amplitude modulated fluorometer at each interval along with pigment analysis of chlorophyll and β-carotene at the 7-d interval. Fv/Fm and pigment analysis yielded the same results. A Fluridone concentration of 12 μg L−1 and an analysis interval of 7 d were found to be optimal in determining invasive wa...

  • Fluridone resistant hydrilla hydrilla verticillata is still dominant in the kissimmee chain of lakes fl
    Invasive Plant Science and Management, 2015
    Co-Authors: Michael D. Netherland, Dean Jones
    Abstract:

    The invasive aquatic plant hydrilla rapidly spread through the 28,500 ha Kissimmee Chain of Lakes (KCOL) system in Florida in the late 1980s and early 1990s. Large-scale herbicide treatments with Fluridone were initiated in 1993 and resulted in widespread reduction in hydrilla; however, by 2000, sustained use of Fluridone resulted in dominance of Fluridone-resistant strains of hydrilla throughout these lakes. The last large-scale Fluridone applications on the KCOL were conducted in 2004, and in 2012, a sampling effort was initiated to determine the status of Fluridone-resistant strains of hydrilla given an 8-yr period with no further selection pressure from Fluridone. A total of 260 sites were sampled on the lakes during March, May, September, and December 2012. Plants were returned to the lab and exposed to Fluridone at concentrations of 5, 10, and 20 μg L−1 and a pulse-amplitude-modulated (PAM) fluorometer was utilized to measure fluorescence yield of new shoot tissue growth following a 14-d exposure pe...

  • sensitivity of freshwater molluscs to hydrilla targeting herbicides providing context for invasive aquatic weed control in diverse ecosystems
    Journal of Freshwater Ecology, 2015
    Co-Authors: Jennifer M Archambault, Christine M Bergeron, Gregory W Cope, Mark A Heilman, Edward J Corey, Robert J. Richardson, Michael D. Netherland, Ryan J. Heise
    Abstract:

    Hydrilla (Hydrilla verticillata) is an invasive aquatic weed that has spread rapidly throughout the USA, especially in the southeast. A common control method is the application of aquatic herbicides, such as Fluridone and endothall. However, there is limited documentation on the effects of herbicides commonly used to control hydrilla and other aquatic weeds on many non-target freshwater species and no published information exists on the toxicity of these herbicides to freshwater molluscs. We exposed juveniles (96 h) and glochidia (48 h) of the unionid mussel Lampsilis siliquoidea and adults (28 d) of Lampsilis fullerkati to a formulation of Fluridone (Sonar – PR®) in laboratory toxicity tests. The early life stages of L. siliquoidea were also exposed to a formulation of the dipotassium salt of endothall (Aquathol – K®) in separate tests. Juveniles of the freshwater gastropod snail, Somatogyrus viriginicus (Lithoglyphidae), were exposed (96 h) to the Sonar – Genesis® Fluridone formulation. Endpoints were s...

  • laboratory documentation of multiple herbicide tolerance to Fluridone norflurazon and topramazone in a hybrid watermilfoil myriophyllum spicatum m sibiricum population
    Weed Science, 2015
    Co-Authors: Sarah T Berger, Michael D. Netherland, Gregory E Macdonald
    Abstract:

    Abstract Invasive watermilfoils, specifically Eurasian watermilfoil and the interspecific hybrid of Eurasian watermilfoil × northern watermilfoil, continue to be problematic for water resource managers. Herbicides are often used to control these nuisance weeds and have been historically successful in controlling Eurasian watermilfoil. A population of hybrid watermilfoil from Townline Lake in Michigan has shown increased tolerance to the herbicide Fluridone. The objective of this work is to determine if cross- and multiple tolerance have also developed in this population. Eurasian watermilfoil plants collected from multiple sites and plants from Townline Lake were treated with 0, 5, 10, 20, 40, or 80 µg L−1 of Fluridone, norflurazon, or topramezone. Fluridone and norflurazon inhibit phytoene desaturase, whereas topramezone is a 4-hydroxyphenylpyruvate dioxygenase-inhibiting herbicide. Chlorophyll fluorescence (Fv/Fm) and pigment content was measured at 10 d after treatment. Townline Lake plants responded d...

