Location: Sugarcane Research
2020 Annual Report
Objectives
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.
Approach
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.
Progress Report
In fiscal year (FY) 2020, sites were located for all 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 than traditional EC mapping systems. EC data will be collected from all sites in July/August 2020. Raw EC data will then be used to develop VR management zones for all fields and soil samples will be collected in August/September 2020.
Two plant-cane fields for unmanned aerial vehicle (UAV) trials were located and trials initiated in July 2020 on commercial sugarcane farms. Fields selected were planted to major Louisiana varieties and were approximately 5 hectares in size. In July 2020, UAV imagery was collected from both sites using a drone equipped with a multi-spectral sensor. Imagery will be collected by ARS researchers from Houma, Louisiana, from each field monthly until harvest. Fields will be harvested by in the fall of 2020 using a weigh wagon and sugarcane harvester equipped with a commercial yield monitor.
In FY 2020, progress was made by ARS researchers from Houma, Louisiana, in identifying sugarcane germplasm resistant to economically important diseases. Varieties (81) for possible release into commercial production within the next five years were screened through artificial inoculation in the field for susceptibility to smut and leaf scald. In other ARS breeding trials and nurseries, candidate varieties were observed for natural infection by pathogens that cause mosaic, brown and orange rust, sugarcane yellow leaf, smut, and leaf scald diseases. Pathology recommendations were made at variety advancement and variety release meetings. Disease ratings were used as criteria to release a new sugarcane variety (Ho 13-739) in 2020.
In FY 2020, populations of the viruses that cause mosaic in sugarcane were monitored for genetic diversity. Sorghum mosaic virus (SrMV) remained the predominant virus causing mosaic. No isolates were identified 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. A phylogenetic analysis was performed by ARS researchers from Houma, Louisiana, using the RT-PCR product sequences of 74 SrMV isolates. Isolates were assigned to five groups based on sequence similarity. Twenty SrMV isolates from among the five groups were selected 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 in commercial fields. Highly susceptible clones were not advanced to the next stage of the variety development program.
ARS researchers from Houma, Louisiana, in collaborative studies with researchers in the Rio Grande Valley sugarcane production area of Texas, orange rust was observed for the first time in 2017. Orange rust was observed in variety trials in 2020, but was not observed in commercial plantings although the most widely grown variety, CP 89-2143, is known to be susceptible.
A greenhouse experiment was initiated by ARS researchers from Houma, Louisiana, in February 2020 to evaluate the effect of synthetic auxin herbicides and 4-hydroxyphenylpyruvate dioxygenase-inhibiting herbicides applied separately and in mixtures on flower abortion and reproductive development of divine nightshade. Treatments were applied to 8 to 14” tall divine nightshade at the reproductive growth stage. Three stages of reproductive development were targeted: pre bloom, 50% bloom, and 100% bloom by attaching uniquely colored ties to stem segments adjacent to floral clusters. Fully developed fruits were counted weekly and harvested for dry biomass approximately 56 days after herbicides were applied. Harvested seed will be germination tested from October to December 2020 in the greenhouse.
To prepare for sugarcane planting in late summer, traditional field practices to remove old sugarcane roots were implemented in late spring and summer. Land was precision-graded for improved drainage and rows were marked, shipped, and maintained weed-free for optimal sugarcane planting. In August 2020, several replicated field trials will be planted to L 01-299, covered with 3” of soil, and packed to evaluate the effect of several rates of pyroxasulfone on sugarcane. Herbicide treatments were broadcast applied at 20 gallons per acre immediately following sugarcane planting. Soil applied herbicides require moisture for activation; therefore, overhead irrigation will be applied if an activating rainfall does not occur within 7 to 10 days. 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 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, a problematic winter annual grass weed.
Accomplishments
Review Publications
Wilson, B.E., Beuzelin, J.M., Richard, R.T., Johnson, R.M., Gravois, K.A., White, W.H. 2019. West Indian Canefly (Hemiptera: Delphacidae): An emerging pest of Louisiana sugarcane. Journal of Economic Entomology. 113(1):263-272. https://doi.org/10.1093/jee/toz284.
Spaunhorst, D.J. 2020. Influence of establishment timing on growth and fecundity of two itchgrass (Rottboellia cochinchinensis) biotypes grown in Louisiana. Weed Science. 68:418-425. https://doi.org/10.1017/wsc.2020.30.
Spaunhorst, D.J., Orgeron, A.J. 2019. Dry heat and exposure time influence divine nightshade and itchgrass seed emergence. Agronomy Journal. 3(5):2226-2231. https://doi.org/10.2134/agronj2019.02.0072.
Spaunhorst, D.J., Orgeron, A.J., White Jr, P.M. 2019. Burning post-harvest sugarcane residue for control of surface-deposited divine nightshade (Solanum nigrescens) and itchgrass (Rottboellia cochinchinensis) seed. Weed Technology. 33(5):693-700. https://doi.org/10.1017/wet.2019.65.
Grisham, M.P., Warnke, K.Z., Maggio, J.R., Davidson, W., Haudenshield, J.S., Hartman, G.L., Hernandez, E., Scott, Jr., A.W., Comstock, J.C., Mccord, P.H. 2020. First report of Puccinia kuehnii causing orange rust of sugarcane in Texas, USA. Plant Disease. https://doi.org/10.1094/PDIS-10-19-2117-PDN.
Rice, J.L., Hoy, J.W., Hale, A.L., Todd, J.R., Grisham, M.P., Kimbeng, C.A., Pontif, M.J. 2019. Evaluation of susceptibility to mosaic in Louisiana's sugarcane breeding program. Journal of the American Society of Sugar Cane Technologists. 39:1-11.
Alencastre-Miranda, M., Johnson, R.M., Krebs, H.I. 2021. Convolutional neural networks and transfer learning for quality inspection of different sugarcane varieties. IEEE Transactions on Industrial Informatics. 17(2):787-794. https://doi.org/10.1109/TII.2020.2992229.
Rice, J.L., Hoy, J.W., Grisham, M.P. 2019. Sugarcane mosaic distribution, incidence, increase, and spatial pattern in Louisiana. Plant Disease. 103:2051-2056. https://doi.org/10.1094/PDIS-01-0099-RE.
