Location: Sugarcane Research
2018 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
Eight replicated field studies were established in 2018 with sugarcane varieties HoCP 96-540 and L 99-299 to determine the effects of several new herbicides and herbicide tank-mixtures on crop injury, weed control, and cane and sugar yields. Many of these studies are the second experimental run from studies initiated in 2017. Studies initiated in 2017 were continued into 2018. Herbicide treatments were applied throughout the spring and ceased at layby time (June 1st). In some studies, weed densities and biomass measurements were recorded. In August 2018, sugarcane stalk counts and heights will be measured. Plant-cane and ratoon sugarcane will be machine harvested from October through December 2018 when the cane crop has fully matured. Four of the studies are being conducted on cooperators’ fields in the Louisiana parishes of Terrebonne and Assumption.
Soil samples collected from fallow-planted sweet sorghum and soybean plots will be analyzed for presence of sorgoleone and other potential allelochemicals, which have shown to have negative impacts on plant growth. The experiments were treated with pre and post emergence herbicides to manage annual weed infestations and were cultivated as necessary to reform the edges of eroded raised beds. Plant-cane (experimental run 2) and first-ratoon (experimental run 1) will be harvested in December and November 2018, respectively, after sugarcane shoot counts and heights are recorded. In 2017, severe stalk damage inflicted by raccoons greatly reduced plant-cane yield in plots planted to sugarcane variety HoCP 09-804. HoCP 09-804 is an early maturing cultivar; therefore, measures will be taken to deter raccoons in both experiments in 2018.
In the fall of 2016, a study was planted with sugarcane varieties 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. This data will then be related to borer infestation data from separate yield reduction studies. The plots were sprayed with insecticide to maintain the plots free of sugarcane borers in the spring and summer of 2017. Stalks were collected on a monthly interval from June through September for fiber component analysis. All plots were harvested in November 2017 to determine cane and sugar yields of the plant-cane crop. Fiber component analysis of the 2017 crop samples is currently being performed. In 2018, the first-ratoon crop was also sprayed with insecticide to maintain the plots free of sugarcane borers in the spring and summer of 2018. 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 2018. All plots will be harvested in November 2018 to determine cane and sugar yields of the first-ratoon crop.
In the spring of 2018, several fields with yellow sugarcane aphid infestations were located and subsequently evaluated for potential use in insecticide and grid mapping studies. However, the populations decreased rapidly and it was estimated that the effects of sugarcane cane yields would be negligible. Cane fly infestations were not observed during the spring of 2018, most likely due to the severe winter experienced during 2018. Fields will be monitored throughout the summer months and if a suitable location is found a grid mapping experiment will be initiated. If a suitable location is found, 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 2018 to determine the effects of the pest complex on yields.
Accomplishments
1. Divine nightshade (Solanum nigrescens): A potentially problematic nightshade weed species in Louisiana sugarcane. An invasive perennial broadleaf weed that exhibited biological characteristics similar to plants in the Solanum genus was identified in a commercial sugarcane field. The invasive weed was identified as divine nightshade and has been identified in 17 of the 24 parishes where sugarcane is produced. ARS researchers at Houma, Louisiana, applied industry standard pre- and post- emergence herbicides to divine nightshade infested fields currently under sugarcane cultivation to identify if currently-labeled herbicides provide acceptable control. Season-long competition reduced cane and sugar yield by 24 Mg ha-1 and 1,120 kg ha-1, respectively, and currently available herbicides resulted in moderate to poor divine nightshade control. Triclopyr applied at 1,120 g ae ha-1 resulted in 97% control of emerged divine nightshade and had 18% more sugarcane stalks than the non-treated check. In 2017, Trycera was granted an emergency exemption from registration label (section 18) for Louisiana parishes where divine nightshade has been identified, and more recently the manufacturer of Trycera (Helena Chemical) and the owner of triclopyr (Dow AgroSciences) are pursuing a section 3 pesticide label. More recent research indicates some problematic perennial grass species that commonly infest sugarcane fields are susceptible to herbicide mixtures that contain triclopyr, which could provide growers additional herbicide options for managing problematic grass and broadleaf weeds in sugarcane.
Review Publications
Spaunhorst, D.J., Johnson, W.G. 2017. Variable tolerance among Palmer amaranth (Amaranthus palmeri) biotypes to glyphosate, 2,4-D amine, and premix formulation of glyphosate plus 2,4-D choline (Enlist Duo®) herbicide. Weed Science. 65(6):787-797.
Spaunhorst, D.J., Devkota, P., Johnson, W.G., Smeda, R.J., Meyer, C.J., Norsworthy, J.K. 2018. Phenology of five Palmer amaranth (Amaranthus palmeri) populations grown in northern Indiana and Arkansas. Weed Science. 66(4):457-469. https://doi.org/10.1017/wsc.2018.12.
Orgeron, A.J., Schilling, E.E., Urbatsch, L.E., Ma, Q., Spaunhorst, D.J. 2018. Solanum nigrescens: A potentially problematic nightshade weed species in Louisiana sugarcane. Journal American Society of Sugar Cane Technologists. 38:23-43.
Webber III, C.L., White Jr, P.M., Landrum, D.S., Spaunhorst, D.J., Wayment, D.G., Dorvil, E.N. 2018. Sugarcane field residue and root allelopathic impact on weed seed germination. Journal of Agricultural Science. 10(1):66-72. https://doi.org/10.5539/jas.v10n1p66.
Webber III, C.L., White Jr, P.M., Spaunhorst, D.J., Wayment, D.G., Landrum, D.S. 2018. Sugarcane crop residue and bagasse allelopathic impact on oat (Avena sative L.), tall morningglory (Ipomoea purpurea L. Roth), and redroot pigweed (Amaranthus retroflexus L.) germination. Journal of Agricultural Science. 10(2):15-22. https://doi.org/10.5539/jas.v10n2p15.