  • cross resistance in Fluridone resistant hydrilla to other bleaching herbicides
    Weed Science, 2009
    Co-Authors: Atul Puri, William T Haller, Michael D. Netherland
    Abstract:

    Abstract The development of Fluridone resistance by hydrilla has significantly impacted hydrilla management, and research is ongoing to develop alternate herbicides for effective hydrilla control. We determined the potential cross-resistance in Fluridone-resistant hydrilla to other bleaching herbicides norflurazon, mesotrione, and topramezone-methyl. Phytoene, β-carotene, and chlorophyll contents as a function of hydrilla biotype and herbicide treatment were evaluated. Hydrilla shoot tips were collected from Fluridone-susceptible (S) and -resistant (R) biotypes and exposed to 5, 25, 50, 75, and 100 µg L−1 of herbicide. The susceptible biotype showed an increase in phytoene and a decrease in β-carotene and chlorophyll contents when treated with 5 µg L−1 Fluridone, whereas higher doses of Fluridone were required to affect these pigments in the resistant biotype. There was no difference in response by S and R biotypes to mesotrione and topramezone-methyl, with both biotypes showing significant affects on pig...

Patrick Wickham - One of the best experts on this subject based on the ideXlab platform.

  • uv light and temperature induced Fluridone degradation in water and sediment and potential transport into aquifer
    Environmental Pollution, 2020
    Co-Authors: Patrick Wickham, Pramod K Pandey, Thomas Harter, Samuel Sandovolsolis
    Abstract:

    Abstract Fluridone is widely used in ambient water bodies to control the spread of invasive aquatic plants. While the ability of Fluridone to control aquatic weeds such as water hyacinth is well reported, an improved understanding of Fluridone persistence in water and sediment is still needed to determine potential residues of Fluridone in the water column and bed sediment of ambient water bodies. In this study, experiments were conducted over a three-month period to examine the degradation of Fluridone in saturated sediment and water under various levels of UV-light (0–1000 μW/cm2), and temperature (4–40 °C). Results showed a large decrease in the half-life of Fluridone in water with increasing UV light intensity, but in saturated sediment the impact of UV light exposure on Fluridone degradation was minimal. At low temperature (4 °C), the degradation of Fluridone in both water and sediment was minimal. At elevated temperature (20–40 °C), Fluridone degradation was increased in water and sediment. Additionally, the persistence of Fluridone in sediment was reduced by increasing sand content in the sediment matrix. Possible Fluridone transport through the subsurface was estimated over a range of initial concentrations, groundwater velocities, Fluridone half-lives, and Fluridone sorption coefficients which may be seen in a field environment. A form of the Ogata-Banks equation which accounts for 1st order decay was used for describing the dispersion of Fluridone, while a related equation from Bear1979 was utilized to quantify advection. In all tested scenarios, maximum transport was less than 10 m over one month of observation. Results of this study will improve our existing understanding of Fluridone persistence and in water and sediment.

  • development of extraction and detection method for Fluridone in water and sediment by hplc uv
    AMB Express, 2019
    Co-Authors: Patrick Wickham, Pramod K Pandey, Latika Singh, Sarah Lesmeister, Patricia Gilbert, Michael Kwong, Jeffrey Caudill, Jon Obrien, Sagor Biswas
    Abstract:

