Location: Sugarcane Research
2019 Annual Report
Objectives
The main objectives proposed in this Project Plan are to develop and improve sustainable management strategies for weeds and insects. Effective integrated pest management (IPM) programs are vital to a sustainable cropping system. Over the next 5 years, the project will focus on the following objectives:
Objective 1: Evaluate newer herbicide chemistries (i.e., 4-hydroxyphenylpyruvate (HPPD) inhibitors, cell wall biosynthesis inhibitors, etc.) for efficacy of weed control in sugarcane and crop safety, as well as older, currently registered herbicides to improve weed management (tank-mix combinations, timing of application, use of spray adjuvants, etc.).
Objective 2: Evaluate cultural control methods for reducing weed interference in sugarcane including, but not limited to: varietal differences in competitiveness of sugarcane, inter-row tillage timing, type, frequency, and rotational crops (including green manure cover crops) that could be used during fallow season compared with chemical fallow, and site-specific management.
Objective 3: Enhance the role of plant resistance in managing damaging infestations of stem borers (i.e., sugarcane borer and Mexican rice borer) in sugarcane.
Sub-objective 3.A: Characterize fiber among commercial sugarcane cultivars resistant to the sugarcane borer and Mexican rice borer.
Sub-objective 3.B: Identify borer resistant progeny in high sucrose bi-parental crosses.
Objective 4: Identify control tactics for managing damaging infestations of a hemipteran complex (e.g., sugarcane aphid, yellow sugarcane aphid, West Indian canefly, and sugarcane delphacid) to include the role of soil health on these infestations and new insecticides for controlling the complex.
Approach
The approach to meeting the objectives of this project plan will be primarily in the form of replicated field experiments. Some of these field experiments will also be supported by laboratory analyses. New herbicide chemistries, when they become available, will provide the potential for greater efficacy in weed control; however, determining appropriate application rates, application timing, and application methodology will require replicated field experimentation that are repeated in multiple years. Results from these experiments will be used for obtaining labeling by EPA and ultimately in formulating extension recommendations to sugarcane growers. Cultural controls provide opportunities for reducing weed pressure by planting sugarcane varieties with greater competitiveness resulting in more efficient tillage practices (i.e. fewer cultivations). Planting rotational crops (e.g. soybean and sweet sorghum) will provide an additional income stream to growers while also aiding in suppressing weed infestations. To develop these improved cultural practices will also require a series of field experiments. The results from these studies will also be used to develop extension recommendations for sugarcane growers. Enhancing the role of plant resistance in controlling the sugarcane borer and Mexican rice borer will require a more in-depth knowledge of fiber composition in commercial sugarcane varieties. A replicated field experiment consisting of sugarcane varieties with known reaction to sugarcane borer and Mexican rice borer will provide plant tissue for detailed fiber analyses. Ultimately a fiber profile will be qualified and quantified that will allow selection for stem borer resistance in the absence of the insect pest. Finally, field experiments will be conducted to identify control tactics for managing damaging infestations of a four-species hemipteran complex infesting sugarcane. These experiments will seek to better refine damage thresholds and ultimately establish action thresholds for initiating insecticide applications. The most effective insecticide formulations will need be to be identified as well as determining their most economical application rates. Ultimately, the findings from this Project Plan will be used to develop improved and sustainable management strategies for weeds and insects pest of sugarcane primarily in Louisiana, but the findings are generally applicable for sugarcane grown in Florida and Texas.
Progress Report
ARS scientists in Houma, Louisiana, along with scientists at Nicholls State University in Thibodaux, Louisiana, developed a method for extracting and detecting sorgoleone in soil samples. Using the method, the scientists observed only very low levels of sorgoleone, less than 1 part per million, in soil samples taken immediately after sorghum was harvested. Although very low levels of sorgoleone were detected, plant-cane sucrose yields following sweet sorghum were lower when compared to sugarcane that followed soybean, chemical fallow, or traditional tillage fallow. Consequently, growers might consider other options besides sorghum as a rotational crop. In past research, scientists at Houma, Louisiana, demonstrated that legumes such as soybean, cowpea, or Sunn hemp did not reduce sugarcane yields of the subsequent crop. Prior to sugarcane harvest, weeds were identified by species and counted to determine infestation levels within each treatment-cultivar combination. Sugarcane stalks and stalk height will be recorded in August. The second- and first-ratoon crops will be harvested in November for run 1 and 2, respectively. A subsequent three-factor experiment was established in May 2019 to compare fallow tillage practices (flat chopped and non-flat chopped/crop terminated with glyphosate), legume cover crops (cow peas, Sunn hemp, cow pea and Sunn hemp mixture, and no cover crop), and preemergence herbicides (pendimethalin, metribuzin, and no herbicide) on cover crop, sugarcane establishment, and weed control.
