Location: Sugarcane Research
2023 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.
4. Integrate pest management systems into sugarcane production systems including genetic sources of host-plant resistance for greater sugarcane yield, sustainability, and ratoon longevity. [NP305, Component 1, Problem Statement 1A]
4.A. Determine the required level of sugarcane borer control after subsequent borer damage to ratoon crops.
4.B. Assess compatibility of billet seed treatments with biological control of the sugarcane borer.
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. Soil EC mapping will be used to develop management zones to optimize nutrient application with variable-rate application procedures. 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. Imagery acquired by unmanned aerial vehicles (UAV) will be utilized to predict cane and sucrose yields prior to harvest.
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, three new 4-hydroxyphenylpyruvate dioxygenase (HPPD) herbicides will be evaluated for their efficacy in controlling problematic weeds postemergence in sugarcane. 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.
To address the fourth objective, methods will be developed to assist in preventing and managing infestations of the primary economic pest of sugarcane in Louisiana, the sugarcane borer (Diatraea saccharalis (F.); Lepidoptera: Crambidae). We will determine the required level of sugarcane borer control after subsequent borer damage to ratoon crops by comparing yield, borer infestation levels, and natural enemy presence in the first and second year of growth after plants have accumulated different levels of borer damage. We will also assess the compatibility of billet seed treatments with biological control of the sugarcane borer by estimating the arthropod community activity density changes after treatment with insecticides (neonicotinoid) and fungicides (azoxystrobin and propiconazole) alone and in combination.
The end product of this research will be new crop, soil, disease, weed and insect management strategies that ensure efficiency and sustainability of sugarcane production while increasing ratoon longevity.
Progress Report
In fiscal year (FY) 2023 treatments were applied to 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 facilitated the collection of EC data under a wider range of environmental and soil conditions than traditional EC mapping systems. Raw EC data was used to develop VR management zones for all fields. VR soil samples were collected, and management zones were created for all fields. Yield data from all trials was harvested in November/December 2022 using a weigh wagon and sugarcane harvester equipped with a commercial yield monitor. Data from 2023 trials will be collected as outlined above in the fall of 2023. Soil samples will be collected after harvest.
Four fields for the unmanned aerial vehicle (UAV) trials were initiated in July 2022 on commercial sugarcane farms. The fields selected were planted to major Louisiana varieties and were approximately 5 hectares in size. UAV imagery was collected using a drone equipped with a multi-spectral sensor from each field monthly until harvest. Fields were harvested in the fall of 2022 as described above. Three additional UAV trials were initiated in 2023 to supplement the data already acquired. These trials will be harvested in the fall of 2023 as outlined above. Data analysis is underway.
In FY 2023, progress was made by ARS researchers from Houma, Louisiana, in identifying sugarcane germplasm resistant to economically important diseases. Varieties (68) 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. New assignment varieties (33) were also screened for ratoon stunting disease by artificial inoculation with the causal bacterium. 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.
In FY 2023, 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. 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. Brown rust continues to be observed in commercial fields in susceptible varieties. Highly susceptible clones to either brown or orange rust are not advanced to the next stage of the variety development program. Efforts have continued to investigate new or developing exotic pathogens in variety trials and commercial fields.
Pyroxasulfone, a herbicide for controlling annual grasses, broadleaf weeds, and sedges, was applied at different rates with and without adjuvant to L 01-299 cane at second ratoon in March. A second series of plots was planted in September of 2022 to replicate this study, and these were also treated in March. In addition, pyroxasulfone was applied with S-metolachlor to plant cane for varieties L 01-299, HoCP 09-804, and Ho 12-615. For all plots, sugarcane was assessed for injury and weed counts and weed injury ratings were made two, four, and six weeks after herbicide treatment. Stalk counts and stalk height will be assessed prior to harvest. Sugar yield will be determined at harvest. Studies planted in 2022 will be carried forward into first ratoon. In August sugarcane will be planted to replicate the pyroxasulfone and S-metolachlor treatments.
