To improve management and control of jointed goatgrass (Aegilops cylindrica Host.) on traditional winter wheat (Triticum aestivum L.) cropland, a better understanding of the effects spring crop and wheat planting date have on weed populations and wheat yield is needed. A study of the effects of safflower (a spring crop) and wheat planting dates (early vs late) was conducted over a 2-yr period. Long term effects will be examined over a 5-yr period. The effects these treatments had on yield, weed seed contamination, jointed goatgrass population density, and soil seedbank concentration were measured. Two identical experiments were initiated, the first beginning in 1996, the second in 1997. In experiment one, initial plant counts showed similar numbers of jointed goatgrass plants in all treatments. In experiment two, initial spring plant counts showed increased numbers of jointed goatgrass in unplanted plots prior to planting safflower, and slightly reduced population densities in October-planted wheat when compared to September-planted wheat. Winter wheat yields were 25% and 35% higher in September-planted wheat than in October-planted wheat, in 1997 in experiment one, and1998 in experiment two, respectively. Crop contamination with jointed goatgrass propagules was four times higher in early vs late-planted wheat in 1997, and 36% higher in 1998. Jointed goatgrass plants in safflower were reduced 97% compared to preplan! counts in both experiments. In experiment one, 1998 fallow season plant counts showed 55% and 75% less jointed goatgrass in fallow safflower plots than in fallow plots of September- and October-planted wheat, respectively, with fallow plots of September-planted wheat having 46% less than fallow plots of October-planted wheat. Soil seed bank concentrations were highest at the 0-5 cm depth of October-planted wheat, which had nearly a 10-fold higher concentrations compared to safflower and September-planted wheat at this depth. There were no differences at depths below 5cm. This study showed the use of safflower to be a very useful management tool for reducing jointed goatgrass populations. September-planted wheat, with similar jointed goatgrass populations, yielded higher, and had less contamination and was therefore more competitive with jointed goatgrass than wheat planted in October, observed through a reduction in jointed goatgrass propagule production. Planting wheat in October, for the purpose of controlling jointed goatgrass through additional tillage, proved ineffective. Jointed goatgrass population densities were not reduced in experiment one, and only slightly reduced in experiment two. The dramatic loss of yield, associated with the later plantings, far outweighs any benefits gained by delaying wheat planting.

<p>Reductions in atmospheric deposition of sulfur (S) coupled with increases in yields of <i>Glycine Max</i> (L.) Merr. (soybean) has led to S deficiencies in Indiana. Poor nodulation due to limited S, and thus a decrease in nitrogen (N) supply, restricts the yield and quality of soybean grain (i.e., protein). Sulfur is a key component of methionine and cysteine, which are important amino acids in the nutrition of foodstuffs. The objective of the first study is to improve yield and composition of soybean through various applications of N and S. Ten N+S fertility treatments were factored by 2 planting dates (early vs. late) at West Lafayette, IN in 2018 and 2019. The same 10 N+S fertility treatments were factored by 2 varieties (Asgrow 24x7 and 34x6) at Wanatah, IN in 2018 and 2019. Soybean yield increases among the N+S fertility treatments of the May 11th planting (early) were 380 to 1006 kg ha^-1 over the untreated control, with no difference within the June 5th planting (late) in 2018. Cool and wet conditions that limited mineralization of N and S from the early planting are likely the source of yield improvements. Protein concentrations were maintained and even increased with N and S treatments that were coupled with yield improvements. The Wanatah location showed that protein levels were increased with the ATS and R4+ NS treatments, while the UAN Direct treatment had the lowest protein in both varieties, suggesting that having no source of S could limit protein development. Although variety did not affect yield, fertility improved yields with the V4R3 NS, Plant NS, R3 NS, R4+ NS, and V4 NS treatments. The yield improvements that developed with these treatments is interesting because each treatment contained a source of N equaling at least 44.8 kg N ha^-1.</p><p>Secondly, the optimal rate and timing of foliar S applications were determined at a S-deficient location (La Crosse, IN) in 2018 and 2019. Three target application timings; V4, R3, and V4 + R3, were crossed with 4 rates of foliar S at 1.12, 2.24, 4.49, 6.73 kg S ha^-1 with each application. Therefore, the sequential application (V4 + R3) received a total of 2.24, 4.49, 8.96, and 13.44 kg S ha^-1. The optimal rate with 2018 yields was 4.5 kg S ha^-1 at V4 or R3; whereas, the optimal rate was 7.9 kg S ha^-1 with the sequential V4 + R3 treatment in 2019. Leaf tissue concentrations of S were nearly deficient (0.25%) post-V4 and post-R3. Higher rates of S had greater S concentrations in the leaf; furthermore, most cases resulted in a linear increase of S concentration with the rate of S applied. Foliar applications of S also reduced N:S ratio. Protein levels in 2018 increased at an equal rate for both the V4 and the R3 timings. In 2019, at a 6 lb ac^-1 rate of S the protein levels were 39.5 and 39.8% for V4 and R3 timings, respectively. Foliar S applications at V4 vs. R3 timings had little variation in yield or protein levels, thereby resulting in flexibility for application timing for growers.</p>