Several replicated field studies previously established in 2017 and 2018 were evaluated in 2019 to determine the effects of experimental and recently labeled herbicides on sugarcane yield and weed injury. Herbicide tank mixtures were also evaluated. The majority of herbicide treatments were applied throughout the spring before fertilization occurred; however, some treatments were applied at layby (last cultivation before the crop is too tall to be passed with ground equipment). Sugarcane stalk counts and heights will be measured in early August before the crop lodges. Plant-cane and ratoon sugarcane will be machine harvested beginning in October until December 2019 when the crop has matured. Four studies that focus on managing bermudagrass are being conducted on cooperators’ fields in Assumption and Terrebonne Parish. The bermudagrass experiments have been evaluated continuously on grower fields in the parishes of Assumption and Terrebonne for the past 2 and 3 years, respectively.
Due to poor divine nightshade control using industry standard herbicides, alternative weed management strategies were investigated to manage divine nightshade and itchgrass seed before emergence. The first experiment investigated dry heat and the duration of exposure on seeds of both species. To determine the effect of heat and exposure time, seeds were evaluated by counting the number of seedlings that emerged in the greenhouse following exposure to heat treatment. It was observed that seeds of both species were sensitive to heat treatment; however, a higher percentage of divine nightshade seed, survived versus a higher percentage of itchgrass seed when exposed to high temperatures (150 to 200 C) for short periods (5 to 20 seconds of exposure). Because the seeds of divine nightshade are encapsulated inside the fruiting structure, they may have been better protected from the heat. A second experiment was conducted in the field to determine if burning post-harvest sugarcane residue (PHR) and residue moisture influence divine nightshade and itchgrass seed emergence. Seeds of each species were exposed to four PHR levels and two residue moisture levels that were subsequently burned.
In the fall of 2016, a trial was planted with HoCP 85-845, HoCP 04-838, Ho 07-613 and HoCP 00-950 to determine how the fiber components of the four varieties changed during the growing season. In 2019, the second-ratoon crop was also sprayed with insecticide to maintain the plots free of sugarcane borers in the spring and summer of 2019. Stalks will be collected on a monthly interval from June through September for fiber component analysis and stalk counts will be determined in August of 2019. All plots will be harvested in November 2019 to determine cane and sugar yields of the second-ratoon crop. Fiber component analysis of the 2019 crop will begin in July 2019.
In the spring of 2019, a sugarcane borer (Diatraea saccharalis) and hemipteran (sap feeding insects) survey was conducted across the Louisiana sugarcane belt. An early indication of sugarcane borer infested fields is the presence of deadhearts (inner whorl of leaves is killed). Twelve parishes were sampled for a total of 57 locations. The number of sugarcane tillers were lower than 2018 and deadhearts averaged 86 per acre, which was greater than deadheart counts from the previous two years. West Indian cane flies were present in 25% of locations surveyed, while the sugarcane aphid and yellow sugarcane aphid were present in 3 and 14% of fields, respectively. The insects were found at several locations, but not in sufficient numbers to initiate a mapping trial. Fields will be monitored throughout the summer months and if a suitable location is found a grid mapping experiment will be initiated. Hemipteran pest numbers will be determined at selected grid sample points throughout the field to determine their distribution and density in the field. Soil and leaf samples will also be collected at each sample point to determine if the pest numbers can be related to soil and plant nutrient levels. Cane and sugar yields will be determined by harvesting selected rows of the field in the fall of 2019 to determine the effects of the pest complex on yields.
Two insecticide trials were initiated in June 2019, one in a plant-cane field of HoCP 09-804 and the second in a first-ratoon field of HoCP 00-950. The trial will evaluate the efficacy of two commercial insecticides on the control of sugarcane borers. In addition, an early (pre-threshold) application of both materials will be compared to the standard threshold timing. Cane and sugar yields will be determined to evaluate the effects of each insecticide on sugarcane borer control. In addition, stalk samples will also be collected (before combine harvest) to determine bored internodes for a direct evaluation of the insecticide’s efficacy.
