WEED MANAGEMENT IN RICE

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: HATCH
• Reporting Frequency: Annual
• Accession No.: 1022198
• Project Start Date: Feb 12, 2020
• Project End Date: Jan 1, 2025
• Program Code: [(N/A)]- (N/A)

Recipient Organization
LOUISIANA STATE UNIVERSITY
202 HIMES HALL
BATON ROUGE,LA 70803-0100

Performing Department
School of Plant, Environmental, and Soil Sciences

Non Technical Summary
Since record keeping began in 1895, U.S. rice (Oryza sativa L.) planting peaked in 1981 at 1.549 million hectares and rice prices topped out at $369.60/metric ton in 2008 (USDA/NASS 2016). The 2008 price level resulted in the peak value of production for rice worth $3.603 billion. U.S. average rice yields have been as low as 957 kg/ha in 1896 and as high as 8600 kg/ha in 2013 with a production value worth $2.98 billion (USDA/NASS 2019). The primary U.S. rice producing states are Arkansas, Louisiana, Mississippi, Missouri, Texas, and California. In Louisiana, rice production began in 1718 and expanded until 1994 when 251,000 ha were planted (Linscombe 1999). From 2005 to 2007, Louisiana planted 142,000 to 215,000 ha with an average total farm value of $2.17 million (LSUA 2012, 2018). In 2006, the amount of rice planted decreased primarily due to reduced commodity prices and damage from Hurricanes Katrina and Rita in 2005 (Steve D. Linscombe[1], Personal communication). In 2018, 178,137 ha of rice was planted in Louisiana with a total value of $3 billion (USDA/NASS 2018, 2019). Approximately 92 million ha of farmland received a herbicide application in 2007 compared with 37 million ha treated with an insecticide (USDA/NASS 2007). In 2000, the amount of active ingredient (ai) applied per ha for herbicides was 1.5 kg/ha and all other pesticides combined totaled 1.1 kg/ha. In rice alone, 97% of the planted rice acres received a herbicide application in 2014 compared with 49 and 28% treated with fungicides and insecticides, respectively (USDA/NASS 2014). These data indicate that production decisions are often based on weed management rather than any other pest problems.Applying two or more herbicides sequentially is a common practice to improve the spectrum of weed control, reduce production costs, and/or to prevent herbicide resistance (Zhang et al. 1995). ACCase herbicides are often times antagonized when applied in a mixture with a broadleaf herbicide; however, in some cases a sequential application of the ACCase herbicide applied alone can overcome the antagonism that occurred at the earlier application date. Rustom et al. (2018, 2019) observed antagonism of quizalofop in a mixture with bispyribac, bensulfuron, halosulfuron, imazosulfuron, orthosulfuron plus halosulfuron, orthosulfuron plus quinclorac, penoxsulam, and penoxsulam plus triclopyr on either weedy rice or barnyardgrass at either 14 and/or 28 DAIT. A second application of quizalofop applied alone at 28 DAIT resulted in a neutral response at 42 DAIT for all herbicide mixtures except for penoxsulam containing mixtures. In a separate study evaluating sequential applications of quizalofop and propanil plus thiobencarb, at 28 days after treatment quizalofop activity on weedy rice and barnyardgrass was 45 to 76% when applied 0 to 3 days after propanil plus thiobencarb (DAPT); however, quizalofop applied 7 DAPT provided 81 to 86% control of weedy rice and barnyardgrass.Herbicide mixtures are an integral component of cultivated rice production in order to broaden the spectrum of weed control, save time and application costs.[1] Steven D. Linscombe, Professor and Director, Louisiana State University AgCenter, Southwest Region, 1373 Caffey Road, Rayne, LA 70578.

