Herbicide Active Ingredient Research Articles

History of chemical weeding from 1944 to 2011 in France: Changes and evolution of herbicide molecules

Herbicide development in France has been analysed from a historical and agronomical perspective. A database was built up from data collected from the archives of the Ministry of Agriculture Food and Fisheries and from French phytosanitary compendia edited since 1961 by the Association de Coordination Technique Agricole. Only herbicides used in cultivated areas were retained. The first organic synthetic herbicides were registered on cereals after the Second World War. Since 1944, a total of 225 herbicidal active ingredients have been registered in France. The number of active ingredients regularly increased with a maximum of 138 in 2002; 104 were still authorized in 2011. Different combinations (maximum of 156 in 2002) were available that combined 2–5 active ingredients. On average, a given active ingredient has been used for more than twenty years. Nevertheless, some of them have been used for 67 years. A decrease in the number of active ingredients was observed after 2003 due to European and French strengthened regulations. The lack of tools to control some weed groups, the decrease in diversity of active ingredients in terms of HRAC groups and herbicide withdrawals in minor crops will inevitably lead to agronomical dead ends if no alternative solutions are proposed. This evolution induces a risk; the repeated use of fewer active ingredients belonging to a few HRAC (Herbicide Resistance Action Committee) groups may favour the selection of herbicide resistant weeds.

Engineering Core/hallow Shell Nanomaterials to Load Herbicide Active Ingredient for Controlled Release

Engineering Core/hallow Shell Nanomaterials to Load Herbicide Active Ingredient for Controlled Release

Environmental and agronomic monitoring of adverse effects due to cultivation of genetically modified herbicide tolerant crops

Herbicide tolerance allows a specific crop variety to survive a herbicide treatment without injury despite the fact that the herbicide cannot be used selectively in a common variety of the same crop. Widely adopted and used worldwide are genetically modified herbicide tolerant (GMHT) crops with tolerance to the non-selective herbicide active ingredients glyphosate and glufosinate. Development of GMHT crops has substantially changed weed control systems and sometimes crop rotations and soil tillage systems. Attention must be given to the environmental and agro-environmental aspects and sustainability of agro-ecosystems based on HT crops because some adverse effects with this technology can appear, especially if used without knowledge of the risks involved and their prevention. This paper identifies main areas that should be monitored and discusses such potential adverse effects as hybridization with related taxa, occurrence of feral crops, and evolved herbicide resistance within weed communities. If there is no principal difference between conventional and GM crop cultivation, we propose monitoring approaches shall be based mainly on existing methods and monitoring networks. Scientific approaches as basis, decentralization with site-specific focus, as well as reasonable extent of data collection and their effective utilization should be the main features of the monitoring.

Performance of lactating dairy cows fed corn as whole plant silage and grain produced from genetically modified corn containing event DAS-59122-7 compared to a nontransgenic, near-isogenic control

The nutritional equivalency of grain plus whole plant silage from genetically modified corn plants containing the DAS-59122–7 (59122) event expressing the Cry34Ab1 and Cry35Ab1 proteins to grain and silage from a near-isogenic corn hybrid without this trait (control) was assessed using lactating dairy cows. Corn plants with event 59122 are resistant to western corn rootworm and tolerant to the herbicide active ingredient glufosinate-ammonium. Effects on feed intake, milk production, and milk composition were determined. The 59122 grain and the control grain were produced in 2005 from isolated plots in Richland, Iowa. Whole plant corn silage for the 59122 and control treatments were grown in isolated plots at the Kansas State University Dairy Center and ensiled in Ag-Bags. Thirty lactating Holstein cows blocked by lactation number, day of lactation, and previous energy-corrected milk production were used in a switchback design. All cows were fed diets that contained 22.7% grain plus 21.3% whole plant silage from either the 59122 or the control hybrid, in addition to 21% wet corn gluten feed, 12.3% protein mix, 8.0% whole cottonseed, and 14.7% alfalfa hay. Each period of the switchback trial included 2 wk for diet adjustment followed by 4 wk for data and sample collection. Milk samples (a.m. and p.m.) collected from 2 consecutive milkings of each collection wk were analyzed for fat, protein, lactose, solids-not-fat, milk urea nitrogen, and somatic cell count. Percentages of milk fat, protein, lactose, and solids-not-fat were not affected by dietary treatment. Yields of milk, 4% fat-corrected milk, energy-corrected milk, solids-corrected milk, and the concentrations and yields of milk fat, milk protein, milk solids, and milk lactose were not significantly different between treatments. Efficiencies of milk, fat-corrected milk, energy-corrected milk, and solids-corrected milk production also were not different when cows were fed crops from 59122 than when they were fed the control hybrid. Milk production efficiency averaged 1.48 and 1.50kg/kg of dry matter intake for cows fed diets containing the control and 59122 corn, respectively. These data indicate that the nutritional value for milk production was not different between a diet containing grain plus whole plant corn silage produced from a 59122 corn hybrid versus a diet containing grain and corn silage from its near-isogenic control corn hybrid.