The need for profitable soybean production practices gain continually with increasing input costs and reduced profit margins. Constant cultivar and product developments has resulted in limited current data available regarding the profitability of preventative fungicide applications and physiological benefits that can occur from these applications. Research was conducted during 2017 and 2018 to determine optimal fungicide application timing, while assessing multiple fungicide options and resulting effect on soybean grain yield, seed quality, and profitability. Additional research was conducted to determine optimal row spacing, planting date and fungicide application combinations to maximize soybean production profitability. These data suggest using multi-mode of action fungicide treatments increased soybean grain yield, regardless of application timing. These data also suggest, profitability from application of multi-mode of action fungicides can be observed at lower adjusted market prices.

The Mississippi River Valley Alluvial Aquifer (MRVAA) aquifer is the principal water source for Mid-South irrigators, but the current rate of withdrawal from the aquifer is not sustainable. Means to increase the sustainability of the MRVAA is to improve corn’s water use efficiency (WUE) while, concurrently, maintaining or improving profitability. The objectives of this experiment were to determine the effects of sensor-based irrigation threshold, planting date, and hybrid on corn grain yield, WUE, and net returns above seed and irrigation cost. Season long irrigation thresholds of -50 kPa full irrigation (FI) and -125 kPa limited irrigation (LI) were used, utilizing furrow irrigation. In conclusion, utilizing a delayed irrigation trigger of -125 kPa decreases grain yield and, ultimately, net returns in years with less naturally occurring rainfall, but increases WUE. Shifting the planting date earlier and using full-season (FS) hybrids, increases grain yield, WUE, and net returns.

Soybean seed is one of the most costly inputs for soybean producers. Research was conducted in 2016 and 2017 in Mississippi to evaluate the impact of row spacing, planting date and seeding rate on soybean yield. Additional research was conducted to determine the optimal replant seeding rate, following a sub-optimal stand of soybean, to maximize soybean yield. These data suggest an early planting date, mid-April, at a seeding rate of 296,400 seeds ha-1, no matter the row spacing, resulted in the greatest soybean yield. No yield differences were observed for a replant seeding rate of 160,500 seeds ha-1 added to a 50% reduced stand when compared to the optimum stand treatment. Soybean yield was greater for the optimum stand treatment when compared to complete removal followed by full replant treatment, or 321,000 seeds ha-1.

Cotton (Gossypium hirsutum L.) growth and development, lint yield, and fiber quality are influenced by many management decisions. Three field experiments examining the interaction of plant population and planting date, and cultivar or herbicide and plant growth regulator application on these parameters were conducted in Virginia during 2005 and 2006 and in North Carolina, South Carolina, and Louisiana during specific years. Experiment I: Plant Population and Planting Date Lint yields were highest with populations of 8.9 and 12.8 plants m¯² compared to 5.3 plants m¯² in Virginia and North Carolina, while in Louisiana the highest yields resulted from populations of 5.8 and 9.5 plants m¯² compared to 17.1 plants m¯². Earlier planted (1 May) cotton produced higher yields relative to later planted (21 May) cotton in Louisiana, while yield was not influenced by planting date in Virginia and North Carolina. The impact of plant population and planting date on cotton appeared to be influenced significantly by heat unit accumulation. Experiment II: Cultivar and Mepiquat Pentaborate Application Mepiquat pentaborate (MPB) application consistently decreased plant height, HNR, and enhanced maturity for all cultivars, compared to untreated cotton. A trend of decreasing yield with increasing MPB application in Virginia was observed. These data suggests that cotton response to MPB application is influenced by cultivar maturity or fruiting interval. Experiment III: Trifloxysulfuron-sodium and Mepiquat Chloride Application Trifloxysulfuron-sodium (TFS) did not influence vegetative growth, maturity, or yield in comparison to untreated cotton. Mepiquat chloride (MC) application reduced vegetative growth and enhanced maturity in most years. The results of this experiment demonstrate that TFS application does not have the same effects on plant growth as MC application. / Master of Science

