Cultivated rice is the most important staple crop in the world, but diseases cause substantial losses in grain yield and quality. Sheath blight disease caused by the fungus Rhizoctonia solani is the second most important disease in rice. Most U.S varieties are tropical japonica type, but known sources of resistance in this subspecies are rare. Silva et al. (2012) identified candidate SNP associated with resistance to sheath blight by whole genome sequencing. The objectives of this study were to develop SNP-based markers from the information reported by Silva et al. (2012), to validate the markers by selective genotyping in the RiceCAP SB2 mapping population, and to develop and evaluate breeding lines resistant to sheath blight by marker-assisted selection coupled with backcrossing, anther culture, and field assessment methods. A total of 136 SNP-based markers were developed and screened in extreme resistant and susceptible phenotypic groups from the RiceCAP SB2 mapping population. SNPs in reported genomic regions for sheath blight resistance were identified including eight markers located on chromosomes 6, 8, 9, and 12 that were used in a marker-assisted backcrossing strategy by crossing seven different resistant lines to four susceptible U.S. commercial varieties. A total of 45 doubled-haploid (DH) lines were developed from 28 BC2F1 individuals containing different combinations of selected SNPs. Field evaluation of selected DH lines was carried out in 2014 and 2015. Additional evaluations were performed using a mist chamber to reproduce optimal conditions for disease development. Fourteen DH lines containing different combinations of resistant alleles from chromosomes 2, 6, 8, 9 and 12 showed high levels of resistance after inoculation with R. solani. Results from this research suggest that development of disease resistant rice can be successfully accomplished using whole genome sequencing information combined with standard breeding approaches.

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Bermudagrass is grown on many athletic surfaces in the southern United States because of its aesthetics, vigorous growth, and excellent wear and stress tolerances. Establishment of bermudagrass vegetatively from sprigs provides an economical propagation method for large-acreage sites. During sprig establishment, irrigation and N are often applied at high application rates and/or frequencies to accelerate plant growth for faster, denser canopy coverage. Conventional wisdom suggests high rates of N applied more frequently accelerates bermudagrass growth to shorten the establishment duration for playability or susceptibility to erosion. However, during the establishment phase, low initial plant densities, frequent irrigation application, and high nitrogen (N) fertility can lead to increased risks of surface runoff, erosion, and nutrient movement. Therefore, an experiment was conducted to examine the factors of sprig plant rates at 80, 160, 320, and 480 bu ha-1 of bermudagrass cv. Celebration fertilized at 0, 12.5, 25, and 50 kg N ha-1 wk -1 over an 8 week establishment period. Celebration planted at 360 or 480 bu ha-1 attained0 ≥85% canopy coverage and greater biomass 6 WAP at N applied at ≥12.5 kg N ha-1 wk-1. Higher N application rates were not able to accelerate lower sprig planting rates of 80 and 160 bu ha-1. In the second experiment, the effect of total solid and N losses were examined for sprig planting rates of 160 and 320 bu ha-1 fertilized at 12.5 or 50 kg N ha-1 wk -1. Treatments were subject to three rainfall simulations. Sprigs planted at 320 bu ha-1 resulted in faster canopy coverage compared to the lower sprig planting rate regardless of N application rates. However, N losses were 5 times greater for sprigs fertilized at 50 kg N ha-1 wk -1 regardless of sprig planting rate. The data from the two experiments indicate sprig planting rates >320 bu ha-1 fertilized at 12.5 kg N ha-1 wk -1 accelerate Celebration bermudagrass establish while reducing potential N losses.

