HearNPV was applied to a soybean field and evaluated for residual efficacy at different time intervals (0, 12, 24, 36, 48, and 72 hours) after application in laboratory bioassays with treated leaves. Larval mortality was rated at five, seven and twelve days after larval infestation. Larval mortality increased as the number of days after infestation increased. To evaluate the feeding habits of Helicoverpa zea at the 2nd and 3rd instar, HearNPV exposed larvae and untreated larvae were weighed at zero (before diet exposure), four, and seven days. At four days after exposure, larval weight gain of specimens exposed to HearNPV was reduced by 80% and 45% for 2nd and 3rd instar larvae, respectively. At seven days after exposure, larval weight gain of 3rd instar specimens exposed to HearNPV was reduced by 60%.

Current maximum efficiency of phosphorus (P) fertilizers that is utilized by plants in the same year of application ranges from near zero to thirty percent. Despite low utilization of P in crop production, yields are often limited by P deficiencies. Innovative technology is requisite to achieve greater efficiency as fertilizer demands are increasing, while phosphorus mineral resources are rapidly being depleted. A growing environmental concern for nutrient pollution of surface waters also carries significant weight. A novel new product, Carbond® P, is promising technology to increase P use efficiency. Research is needed to understand its capabilities and the functioning mechanisms imbedded within its technology. Several research studies were conducted to evaluate Carbond® P (CBP) against traditional fertilizers ammonium polyphosphate (APP) and monoammonium phosphate (MAP). A soil column leaching study was conducted to determine P mobility through three soils, at two rates (20 and 30 kg P ha-1) in either a banded or mixed soil application. Mobility of P was evaluated at 24, 48, 110 and 365 d after fertilization. CBP showed significantly greater total P leachate values across all soil types and application rates averaged across all readings taken until 365 daf for both application types. In the banded applications, CBP generally produced significantly greater solubility than MAP or APP up until 110 daf. For applications mixed with soil, CBP and MAP had greater solubility than APP at 24 days after application, but by the later evaluation dates (48 and 110 daf) the CBP was significantly higher than both MAP and APP. No statistical significance was found in the leachate P 365 daf in either the banded or mixed applications. One glasshouse study on maize (Zea mays L.) grown in three soils were conducted at 0, 5, 10, 20, 40, 80, and 160 kg P ha-1 comparing CBP and APP fertilizer impacts on early season growth. CBP produced significantly more biomass in two soils when averaged across rates (and at the 20 kg P ha-1 rate in a third soil), increased petiole P in one soil and thicker stems in another. Two field trials showed similar physiological advantages with CBP over APP at later growth stages. CBP maize responded with significantly more biomass and P uptake at the V12-V18 growth stages in one field, as well as plant height in another. At the R2-R3 growth stages, CBP also produced thicker stalks in both fields than APP. These growth enhancements were strongest in medium to highly calcareous soil (6-12 %) low in P (7 mg kg-1). These observations warrant the use of CBP and further investigation to understand its benefits and limitations.

No description available.

Master of Science (MSc)

A single application of aerobically digested sewage sludge was applied by Rappaport et al. (1988) in 1984 at rates up to 210 dry Mt ha⁻¹ on a Davidson clay loam (clayey, kaolinitic, thermic, Rhodic KandiuduIts). The heavily contaminated sludge supplied up to 760 kg Cu and 620 kg Zn ha⁻¹, which are below current cumulative limits, but above annual loading limits for these metals (USEPA, 1993). Rappaport et al. (1988) reported an increase in DTPA extractable Cu and Zn with increasing sludge rate. They observed a linear increase in com yields with an increase in sludge rate, which was attributed to high levels of available N supplied by the sludge. In the present residual study, conducted at the same research site, DTPA extractable Cu and Zn followed the trend observed by Rappaport et at. (1988). However, a linear decrease in corn and sorghum yields was observed with increasing sludge rate. The sludge-related decrease in yields was attributed to phytotoxicity (probably a combination of Al, Cu, Mn, and Zn) induced by low soil pH levels. Whole plant tissue concentrations of eu and Zn at the high sludge rates were above the normal range, however grain concentrations were within the normal range. An adsorption study was conducted, in which soils were amended with Ca(OH)₂ and Al₂(S0₄)₃, to ascertain the effect of decreased pH on Cu adsorption on the soil. Copper adsorption maxima decreased with a reduction in soil pH in all treatments. The effect of ionic strength on Cu adsorption was also investigated. Regardless of pH or ionic strength, Cu adsorption increased with an increase in sludge rate. This adsorption increase was attributed to the higher organic matter content of the sludge treatments. The organic matter at the highest sludge rate was approximately double that of the control after 11 years. The adsorption study shows that sludge amendment has long-term effects on metal retention in soils and the field study reveals that careful management of sludge-amended soils is necessary to prevent phytotoxicity. / Ph. D.