Animal Health Component

100%

Research Effort Categories

Basic

(N/A)

Applied

100%

Developmental

(N/A)

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
213	1530	1140	100%

Knowledge Area
213 - Weeds Affecting Plants;

Subject Of Investigation
1530 - Rice;

Field Of Science
1140 - Weed science;

Keywords

rice

flooding

herbicides

Goals / Objectives
Objective 1. Evaluate herbicides for weed control and rice tolerance under drill- and water-seeded cultureResearch to evaluate efficacy and crop safety of experimental herbicides will continue. It is important to determine the fit for any new herbicides that may be labeled in drill- and/or water-seeded rice since within the state weed populations and environmental conditions differ. This research is even more important considering the fact that weed resistance to some currently labeled herbicides has been confirmed in Louisiana. Preemergence programs, postemergence programs, and preemergence applications followed by postemergence applications for a total weed control program, reduced rate programs, and weed management strategies for reduced tillage systems in drill- and water-seeded rice will be investigated. It is important for university researchers and county agents, growers, and consultants to understand the interactions that can occur to better determine weed management practices. The overall objective of these research efforts will be to develop cost effective weed control options for growers with diverse weed problems.Herbicide treatments will be applied with a CO2-pressurized backpack sprayer calibrated to deliver 140 L/ha. Plot size and number of replicates will vary depending on rice production systems and research location. Field studies will be conducted at the LSU AgCenter Rice Research Station near Crowley Louisiana and the Northeast Research Station near St. Joseph, Louisiana and off-station locations in order to have access to specific weeds not present at the LSU AgCenter Research Stations.Data collected from experiments will include in many cases visual ratings for weed control and crop injury. Ratings will be based on a scale of 0 to 100% with 0 = no control or injury and 100 = complete control or injury. For some studies more extensive data including plant height, plant biomass, and yield components, such as, test weight, moisture, seeds weight, milling quality, etc. will be collected. When rice is harvested the center 0.75 by 6 m area of each plot will be harvested using a mechanical plot harvester. Rough rice yield will be adjusted to 12% moisture. Percent milling will be determined by obtaining a 125 g sample of harvested rough rice from each plot and placed in a #2 McGill miller. Milling will be recorded as percent whole kernels over the percent whole plus broken kernels. Milled samples will be sent to a local buyer in the Crowley, Louisiana area for grading.Data will be subjected to the Mixed Procedure of SAS (SAS 2003). Type III statistics will be used to test all possible effects of fixed factors and least square means were used for mean separation at the 5% probability level (p ≤ 0.05). Data from studies will be subjected to appropriate statistical analysis based upon the experimental design used.

Project Methods
Data will be subjected to the Mixed Procedure of SAS (SAS 2003). Type III statistics will be used to test all possible effects of fixed factors and least square means were used for mean separation at the 5% probability level (p ≤ 0.05). Data from studies will be subjected to appropriate statistical analysis based upon the experimental design used.

Progress 02/12/20 to 09/30/20

Outputs
Target Audience:It is a goal of this project to extend the findings from this research project to producers, county agents, consultants, and scientists not only in Louisiana but around the world. Graduate students working under this project are constantly learning and evaluating new tools that can be used to manage weeds in rice. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest?Grower meetings, newsletters, annual reports. Training seminars and hands-on educational opportunities, both formal and informal, are continually being conducted. The results are often presented at field days, parish meetings, national and regional scientific and grower meetings. What do you plan to do during the next reporting period to accomplish the goals?Research on rice weed management will continue at research locations and grower fields. Research results will be published in conference proceedings, scientific journal articles, newsletters, and popular press articles.