Thesis (M. Agricultural Management (Agronomy)) -- University of Limpopo, 2018 / A survey study identified indigenous leafy vegetables (ILVs) utilized by rural communities in Limpopo Province in the three districts of Capricorn, Sekhukhune and Vhembe focusing on their availability, agronomic practices, marketing, medicinal and cultural roles, as well as their nutritional value. An ILV that was highly preferred and with good marketing potential was identified for further studies on its response to planting density and nitrogen fertilizer rate. A questionnaire survey was used to gather information about types of ILVs utilised, their production practices, marketing of ILVs and their importance in medicinal and cultural roles. Data collected were subjected to analysis using the Statistical Package for Social Sciences (SPSS) using descriptive statistics. Results showed that there were 45 different types of ILVs identified from the three districts in Limpopo Province. Farmers indicated that cultivation of these vegetables was mostly done from October to January in Sekhukhune and Capricorn district while in Vhembe it was practiced all year round. Most of farmers in Vhembe district used inorganic fertilizer during planting while farmers in Sekhukhune and Capricorn districts used organic fertilizers such as cattle manure. Irrigation was commonly used in Vhembe district through furrow irrigation system whereas in Capricorn and Sekhukhune districts most farmers relied on rainfall. Farmers indicated that harvesting was done at an early growing stage of the crop. Indigenous leafy vegetables were mostly marketed in local communities. Several ILVs were identified as preferred and regularly consumed as vegetables. Spider plant (Cleome gynandra) and nightshade (Solanum retroflexum) were identified as the most consumed ILVs in the three districts. Comparing the market potential of the two vegetables, S. retroflexum was chosen for further studies on its response to plant density and nitrogen fertilizer rate. The first study investigated the effect of varying plant density (inter and intra-row spacing) and the second study evaluated the response of intra-row spacing and nitrogen fertilizer (LAN-28%N) rate on growth and yield of S. retroflexum during 2014 (April to May) and 2015 (March to May) growing seasons. The plant density experiment was laid out as a 3 x 4 factorial arrangement in a randomised complete block design (RCBD) with three replications. The treatment factors were 3 inter-row spacings of 30, 45 and 60 cm and 4 intra-row spacings of vi 7.5, 15, 22.5 and 30 cm. The data collected included plant height, plant vigour, number of leaves and branches per plant as well as plant leaf yield. Data were subjected to analysis of variance (ANOVA) using STATISTIX 10.0 package and mean treatments were separated using Turkey HSD at 5% probability level. The results revealed that growth parameters (plant height, plant vigour, number of branches and leaves) and plant leaf yield were significantly influenced by the combined inter and intra-row spacings. Closer inter-row spacings of 30 cm and 45 cm, and intra-row spacings of 7.5 and 15 cm produced the highest values of parameters and plant leaf yield. The combined spacings of 30 x 7.5 cm produced the highest plant leaf yield. The second study was also laid out as a randomised complete block design (RCBD) with three replications. The treatments were 6 x 2 factorial arrangement: 6 levels of nitrogen (LAN-28%N) at 0, 20, 40, 60, 80 and 100 kg N/ha and two intra-row spacings of 15 and 30cm. Inter-row spacing of 30 cm was used. The nitrogen fertilizer was applied a week after transplanting and repeated a week after first harvesting. Data was subjected to analysis of variance (ANOVA) using STATISTIX 10.0 package. Where significant differences were detected, means were separated using Turkey HSD at 5% propability level. The results suggested that both nitrogen fertilizer and spacing can be used to enhance growth and leaf yield of S. retroflexum vegetable. Nitrogen fertilizer rate and plant density significantly (P≤0.05) affected plant growth and plant leaf yields. Growth parameters and leaf yield were optimised using closer spacing of 15 cm and applying nitrogen at 60 kg N/ha. The application of 60 kg N/ha and 15 cm spacing was therefore recommended for the production of S. retroflexum as a vegetable, if planted at 30 cm inter-row spacing. Key words: Indigenous leafy vegetables, agronomic practices, Solanum retroflexum, planting density, nitrogen fertilizer, planting date

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No description available.