    Fluridone is widely used as a herbicide for controlling invasive aquatic plants such as hydrilla in surface water bodies. When applied on surface waters Fluridone can attach to bed sediment, requiring rigorous extraction methods prior to analysis. Currently, very limited information exists in terms of Fluridone residue detection in delta sediment. In this study, we researched Fluridone detection in both water and sediment. To extract Fluridone from sediment, here we have tested two extraction methods: (1) a rotavapor method (RM); and (2) a quick, easy, cheap, effective, rugged and safe (QuEChERS) method (QM). The extraction results of RM were compared with those of QM. To quantify Fluridone concentrations in extracts, a high-performance liquid chromatography (HPLC)-UV detector was used. HPLC separation was achieved using an Allure C18 5 µm 150 × 4.6 mm column with a mobile phase composed of acetonitrile and water (60:40, v/v). The UV detector was operated at 237 nm. The method was tested and validated using a series of water and sediment samples taken from Sacramento–San Joaquin Delta in California. The average recovery of Fluridone was 73% and 78% using RM and QM respectively. The proposed method can be used for testing Fluridone in water and sediment samples.

Kimberly A Riddle - One of the best experts on this subject based on the ideXlab platform.

  • development and accumulation of aba in Fluridone treated and drought stressed vicia faba plants under different light conditions
    Physiologia Plantarum, 1996
    Co-Authors: Losanka P Popova, Kimberly A Riddle
    Abstract:

    The effects of Fluridone on guard cell morphology, chloroplast ultrastructure and accumulation of drought stress-induced abscisic acid (ABA) were studied in Vicia faba L. plants grown under different light conditions. Drought stress was induced by allowing the leaves to lose 12% of their fresh weight. The appearance of defective and undeveloped stomata, and chloroplasts with a destroyed thylakoid membrane system was found in Fluridone-treated plants grown at a photosynthetic photon flux (PPF) of 600 μmol m -2 s -1 . Plants grown at a PPF of 40 μmol m -2 s -1 had diminished levels of ABA after imposition of dehydration. Fluridone treatment reduced the level of ABA in both unstressed and dehydrated leaves. Accumulation of ABA in the control plants was considerably reduced when they were exposed to dark periods of 24, 48 and 72 h just before imposition of the stress. Twenty-four hours after the dark treatment dehydration of the leaves resulted in a 3-fold decrease in the level of stress-induced ABA, and 72 h after dark treatment the amount of stress-induced ABA approximated the prestressed values. Fluridone-treated plants failed to accumulate ABA under water stress. In addition to functionally active chloroplasts, well-developed and functional stomata are required for drought stress to elicit a rise in ABA.

  • Development and accumulation of ABA in Fluridone‐treated and drought‐stressed Vicia faba plants under different light conditions
    Physiologia Plantarum, 1996
    Co-Authors: Losanka P Popova, Kimberly A Riddle
    Abstract:

    The effects of Fluridone on guard cell morphology, chloroplast ultrastructure and accumulation of drought stress-induced abscisic acid (ABA) were studied in Vicia faba L. plants grown under different light conditions. Drought stress was induced by allowing the leaves to lose 12% of their fresh weight. The appearance of defective and undeveloped stomata, and chloroplasts with a destroyed thylakoid membrane system was found in Fluridone-treated plants grown at a photosynthetic photon flux (PPF) of 600 μmol m -2 s -1 . Plants grown at a PPF of 40 μmol m -2 s -1 had diminished levels of ABA after imposition of dehydration. Fluridone treatment reduced the level of ABA in both unstressed and dehydrated leaves. Accumulation of ABA in the control plants was considerably reduced when they were exposed to dark periods of 24, 48 and 72 h just before imposition of the stress. Twenty-four hours after the dark treatment dehydration of the leaves resulted in a 3-fold decrease in the level of stress-induced ABA, and 72 h after dark treatment the amount of stress-induced ABA approximated the prestressed values. Fluridone-treated plants failed to accumulate ABA under water stress. In addition to functionally active chloroplasts, well-developed and functional stomata are required for drought stress to elicit a rise in ABA.

Elsie I Hamadina - One of the best experts on this subject based on the ideXlab platform.