Novel derivatisation technique for the determination of chlorophenoxy acid type herbicides by gas chromatography–mass spectrometry

The analytical detection of chlorophenoxycarboxylic-acid-type herbicides (2,4-D, dichloprop, MCPA, etc.) in environmental samples is often a problem in instrumental analysis, as these compounds containing free carboxylic groups require chemical derivatisation prior to gas chromatographic (GC) methods. Nine chlorophenoxy-acid-type herbicide active ingredients have been derivatised successfully with trimethylsilyl N,N-dimethyl carbamate and t-butyldimethylsilyl N,N-dimethyl carbamate by forming their trimethylsilyl (TMS) and t-butyldimethylsilyl (TBDMS) esters, respectively. The detection and determination of the derivatives were performed by capillary gas chromatography-mass spectrometry. The study included determination of retention indices, mass spectral properties and comparison of derivatives produced. The mass spectra of TBDMS derivatives are usually dominated by very characteristic ions [M-57](+) resulting from the cleavage of t-butyl moiety during electron impact (EI) ionisation in the mass spectrometer. Limits of detection were 5 to 100 pg applying GC with EI-MS detection in full scan mode. The method, using SPE sample preparation, was applied for the analysis of 115 ground water and surface water samples collected in Békés County, Hungary in 2009.

Safety assessment of a modified acetolactate synthase protein (GM-HRA) used as a selectable marker in genetically modified soybeans

Acetolactate synthase (ALS) enzymes have been isolated from numerous organisms including soybeans ( Glycine max; GM-ALS) and catalyze the first common step in biosynthesis of branched chain amino acids. Expression of an ALS protein (GM-HRA) with two amino acid changes relative to native GM-ALS protein in genetically modified soybeans confers tolerance to herbicidal active ingredients and can be used as a selectable transformation marker. The safety assessment of the GM-HRA protein is discussed. Bioinformatics comparison of the amino acid sequence did not identify similarities to known allergenic or toxic proteins. In vitro studies demonstrated rapid degradation in simulated gastric fluid (<30 s) and intestinal fluid (<1 min). The enzymatic activity was completely inactivated at 50 °C for 15 min demonstrating heat lability. The protein expressed in planta is not glycosylated and genetically modified soybeans expressing the GM-HRA protein produced similar protein/allergen profiles as its non-transgenic parental isoline. No adverse effects were observed in mice following acute oral exposure at a dose of at least 436 mg/kg of body weight or in a 28-day repeated dose dietary toxicity study at doses up to 1247 mg/kg of body weight/day. The results demonstrate GM-HRA protein safety when used in agricultural biotechnology.

Subchronic feeding study of grain from herbicide-tolerant maize DP-Ø9814Ø-6 in Sprague-Dawley rats