Spring treatment with HPPD (4-hydroxyphenyl-pyruvate dioxygenase) inhibitors paired with an auxin mimic were repeated in plant cane (planted in September 2022) and first ratoon L 01-299. For sugarcane at first ratoon, residue was burned in late winter prior to herbicide application. Sugarcane injury and weed injury assessments and weed counts were performed two, four, and six weeks after herbicide treatment. Stalk counts and height will be assessed prior to harvest and sugar yield will be determined at harvest. These studies will be carried forward into first and second ratoon.
In fall 2022, plant cane juice and yield data were obtained from the field trial assessing differences in billet and whole stalk plantings with and without seed cane sugarcane borer damage. Data from the fall 2022 plant cane harvest were presented at winter/spring 2023 grower meetings. In June 2023, the field site was treated as stated in the experimental design with insecticide treatments. Sentinel sugarcane borer egg masses to assess borer damage-induced differences in predation and parasitism rates were ordered for deployment on 11 July 2023 for the final set of 24, 48, and 72 h observations. In fall 2023, the first ratoon juice and yield data will be obtained from the field trial assessing differences in billet and whole stalk plantings with and without seed cane sugarcane borer damage.
In fall 2022, the final set of laboratory assays assessing non-target billet seed cane treatment effects on red imported fire ant workers were completed using dip-treated seed cane pieces (treated soil assays were completed in the prior fiscal year). All data from three small plot field trials, two large field trials done in collaboration with Louisiana State University, and two laboratory assessments were entered and analyzed. These data were published in Crop Protection. These data were presented to entomology researchers at Entomology 2022 in fall 2022 and sugarcane researchers at the Louisiana division of the American Society of Sugar Cane Technologists in spring 2023.
Accomplishments
1. Billet seed cane treatments compatible with biological control in sugarcane. Louisiana sugarcane is typically planted using whole plant stalks, but recently growers have increased planting stalks cut into short pieces called billets, which can be cut with the harvester and planted mechanically. Using billets makes the seed cane more likely to be damaged by diseases and pests; but this damage can be prevented by using fungicides and insecticides at planting. However, these treatments may also harm predatory insects like the red imported fire ant that provide biological control of crop pests. ARS scientists at Houma, Louisiana, in conjunction with scientists at Louisiana State University in St. Gabriel, Louisiana, tested if certain fungicide and insecticide billet seed cane treatments applied at planting harm the red imported fire ant and other insect predators. Results from three small plot field tests, two large plot field tests, and two laboratory assays indicated that these treatments did not decrease the number of predatory insects or their biological control potential relative to untreated controls. The results indicate that sugarcane growers can readily use seed cane treatments at planting without interfering with biological control of crop pests throughout the growing season. The data were presented at several grower and consultant meetings and two scientific conferences and were recently published in Crop Protection.
2. Impacts of active ingredient, application timing, and rate on sugarcane borer control. Active ingredients, application timing, and the rate of active ingredient used may determine the effectiveness of insecticides in the field. In sugarcane, insecticide treatments are applied when 5% of sugarcane stalks have sugarcane borer caterpillars feeding in the leaf sheaths, but this timing allows for early spring generations of borers to cause damage. ARS scientists at Houma, Louisiana, conducted a field study over two years using the variety HoCP 09-804 to compare the efficacy of two active ingredients (tebufenozide and chlorantraniliprole) applied either at standard rates when 5% of stalks were infested or at higher rates earlier in the growing season to potentially prevent early borer damage. Results indicated that plots treated with either rate/timing of chlorantraniliprole had less borer damage than the untreated controls, while plots treated with tebufenozide had numerically but not statistically less damage than untreated controls. However, none of the treatments impacted stalk fiber, stalk sugar content, or sugar yield. These results will be used to guide sugarcane borer active ingredient use and treatment timing in Louisiana and were published in Management Tests as well as presented at grower and agricultural consultant meetings.