Impacts
What was accomplished under these goals? Loyant Impregnated on Urea Fertilizer for Aquatic Weed Management. Based on research conducted in 2019 it was determined at least 150 lb/A of urea fertilizer was needed when impregnating Loyant at 16 oz/A onto the fertilizer granule for weed management. In 2020, two studies were conducted to evaluate Loyant coated on urea fertilizer to best determine activity on several aquatic weeds at different growth stages. The first study evaluated activity of Loyant on 3- to 4-inch weeds and the second trial evaluated control of 8- to 10-inch weeds. The weeds evaluated were barnyardgrass, yellow nutsedge, ducksalad, grassy arrowhead, creeping burhead, pickerelweed, creeping waterprimrose, alligatorweed and Indian jointvetch. The smaller sized weeds were mostly submerged to no more than 3" to 4" above the waterline. The larger plants were 4" to 8" exposed above the waterline. In both trials, Loyant applied on urea as the carrier controlled yellow nutsedge, ducksalad, and creeping burhead similar to the Loyant applied as a spray. Control degreased with Loyant applied on urea for barnyardgrass, grassy arrowhead, pickerelweed, creeping waterprimrose, and alligatorweed when compared with Loyant as a spray. Rice treated with Loyant as a spray resulted in slightly higher yields than rice treated with Loyant on the urea. In many cases growth of the weed ceased soon after treatment; however, total plant death did not occur. This cessation of growth appeared to reduce the competitiveness of the weed with rice. The method of applying Loyant on a fertilizer granule has a great deal of potential in Louisiana. A third study evaluated Loyant applied at 4, 8, and 16 oz/A on a fertilizer granular or as a spray formulation at the same rates. The same weeds were evaluated as previously discussed. At 42 days after treatment, Indian jointvetch, ducksalad, creeping burhead, and yellow nutsedge were controlled above 90% regardless of rate evaluated when treated with Loyant as a spray. Control decreased for all weedsevaluated when treated with Loyant applied on urea. Loyant applied on urea controlled ducksalad, creeping burhead, and yellow nutsedge similar to the spray solution. Control of barnyardgrass, grassy arrowhead, pickerelweed, creeping waterprimrose, alligatorweed and Indian jointvetch decreased significantly when treated with Loyant on urea compared with sprayed Loyant treatments regardless of rate evaluated. Provisia Rice Line PVL01, PVL02, 2074, 2174, and 2178 tolerance. A study was conducted evaluating the tolerance of five Provisia rice lines. The commercial available lines, PVL01 and PVL02, were used as comparisons against three experimental lines. Three rates/programs of Provisia were applied at the 2- to 3-leaf stage followed by a 4- to 5-leaf stage. The three rates of Provisia were applied in two applications, 15.5 oz/A followed by 15.5 oz/A, 31 oz/A followed by 31 oz/A, and 46.5 oz/A followed by 46.5 oz/A. A nontreated was added for comparison for each line evaluated. At 14 days after the 2- to 3-leaf timing, PVL01 was injured 8%, 23%, and 28% as the rate of Provisia increased. PVL02 was injured 7%, 13%, and 17% at 14 days after treatment. The three experimental lines were similar to the injury observed on PVL02. At 14 days after the final application, PVL01, PVL02, 2074, 2174, and 2178 treated with Provisia at 46.5 oz/A resulted in injury of 18%, 10%, 5%, 10%, and 8%, respectively. The yield of PVL02 and 2074 appeared to be more consistent compared with the other lines evaluated. Evaluation of Gambit when Mixed with Propanil. Reports from producers indicate when propanil is mixed with Gambit there appears to be a reduction in alligatorweed control. A study was initiated to evaluate alligatorweed control when treated with Gambit applied at 0.5, 1.0 and 1.5 oz/A mixed with Stam or SuperWham at 3 qt/A. All herbicides were applied alone as comparisons. At 14 days after treatment, Gambit applied at 0.5 oz/A reduced alligatorweed control 55% when mixed with either propanil formulation. As the rate of Gambit increased to 1 oz/A, alligatorweed control was reduced 43% and 30% when mixed with Stam or SuperWham, respectively. The antagonism observed with Gambit applied at the high rate when mixed with different propanil formulations reduced alligatorweed control 12 to 16% compared with Gambit applied alone. This was a preliminary study, and all indications are that there is some antagonism of Gambit when mixed with any formulation of propanil. I have a new graduate student who started in August. He will be responsible for investigating this issue on alligatorweed and other weeds controlled by Gambit. Evaluation of Provisia Rates on Red Rice and CLXL-745, Mermentau, and CL 111. This study was conducted in 2019 and 2020. Provisia was applied at 3, 6, 9, 12, and 15 oz/A on all three lines at the 2- to 3-leaf or panicle initiation (PI) growth stages. CLXL-745 in the 2- to 3-leaf stage required 9 oz/A to achieve at least 90% control at 14 to 28 days after treatment; however, Mermentau and CL 111 needed 6 oz/A to achieve the same amount of control. As CLXL 745, Mermentau and CL 111 reached the PI growth stage, a rate of 15 oz/A was needed to achieve 90% control. Rice in the 2- to 3-leaf growth stages will require less Provisia to achieve greater than 90% control; however, in a salvage situation, Provisia at 15 oz/A will be needed to control larger escapes.

