<p>&nbsp; &nbsp; Razvojem testova inhibicije rasta na vrstama&nbsp; roda&nbsp;<em> Myriophyllum&nbsp;</em> ispitan je<br />potencijal&nbsp; vrsta <em>Myriophyllum&nbsp; aquaticum</em>&nbsp; (Vell.) Verd.&nbsp; i&nbsp;<em> Myriophyllum spicatum</em>&nbsp; L. u<br />ekolo&scaron;koj proceni rizika&nbsp; od herbicida i kontrole kvaliteta sedimenta. Ispitana je<br />primenljivost&nbsp; kontaktnog testa toksičnosti sedimenta sa vrstom&nbsp; M. aquaticum&nbsp; u<br />retrospektivnoj&nbsp; proceni&nbsp; rizika&nbsp; sedimenta&nbsp; na uzorcima iz prirode&nbsp; &ndash;&nbsp; na sedimentu&nbsp; reka Tami&scaron;, Krivaja i Jegrička.&nbsp; Testom toksičnosti sedimenta obogaćenog atrazinom,<br />analiziran je i potencijal kontaktnog testa u preventivnoj proceni rizika od hemikalija<br />koje pokazuju afinitet vezivanja za sediment. Testovima inhibicije rasta <em>M. aquaticum</em><br />i&nbsp; <em>M. spicatum&nbsp;</em> u voda-sediment sistemu ispitana je osetljivost i mogućnost primene<br />metode u preventivnoj proceni rizika od herbicida i regulatora rasta.<br />&nbsp; &nbsp; Deo rezultata dobijenih u radu uključen je u zavr&scaron;ne izve&scaron;taje internacionalnih<br />testova interkalibracije metoda,&nbsp; a kao rezultat ovih aktivnosti usvojene su nove<br />standardne metode na ukorenjenim akvatičnim makrofitama ISO 16191/2013 i OECD 239/2014.<br />&nbsp; &nbsp; &nbsp; Na osnovu istraživanja, zaključeno je da je kontaktni test toksičnosti<br />sedimenta&nbsp; jednostavan i lak za izvođenje, kao i da je vrsta<em>&nbsp; M. aquaticum</em>&nbsp; u jedno-komponentnom sistemu (sediment)&nbsp; adekvatan test model. Rastom kontrolnih biljaka, niskom varijabilno&scaron;ću i visokom osetljivo&scaron;ću biolo&scaron;kih&nbsp; odgovora zadovoljen je kriterijum validnosti testa. Preporučeno je kori&scaron;ćenje dodatne kontrole&nbsp; u&nbsp; slučajevima kada postoje značajna odstupanja u strukturi između&nbsp; standardnog sintetičkog kontrolnog i&nbsp; testiranog prirodnog sedimenta.&nbsp; Kontaktnim&nbsp; testom toksičnosti sedimenta obogaćenog&nbsp; atrazinom&nbsp; pokazano je da se ovaj test&nbsp; može smatrati potencijalno dobrom metodom za pro&scaron;irenje ekolo&scaron;ke procene rizika od hemikalija koje pokazuju afinitet vezivanja za sediment.<br />&nbsp; &nbsp; Ispitivanjem potencijala&nbsp; testa&nbsp; inhibicije rasta vrsta roda&nbsp;<em> Myriophyllum</em>&nbsp; u voda-sediment sistemu&nbsp; utvrđeno je da su testovi&nbsp; izvodljivi u praksi, da pokazuju&nbsp; visoki stepen stabilnosti, statističku snagu i malu varijabilnost&nbsp; većine&nbsp; ispitivanih parametara rasta. Poređenjem testova sa vrstama&nbsp;<em> M. aquaticum</em>&nbsp; i&nbsp;<em> M. spicatum</em>, nije utvrđena značajna&nbsp; razlika u osetljivosti na odabrane herbicide.&nbsp; Osetljivost&nbsp; testova na vrstama roda&nbsp; <em>Myriophyllum</em>&nbsp; i standardnih&nbsp; Lemna&nbsp; testova je bila slična,&nbsp; osim u slučaju auksin simulatora gde su&nbsp; vrste roda <em>Myriophyllum</em>&nbsp; sp. bile osetljivije,&nbsp; &scaron;to&nbsp; ukazuje&nbsp; na njihovu primenljivost u proceni rizika od pesticida specifičnog mehanizma toksičnog dejstva.<br />&nbsp; &nbsp; Iako&nbsp; obe vrste roda&nbsp; <em>Myriophyllum</em>&nbsp; imaju&nbsp; prednosti i nedostatke&nbsp; kao test<br />organizmi,&nbsp; vrste se&nbsp; mogu&nbsp; smatrati reprezentativnim akvatičnim ukorenjenim<br />makrofitama i predstavljati&nbsp; adekvatne&nbsp; dopunske test vrste u vi&scaron;im nivoima ekolo&scaron;ke<br />procene rizika od herbicida i regulatora rasta.