Stink bugs, including native brown stink bug (Euschistus servus) and invasive brown marmorated stink bug (Halyomorpha halys), cause damage to a variety of crops including field corn (Zea mays). Frequency and size of stink bug infestations have increased in corn fields in the Mid-Atlantic U.S., and there are growing concerns that these infestations may contribute to reductions in grain quality including increased mycotoxin concentrations. Prior research on native and invasive stink bugs has focused on understanding their biology, the damage they cause, and elucidating effective and economic management strategies. However, few studies examined the potential for stink bugs to facilitate fungal infection and mycotoxin contamination of corn grain. Thus, the objectives of this research were to: 1) assess the relationship between invasive brown marmorated stink bug (H. halys) feeding injuries and fumonisin contamination of field corn in the Mid-Atlantic U.S., 2) determine if stink bugs are a vector for mycotoxigenic Fusarium spp. in corn, and 3) evaluate the efficacy of pesticides for mitigating stink bug feeding injury and associated mycotoxin contamination in field corn. A correlation between H. halys feeding injury and fumonisin concentrations was identified, and the ability of H. halys to increase F. verticillioides infection and fumonisin concentrations in corn was demonstrated in field experiments. Fusarium species including fumonisin-producing F. verticillioides and F. proliferatum were isolated from field-collected stink bugs, and in laboratory experiments, E. servus was able to transmit F. verticillioides to non-infected corn ears after feeding on F. verticillioides-infected corn. In field studies, both fungicide and insecticide reduced stink bug-associated mycotoxin concentrations in corn, but levels of control were inconsistent. Thus, additional tactics that target both the stink bug and Fusarium should be implemented to mitigate risks of mycotoxin contamination in corn. / Doctor of Philosophy / Native and invasive stink bugs can severely damage crops including field corn. Frequency and size of stink bug infestations in Mid-Atlantic U.S. corn fields have increased, and there is growing concern that this may contribute to reductions in grain quality. Insect feeding injury is a risk factor for fungal infection and mycotoxin contamination in corn. Mycotoxins are toxic chemicals produced by certain fungi that have detrimental health effects on animals including livestock and humans. The relationship between stink bug feeding injuries and mycotoxin contamination in corn grain is not well understood, and management strategies to minimize the risk of mycotoxin contamination in corn need to be identified. The main goal of this research was to characterize interactions between stink bugs and mycotoxin-producing fungi and identify tactics for controlling both the insect pest and pathogen. Specific objectives were to: 1) assess the relationship between invasive brown marmorated stink bug (H. halys) feeding injuries and fumonisin contamination of field corn in the Mid-Atlantic U.S., 2) determine if stink bugs are a vector for mycotoxin-producing Fusarium spp. in corn, and 3) evaluate the efficacy of pesticides for mitigating stink bug feeding injury and associated mycotoxin contamination in field corn. Results from this work indicated that stink bugs have the ability to cause feeding injuries which facilitate invasion of mycotoxin-producing Fusarium species, leading to increases in mycotoxin concentrations in corn grain. Studies also demonstrated that stink bugs can vector Fusarium species during feeding and increase Fusarium infection of corn resulting in subsequent mycotoxin contamination. Field studies indicated that pesticide applications targeting both the stink bugs and mycotoxigenic fungi may be needed to minimize risk of mycotoxin contamination in corn. However, under low pest pressure, application of pesticides is unlikely to be profitable.