Accomplishments
1. Dry heat and exposure time influence divine nightshade and itchgrass seed emergence. Divine nightshade and itchgrass are highly competitive with sugarcane and can reduce sucrose yield when not managed. Although itchgrass continues to be problematic in the industry, divine nightshade has recently become a significant pest in sugarcane. ARS researchers in Houma, Louisiana, exposed divine nightshade and itchgrass seed to three temperature levels (100, 150, and 200 C) for seven exposure timings (0, 5, 10, 20, 40, 80, 160 seconds) to determine if heat can be used to prevent seeds from emerging. Results indicated seed encapsulated inside divine nightshade fruit reduced emergence 6 to 29% when exposed to 150 or 200 C for 5 to 20 seconds. Divine nightshade emergence was not completely inhibited at 200 C for 160 seconds. However, itchgrass seed failed to emerge when exposed to 150 C for 40 seconds or longer, or to 200 C for 20 seconds or longer. The aforementioned temperature and exposure duration that allowed divine nightshade to survive introduced the potential for divine nightshade to become more abundant when both species coexist.
2. Burning post-harvest sugarcane residue (PHR) for control of surface deposited divine nightshade (Solanum nigrescens) and itchgrass (Rottboellia cochinchinensis) seed. Burning post-harvest sugarcane residue (PHR) is a standard practice to remove extraneous leaf material to reduce sugarcane yield loss. Live-fires were simulated by ARS researchers in Houma, Louisiana, from field-collected PHR. Seeds of divine nightshade and itchgrass were exposed to dry and moistened (by simulated rainfall) PHR at four densities (6.1, 12.1, 18.2, and 24.2 Mg ha-1). Burning PHR with 44% moisture when wind speeds were lower allowed the fire to continue and created a smoldering effect which reduced weed emergence by 23% when compared to burning PHR with 30% moisture during breezy conditions. Fields with the least amount of residue (6.1 Mg ha-1) that were moistened by rainfall had 53% more divine nightshade and itchgrass emergence when compared to dry 6.1 Mg ha-1 PHR after burning, and greater emergence was attributed to more divine nightshade seed survival than itchgrass. Burning PHR from fields with poor stands, especially when PHR is abundantly wet will not produce temperatures lethal to divine nightshade and itchgrass seed. Further investigation into technologies that implement heat to control surface deposited weed seed, such as direct flaming and infrared heat, are needed to determine if such methods are more effective in controlling surface deposited weed seed following harvest.
Review Publications
Spaunhorst, D.J., Nie, H., Todd, J.R., Young, J.M., Young, B.G., Johnson, W.G. 2019. Confirmation of herbicide resistance mutations Trp574Leu, G210, and EPSPS gene amplification and control of multiple herbicide-resistant Palmer amaranth (Amaranthus palmeri) with chlorimuron-ethyl, fomesafen, and glyphosate. PLoS One. 14(3):e0214458.
Korres, N.E., Norsworthy, J.K., Young, B.G., Reynolds, D.B., Johnson, W.G., Conley, S.P., Smeda, R.J., Mueller, T.C., Spaunhorst, D.J., Gage, K.L., Loux, M., Kruger, G.R., Bagavathiannan, M.V. 2018. Seedbank persistence of Palmer amaranth (Amaranthus palmeri) and waterhemp (Amaranthus tuberculatus) across diverse geographical regions in the United States. Weed Science. 66(4):446-456. https://doi.org/10.1017/wsc.2018.27.
Webber III, C.L., White Jr, P.M., Shrefler, J.W., Spaunhorst, D.J. 2018. Impact of acetic acid concentration, application volume, and adjuvants on weed control efficacy. Journal of Agricultural Science. 10(8):1-6. https://doi.org/10.5539/jas.v10n8p1.
Webber III, C.L., White Jr, P.M., Gu, M., Spaunhorst, D.J., Lima, I.M., Petrie, E.C. 2018. Sugarcane and pine biochar as amendments for greenhouse growing media for the production of bean (Phaseolus vulgaris L.) seedlings. Journal of Agricultural Science. 10(4):58-68. https://doi.org/10.5539/jas.v10n4p58.
Webber III C.L., White Jr, P.M., Spaunhorst, D.J., Lima, I.M., Petrie, E.C. 2018. Sugarcane biochar as an amendment for greenhouse growing media for the production of cucurbit seedlings. Journal of Agricultural Science. 10(2):104-115. https://doi.org/10.5539/jas.v10n2p104.
Spaunhorst, D.J., Todd, J.R., Hale, A.L. 2019. Sugarcane cultivar response to glyphosate and trinexapac-ethyl ripeners in Louisiana. PLoS One. 14(6):e0218656. https://doi.org/10.1371/journal.pone.0218656.