&nbsp; Takođe, vrsta <em>M. aquaticum&nbsp; </em>je pogodna za&nbsp; testiranje u&nbsp; različitim test sistemima,&nbsp; a samim tim&nbsp; ima i veći&nbsp; potencijal primene u preventivnoj, ali i retrospektivnoj ekolo&scaron;koj proceni rizika.</p> / <p>Growth inhibition tests on <em>Myriophyllum&nbsp; aquaticum</em>&nbsp; (Vell.) Verd.&nbsp; and <em>Myriophyllum spicatum</em>&nbsp; L.&nbsp; were conducted in order to assess their use in refined risk assessment&nbsp; of chemicals, as well as in&nbsp; sediment&nbsp; risk assessment.&nbsp; The applicability, stability and sensitivity of the&nbsp;<em> M.&nbsp; aquaticum&nbsp; </em>sediment contact test on natural sediments (from rivers Tami&scaron;, Krivaja and&nbsp; Jegrička) was assessed for use in retrospective ecological risk assessment (ERA). The potential use of the spiked sediment contact test in risk assessment&nbsp; of&nbsp; sediment bound chemicals was&nbsp; also investigated. The sensitivity and applicability of the growth inhibition tests on&nbsp;<em> M. aquaticum</em>&nbsp; and&nbsp; <em>Myriophyllum </em>spicatum&nbsp; in a water-sediment system was assessed for potential use in prospective ERA of plant protection products.</p><p>A part of the results of this study was included in the final report of the two&nbsp; international ring tests, which resulted with new standardised methods with rooted macrophytes:&nbsp; ISO 16191/2013 i&nbsp; OECD&nbsp; 239/2014. Tests on&nbsp; <em>Myriophyllum</em>&nbsp; species were compared to standard Lemna&nbsp; tests.&nbsp; Test substances in <em>M. aquaticum</em>&nbsp; and&nbsp; <em>Lemna minor&nbsp; L</em>. tests were 3,5 dichlorphenol, atrazine, isoproturon, trifluralin, 2,4 D and dicamba, while substances used in&nbsp;<em> M. spicatum&nbsp;</em> tests were atrazine, isoproturon and 2,4 D.</p><p>The sediment contact test proved to be simple and robust, while <em>M. aquaticum</em> can be considered as an adequate test model in a one-compartment (sediment) test. The validity criteria regarding control plant growth and variability was met. The use of an additional control is suggested when testing of sediments with considerably different properties of the standard synthetic control is taking place.&nbsp; The spiked sediment contact tests with atrazine showed that the method could be applied in prospective risk assessment of sediment bound chemicals.</p><p>The water-sediment growth inhibition test with&nbsp; <em>Myriophyllum</em>&nbsp; species proved to be applicable in practice, with high stability, statistical power and low variability of the majority of the growth parameters.<em>&nbsp; M. aquaticum&nbsp;</em> and&nbsp; M. spicatum&nbsp; didn&rsquo;t show major&nbsp; differences&nbsp; in sensitivity to tested substance.&nbsp; The sensitivity of&nbsp; <em>Myriophyllum</em> and&nbsp; Lemna&nbsp; tests was also similar, except to auxin simulators, where&nbsp; <em>Myriophyllum </em>species were considerably more sensitive, which makes them adequate&nbsp; candidates for use in risk assessment of chemicals with specific mode of action.</p><p>Even though both&nbsp; <em>Myriophyllum</em>&nbsp; species show advantages and disadvantages as test organisms, they can be regarded as representative rooted aquatic macrophyte species and additional test species in refined risk assessment of herbicides and growth regulators. &nbsp;Also,&nbsp; <em>M. aquaticum&nbsp; </em>can be tested in various test syytems, which makes this species &nbsp;applicable in prospective as well as retrospective ecological risk assessment.</p>