This 13-week feeding study conducted in Sprague-Dawley rats evaluated the potential health effects from long-term consumption of a rodent diet formulated with grain from genetically modified (GM), herbicide-tolerant maize DP-Ø9814Ø-6 (98140; trade name Optimum® GAT® (Optimum® GAT® is a registered trademark of Pioneer Hi-Bred)). Metabolic inactivation of the herbicidal active ingredient glyphosate was conferred by genomic integration and expression of a gene-shuffled acetylase coding sequence, gat4621, from Bacillus licheniformis; tolerance to acetolactate synthase (ALS) inhibiting herbicides was conferred by overexpression of a modified allele (zm-hra) of the endogenous maize ALS enzyme that is resilient to inactivation. Milled maize grain from untreated (98140) and herbicide-treated (98140+Gly/SU) plants, the conventional non-transgenic, near-isogenic control (091), and three commercial non-transgenic reference hybrids (33J56, 33P66, and 33R77) was substituted at concentrations of 35–38% w/w into a common rodent chow formula (PMI® Nutrition International, LLC Certified Rodent LabDiet® 5002) and fed to rats (12/sex/group) for at least 91 consecutive days. Compared with rats fed diets containing grain from the conventional near-isogenic control maize, no adverse effects were observed in rats fed diets containing grain from 98140 or 98140+Gly/SU maize with respect to standard nutritional performance metrics and OECD 408-compliant toxicological response variables [OECD, 1998. Section 4 (Part 408), Health Effects: Repeated Dose 90-Day Oral Toxicity Study in Rodents, Guideline for the Testing of Chemicals. Organisation of Economic Co-operation and Development, Paris, France]. These results support the comparative safety and nutritional value of maize grain from genetically modified Optimum® GAT® and conventional, non-transgenic hybrid field corn.

Breeding for CLEARFIELD Herbicide Tolerance: Registration of ‘ND901CL’ Spring Wheat

‘ND901CL’ (Reg. No. CV‐1029, PI 655233) hard red spring wheat (HRSW) (Triticum aestivum L.) was developed at North Dakota State University (NDSU) and released by the North Dakota Agricultural Experiment Station (NDAES). ND901CL was released in 2008 primarily for its tolerance to imadazolinone herbicides. It has superior adaptation to rainfed wheat production in western regions of North Dakota and counties in adjacent states. It is a CLEARFIELD‐tolerant wheat intended to be used with Beyond herbicide (active ingredient imazamox, 2‐[4,5‐dihydro‐4‐methyl‐4‐(1‐methylethyl)‐5‐oxo‐1H‐imidazol‐2‐yl]‐5‐(methoxymethyl)‐3‐pyridinecarboxylic acid; BASF Corporation, Research Triangle Park, NC). The tolerance to CLEARFIELD herbicide in ND901CL is controlled by two genes. The als1 locus for acetolactate synthase, is located on the D genome and was transferred from ‘FS4’ wheat. The als2 locus is located on the B genome and originated from ‘Teal 11A’ wheat. ND901CL was derived from the Teal 11A/3/‘Grandin’ (PI 531005)/FS4//*3 ‘Kulm’ cross made at NDSU in 2002. Grandin and Kulm are two HRSW cultivars released by NDAES in 1989 and 1994, respectively. Both FS4 and Teal 11A were provided by the BASF Corporation to our breeding program. ND901CL was produced from a bulk of one purified F4:5 plot selected in 2004 at Christchurch, New Zealand. ND901CL was released because it combines high yield with good end‐use quality and tolerance to BEYOND herbicide.

Subchronic feeding study with genetically modified stacked trait lepidopteran and coleopteran resistant (DAS-Ø15Ø7-1xDAS-59122-7) maize grain in Sprague-Dawley rats

DAS-Ø15Ø7-1xDAS-59122-7 (1507 × 59122) is a genetically modified (GM) maize hybrid that was produced by crossing of two GM maize inbreds; DAS-Ø15Ø7-1 and DAS-59122-7. This hybrid cross expresses four transgenic proteins: Cry1F and PAT (from DAS-Ø15Ø7-1) and Cry34Ab1/Cry35Ab1 and PAT (from DAS-59122-7) that confer resistance to lepidopteran and coleopteran pests and tolerance to the herbicidal active ingredient glufosinate-ammonium. The current subchronic feeding study was conducted in Sprague-Dawley rats to evaluate the potential health effects of long-term consumption of a rodent diet containing 1507 × 59122 maize grain compared with a diet containing maize grain from its near-isogenic control (091). Diets formulated with three unrelated non-GM commercial hybrids (3573, 35P12, 36G12) were also included for within study reference data. All diets contained 34% (w/wt) maize grain and were prepared according to the specifications of PMI ® Nutrition International, LLC Certified Rodent LabDiet ® 5002 (PMI ® 5002). Diets were fed ad libitum to rats for at least 92 days. OECD 408 response variables from rats fed the 1507 × 59122 diet were compared with those from rats fed the 091 control diet. No toxicologically significant differences were observed in nutritional performance variables, clinical and neurobehavioral signs, ophthalmology, clinical pathology (hematology, clinical chemistry, coagulation, and urinalysis), organ weights, and gross and microscopic pathology between rats in the 091 and 1507 × 59122 treatment groups. The results from this study demonstrate that 1507 × 59122 maize grain is as safe and nutritious as non-GM maize grain and support the concept that crossing of two safe GM maize events results in production of a safe stacked GM event.