Silicon (Si) fertilization provides numerous benefits to plants which can in turn lead to improved crop yields. Field studies were established at multiple sites in Louisiana on alluvial flood plain soils to establish an optimum application rate for CaSiO3 slag for wheat (Triticum aestivum) and determine which parameters contribute to grain yield increases. Treatments were arranged in a randomized complete block design with four replications consisting of twelve treatments: a factorial combination of two N (101 and 145 kg ha-1) and five Si rates (0, 1, 2, 4.5, and 9 Mt ha-1 as calcium silicate slag - CaSiO3, 14% Si), and two control plots (with and without lime). Grain yield and yield components were determined. Straw and grain samples were analyzed for Si and essential nutrient content. Soil samples taken at midseason and harvest were analyzed for Mehlich-3 extractable nutrients and Si content by 0.5 M acetic acid extraction procedure. In 2013, higher grain yields were observed at 101 kg N ha-1 compared to 145 kg N ha-1 with the highest yields seen with 2 Mt ha-1 CaSiO3. In 2014, higher yields were achieved at the higher N rate of 145 kg ha-1. Analysis of variance (AOV) at P<0.1 showed effects of N on tiller and panicle number, spike length, and increased weight of 1,000 grains and spikes, and increased grain weight. Silicon effects were observed in spike weight and length, weight of 1,000 grains and the number of grains per spike. Mean separation using Fishers LSD (P<0.1) showed effects of Si on further yield components such as the number of grains per spike. Data show an increase in some essential nutrients in the soil (e.g. Ca, Mg, S). Nitrogen and Si both influenced the concentration and uptake of nutrients and certain heavy metals in straw and grain. Increased N application lead to greater leaf rust coverage (P<0.01) but significant effects of Si were not observed. Although further research is necessary, the results of this research will help establish the links among Si fertilization rates, level of soil Si and plant essential nutrients, grain yield and its components.

In some corn (Zea mays L.) producing regions of the US, soil testing is still recognized as an effective decision tool for nitrogen (N) fertilizer recommendation. This study was conducted to investigate the early-season N requirement of corn based on early-season soil nitrate level and document the seasonal changes of inorganic N distribution throughout the soil profile. A Gigger silt loam soil and a Sharkey clay soil were selected to establish the trial located in northeastern Louisiana. Treatments of varying N rates were arranged in a randomized complete block design with four replications. Nitrogen fertilizer rates of 0, 67, 134, 201, 268, 335, and 403 kg N ha-1 were applied at early-season VE-V3 leaf stage. Four split application treatments of the Louisiana N recommendation (268 kg N ha-1) were applied at early-season and midseason V7-V9 leaf stages (0-268, 67-201, 134-134, 201-67 kg N ha-1). Grain yield and yield components were determined. Soil inorganic N content was determined by 1 M KCl extraction procedure followed by continuous flow injection analysis. Gigger silt loam reached a maximum yield of 13.2 Mg ha-1 when the N rate was 134-134 kg N ha-1 and soil inorganic N content was 80 kg N ha-1. Sharkey clay achieved a maximum yield of 13.1 Mg ha-1 when 268 kg N ha-1 was applied in early-season and soil inorganic N content was less than 60 kg N ha-1. Split N applications optimized yield for the Gigger silt loam, but experience a yield reduction for the Sharkey clay. The optimum N rate for the Gigger silt loam was 134-134 kg N ha-1 treatment and 201 kg N ha-1 for the Sharkey clay soil applied only at early-season (P<0.05). Nitrogen rate had a significant effect on grain yield and 100-grain weight (P<0.01) as well as N uptake and total N grain content (P<0.05). Seasonal changes in inorganic N content occurred mostly in the 0-15 cm soil layer with decreasing variability with depth. These results show the potential for using inorganic N content to determine N application method in northeastern Louisiana corn production systems.

Nitrogen (N) is often the most yield limiting nutrient, particularly in corn (Zea mays L.) production systems. In the Mid-South, high N application rates have the potential to lead to high N loss. To minimize this loss, proper N management should focus on improving N use efficiency (NUE) while optimizing productivity. The potential to achieve both tasks can be met using enhanced efficiency N fertilizer (EENF). However, limited research has directly compared the active chemicals in EENFs for corn production in the Mid-South. A study was conducted in 2013 and 2014 at two locations in Louisiana to determine the effectiveness of EENFs on yield, grain N uptake, and NUE over varying N rates. Corn grain yield significantly increased when using EENFs compared to untreated urea (average of 1.54 Mg ha-1 Winnsboro, LA and 1.30 Mg ha-1 Saint Joseph, LA [P <0.0001]). Two stabilizers paired together (NBPT and DCD) in Super U, improved yields by nearly 3.0 Mg ha-1 when applied at the recommended N rate. The rate of N transformation was observed in greenhouse experiments, to determine the effectiveness of EENFs over multiple durations of time based on NH4+ and NO3- content in the soil system. While NH4+ concentration declined within 7 days post-application, nitrification inhibitors particularly Instinct had high NH4+ concentration and low NO3- concentration in both trials. This slower transformation minimizes the potential of N fertilizer to be lost. These results suggest crop uptake of N fertilizer would increase with higher NUE. Utilizing EENFs has the potential to increase NUE through specified conditions and time periods.

