Location: Sugarcane Research2021 Annual Report
1. Develop systems-level precision agriculture strategies and tools based on climate, soil, water and nutrients to increase sugarcane yield, sustainability, and ratoon longevity. [NP 305, Component 1, Problem Statement 1A] 1.A. Develop variable-rate nutrient application systems to increase yields, ratoon longevity and sustainability. 1.B. Utilize UAV-based remote sensing systems to estimate yields prior to harvest. 2. Analyze the impacts of existing and emerging pathogens that affect sugarcane or its wild relatives to enhance genetic control and chemical control strategies. [NP 305, Component 1, Problem Statement 1A] 2.A. Identify germplasm of hybrid sugarcane and wild relatives of sugarcane for resistance to economically limiting diseases that breeders can use for parental clones. 2.B. Characterize races, strains, or other biotypes of endemic pathogens and monitor the Louisiana sugarcane industry for the emergence of new pathogens. 3. Optimize and integrate the chemical and cultural control of weeds including identifying key factors that promote proliferation in sugarcane production. [NP 305, Component 1, Problem Statement 1A] 3.A. Develop new herbicide programs that optimize application timing, placement, and herbicide use rates for management of problematic grass and broadleaf weed species in sugarcane. 3.B. Identify weedy characteristics that promote divine nightshade proliferation.
To address the first objective, precision agriculture (PA) methods such as soil electrical conductivity (EC) mapping, variable-rate application and remote-sensing will be utilized to increase sugarcane yield, sustainability, and ratoon longevity. All research will be conducted on commercial sugarcane farms in Louisiana on silt-loam and clay soils and treatments will be arranged in a randomized complete block design with four replications. Soil EC mapping will be used to develop management zones to optimize nutrient application with variable-rate application procedures. This will ensure that nutrients are not under or over applied which can lead to decreased yields or adverse environmental impacts, respectively. Sugarcane yields in the successive ratoon crops of PA systems will be used as an index of the progress made in increasing ratoon longevity as compared to conventional management methods. Finally, imagery acquired by unmanned aerial vehicles (UAV) will be utilized to predict cane and sucrose yields prior to harvest. This will allow farmers to more accurately determine harvest schedules and adjust crop management strategies to optimize cane and sugar yields. To address objective two, we will identify and develop parental germplasm with resistance to the economically limiting diseases affecting sugarcane in the United States. Highly domesticated and wild clones of sugarcane and near relatives will be evaluated for disease resistance following either natural infections or artificial inoculation. Genotypic and phenotypic expressions of variability within populations of pathogens will be used to identify the genetic variability among pathogen populations and determine the distribution of races, strains, or biotypes. The domestic sugarcane industry will be monitored for the introduction of exotic pathogens. To address the third objective, a holistic weed management strategy designed for sustainable sugarcane cultivation will be developed that addresses application optimization, herbicide mixtures, use rates that result in adequate weed control, crop tolerance, and evolution of herbicide resistant weeds. Three new 4-hydroxyphenylpyruvate dioxygenase (HPPD) herbicides will be evaluated for their efficacy in controlling problematic weeds postemergence in sugarcane. Treatments will be arranged in a randomized complete block design with at least four replications. The HPPD herbicides will be applied separately and tank-mixed with various herbicides to evaluate the weed spectrum controlled. Analysis of both herbicide efficacy data and yield data, will allow us to determine effective herbicides and herbicide use rates that maximizes weed control while at the same time minimizes injury to the sugarcane crop. Research will also be conducted to understand the phenology of divine nightshade during a sugarcane cropping cycle to assist in developing the necessary management tactics to prevent weed proliferation. The end product of this research will be new crop, soil, disease, and weed management strategies that ensure efficiency and sustainability of sugarcane production while increasing ratoon longevity.