Mass Spectrometric Assessment and Analytical Methods for Quantitation of the New Herbicide Aminocyclopyrachlor and Its Methyl Analogue in Soil and Water

Analytical methods have been developed for the detection and quantitation of a new herbicide active ingredient, aminocyclopyrachlor, and its analogue aminocyclopyrachlor methyl in environmental samples. The analytes were purified from soil extracts and water samples using solid phase extraction based on mixed-mode cation exchange/reverse phase retention. Analyte identification and quantitative analyses were performed by high performance liquid chromatography coupled to tandem mass spectrometry by an electrospray ionization source. External standards prepared in neat solvents were used for quantitation, providing acceptable accuracy, with no matrix effects observed during method validation. The method limits of quantitation (LOQ) were 0.10 ng/mL (ppb, parts-per-billion) in water and 1.0 ng/g in soil for both compounds. The limit of detection (LOD) in water was estimated to be 20 ng/L (ppt, parts-per-trillion) for aminocyclopyrachlor and 1 ng/L for aminocyclopyrachlor methyl, while LODs in soil were 100 ng/kg and 10 ng/kg for aminocyclopyrachlor and aminocyclopyrachlor methyl, respectively. The stability of both compounds in various solvents was evaluated as part of method development. Tandem mass spectrometry experiments were also conducted to investigate the gas-phase fragmentation of aminocyclopyrachlor and its methyl analogue, and the results are reported. A statistical analysis of method validation data generated at two laboratories by multiple chemists authenticates the ruggedness and good reproducibility of the analytical procedures tested.

Comparison of Broiler Performance and Carcass Yields When Fed Diets Containing Transgenic Maize Grains from Event DP-Ø9814Ø-6 (Optimum GAT), Near-Isogenic Control Maize Grain, or Commercial Reference Maize Grains

A genetically modified maize (Zea mays L.) line that contains the Optimum GAT trait (event DP-Ø9814Ø-6; 98140) was produced by integration of the gat4621 and zm-hra genes. The expressed GAT4621 and ZM-HRA proteins confer tolerance to the herbicidal active ingredient glyphosate and acetolactate synthase-inhibiting herbicides, respectively. The objective of this study was to compare the nutritional performance of 98140 maize grain to nontransgenic maize grain in a 42-d feeding trial in broiler chickens. Diets were prepared using grain from untreated 98140 plants and from plants treated with an in-field application of herbicides (98140 + Spray). For comparison, additional diets were produced with maize grain obtained from the nontransgenic near-isogenic control (control) and nontransgenic commercial reference Pioneer brand hybrids 33J56, 33P66, and 33R77. Diets were fed to Ross x Cobb broilers (n = 120/group, 50% male and 50% female) in 3 phases: starter, grower, and finisher containing 58.5, 64, and 71.5% maize grain, respectively. No statistically significant differences were observed in mortality, growth performance variables, or carcass and organ yields between broilers consuming diets produced with maize grains from unsprayed or sprayed 98140 and those consuming diets produced with near-isogenic control maize grain. Additionally, all performance and carcass variables from control, 98140, and 98140 + Spray test maize treatment groups were within tolerance intervals constructed using data from reference maize groups. Based on these results, it was concluded that 98140 maize grain (unsprayed or sprayed with a herbicide mixture) was nutritionally equivalent to nontransgenic control maize with comparable genetic background.