  • Pre-tuber Application of Fluridone: Effect of Foliar and Root Absorption on Sprouting of Yam ( Dioscorea alata L.) Tubers
    2020
    Co-Authors: Somina Braide, Elsie I Hamadina
    Abstract:

    The absorption of Fluridone (an abscisic acid biosynthesis inhibitor), prior to yam tuber formation has been shown to induce precocious sprouting on the new tubers that form. However, the use of hydroponics system to achieve root absorption of Fluridone requires high skills and capital, and the effect of pre-tuber application of Fluridone on sprouting of yam tubers produced in a soil medium is not known. Thus, the objectives of this study were to: (1) determine the effect of 30µM Fluridone on sprouting of soil produced yam tubers, and (2) to determine the effect of different methods of applying (root and foliar application) 30µM Fluridone on the timing of sprouting of soil produced yam tubers. The treatments were: (1) nutrient solution medium (Control 1) (2) nutrient solution medium + 30µM Fluridone (root absorbed) (3) soil medium irrigated with distilled water (Control 2) (4) soil medium+ 30µM Fluridone (foliar absorbed) (5) soil medium + 30µM Fluridone (root absorbed). The study was a completely randomized design with five treatments. Results showed that Fluridone treatments induced sprouting on both aerial and new underground tubers while the controls did not. Soil + 30µM Fluridone (foliar absorbed) treatment yielded 36% less sprouting underground tubers but over 50% more sprouting aerial tubers compared to the nutrient solution + 30µM Fluridone treatment. Both treatments however, produced sprouts at 5 weeks after treatment application. Soil + 30µM Fluridone (foliar absorption) treatment induced significantly (P

  • Scarification and Soaking in Fluridone for Manipulation of Germination of Seeds from Immature Allanblackia floribunda Fruits
    2020
    Co-Authors: Cynthia Smooth, Elsie I Hamadina
    Abstract:

    Rate of germination and the timing of sprouting has been significantly increased and shortened by propagating Allanblanckia seeds obtained from immature fruits rather than seeds from mature fruits. Also, soaking scarified seeds from immature fruits in 10 µM Fluridone for 6 or 12 hr has led to 72% germination in 75 days. Unfortunately, the effect of Fluridone on un-scarified seeds from immature fruits is not known and, the optimum soak duration for inducing the maximum effect on germination is not clear. Therefore, the objective of this study was to determine the effect of 0, 6, 12, 24 and 48 h of soak in 10 µM Fluridone on the timing and percentage germination of mature un-scarified and scarified Allanblanckia seeds extracted from immature fruits. Results showed that scarified seeds commenced germination after a short period (about 50 days after treatment) while germination was delayed in un-scarified seeds (about 100 days after treatment). Rate of germination in scarified seeds was higher (≥ 38% in 77 d) than un-scarified seeds (≤5% in 100 d). Soaking un-scarified seeds in 10 µM Fluridone led to only about 10% germination (plumule). Soaking scarified seeds in 10 µM Fluridone significantly (p

  • Bioassay of Residual Fluridone Following Prolonged Wet and Dry Cycles in Coastal Plain Soil of Niger Delta
    Resources and Environment, 2020
    Co-Authors: Mohammed K Hamadina, Elsie I Hamadina
    Abstract:

    Decades ago, Fluridone was formulated to control aquatic weeds. Recently, Fluridone is used in manipulating plant physiological processes, and also as terrestrial herbicides. Fluridone may enter the soil through different pathways; but its persistence in soils is not clearly understood, especially following a prolonged dry period. Bioassays using responsive plants species are useful in assessing carryover effects of herbicides. Fluridone (three applications of 100 ml of 30 µmol solution each) and No Fluridone control were subjected to 30 days of wet and dry cycles, followed by 77 days of dry periods, and thereafter planted with maize (variety Oba Super 6), i.e., after rewetting the soils. Height and chlorophyll measurements were done on the maize seedlings at 5 DAP and 10 DAP. The morphology of the seedlings was observed throughout the duration of the bioassay study. The shoots of the maize seedlings were harvested at 10 DAP, roots sampled by washing off the soil, and both shoot and roots were oven dried to constant weight. Seedling heights did not differ, but seedlings growth rate from 5th to 10th DAP declined drastically as compared to the period before 5 DAP. Leaf chlorophyll at 10 DAP was significantly reduced in seedlings growing in SA treatments. The leaves of seedlings growing in SA treatment began to whiten by 6th DAP and the bleaching effect progressed up to 10 DAP, apparently manifesting the reduced chlorophyll content. The shoot dry matter contents, root dry weight and shoot:root of the maize seedlings varied significantly (P