In fiscal year (FY) 2021, sites were located by ARS scientists at Houma, Louisiana for all repeated variable-rate (VR) fertilizer studies on commercial sugarcane farms. A collaboration with ARS researchers from Houma, Louisiana, and commercial sugarcane farms was developed to collect soil electrical conductivity (EC) data from all studies using a non-contact, EC mapping system that will facilitate collection of EC data under a wider range of environmental and soil conditions rather than traditional EC mapping systems. EC data will be collected by ARS scientists at Houma, Louisiana from all repeated sites in July/August 2021. Raw EC data will then be used by ARS scientists at Houma, Louisiana to develop VR management zones for all fields and soil samples will be collected in August/September 2021. VR soil samples were collected, and management zones were created by ARS scientists at Houma, Louisiana for all fields mapped in 2020. Plant-cane data will be harvested by ARS scientists at Houma, Louisiana in the fall of 2021 using a weigh wagon and sugarcane harvester equipped with a commercial yield monitor. Two plant-cane fields for unmanned aerial vehicle (UAV) repeated trials were located and trials initiated by ARS scientists at Houma, Louisiana in July 2021 on commercial sugarcane farms. Fields selected were planted by ARS scientists at Houma, Louisiana to major Louisiana varieties and were approximately 5 hectares in size. UAV imagery will be collected by ARS scientists at Houma, Louisiana from sites initiated in 2020 and 2021 using a drone equipped with a multi-spectral sensor from each field monthly until harvest. Fields will be harvested by ARS scientists at Houma, Louisiana in the fall of 2021 as described above. In FY 2021, progress was made by ARS researchers from Houma, Louisiana, in identifying sugarcane germplasm resistant to economically important diseases. Varieties (83) for possible release into commercial production within the next five years were screened by ARS scientists at Houma, Louisiana through artificial inoculation in the field for susceptibility to smut and leaf scald. In other ARS breeding trials and nurseries, candidate varieties were observed by ARS scientists at Houma, Louisiana for natural infection by pathogens that cause mosaic, brown and orange rust, sugarcane yellow leaf, smut, and leaf scald diseases. Pathology recommendations were made by ARS scientists at Houma, Louisiana at variety advancement and variety release meetings. Disease ratings were used by ARS scientists at Houma, Louisiana as criteria to release two new sugarcane varieties (Ho 14-885 and L14-267) in 2021. Ho 14-885 was shown to be well adapted for the Rio Grande Valley of Texas sugarcane industry, as well as the Louisiana industry. In FY 2021, populations of the viruses that cause mosaic in sugarcane were monitored by ARS scientists at Houma, Louisiana for genetic diversity. Sorghum mosaic virus (SrMV) remained the predominant virus causing mosaic. No isolates were identified by ARS scientists at Houma, Louisiana as Sugarcane mosaic virus (SCMV), another virus that causes mosaic symptoms in sugarcane, from samples collected among commercially released and experimental varieties. Sequence data suggest the SrMV population contains multiple genotypes. Forty SrMV isolates from a diverse population of sugarcane varieties, some from varieties that were commercially significant over the past four decades, were selected by ARS scientists at Houma, Louisiana for high throughput sequencing to obtain full genomic sequences for further analyses. Climatic conditions were favorable for orange rust among variety trials at the ARS research farm in Houma, Louisiana; however, no epidemics have been observed by ARS scientists at Houma, Louisiana in commercial fields. Highly susceptible clones were not advanced to the next stage of the variety development program. A hard freeze in mid-February 2021 was followed by a wetter than average spring and early summer. To prepare for sugarcane planting in late summer, traditional field practices to remove old sugarcane roots were implemented by ARS scientists at Houma, Louisiana in late spring and summer. Land was precision-graded for improved drainage and rows were marked, shaped, and maintained weed-free by ARS scientists at Houma, Louisiana for optimal sugarcane planting. In August-September 2021, several replicated field trials will be planted by ARS scientists at Houma, Louisiana to L 01-299, covered with 3” of soil, and packed to evaluate the effect of several rates of pyroxasulfone on sugarcane. Pyroxasulfone is a preemergence herbicide with activity on annual grass and small seeded broadleaf weeds but is currently not labeled in sugarcane. Another experiment will be implemented by ARS scientists at Houma, Louisiana at sugarcane planting to evaluate residual activity of pyroxasulfone and S-metolachlor, a newly commercialized herbicide in sugarcane with a similar weed control spectrum as pyroxasulfone, on control of Italian ryegrass. Experiments with nightshade will be repeated by ARS scientists at Houma, Louisiana by planting seeds directly into field plots in August-September 2021. All existing experiments will be harvested by ARS scientists at Houma, Louisiana in the fall of 2021 with a weigh wagon and sugarcane combine harvester.
1. Fertilizer sulfur can increase cane and sugar yields in Louisiana Sugarcane. ARS scientists at Houma, Louisiana, determined for many years sugarcane producers in Louisiana would only apply nitrogen fertilizer due to the high cost of potassium, phosphorus, and sulfur fertilizers. ARS scientists at Houma, Louisiana, have recently demonstrated the importance of potassium fertilizers and also that phosphorus is not needed for sugarcane in Louisiana. However, the effects of sulfur fertilizer have not recently been reported. A series of experiments were conducted by ARS scientists at Houma, Louisiana, on light (silt loams) and heavy soils (silty clay loams and clays) on plant-cane and stubble fields of HoCP 96-540, L01-299, and HoCP 09-804 to study the effects of sulfur fertilizer on sugarcane yields. Results from these studies demonstrate that increases in both cane and sugar yields can be achieved with sulfur fertilizer application in both plant-cane and ratoon fields of three of the major Louisiana sugarcane varieties in both light and heavy soils. An ARS scientist at Houma, Louisiana, reported these results at numerous field days and growers’ meetings and a majority of Louisiana sugarcane growers have adopted his sulfur recommendations.
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