al caerse de un andamio
11 SITUACIÓN FACTOR O FACTORES GRUPO
K. McPherson1, G. Lorenz1, N. Taillon1, N. Bateman2, T. Clayton2,
A. Plummer1, J. Black3, A. Cato3, and L. McCullars3
Abstract
Rice water weevils are an early season pest of rice which can cause economic damage when larvae feed on the roots during permanent flood. An insecticide seed treatment study was conducted in a randomized strip block design to evaluate the efficacy of in- secticide seed treatments for control of rice water weevil and the impact on grain yield in 2017. The results of this study indicate that insecticide seed treatments can provide control for rice water weevil larvae and have the potential to increase yield.
Introduction
The rice water weevil (RWW), Lissorhoptrus oryzophilus, is a major pest in rice. Once permanent flood is established, adults infest fields and feed on the leaves causing small linear scars where leaf tissue has been removed (Bernhardt and Richards, 2002). Leaf scarring can be heavy but even the heaviest scarring rarely results in economic damage (Wilf et al., 2008). Economic damage is most often associated with RWW larvae that feed on the root system causing nutrient deficiency, stunted growth, and delayed maturity (Hix et al., 1997). Plants with a severely pruned root system may lean in the water and float when physically disturbed causing a significant stand reduction and yield loss (Lorenz and Hardke, 2013). Seed treatments have been documented to increase plant stand, height, vigor, and provide significant benefits in terms of yield (Lorenz et al., 2013). The objective of this study was to evaluate the impact of insecti- cide seed treatments (IST) in large block field trials in typical grower fields for control of RWW larvae.
1 Program Associate, Extension Entomologist, Program Associate, and Program Associate, respectively,
Department of Entomology, Lonoke.
2 Rice Entomologist and Program Associate, respectively, Department of Entomology, Stuttgart. 3 Graduate Research Assistant, Graduate Research Assistant, and Graduate Research Assistant, Depart-
Procedures
Experiments were conducted at the University of Arkansas System, Division of Agriculture’s Pine Tree Research Station (PTRS) near Colt, Ark. and at on-farm sites in Lonoke County and Jefferson County: 2 at PTRS, 1 at Lonoke County, and 1 at Jefferson County. Treatments included: a fungicide only treatment (UTC) with Apron (mefenoxam) 0.365 fl oz/cwt and Maxim (fludioxonil) 0.046 fl oz/cwt; CrusierMaxx Rice (thiamethoxam) 7 fl oz/cwt, and NipsIt SUITE (clothianidin) 2.4 fl oz/cwt. Experi- mental design was a randomized complete strip block. Depending on available space, experiments included 3 or 4 replications. The RWW larvae were evaluated by taking 5 core samples per plot with a 4-in. core sampler 21 days after flood was established. Samples were transported and evaluated at the Lonoke Extension Center, Lonoke, Ark. Each core was washed, with water to loosen soil and remove larvae from the roots, into a 40-mesh sieve. The sieve was immersed in a warm saturated salt solution which caused the larvae to float for counting. Yield samples were collected and adjusted to 12% moisture. Data was analyzed using Agriculture Research Manager 2017 (Gylling Data Management, Inc., Brookings, S.D.) and Duncan’s New Multiple Range Test (P = 0.10) to separate means.
Results and Discussion
In both the PTRS experiments and the Jefferson County experiment, both ISTs reduced RWW compared to the UTC (Table 1). RWW were extremely low in the Lonoke County experiment, therefore no differences were observed at that location. Although low levels of RWW were recorded, there was a trend for increased yield in 3 of the 4 experiments compared to the UTC (Table 2).