Publications

• Type: Journal Articles Status: Published Year Published: 2020 Citation: Rustom S.Y., E.P. Webster, D.C. Blouin, and B.M. McKnight. 2020. Evaluation of sequential applications of quizalofop-p-ethyl and propanil plus thiobencarb in acetyl-coA carboxylase inhibitor-resistant rice. Weed Technol. 34:506-510.
• Type: Journal Articles Status: Published Year Published: 2020 Citation: Webster E.P., G.M. Tel�, S.Y. Rustom, B.M. McKnight, and D.C. Blouin. 2020. Quizalofop-p-ethyl application in water-seeded coenzyme A carboxylase inhibiting herbicide-resistant rice with different flood system. Weed Technol 34:188-192.
• Type: Journal Articles Status: Published Year Published: 2020 Citation: Webster, L.C., E.P. Webster, D.C. Blouin, and B.M. McKnight. 2020. Do adjuvants reduce the antagonism of quizalofop-p-ethyl when mixed with bispyribac-Na? Weed Technol 34:180-187.
• Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: Webster, E.P., B.M. McKnight, S.Y. Rustom, L.C. Webster, D.C. Walker and W.B. Greer. 2020. Use and management of ACCase-resistant rice technology in the United States. Proceedings 7th Temperate Rice Conference, Pelotus, RS, Brazil, February 10-12, 2020. 7: https://online.flowpaper.com/755e074b/Proceedings7thITRC/#page=98. Verified August 13, 2020.
• Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: Greer, W.B., E.P. Webster, B.M. McKnight, D.C. Walker, L.C. Webster, and S.Y. Rustom. 2020. Herbicide surface-coated urea for aquatic weed control in rice. Proceedings 7th Temperate Rice Conference, Pelotus, RS, Brazil, February 10-12, 2020. 7:https://online.flowpaper.com/ 755e074b/Proceedings7thITRC/#page=85. Verified August 7, 2020.
• Type: Conference Papers and Presentations Status: Awaiting Publication Year Published: 2020 Citation: Greer, W.B., E.P. Webster, B.M. McKnight, D.C. Walker, S.Y. Rustom, and L.C. Webster. 2020. Is florpyrauxifen-benzyl volatile when applied to rice foliage, bare soil or open water? Rice Tech Work Grp 38:in press.
• Type: Conference Papers and Presentations Status: Awaiting Publication Year Published: 2020 Citation: Greer, W.B., E.P. Webster, B.M. McKnight, S.Y. Rustom, L.C. Webster, and D.C. Walker. 2020. New technologies for weedy rice control in Louisiana. Proc. South. Weed Sci. Soc. 73:in press.
• Type: Conference Papers and Presentations Status: Awaiting Publication Year Published: 2020 Citation: Greer, W.B., E. P. Webster, B.M. McKnight, D.C. Walker, S.Y. Rustom, L.C. Webster. 2020. Options for managing weedy rice in Louisiana. Weed Sci. Soc. Am. Abstr. 60:in press.
• Type: Conference Papers and Presentations Status: Awaiting Publication Year Published: 2020 Citation: McKnight, B.M., E. P. Webster, S.Y. Rustom Jr., L.C. Webster, W.B. Greer and D.C. Walker. 2020. Aquatic weed response to herbicide application in Louisiana rice production. Proc. south. Weed Sci. Soc. 73:in press.
• Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: McKnight, B.M., E. P. Webster, S.Y. Rustom Jr., L.C. Webster, W.B. Greer and D.C. Walker. 2020. Evaluation of postemergence herbicide activity on Louisiana aquatic weeds. Proceedings 7th Temperate Rice Conference, Pelotus, RS, Brazil, February 10-12, 2020. 7:https://online. flowpaper.com/755e074b/Proceedings7thITRC/#page=106. Verified August 7, 2020.
• Type: Conference Papers and Presentations Status: Awaiting Publication Year Published: 2020 Citation: McKnight, B.M., E. P. Webster, S.Y. Rustom Jr., L.C. Webster, W.B. Greer and D.C. Walker. 2020. Herbicide activity on common Louisiana aquatic weeds. Rice Tech. Work. Grp. 38:in press.
• Type: Conference Papers and Presentations Status: Awaiting Publication Year Published: 2020 Citation: McKnight, B.M., E. P. Webster, S.Y. Rustom Jr., L.C. Webster, W.B. Greer and D.C. Walker. 2020. Response of common Louisiana aquatic weeds in rice herbicides. Weed Sci. Soc. Am. Abstr. 60: in press.
• Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: Rustom, S.Y., E. P. Webster, B.M. McKnight, L.C. Webster, W.B. Greer, and D.C. Walker. 2020. Analysis of new rice herbicides applied in a salvage situation in Louisiana rice. Proceedings 7th Temperate Rice Conference, Pelotus, RS, Brazil, February 10-12, 2020. 7: https://online.flowpaper.com/755e074b/Proceedings7thITRC/#page=108. Verified August 7, 2020.
• Type: Conference Papers and Presentations Status: Awaiting Publication Year Published: 2020 Citation: Rustom, S.Y., E. P. Webster, B.M. McKnight, L.C. Webster, W.B. Greer, and D.C. Walker. 2020. Evaluation of florpyrauxifen-benzyl activity on aquatic weeds in Louisiana rice and crawfish production. Proc. South. Weed Sci. Soc. 73:in press
• Type: Conference Papers and Presentations Status: Awaiting Publication Year Published: 2020 Citation: Rustom, S.Y., E. P. Webster, B.M. McKnight, L.C. Webster, W.B. Greer, and D.C. Walker. 2020. Evaluation of new rice herbicides applied in a salvage situation. Weed Sci. Soc. Am. Abstr. 60:in press.
• Type: Conference Papers and Presentations Status: Awaiting Publication Year Published: 2020 Citation: Rustom, S.Y., E. P. Webster, B.M. McKnight, L.C. Webster, W.B. Greer, and D.C. Walker. 2020. Potential for new rice herbicides applied in a salvage situation. Rice Tech Work Grp 38: in press.
• Type: Conference Papers and Presentations Status: Awaiting Publication Year Published: 2020 Citation: Walker, D.C. E. P. Webster, B.M. McKnight, S.Y. Rustom, L.C. Webster, and W.B. Greer. 2020. Controlling weedy rice using reduced rates of quizalofop. Proc. South. Weed Sci. Soc. 73:in press.
• Type: Conference Papers and Presentations Status: Awaiting Publication Year Published: 2020 Citation: Walker D.C., E. P. Webster, D.O. Stephenson, B.M. McKnight, S.Y. Rustom, L.C. Webster, and W.B. Greer. 2020. How do reduced rates of florpyrauxifen applied to soybean affect soybean yield components? Proc. South. Weed Sci. Soc. 73:in press.
• Type: Conference Papers and Presentations Status: Awaiting Publication Year Published: 2020 Citation: Walker, D.C., E. P. Webster, B.M. McKnight, S.Y. Rustom, L.C. Webster, and W.B. Greer. 2020. The effect of reduced rates of florpyrauxifen-benzyl on soybean yield components. Rice Tech. Wrkg. Grp. 38:in press.