<p dir="ltr">In response to fluctuating corn (<i>Zea mays</i> L.) prices, climatic variability, and emerging diseases, farmers are increasingly adopting diverse and intensive management practices to enhance yield and profitability. This research investigates the performance of various inputs and management practices on corn production across multiple site-years, with a focus on yield components, grain fill duration, kernel development, disease severity, and economic outcomes. A multi-state research trial was established to evaluate the impact of seven inputs and management practices across multiple locations and environments in Indiana, Kentucky, and Michigan in 2022 and 2023. Each location included eight treatments: 1) control treatment (C) based on Purdue University seed rate and nitrogen (N) fertilizer recommendations (Camberato et al., 2022; Nielsen et al., 2022): 30K seeds per acre and N fertilizer application as starter (2x2) and V5 growth stage sidedress. Total N rates ranged between 180 and 200 lbs N per acre and agronomic optimum nitrogen rates (AONR) were used, 2) C + banded (2x2) fungicide, 3) C + 20% increase in corn seeding rate, 4) C + sulfur (S) fertilizer, 5) C + foliar micronutrients, 6) C + late-season N fertilizer application (V10-12 growth stage), 7) C + R1 foliar fungicide, and 8) intensive treatment (all additional inputs/management practices applied). The intensive treatment significantly increased yield by 16.4 and 18.4 bu ac^-1 in 2022 and 2023, respectively when compared to the control across locations, but did not enhance net profit across multiple corn price scenarios due to high application costs. Conversely, R1 fungicide applications increased yield by 16.2 and 16.7 bu ac^-1 in 2022 and 2023, respectively, and S applications increased yield by 12.9 bu ac^-1 in 2023, when compared to the control, with both treatments improving net profit under multiple corn price scenarios. In addition, kernel development studies in West Lafayette, IN, during 2022 and 2023 revealed that banded fungicide applications at planting and foliar fungicide applications at the R1 growth stage can reduce leaf disease severity by 3.2% to 6.6%, extend grain fill duration by 3.5 to 4.5 days, and increase maximum dry kernel weight at plant maturity by 5.7 to 9.4%, respectively, leading to further insights into the yield response mechanisms. Furthermore, a meta-analysis of 24 at-plant flutriafol fungicide placement trials across Indiana (2020 – 2023) highlighted the effectiveness of at-plant fungicides, with banded (2x2 or 2x0) applications leading to the highest yield increase of 7.8 bu ac^-1 and both banded and in-furrow applications reducing disease severity on corn ear leaves at the R5 growth stage by 2.1 - 2.3% when compared to the control. These findings suggest both at-plant banded and R1 foliar fungicide applications have the potential to reduce disease severity, extend corn grain fill duration, and improve yield when conditions are conducive for a response (e.g., foliar disease presence). Overall, this research highlights the ability of targeted input applications for improving both corn yield and profitability when examined across diverse environments and locations, rather than prophylactic applications of multiple inputs and increased management intensities.</p>

Current interest in cover cropping is focused on enhancing ecosystem services beyond soil conservation. Cover crop (CC) species function uniquely in their effects on ecosystem services when grown in monoculture or mixtures. This research integrated field experiments and a literature synthesis to evaluate the role of cover crops in improving nitrogen (N) management and simultaneously providing multiple ecosystem services. Legume CC fertilized with poultry litter (PL) could replace 101 to 117 kg N ha-1 of fertilizer in corn (Zea mays L.) production. Rye (Secale cereale L.) CC fertilized with PL had a negligible effect on corn production. Biculture fertilizer equivalence ranged between -12 to +75 kg N ha-1. Fertilizer equivalence of legume-containing treatments increased across time. Without CC, fall-applied PL failed to supply N to corn. Ecosystem services of CC and PL illustrate complex species functions. Bicultures produced more total biomass than monocultures in year 1 but less than rye in year 2. Bicultures were as effective in suppressing weeds as rye, produced corn yield similar to legume, and by the second year had similar amounts of available soil N as the legume. Poultry litter effects and interspecific effects cover crop species biomass differed. Rye yield increased, while legume yield decreased slightly in biculture. Poultry litter increased legume N content and a decrease in legume C:N, while rye N content and C:N were unaffected. The synthesis corroborates that mixed and biculture cover crops yield more than the individual component species. Overyielding was transgressive in 60% of cases studied. Mixture effects varied by species: rye and brassica yield increased, while legume decreased in mixtures. The effect of mixed CC on crop yields varied by crop species and management practices, though generally crops increased 8 to 18% overall. This work can be applied to the design of complex CC and PL systems that optimize individual species functions to enhance ecosystem services. / Ph. D. / Current interest in cover cropping is focused on enhancing ecosystem services beyond soil conservation. Cover crop (CC) species function uniquely in their effects on ecosystem services when grown in monoculture or mixtures. This research integrated field experiments and a literature synthesis to evaluate the role of cover crops in improving nitrogen (N) management and simultaneously providing multiple ecosystem services. Legume CC fertilized with poultry litter (PL) could replace almost half of the inorganic fertilizer required by spring corn (<i>Zea mays</i> L.) production. Rye (<i>Secale cereale</i> L.) CC fertilized with PL had a negligible effect on corn production. Fertilizer equivalence of legume-containing treatments increased across time. Without CC, fall-applied PL failed to supply N to corn. Bicultures produced more total biomass than monocultures in year 1 but less than rye in year 2. Bicultures were as effective in suppressing weeds as rye, produced corn yield similar to legume, and by the second year had similar amounts of available soil N as the legume. Poultry litter effects and interspecific effects cover crop species biomass differed as well. Rye yield increased, while legume yield decreased slightly in biculture. Poultry litter increased legume N content and a decrease in legume C:N, while rye N content and C:N were unaffected. The synthesis corroborates that mixed and biculture cover crops yield more than the individual component species. Mixture effects varied by species: rye and brassica yield increased, while legume decreased in mixtures. The effect of mixed CC on crop yields varied by crop species and management practices, though generally crops increased 8 to 18% overall. This work can be applied to the design of complex CC and PL systems that optimize individual species functions to enhance ecosystem services.