V práci je popsán princip synchronní detekce (SD), který byl uplatněn při měření s biosenzory. Metoda SD umožňuje dosažení výrazně lepšího poměru signálu k šumu, vyššího limitu detekce a celkové zlepšení robustnosti měření. Uplatnění SD při měření s biosenzory umožní zlepšit analýzu jeho odezvy a umožní odstranění nežádoucích interferencí nebo šumů, které mohou být způsobeny například mícháním roztoku, elektromagnetickými vlivy nebo parazitními proudy. SD také umožňuje rozložit získaný signál na odezvu stimulace a na dlouhodobý signál jiného procesu, a dále také identifikovat jevy druhého řádu. Pro identifikaci stimulačního signálu ve výstupním signálu měření byl na základě lineárního statistického modelu vyvinut specializovaný software. SD byla ověřena na modelovém případu výstupního signálu biosenzoru s aplikovaným komplexem fotosystému II (PSII) a jeho odezvě na stimulaci světlem. Odezva PSII se řídí kinetikou prvního řádu a může být také ovlivněna inhibitory. Kinetické konstanty vazby herbicidu na PSII závisí lineárně na koncentraci herbicidu. To umožňuje jejich měření také při nízkých koncentracích herbicidu.

La presenza di pesticidi nelle acque di falda è emersa come un importante problema ambientale negli ultimi decenni. In base a “Rapporto nazionale pesticidi nelle acque - Dati 2015-2016” (ISPRA, 2018), in Italia, gli erbicidi triazinici e i loro metaboliti sono tra le sostanze identificate con più frequenza nelle acque, sebbene l’atrazina sia stata bandita nel 1992 e l’utilizzo di terbutilazina sia sottoposto a severe restrizioni. Lo scopo di questo progetto è valutare e quantificare la presenza di atrazina, terbutilazina e dei loro metaboliti nelle acque di falda in aree maidicole italiane. I risultati dimostrano come le molecole oggetto di studio siano state frequentemente individuate nei campioni di acqua di falda, anche se a concentrazioni inferiori al limite stabilito dalla Commissione Europea. Considerando che l’utilizzo di questi erbicidi è proibito o fortemente regolamentato, è interessante valutare il loro comportamento in una scala temporale pluriennale al fine di mettere in evidenza la contaminazione delle acque di falda dovute all’uso diffuso e alla persistenza ambientale di tali molecole. / The presence of pesticides in groundwater has emerged as an important environmental issue in the last decades. According to “Rapporto nazionale pesticidi nelle acque - Dati 2015-2016” (ISPRA, 2018), in Italy triazine herbicides and their metabolites are among the substances most frequently detected in water. While terbuthylazine is still used under restriction, atrazine was banned in 1992. The aim of research project is to investigate the presence of atrazine, terbuthylazine and their metabolites in groundwater in Italian maize-growing areas in order to supply data and information on the groundwater quality. The results show that atrazine, terbuthylazine and their metabolites were often detected in groundwater, even if their concentrations were below the limit established by European Commission. Considering these molecules are banned or heavily regulated, it is interesting to evaluate their behavior on a multiannual time scale in order to highlight the groundwater contamination due to the widespread use and to the environmental persistence of these substances.

Tall fescue (Schedonorus arundinaceus), is a cool season perennial that provides grazing into the early summer months for southern livestock. Grazing the tall fescue variety, Kentucky-31, has negative effects on animal health, particularly after jointing. Two studies were arranged as randomized complete blocks in a split-plot design, with three replicates to compare: the effect of ten herbicides on seedhead suppression, or the effect of inter-seeding legumes [white clover (Trifolium repens) or alfafla (Medicago sativa)] coupled with nitrogen supplementation on fescue yield and forage nutritive value. The herbicides imazethapyr + 2,4-D and without, metsulfuron + chlorsulfuron, reduced seedheads emergence, but not yield compared to the control. Kentucky-31 inter-seeded with white clover and fertilized with 11 kg N ha-1 produced greater biomass than tall fescue fertilized with 11 kg N ha-1. The inter-seeding of white clover produced composite forage samples with greater in vitro dry matter disappearance than nitrogen supplemented alfalfa.