Natural compounds with herbicidal activity

Research about phytotoxic activity of natural compounds could lead both to find new herbicidal active ingredients and to plan environmental friendly weed control strategies. Particularly, living organisms could be a source of compounds that are impossible, for their complexity, to synthesize artificially. More over, they could have alternative sites of action respect to the known chemical herbicides and, due to their origin, they should be more environmental safe. Many living organism, such as bacteria, fungi, insects, lichens and plants, are able to produce bioactive compounds. They generally are secondary metabolites or simply waste molecules. In this paper we make a review about these compounds, highlighting potential and constraints.

A Gene-Shuffled Glyphosate Acetyltransferase Protein from Bacillus licheniformis (GAT4601) Shows No Evidence of Allergenicity or Toxicity

The glyphosate acetyltransferase (gat) gene from Bacillus licheniformis was subjected to multiple rounds of gene shuffling to optimize kinetics of corresponding GAT proteins to acetylate the herbicide active ingredient glyphosate. Genetically modified soybeans expressing the gat4601 gene (356043 soybeans) are tolerant to the application of glyphosate. The current manuscript reports the outcome of the allergenicity and toxicity assessment for the GAT4601 protein. Bioinformatic comparison of the amino acid sequence of GAT4601 did not identify similarities to known allergenic or toxic proteins. In vitro studies conducted with heterologously produced GAT4601 protein demonstrated that it was rapidly degraded in simulated gastric fluid containing pepsin (< 30 s) and in simulated intestinal fluid containing pancreatin (< 2 min) and completely inactivated at temperatures above 56 degrees C. The GAT4601 protein expressed in planta is not glycosylated and similar protein profiles were observed in flour extracts from 356043 soybeans and nontransgenic near isoline comparator soybeans (Jack) using serum from soy allergic persons. No evidence of adverse effects was observed in mice following acute oral exposure to 2000 mg/kg of GAT4601 protein or in a repeated dose dietary exposure study at doses of 800-1000 mg/kg/day. This comprehensive assessment demonstrates that the GAT4601 protein does not present a risk for adverse effects in humans when used in the context of agricultural biotechnology.

Comparison of Broiler Performance When Fed Diets Containing Event DP-356Ø43–5 (Optimum GAT ), Nontransgenic Near-Isoline Control, or Commercial Reference Soybean Meal, Hulls, and Oil

Event DP-356Ø43–5 (356043; Optimum GAT) is a genetically modified soybean (Glycine max) that was produced by insertion of the gat4601 and gm-hra genes. The expression products of these genes are the glyphosate acetyltransferase 4601 and acetolactate synthase proteins, respectively. Expression of the glyphosate acetyltransferase 4601 protein confers tolerance in planta to the herbicidal active ingredient glyphosate, whereas expression of the acetolactate synthase protein confers tolerance to sulfonylurea and imidazolinone herbicides. The objective of this study was to compare the nutritional equivalence of 356043 soybeans to nontransgenic soybeans in a 42-d feeding trial in broiler chickens. Diets were prepared using processed fractions (meal, hulls, and oil) from untreated 356043 soybean plants or from soybean plants treated with a mixture of glyphosate, chlorimuron, and thifensulfuron (356043 + Gly/SU). For comparison, additional diets were produced with soybean fractions obtained from a nontransgenic near-isoline (control; 091) and nontransgenic commercial Pioneer varieties (93B86, 93B15, and 93M40). Diets were fed to Ross × Cobb broilers (n = 120/group, 50% male and 50% female) in 3 phases. Starter diets contained 30% soybean meal, grower diets 26% soybean meal, and finisher diets 21.5% soybean meal. Soybean hulls and oil were added at 1.0 and 0.5%, respectively, across all diets in each phase. No statistically significant differences were observed in mortality, growth performance variables, or carcass and organ yields between broilers consuming diets produced with 356043 or 356043 + Gly/SU soybean fractions and those consuming diets produced with near-isoline control soybean fractions. Additionally, all performance and carcass variables from control, 356043, and 356043 + Gly/SU soybean treatment groups fell within the tolerance intervals constructed using data from reference soybean groups. Based on the results from this study, it was concluded that 356043 soybean was nutritionally equivalent to nontransgenic control soybean with a comparable genetic background.