Reducing herbicide carryover in soybean production is imperative to sustain future soybean cropping systems in Mississippi and the rest of the world. This research was conducted to determine the response of inoculated soybean to corn (Zea mays L.) residual herbicides. The herbicide treatments included aatrex (atrazine), callisto (mesotrione), lexar (atrazine+mesotrione+s-metolachlor), and steadfast (nicosulfuron+rimsulfuron) at 100%, 75%, 50%, and 25% of the total label rate. Inoculant treatments were Bradyrhizobium japonicum, Bacillus subtilis, and no inoculant. Bacterial inoculants positively impacted most shoot and root growth parameters, significantly increasing depending on the herbicide x inoculant treatment combination and its rate. B.japonicum alone and in combination with B.subtilis can be potentially used in soybean production to alleviate corn residual herbicide carryover effects. However, due to the complex interaction between soybean, rhizobia, and herbicides, further long-term evaluations are needed to develop a more robust technology and make recommendations for use by farmers.

Im Rahmen der Biogasgewinnung in Deutschland wurde Mais schnell zum beliebtesten Substrat für den Einsatz in Biogasanlagen. Die damit verbundene, rasante Steigerung der Maisanbaufläche wurde mit Einführung des „Maisdeckels“ (EEG 2012, § 27) vorerst gestoppt. Dieser begrenzt die Nutzung von Mais und Getreidekorn als Substrat in Biogasanlagen (mit Inbetriebnahme nach 1.1.2012) bei 60 % sofern ein Anspruch auf Förderung bestehen soll. Dennoch ist die Akzeptanz des Maisanbaus in der Öffentlichkeit stark gesunken und wird unter dem Begriff „Vermaisung“ mit einer Vielzahl negativer Aspekte diskutiert. Hierzu gehören neben ökologische Folgen, wie Biodiversitätsverlust und Grünlandumbrüchen auch ökonomische wie eine Erhöhung der Pachtpreise und ethische Argumente wie der „Teller oder Tank“ Konflikt. Um zukünftig sowohl ökonomischen als auch ökologischen Ansprüchen zu genügen, bietet der Maisanbau mit Stangenbohnen in Mischkultur eine interessante Alternative. Die Stangenbohnen bieten eine Nahrungsquelle für Bestäuberinsekten und das Potential die Stickstoffdüngung in der Mischkultur zu reduzieren. Zur Nahrungsmittelproduktion ist dieses System in den Tropen weit verbreitet und auch in Deutschland konnte es auf Anhieb in Vorversuchen zur Biomasseproduktion sehr hohe Erträge erzielen. Die vielversprechenden ersten Erfahrungen führen zu der Frage, ob spezielle Maisgenotypen und –zuchtprogramme sinnvoll sind, welche die Erträge weiter steigern können, oder ob die gängigen Maissorten geeignet sind. Hierzu wurden zunächst 2012 180 Testhybriden (90 Flintlinien mit einem Denttester sowie 90 Dentlinien mit einem Flinttester) sowohl im Reinanbau (10 Maispflanzen /m²) als auch in Mischkultur (7,5 Maispflanzen/m²) mit der Stangenbohnensorte „Neckarkönigin“ (7,5 Bohnenpflanzen/m²) an drei Standorten (Göttingen, Einbeck, Grucking) angebaut, von denen lediglich Einbeck auswertbar war. Aufgrund der Gesamttrockenmasseleistung ihrer Testkreuzungen wurden für jedes Anbausystem die besten 20 Flint- und 20 Dentlinien selektiert. Die Bohnenertragsanteile lagen auf Grund der Frühreife der „Neckarkönigin“ bei durchschnittlich nur 5 % und resultierten in der Aufnahme der Bohnensorten „Bobis a grano nero“ und „Anellino verde“ in die Versuche der Mischkultur im folgenden Jahr. Die selektierten Maislinien wurden im Winterzuchtgarten erneut mit einem Tester