3. Identifying weeds in sugarcane fields with remote imagery. Controlling weeds in sugarcane fields is critical for profitable sugarcane production systems. Weeds compete for light, nutrients, and water, and if they are not managed properly can negatively impact sugarcane yields. ARS scientists at Houma, Louisiana, in cooperation with scientists from Louisiana State University and Texas A&M University detected weeds in comparison to sugarcane varieties using leaf reflectance measurements and pigment analyses. Leaf samples were collected from four commercial Louisiana sugarcane varieties, and nine weed species commonly found in sugarcane fields. In all cases, leaf reflectance data successfully differentiated sugarcane from weeds. The accuracy of the classification varied from 67% to 100% for individual sugarcane varieties and weed species and in all cases, sugarcane was not misclassified as a weed. Plant pigment levels exhibited marked differences between sugarcane varieties and weed species with differences in chlorophylls and carotenoids explaining much of the observed variation in leaf reflectance. The ratio of chlorophyll a to chlorophyll b showed significant differences between sugarcane and all weed species. The successful implementation of this technology as either an airborne system to scout and map weeds or a tractor-based system to identify and spray weeds in real-time would offer sugarcane growers a valuable tool to manage their crops. By accurately targeting weeds in an emerged, and growing sugarcane field, the total amount of herbicide applied could be decreased, resulting in cost savings for the grower and reduced environmental impacts.
4. Annual ryegrass (Lolium multiflorum) is resistant to photoperiod system II herbicide. Herbicide resistant weeds are a problem in crops worldwide and pose a threat to the continued efficacy of herbicides. In crops like sugarcane, where herbicide options are limited, resistance is particularly a concern. ARS scientists from Houma, Louisiana, in collaboration with researchers at Louisiana State University, confirmed photosystem II (PSII) inhibitor resistance in annual ryegrass populations collected from Louisiana sugarcane. These populations exhibit resistance to both pre-emergence and post-emergence application of PSII inhibitor herbicides including atrazine, metribuzin, and diuron. Terbacil, also a PSII inhibitor, still provided control at the full rate. S-metolachlor, clomazone, glyphosate, and clethodim controlled these ryegrass populations. Sequence analysis of psbA, which encodes the target site for these PSII inhibitors, did not show the presence of a resistance-conferring point mutation. These data suggest the mechanism is likely non-target site. As annual ryegrass largely outcrosses, there is concern that this resistance trait can spread to other populations, thereby limiting control of this weed. This research has been presented at grower meetings and the annual meetings of the Weed Science Society of America and American Society of Sugarcane Technologists.
Review Publications
Wright, A.A., Harper, S.J. 2022. Draft genome sequence of a Washington isolate of Candidatus Phytoplasma pruni. Microbiology Resource Announcements. 11(12):e00790-22. https://doi.org/10.1128/mra.00790-22.
Elliott, L., Martinez, I., Pereira, E., Choudhury, R., Penn, H. 2023. Tree canopy cover and elevation affect the distribution of red harvester ant nests in a peri-urban setting. Insect Conservation and Diversity. pp. 1-11. https://doi.org/10.1093/ee/nvad025.
Penn, H., Richard, R.T., Johnson, R.M. 2023. Impact of insecticide, rate, and timing combinations against sugarcane borer, 2019-2020. Arthropod Management Tests. 48(1):1-2. https://doi.org/10.1093/amt/tsad055.
Penn, H., White Jr, P.M., Wilson, B.E., Richard, R.T. 2023. Non-target potential of neonicotinoid and fungicide seed cane treatments on Solenopsis invicta. Crop Protection. 170(106278):1-11. https://doi.org/10.1016/j.cropro.2023.106278.
Salgado, L.D., Wilson, B.E., Penn, H., Richard, R.T., Way, M.O. 2022. Characterization of resistance to the Mexican rice borer (Lepidoptera: Crambidae) among Louisiana sugarcane cultivars. Insects. 13(10):890. https://doi.org/10.3390/insects13100890.
Harper, S.J., Northfield, T.D., Nottingham, L.R., Dupont, S.T., Thompson, A.A., Sollato, B.V., Serban, C.F., Shires, M.K., Wright, A.A., Catron, K.A., Marshall, A., Molnar, C., Cooper, W.R. 2023. Recovery plan for X-disease in stone fruit caused by 'Candidatus Phytoplasma pruni'. Plant Health Progress. 24(2):258-295. https://doi.org/10.1094/PHP-02-23-0016-RP.
Johnson, R.M., Orgeron, A., Spaunhorst, D.J., Zimba, P.V. 2023. Discrimination of weeds from sugarcane in Louisiana using hyperspectral leaf reflectance data and pigment analysis. Weed Technology. p.1-9. https://doi.org/10.1017/wet.2023.14.