Developing improved cotton cultivars depends on how cotton cultivars perform the best when under stresses. Reniform nematode is a major plant pathogen, causing 4-6% yield loss in southern United States. A variation in reproduction and pathogenicity across reniform isolates collected from Louisiana on susceptible cotton was reported. This study was conducted to determine the response of resistant/tolerant cotton genotypes to multiple reniform isolates by inoculating 10,000 juveniles into seven days old seedlings. Across genotypes, the Evan and Avoyelles isolates had significantly higher vermiform nematodes (33,793 and 27,800/250 g soil, respectively) than other isolates. Across isolates, the number of juveniles on A2-190 and Lonren-2 (5,573 and 6,013, respectively) were significantly lower than that on other genotypes. There was a significant interaction between the genotypes and isolates suggesting that the response of genotypes to reniform isolates was different. Salt stress is a major abiotic stress, affecting cotton production in the Macon Ridge and Red River regions in Louisiana. In a preliminary study, 150 day neutral primitive cotton accessions were screened at 0, 125, 250 mM NaCl under hydroponics. A promising subset was rescreened for salt tolerance in pot culture. MT11 had the lowest reduction in plant height and dry shoot weight (32% and 47%), significantly less than FM958 (43% and 66%) across salt concentrations. MT1219 had the lowest accumulation of Na+ (1,026.37 mM) at 250 mM NaCl, and significantly lower than FM958 (2,135.39 mM). Based on reduction in plant parameters, MT11, MT1219, MT45, and MT245 performed better than other genotypes. This study also showed that both hydroponics and pot culture are effective in the screening of a large number of cotton genotypes against elevated salt concentrations. In addition to stresses, cotton breeders are interested to develop a selection index, which aids in an efficient selection of multiple fibers traits. Using the data mining techniques, all developed models agreed that fiber length and strength are the most important fiber properties in determining the spinning consistency index (SCI). This study showed that SCI can be used as alternative selection index for combining the multiple fiber traits to enhance yarn spinning.

Leaf and crown rot of Liriope is an increasing problem affecting Liriope in the nursery and landscape for the past eight years primarily in the southeastern United States. Symptoms start with water soaking of leaves at the crown area, followed by yellowing of the entire leaf starting at the base. Affected crowns rot and leaves turn brown leading to death of the plants. Phytophthora palmivora and Fusarium oxysporum were isolated and identified from Big Blue Liriope symptomatic plants taken from the nursery and landscape. The pathogens were positively identified by morphological features of the pathogens and then confirmed with polymerase chain reaction. Pathogenicity tests were performed in the greenhouse using three Liriope cultivars including Emerald Goddess and Super Blue, considered to be tolerant to this disease, and Big Blue which was considered to be more susceptible. Four inoculation treatments were used: water control, Phytophthora palmivora, Fusarium oxysporum and P. palmivora + F. oxysporum. Results from this study confirm the pathogenicity of previously identified P. palmivora and F. oxysporum microorganisms causing leaf and crown rot. P. palmivora was the primary microorganism causing leaf and crown rot on Emerald Goddess and F. oxysporum on Big Blue leading to increased disease incidence and a decrease in fresh and dry weight of leaves. Super Blue showed no significant differences in fresh and dry weight of leaves and roots, and in percentage of disease incidence between the inoculation treatments (P>0.05). A survey was conducted at 11 wholesale and 7 retail nurseries in Louisiana to confirm that leaf and crown rot was a problem in Liriope production. P. palmivora and F. oxysporum were recovered from plants exhibiting leaf and crown rot symptoms which indicated that the disease was present in all nurseries. Poor sanitation and cultural practices were found to be the primary factors leading to the development and spread of leaf and crown rot disease.