des anderen Genpools gekreuzt und 2013 in dem Anbausystem angebaut, in dem sie im Vorjahr selektiert wurden. Der Anbau erfolge an drei Standorten (Göttingen, Einbeck, Eutingen). Auf Grund der schlechten Frühjahrswitterung konnten nur die Versuche in Göttingen und Einbeck auswertet werden. Die Bohnenertragsanteile 2013 lagen bei durchschnittlich nur 2 %, jedoch konnte sich „Anellino verde“ durch eine ausgeprägte Spätreife auszeichnen. Aus den 20 Testhybriden je Genpool und Anbausystem wurden die besten 5 Flint- bzw. Dentlinien je Anbausystem selektiert. Bei den Flintlinien aus der Mischkultur wurde aus versuchstechnischen Gründen nur 4 Linien selektiert. Im Winterzuchtgarten wurden die 5 Flint- und Dentlinien, welche im Reinanbau selektiert wurden, faktoriell miteinander gekreuzt. Gleiches gilt für die 4 Flint- und 5 Dentlinien aus der Mischkultur. So entstanden 45 Experimentalhybriden, welche im letzten Versuchsjahr 2014 sowohl in Reinanbau mit 7,5 Maispflanzen/m² und 10 Maispflanzen/m² als auch in Mischkultur mit „Anellino verde“ (7,5 Maispflanzen/m² und 10 Bohnenpflanzen/m²) an den Standorten Göttingen, Einbeck und Eutingen untersucht wurden. In diesem Jahr konnten Bohnenertragsanteile von bis zu 13 % erreicht werden. In der Maiszüchtung werden bei der Selektion der Trockenmasseertrag und der Trockensubstanzgehalt betrachtet. Zur Berechnung des erwarteten Selektionserfolges wurde daher mit dem reifekorrigierten Ertrag (RekoE) ein Merkmal berechnet, welches Trockenmasseertrag und Trockensubstanzgehalt berücksichtigt. Für dieses Merkmal zeigen 2012 signifikante Maisgenotyp x Anbausystem Interaktionen, dass ein spezielles Zuchtprogramm zur Entwicklung von Maissorten für den Anbau in Mischkultur sinnvoll sein kann. Allerdings lagen die genetischen Korrelationen zwischen RekoE im Reinanbau und RekoE in Mischkultur bei 0,76 – 0,83. Diese hohen Korrelationen lassen eine indirekte Selektion auf Mischkultureignung des Maises attraktiv erscheinen. Hierbei würde im Reinanbau indirekt auf das Zielmerkmal (Mischkultureignung) selektiert. Unter Berücksichtigung, dass eine Selektion in Mischkultur (direkte Selektion) zusätzliche Ressourcen verlangt und Mais ohnehin im Reinanbau in der praktischen Maiszüchtung getestet wird, konnte kein Vorteil auf Seiten der direkten Selektion gegenüber der Selektion im Reinanbau (indirekte Selektion) bei den Flinttesthybriden ermittelt werden. Bei den Denttesthybriden hingegen konnten Vorteile einer direkten Selektion ermittelt werden, da in der Mischkultur die Heritabilität um 0,08 höher war als im Reinanbau. 2014 konnten keine Maisgenotyp x Anbausystem Interaktionen nachgewiesen werden und die Schätzwerte für die genetischen Korrelationen zwischen Reinanbau und Mischkultur lagen bei 1. Dies führt zu der Schlussfolgerung, dass wahrscheinlich kein eigenständiges Zuchtprogramm für Mais in Mischkultur zu rechtfertigen ist. Stattdessen könnte zunächst im Reinanbau eine Vorselektion stattfinden mit einer abschließenden Prüfung in Mischkultur. Obwohl in den Versuchen nur geringe Bohnenanteile realisiert wurden, resultierten aus den in Mischkultur selektierten Linien einige sehr leistungsstarke Hybriden. Für die zukünftige Etablierung der Mischkultur von Mais und Bohnen zur Biomasseproduktion gilt es nun auf Seiten der Bohne das genetische Potential für dieses Anbausystem zu untersuchen und zu nutzen. Erste Begleitversuche im Rahmen dieser Arbeit haben gezeigt, dass hier ein enormes Potential liegt.