Efficacy of Control Measures for European Buckthorn (Rhamnus cathartica L.) in Saskatchewan

Introduced to Saskatchewan in the 1930s as a potential shelterbelt species, European buckthorn is now a prominent understory shrub in riparian woodland and shrub communities around Saskatoon. Locally, the Meewasin Valley Authority (MVA) is actively controlling buckthorn as part of its mandate to conserve natural heritage resources of the South Saskatchewan River Valley, with the goal of restoring the natural biodiversity of remnant patches of native vegetation. European buckthorn is normally dioecious, and MVA has chosen to treat only fruiting stems in an attempt to limit seed production. Two control techniques have been used. In one treatment, glyphosate was applied to stems after cutting; alternatively Garlon 4 Dow AgroSciences herbicide (active ingredient triclopyr) was applied as a chemical girdle directly to the stems using a streamline basal bark spray method. To date, more than 347,000 fruiting stems of buckthorn have been treated. Results indicate good initial progress in limiting seed production in dense buckthorn sites, but at a high cost. Although seed eradication is not a practical short-term goal for the Saskatoon buckthorn population, chemical girdling can substantially and strategically reduce seed and effectively limit spread. Field-tested strategies to reduce costs and improve efficiencies are discussed.

Review of Glyphosate and Als-inhibiting Herbicide Crop Resistance and Resistant Weed Management

Weed management is a perennial challenge for growers, and continual innovation is essential to maintain the effectiveness of management technologies. The first generation of herbicide-resistant crops revolutionized weed control. However, weeds are adapting to crop systems that rely on a single mode of herbicide action. Crops with resistance to multiple modes of herbicide action could help maintain weed management. GAT/HRA is a new multiple herbicide–resistance technology for corn, soybean, and other crops. GAT/HRA combines metabolic glyphosate inactivation with an acetolactate synthase (ALS) enzyme that is insensitive to ALS-inhibiting herbicides. The mechanism to inactivate glyphosate is the glyphosate Nacetyltransferase enzyme, which transforms glyphosate into a nonphytotoxic metabolite. The gat gene is derived from a naturally occurring soil bacterium and optimized by repetitive gene shuffling and screening. The resistance mechanism to ALS-inhibiting herbicides is a double-mutant, highly resistant ALS (HRA) that is insensitive to all five classes of ALS herbicides. GAT/HRA crops will maintain natural tolerance to selective herbicides and thus provide more weed management options for growers to help deter weed spectrum shifts and delay the evolution of herbicide-resistant weeds. Nomenclature: Glyphosate; corn, Zea mays L.; soybean, Glycine max (L.) Merr. Traditionally, growers have used selective herbicides to control weeds in crops. Scientists made these selective herbicides by systematically modifying chemicals to find ones that were safe to the crop while still controlling key weeds. Now, instead of modifying the chemistry, scientists can modify the biology to attain crop safety. These biological modifications can be made through gene transfer or by selection of genetic mutations using seed or tissue-culture screens. Herbicide-resistant crops (HRCs) developed with these technologies quickly had an important impact on agriculture (Duke and Cerdeira 2005; Gutterson and Zhang 2004). However, like other technologies, the first generation of products raised many questions about putative risks, including whether the weed management systems associated with HRCs would increase the evolution of herbicide-resistant weeds (Madsen and Streibig 2004; Owen and Zelaya 2005). The increasing use of HRCs reduced the opportunity for new herbicide active ingredients and made the industry reluctant to invest capital because of shrinking market opportunities (Shaner 2000). As the use of glyphosate increased, the use of other herbicides decreased and pressured industry to reduce support of product registrations. Additionally, as herbicide markets declined, the number of chemicals that must be screened to discover a new herbicide increased from less than 1,000 in 1950 to more than 500,000 today. These trends make expanding the use of currently registered herbicide ingredients increasingly attractive to industry.