Significance of Findings
The purpose of this study was to determine the efficacy of ISTs for control of RWW larvae. At 3 of the 4 experiments, ISTs decreased RWW larvae numbers compared to the UTC. A trend of increased control of RWW larvae in treated plots compared to the UTC was observed in the Lonoke County experiment, but results were not significant. On average, yields increased in treated plots compared to the UTC even when low lev- els of RWW larvae were recorded. Many observations have noted that under stressful conditions, the seed treatment helped to moderate or buffer stress (Taillon et al., 2014). Due to these findings, future research will include the addition of new chemistry and chemistry combinations to control RWW larvae and other rice pests as well as evaluat- ing the impact on grain yield and the value to the grower.
Acknowledgments
Appreciation is expressed to Arkansas rice producers who provide support through the rice check-off program and the support of the University of Arkansas System Divi- sion of Agriculture, Syngenta Crop Protection, and Valent USA Co. for their support.
AAES Research Series 651
Literature Cited
Bernhardt, J., Richards, T. 2002. Screening Rice Lines for Susceptibility to Rice Water Weevil. In: B.R. Wells Rice Research Studies 2002. pp. 135-139. Available at: arkansas-ag-news.uark.edu/pdf/504-23.pdf
Hix, R., Johnson, D., Bernhardt, J., Lavy, T., Mattice, J., Lewis, B. 1997. Develop- ment of an IPM Monitoring Program for Rice Water Weevil Adults. In: B.R. Wells Rice Research Studies 1997. pp. 95-98. Available at: arkansas-ag-news.uark.edu/ pdf/460.pdf
Lorenz, G., Hardke, J. 2013. Insect Management in Rice. In: Arkansas Rice Produc- tion Handbook. University of Arkansas System Division of Agriculture Coopera- tive Extension Service. MP192 pp. 139-162. Available at: www.uaex.edu/publica- tions/pdf/mp192/chapter-12.pdf
Lorenz, G.M., N. Taillon, J. Hardke, and G. Studebaker. 2013. Rice insecticide seed treatments: Is there value to the Arkansas rice producer? In: University of Ar- kansas Agricultural Research and Extension Agriculture and Natural Resources. FSA7085. Available at: arkansas-ag-news.uark.edu/pdf/634.pdf
Taillon, N., Lorenz, G., Black, J., Plummer, W., Chaney, H. 2014. Insecticide Seed Treatments in Rice: Is There Value to the Grower? In: B.R. Wells Rice Research Studies 2014. pp. 137-144. Available at arkansas-ag-news.uark.edu/pdf/626.pdf Wilf, H., Lorenz, G., Colwell, K., Taillon, N. 2008. Efficacy of Rice Insecticide Seed
Treatments for Control of Grape Colaspis (Colaspis brunnea) and Rice Water Weevil (Lissorhoptrus oryzophilus Kuschel). In: B.R. Wells Rice Research Stud- ies 2008. pp. 135-139. Available at arkansas-ag-news.uark.edu/pdf/571.pdf
Table 1. Effect of seed treatments for control of rice water weevil (average/5 cores) at selected locations.
Treatments
Locations UTC† CruiserMaxx rice NipsIt SUITE
Lonoke County 1.53 a‡ 0.73 a 0.87 a
Jefferson County 2 a 1 b 0.73 b
PTRS 1 17 a 6.81 b 6.69 b
PTRS 2 17.2 a 7.87 b 7.07 b
† UTC = untreated check. PTRS = University of Arkansas System Divi-
sion of Agriculture’s Pine Tree Research Station.
‡ Means followed by the same lowercase letter in a column do not significantly differ, least significant difference P = 0.10.
Table 2. Effect of seed treatments on yield at selected locations.
Treatments
Locations UTC† CruiserMaxx rice NipsIt SUITE
---bu/ac---
Lonoke County 177.22 a‡ 183.04 a 187.98 a
Jefferson County 136.33 b 161.67 a 167.00 a
PTRS 1 120.35 a 112.56 a 108.83 a
PTRS 2 143.31 a 144.28 a 143.93 a
† UTC = untreated check. PTRS = University of Arkansas System Divi-
sion of Agriculture’s Pine Tree Research Station
‡ Means followed by the same lowercase letter in a column do not