Spectral vegetation index-based models that are used to estimate yield potential are commonly developed from the relationship between early-season crop canopy reflectance readings and actual yield obtained at harvest. Plant population stand can influence cane yield potential and nutrient requirement. This study was conducted at LSU AgCenter Sugar Research Station in St. Gabriel, LA to evaluate (1) the relation between estimated early season biomass yield and the spectral vegetation indices acquired at the same time, (2) nitrogen (N) response pattern between early-season biomass production and yield at harvest, and (3) the relationship between coefficient of variation (CV) among normalized difference vegetation index (NDVI) readings and stand population of cane planted as whole stalk and billets. Treatments were applied in split plots with a randomized complete block design with four replications. Varieties (Ho 02-113, US 72-114) and N application rates (0, 56, 112, and 224 kg N ha-1) were assigned as main plots and sub-plots, respectively. Another experiment was conducted with planting schemes (whole stalks and billets) and varieties (Ho 02-113, US 72-114, Ho 06-9001, Ho 06-9002, L 01-299, and L 03-371) arranged as main and sub-plots, respectively. Biomass clippings and canopy spectral reflectance readings using Jaz® spectrometer were collected at three, four, and five weeks after N application (WAN). Results showed that early-season biomass yield and its canopy reflectance collected at the same time were correlated. Overall, the relationships between vegetation indices (VIs) and biomass were best described with quadratic model at four WAN. Reflectance from red wavelengths (670 and 690 nm) and VI computed from them consistently performed better than the reflectance from red-edge wavelengths in relating early-season biomass production. Variables collected at four and five WAN showed similar response pattern to variable N rates as with harvest. Under favorable weather, billet-planted cane produced higher initial plant population compared to whole stalk-planted cane in 2013. Negative correlation was found between CV among NDVI and plant population. Coefficient of variation among red-based vegetation indices produced better correlation with plant population than those from different wavelengths. Variety had no effect on canopy spectral reflectance.

Availability of dicamba- and 2,4-D-resistant crops will provide alternative weed management options, but the risk of off-target movement of herbicides to sensitive crops is of concern. Soybean [Glycine max (L.) Merr.] treated with diglycolamine (DGA) salt of dicamba at 4.4 g ae/ha (1/128 of the recommended use rate of 560 g/ha) at V3/V4 (two to three trifoliate) was injured 39% 14 days after treatment (DAT) and injury was 97% with 280 g/ha (1/2 of use rate). For application at R1 (first flower), injury 14 DAT was 23% at 1.1 g/ha (1/512 of use rate) and was 68% at 70 g/ha (1/8 of use rate). Soybean yield for dicamba at 4.4 g/ha was reduced 4% when applied at V3/V4 and 10% at R1; for 17.5 g/ha (1/32 of use rate), yield was reduced 16% at V3/V4 and 36% at R1. Research was also conducted to evaluate volatility of various formulations of 2,4-D applied at 1,120 and 2,240 g ae/ha; dicamba applied at 560 and 1,120 g/ha; and triclopyr applied at 1,680 and 3,360 g ae/ha. Herbicides were applied to tilled soil and potted cotton (Gossypium hirsutum L.) and tomato (Solanum lycopersicum L.) plants were placed in treated strips. Injury was visually rated using four criteria (leaf cupping/crinkling/ drooping; leaf rolling/strapping; stem epinasty; and stem swelling/cracking) and a severity scale of 0 to 5 (0= no injury and 5= severe). A weighted factor assigned to each injury criterion provided an estimate of total injury on a 0 to 100% scale. Only leaf cupping/crinkling/drooping injury was observed for cotton and total injury 14 DAT was no more than 11% for the 1x rates of the herbicides and formulations. Total injury for tomato for the 1x rates of 2,4-D isooctyl ester was 36% 14 DAT and injury was attributed primarily to stem epinasty and stem swelling/cracking. For the 2,4-D dimethylamine (DMA) and acid formulations and for the dicamba DMA, DGA, and acid formulations, total injury for tomato was equivalent and was as high as 24% for the 1x rates. Injury to tomato with triclopyr butoxyethyl ester was 2.1 times that of triclopyr acid.