<p>Soil residual herbicides are a vital component of the best management practices (BMPs), to provide early-season weed control in most cropping systems. The availability of a biologically effective dose of a soil residual herbicide in the soil solution is dependent on several soil parameters including soil texture, organic matter (OM), and pH.  Soil residual herbicides are currently applied as a uniform application rate over an individual field; yet soil properties can vary spatially within agricultural fields. Therefore, areas of the field are being over- and under-applied when using a uniform application rate. By integrating variable-rate (VR) technology with soil residual herbicides, the correct rate could be applied based on the intra-field soil variability. However, the extent of spatial soil variability within a field and the impact on herbicide application rates has not been well-characterized to inform whether soil residual herbicide applications should move towards variable rate applications. Therefore, the objectives of this research were to 1) determine the extent of intra-field variability of soil texture and organic matter in ten commercial Indiana fields, 2) quantify the reliability of five different combinations of spatial soil data sources, 3) determine the impact of soil sample intensity on map development and the classification accuracy for VR applications of soil residual herbicides, 4) quantify the impact of VR herbicide application on the total amount and spatial accuracy of herbicide applied according to product labels, and 5) determine if the intensive spatial characterization of soil properties is related to weed seedbank abundance and species richness to improve predictive weed management using soil residual herbicides.</p> <p><br></p> <p>Commercial soil data was generated by intensively collecting 60 soil samples in a stratified random sampling pattern in 10 agricultural fields across Indiana. Analysis of this data from commercial fields confirmed inherent field variability that would benefit from multiple management zones according to the labeled rate structures of pendimethalin, s-metolachlor, and metribuzin. Therefore, further research was conducted to determine an accurate and reliable method to delineate the fields into management zones for variable-rate residual herbicide applications based on the spatial soil variability and herbicide labels. </p> <p><br></p> <p>A modified Monte Carlo cross-validation method was used to determine the best source of spatial soil data and sampling intensity for delineating management zones for variable-rate applications of pendimethalin, s- metolachlor, and metribuzin. These sources of spatial soil data included: Soil Survey Geographic database (SSURGO) data, intensive soil samples, electrical resistivity sensors, and implement mounted optical reflectance sensors using VNIR reflectance spectroscopy. The mean management zone classification accuracy for maps developed from soil samples with and without electrical conductivity was similar for 75% of all maps developed across each field, herbicide, and sampling intensity. The method of using soil sampling data combined with electrical conductivity (SSEC) maps was most frequently the top performing source of spatial soil data. The most reliable sampling intensity was one sample per hectare which resulted in lower root mean squared error (RMSE) OM values, higher management zone classification accuracy, and more reliable predictions for the number of management zones within each field. </p> <p><br></p> <p>Using VR maps developed from SSEC with one sample per hectare sampling intensity, additional research was conducted to compare the amount of herbicide and field area that was over-or under-applied with a uniform application rate compared to a VR application for 10 corn and soybean residual herbicides. Although research from our previous study documented that spatial soil variability was extensive enough to require two or more management zones for all fields, the same labeled herbicide dose defined for multiple soil conditions led to 20% of all maps not requiring a variable rate application (VRA). Additionally, no difference was shown in the total amount applied of herbicide in an individual field between a variable and uniform application rate for all herbicides. Nonetheless, nearly half of all VR maps had 10% or more of the field area misapplied with a uniform application rate and justifies further research to determine if the proper placement of residual herbicide adds value through increased weed control in the field areas being under-applied. </p> <p><br></p> <p>Similar to soil residual herbicides, weed seedbank abundance and species richness were impacted by the variable soil conditions present within the field area. The seedbanks favor the establishment in areas of the field that promote vigorous germination, growth, and reproduction next to the competing crop. Therefore, soil sampling and weed seedbank greenhouse grow-outs were conducted in four fields to gain a better understanding in the relationship between the spatial soil and weed seedbank variability. All weed seedbank characteristics were shown to be spatially aggregated. Even though no individual or combination of soil parameters consistently explained the variability of weed seedbank abundance, species richness, or individual weed species across all four fields. However, clay content was the most persistent soil parameter to negatively impact (lower seedbank values) the soil weed seedbank.</p> <p><br></p> <p>Further field studies should be conducted across multiple sites to determine if variable-rate residual herbicide applications aid farmers by reducing the risk of crop injury in over-applied field areas and increased weed control in the areas being under-applied.  These studies should also access whether earlier emergence and/or greater weed densities occur in field areas receiving sublethal herbicide doses compared to areas receiving the optimal application rate. Additional research should investigate the utility of VR residual herbicide applications when tank-mixing multiple products during an application. Particularly, when the soil parameters used for selecting the herbicide rate are not defined the same across herbicide labels </p>