  • pre tuber application of Fluridone effect of foliar and root absorption on sprouting of yam dioscorea alata l tubers
    Frontiers in Science, 2018
    Co-Authors: Somina Braide, Elsie I Hamadina
    Abstract:

    The absorption of Fluridone (an abscisic acid biosynthesis inhibitor), prior to yam tuber formation has been shown to induce precocious sprouting on the new tubers that form. However, the use of hydroponics system to achieve root absorption of Fluridone requires high skills and capital, and the effect of pre-tuber application of Fluridone on sprouting of yam tubers produced in a soil medium is not known. Thus, the objectives of this study were to: (1) determine the effect of 30µM Fluridone on sprouting of soil produced yam tubers, and (2) to determine the effect of different methods of applying (root and foliar application) 30µM Fluridone on the timing of sprouting of soil produced yam tubers. The treatments were: (1) nutrient solution medium (Control 1) (2) nutrient solution medium + 30µM Fluridone (root absorbed) (3) soil medium irrigated with distilled water (Control 2) (4) soil medium+ 30µM Fluridone (foliar absorbed) (5) soil medium + 30µM Fluridone (root absorbed). The study was a completely randomized design with five treatments. Results showed that Fluridone treatments induced sprouting on both aerial and new underground tubers while the controls did not. Soil + 30µM Fluridone (foliar absorbed) treatment yielded 36% less sprouting underground tubers but over 50% more sprouting aerial tubers compared to the nutrient solution + 30µM Fluridone treatment. Both treatments however, produced sprouts at 5 weeks after treatment application. Soil + 30µM Fluridone (foliar absorption) treatment induced significantly (P<0.05) more sprouts than soil medium + 30µM Fluridone (root absorption) and sprout was delayed by two weeks in the later. Thus, this study has shown that Soil + 30µM Fluridone (foliar absorption) treatment, which is a cheaper, less skill requiring less cumbersome method, is a potential alternative to the use of nutrient solution + 30µM Fluridone in a hydroponics system for sprout induction.

  • residual Fluridone in humid tropical soils carryover effects on germination and seedling growth of maize zea mays l
    Resources and Environment, 2018
    Co-Authors: Elsie I Hamadina, Mohammed K Hamadina
    Abstract:

    Fluridone is an herbicide that is non-toxic to animals, and it is even being explored for use as drugs for humans. Fluridone helps to release dormancy in plants, with successes achieved for very dormant plants such as yam and Allanblackia. However, little is known about the residual effects of Fluridone in soil, and there is a dearth of information on the carryover effects of soil applied Fluridone on crops. The carryover effects of Fluridone were in a 2 x 3 factorial experiment (2 maize varieties and 3 Fluridone treatments); using Sammaz-40 and Oba Super-6 as test plants sowed in each of these treatments: 1. No Fluridone (NF), 2. Previous Soil-Applied Fluridone (PSAF), and 3. Previous Foliar-Applied Fluridone (PFAF). The Fluridone treatments were applied during the growth cycle of a previous yam crop; soil from that experiment was used in this trial. Three days after planting (DAP) more than half of the Oba-Super 6 hybrid maize seeds planted had emerged, as compared to 13% of Sammaz-40 seeds. In PSAF treatment, 83% of Oba-Super 6 plants had emerged by 6 DAP, as compared to 73.3% and 43.3% for PFAF and NF respectively. The PSAF treatment reduced leaf area and chlorophyll contents, while Sammaz 40 had significantly higher leaf area than that of Oba-Super 6. The carryover effects of soil-applied Fluridone are deleterious to maize seedlings planted after a previous Fluridone application.