Incidence and severity of southern blight caused by Sclerotium rolfsii Sacc. is increasing in the mid-Atlantic region of the U.S. affecting both conventional and organic vegetable production systems. Traditional southern blight management relied on fumigants and fungicides with often inconsistent and uneconomical results. Moreover, with the phase-out of methyl bromide, and the high cost and toxicity of other available fumigants, it is necessary to identify effective and economical southern blight management alternatives. Therefore, the objectives of this research were to 1) evaluate the effect of planting date and potato (Solanum tuberosum L.) cultivar selection on southern blight incidence and tuber yield and quality; 2) compare potato cultivar tuber susceptibility to S. rolfsii in post-harvest settings; and 3) assess the suitability of six cool-season cover crop biomasses and three locally organic materials as carbon sources for anaerobic soil disinfestation (ASD) treatments and their impact on S. rolfsii viability and soil. In a three-year field study, ten commercial potato cultivars and four planting dates per year were evaluated on the Eastern Shore of Virginia. Later potato plantings generally produced greater disease incidence (85-94%) and lower tuber yield (1.8-9.4 Mg ha-1) and quality (47-78%), likely driven by humid, warm weather later in the season that was conducive to disease and detrimental to the potato crop. While no potato cultivar was completely immune to S. rolfsii incidence, cultivar 'Accumulator' consistently had one of the lowest disease incidences (12-71%) and greatest tuber yield among cultivars (6.2-37.3 Mg ha-1), and 'Adirondack Blue' and 'Red Norland' had the overall greatest disease incidence (33-100%). Following harvest of the field experiment, the susceptibility of tubers from the ten cultivars to post-harvest rot caused by S. rolfsii was compared in a laboratory experiment under controlled conditions. 'Atlantic' followed by 'Accumulator' were the least susceptible (3.7-12.6 g of diseased tissue) whereas 'Adirondack Blue', followed by red-skinned potato cultivars had the greatest severity of post-harvest tuber rot (12-17.5 g of diseased tissue). Following three weeks of ASD treatments in growth chamber pot experiments utilizing nine carbon sources incubated at 15/25°C 12/12-h cycle, most carbon sources induced soil anaerobicity (33-90 % iron oxide paint removal), but they did not reduce sclerotial viability compared to nonamended aerobic controls. However, most amended soils undergoing ASD induced greater soil microbial activity (0.7-2.0 % CO2 in vol.) compared to nonamended controls (0.1-0.7 CO2 in vol.), increased soil pH, and some amendments increased soil nitrate accumulation. Overall, results of these studies indicate that southern blight can be effectively managed in potato by coupling early planting dates with cultivar selection, but though promising, additional studies are needed to determine the parameters to effectively decrease S. rolfsii viability with ASD treatments. / Doctor of Philosophy / The fungal disease southern blight, caused by the soilborne plant pathogen Sclerotium rolfsii Sacc., is increasing in the mid-Atlantic U.S. The increase of southern blight is likely due to a multitude of issues such as climate fluctuations, reduction in the use of fumigants, increased soil organic matter through conservation practices, and cropping systems that favor soilborne pathogens. Traditional management of S. rolfsii relied on pesticides and fumigants, but control was often inconsistent and expensive. Moreover, the use of some soil fumigants has been restricted due to environmental concerns, which has limited the options for the management of plant pathogens present in the soil, and management alternatives are needed. Through a series of field, laboratory, and greenhouse experiments, this study 1) evaluated the effect of planting date and potato (Solanum tuberosum L.) cultivar selection on southern blight incidence and tuber yield and quality; 2) compared potato cultivar tuber susceptibility to S. rolfsii in post-harvest settings; and 3) assessed the suitability of six cool-season cover crop biomasses and three locally-sourced organic materials as carbon sources in anaerobic soil disinfestation (ASD) treatments and their impact on S. rolfsii viability and soil. Results of a three-year field study demonstrated that an integrated approach to the management of southern blight that utilizes moderately resistant potato cultivars such as 'Accumulator' and early (March to early April) planting dates will minimize risk of disease and maximize tuber yield. Following harvest, inoculation of potato tubers under controlled conditions revealed that the cultivar 'Atlantic' followed by 'Accumulator' can avoid greater losses due to less tuber rot, while 'Adirondack Blue' followed by red-skinned potatoes have a greater risk of suffering post-harvest tuber decay from southern blight. The anaerobic soil disinfestation (ASD) treatments examined in this study indicated that cover crops biomass and poultry litter are suitable carbon sources to induce soil anaerobic conditions, but they may not reduce the survival of S. rolfsii propagules if treatment temperatures are below 25°C. However, ASD showed benefits such as increased activity of soil microbial communities compared to nonamended soil, increased soil acidity, and some amendments such as mushroom compost, poultry litter, and Austrian winter pea (Pisum sativum subsp. arvense) can contribute soil nutrients such as nitrate. Overall, this research demonstrates that choosing less susceptible cultivars coupled with early planting dates can minimize the negative impact of southern blight on potato yields and quality, and consequently minimize the use of pesticides as the main option to control southern blight on potato across the mid-Atlantic region. Though promising, additional studies are needed to determine the parameters that optimize ASD as an alternative to manage S. rolfsii with ASD treatments.