Quizalofop and florpyrauxifen-benzyl are both new herbicides for rice in the midsouthern U.S. Quizalofop is only effective for control of monocot weed species; therefore, mixtures of florpyrauxifen-benzyl with quizalofop could be beneficial in acetyl CoA carboxylase (ACCase)-resistant rice. Field experiments were conducted at the Delta Research and Extension Center in Stoneville, MS, in 2017 and 2018 to evaluate control of monocot and dicot weed species with sequential applications of quizalofop including auxinic herbicides in the first or second treatment. Other field experiments in 2017 and 2018 evaluated sequential applications of different rates of quizalofop with florpyrauxifen-benzyl included in treatments immediately prior to flooding. A final field experiment in 2017 and 2018 evaluated growth and yield of six ACCase-resistant rice cultivars and advanced lines following POST applications of florpyrauxifen-benzyl.

No description available.

Purple-flowered rhododendron (Rhododendron ponticum L.) and yellow-flowered rhododendron (R. flavum Don.) are two dominant shrub species of the eastern beech (Fagus orientalis L.) understories in the eastern and western Black Sea Region (BSR), respectively. These invasive woody species significantly reduce beech growth and can preclude tree regeneration. The ecological consequence is an aging beech overstory with little or no regeneration to replace the mature trees. Great rhododendron (R. maximum L.) has been increasing in the forests of the Southern Appalachians of the United States, reducing tree regeneration and growth. The BSR and Southern Appalachians bear noteworthy similarities in climate, topography, and the forest flora. Purple-flowered and great rhododendrons also show important similarities in their ecology and the forest vegetation problems they can cause. Current rhododendron-dominated and threatened BSR forests may provide an advanced ecological picture of the forests of the Southern Appalachians in which great rhododendron now thrives. Therefore, new information gained on the ecology and effective and cost-efficient control of purple-flowered rhododendron may significantly improve forest management practices, not only for the current rhododendron-invaded BSR ecosystem, but also for other parts of the world. This dissertation consists of five separate yet related chapters. The first gives relevant literature reviewed for the dissertation. The second chapter focuses on various environmental and disturbance factors that may have shaped the current purple-flowered rhododendron-dominated beech forests of the BSR of Turkey. Chapter 3 assesses the effects of various manual and herbicidal woody control techniques on purple-flowered and yellow-flowered rhododendron in two field experiments in the BSR. The fourth chapter relates a study of uptake and translocation behavior of triclopyr ester and imazapyr in great rhododendron. This information is used to determine the optimum herbicide-surfactant combinations for the greatest active ingredient uptake and root translocation in great rhododendron. The last chapter is a synthesis of the information gained in all of these different experiments. / Ph. D.

Woody plant herbicide screening techniques were evaluated in an attempt to expedite the screening process and decrease amounts of herbicide active ingredient required. Rapid greenhouse screening of woody plant seedlings was performed in less than six months while rapid seed screening was performed in less than twenty days. A traditional field screen, requiring ten months, was performed for comparison purposes. Leaf area – biomass ratios were also examined for their influence on herbicide efficacy. Linear regressions were performed using traditional field screen data as the dependent variable and rapid screening technique data as the independent data. Rapid screens using triclopyr produced more statistically significant regressions compared to those involving imazapyr. Significant regressions were produced that could predict field response of several species using both herbicides and either rapid screening technique. This indicated that rapid screening techniques could determine herbicide efficacy and/or species spectrum of control in much less time with much less herbicide. Rapid seed screens could estimate species spectrum within five days after treatment. The rapid greenhouse screen and rapid seed screen techniques can provide woody plant herbicide developers initial efficacy and spectrum of control data in a cost- and time- effective manner. Testing showed that as woody plants mature from seedling to sapling, there is a decrease in the leaf area — total aboveground biomass ratio. The decrease in this ratio consistently decreased efficacy of both imazapyr and triclopyr at the lower active ingredient rates. Seedlings with the higher leaf area – biomass ratio had, on the average, higher efficacy response rates to herbicide treatments. / Master of Science

Master of Science