The effects of several common anthropogenic contaminants on proliferation of the parasitic oyster pathogen Perkinsus marinus

Estuarine contaminants have varying effects on estuarine inhabitants and host-parasite interactions. Some field collected contaminant mixtures have been shown to increase oyster susceptibility to parasitism by Perkinsus marinus, but little is known about contaminant effects on the parasite itself. This study examined the effects of ammonium, nitrate, phosphate, fluoranthene, phenanthrene and a common herbicide mixture (Weed-B-Gone) on in vitro proliferation of P. marinus. Only the herbicide had a significant effect, but not at or below the manufacture's recommended application rate (7.81 microl ml(-1)). The herbicide's active ingredients (3.1% 2,4-dichlorophenoxyacetic acid, 10.6% mecoprop and 1.3% dicamba) mimic growth hormones of broadleaf plants; over stimulation of growth results in death. The mode of action of these compounds on P. marinus warrants further investigation which may provide insight towards the identification of biocides to control P. marinus.

Efficacy of Herbicide Active Ingredients Against Aquatic Weeds

SS-AGR-44, a 4-page fact sheet by K. Langeland, M. Netherland, W. Haller, and T. Koschnick, provides a table for quick reference to the effectiveness of herbicide active ingredients for controlling common aquatic weeds, and outlines the regulatory conditions and resources for further assistance. Published by the UF Department of Agronomy, September 2006. SS-AGR-44/AG262: Efficacy of Herbicide Active Ingredients Against Aquatic Weeds (ufl.edu)

Thirteen week feeding study with transgenic maize grain containing event DAS-Ø15Ø7-1 in Sprague–Dawley rats

Maize line 1507, containing event DAS-Ø15Ø7-1 (1507), is a genetically modified (GM) maize plant that expresses the cry1F gene from Bacillus thuringiensis (Bt) sbsp. aizawai and the phosphinothricin- N-acetyltransferase ( pat) gene from Streptomyces viridochromogenes throughout the plant including in the grain expression of the Cry1F protein confers in planta resistance to the European corn borer (ECB; Ostrinia nubilalis Hübner: Crambidae) and other lepidopteran pests. Expression of the PAT protein confers tolerance to the herbicidal active ingredient glufosinate–ammonium. The current study evaluated the nutritional performance of rats fed diets containing 1507 maize grain in a subchronic rodent feeding study. The grains in this study, 1507, its near-isogenic control (33P66), and a non-GM commercial hybrid (33J56) contained similar amounts of proximates, amino acids, minerals, anti-nutrients, and secondary metabolites. The subchronic feeding study compared standard toxicology response variables in rats fed diets containing 1507 maize grain with those in rats fed diets containing non-GM maize grains. All diets were prepared according to the specifications of PMI ® Nutrition International, LLC Certified Rodent LabDiet ® 5002 (PMI ® 5002). Diets were fed ad libitum to Sprague–Dawley rats for approximately 90 days. In-life response variables included indicators of dietary performance and weekly evaluations for clinical signs of toxicity. No toxicologically significant differences were observed in the nutritional performance variables, clinical and neurobehavioral signs, ophthalmology, clinical pathology (hematology, clinical chemistry, coagulation, and urinalysis), organ weights, and gross and microscopic pathology between any pair of treatment groups. These results demonstrate that 1507 maize grain is as safe and as nutritious as non-GM maize grain.

Timing of Chopper Herbicide Site Preparation on Bedded Sites

Abstract Vegetation control after different application timings of Chopper herbicide (active ingredient imazapyr) relative to bedding was examined at four lower Coastal Plain study locations. Two bedding regimes, midseason and late-season, were examined at each location. Midseason bedding occurred between May and July and late-season bedding occurred between September and November. Results indicate that many of the historical application timing limitations placed on imazapyr are not necessary. Chopper herbicide in combination with methylated seed oil can be applied as early as February and as late as November, up to the day before bedding and immediately after bedding. Seasonal timing of application also was found to have a major impact on pine growth. For those treatments that provided good vegetation control, earlier season treatments resulted in the best pine growth. Optimal application timings were (1) June through September at least 3 weeks after midseason bedding, (2) February to the day before midseason bedding, and (3) February through July followed by late-season bedding. An exception is that if deciduous woody species such as hardwood or blackberry are targeted, early season applications (February–April) should not occur until these species have leafed out. The optimal timing windows are wide, allowing forest managers plenty of flexibility in scheduling operations. Use of optimal timing windows has the potential to substantially increase productivity without increasing costs.