• Type: Conference Papers and Presentations Status: Published Year Published: 2020 Citation: Walker, D.C., E. P. Webster, B.M. McKnight, S.Y. Rustom, L.C. Webster, and W.B. Greer. 2020. Off-target florpyrauxifen-benzyl and its effect on soybean yield components. Proceedings 7th Temperate Rice Conference, Pelotus, RS, Brazil, February 10-12, 2020. 7: https://online.flowpaper.com/755e074b/Proceedings7thITRC/#page=12. Verified August 7, 2020.
• Type: Conference Papers and Presentations Status: Awaiting Publication Year Published: 2020 Citation: Walker D.C., E. P. Webster, R.J. Levy, B.M. McKnight, S.Y. Rustom, L.C. Webster, and W.B. Greer. 2020. Using reduced rates of quizalofop to control weedy rice. Weed Sci. Soc. Am. Abstr. 60:in press.
• Type: Conference Papers and Presentations Status: Awaiting Publication Year Published: 2020 Citation: Walker, D.C., E.P. Webster, B.M. McKnight, S.Y. Rustom, L.C. Webster, and W.B. Greer. 2020. Using reduced rates of quizalofop for the control of weedy rice. Rice Tech. Wrkg. Grp. 38:in press.
• Type: Conference Papers and Presentations Status: Awaiting Publication Year Published: 2020 Citation: Webster, L.C., E. P. Webster, B.M. McKnight, W.B. Greer, D.C. Walker, and S.Y. Rustom. 2020. Early season residual herbicide strategies in upland rice production. Proc. South. Weed Sci. Soc. 73:in press.
• Type: Conference Papers and Presentations Status: Awaiting Publication Year Published: 2020 Citation: Webster, L.C., E. P. Webster, B.M. McKnight S.Y. Rustom, D.C. Walker, and W.B. Greer. 2020. Long-chain fatty acid inhibiting herbicides in Louisiana rice production. Proc. South. Weed Sci. Soc. 73:in press.
• Type: Conference Papers and Presentations Status: Awaiting Publication Year Published: 2020 Citation: Webster L.C., E. P. Webster, B.M. McKnight, Rustom S.Y., D.C. Walker and W.B. Greer. 2020. Upland rice production residual herbicide overlay. Proceedings 7th Temperate Rice Conference, Pelotus, RS, Brazil, February 10-12, 2020. 7:https://online.flowpaper.com/755e074b/ Proceedings7thITRC/#page=83. Verified August 7, 2020.
• Type: Conference Papers and Presentations Status: Awaiting Publication Year Published: 2020 Citation: Webster, L.C., E. P. Webster, B.M. McKnight S.Y. Rustom, D.C. Walker, and W.B. Greer. 2020. Overlaying residual herbicides in Louisiana upland rice production. Rice Tech Work Grp 38: in press.
• Type: Conference Papers and Presentations Status: Awaiting Publication Year Published: 2020 Citation: Webster, L.C., E. P. Webster, B.M. McKnight S.Y. Rustom, W.B. Greer, and D.C. Walker. 2020. Potential for new Rice herbicides applied in a salvage situation. Rice Tech Work Grp 38: in press.
• Type: Conference Papers and Presentations Status: Awaiting Publication Year Published: 2020 Citation: 23. Webster, L.C., E. P. Webster, B.M. McKnight, D.C. Walker, W.B. Greer, and S.Y. Rustom. 2020. The potential for new residual herbicides in rice. Weed Sci. Soc. Am. Abstr. 60:in press.