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Use of on-farm commercial fields and research stations provides the opportunity to evaluate cultivar performance across a wide range of environmental conditions and management situations. The Arkansas Rice Performance Trials (ARPT) utilize experiment stations and commercial fields throughout the rice-producing regions of Arkansas to evaluate the performance of commercial rice cultivars. These trials provide information on agronomic factors of cultivars such as disease resistance, lodging, plant stand, plant height, grain yield, and milling yield across a range of environmental conditions, growing practices, and soil types. Choosing a cultivar is a critical decision annually for producers. Studies in 2022 were in grower fields in Clay, Desha, Greene, Jackson, Lawrence, and Lonoke counties, and on research stations in Arkansas, Mississippi, Poinsett, and St. Francis counties. The average grain yield across all 10 trials was 176 bu./ac with the highest average yielding location being Arkansas County at 191 bu./ac. Cultivars that had the highest average grain yield across all locations include RT XP780, RT 7521 FP, RT 7401, RT XP753, RT 7302, RT 7331 MA, Ozark, and DG263L. The average milling yield across all cultivars was 56/70 (%HR/%TR), with Addi Jo, Jupiter, Leland, DGL2065, and CLM04 producing the highest average milling yields. [ABSTRACT FROM AUTHOR]

The Arkansas Rice Variety Advancement Trials (ARVAT) are conducted each year to evaluate promising experimental lines from the Arkansas rice breeding program compared to commercially available cultivars from public and private breeding programs. ARVATs are planted on experiment stations and cooperating producer's fields in a diverse range of environments, soil types, and agronomic and pest conditions. The ARVATs were conducted at 6 locations during 2022. Averaged across locations, among conventional long-grains grain yields were highest for RU2201020 at 191 bu./ac compared to the commercial checks RT XP753 (205 bu./ac), Ozark (188 bu./ac), DG263L (188 bu./ac), and Diamond (172 bu./ac). Among Clearfield long-grains grain yields were highest for 21CL1054 at 189 bu./ac, RU1801101 at 186 bu./ac, and RU2101177 at 186 bu./ac compared to the commercial checks RT 7321 FP (190 bu./ac), CLL18 (178 bu./ac), and CLL16 (173 bu./ac). Among conventional and Clearfield medium-grains, grain yields were highest for 21AR1217 at 190 bu./ac and 21AR1222 at 190 bu./ac compared to the commercial checks Taurus (181 bu./ac), Titan (161 bu./ac), and CLM04 (154 bu./ac). Among longgrain aromatics, grain yields were highest for RU2101109 at 174 bu./ac compared to the commercial check ARoma 17 (139 bu./ac). Among Provisia long-grains, grain yields were highest for 22AR2106 at 177 bu./ac compared to the commercial check PVL03 (172 bu./ac). [ABSTRACT FROM AUTHOR]

The Arkansas Long Grain and Aromatic Rice breeding program is actively developing and improving rice varieties that are widely adopted in the U.S. Mid-South. Strict evaluations on desirable characteristics are conducted in different phases of the breeding program. Characteristics that are important include high grain yield potential, excellent milling yields, good plant stature, pest and disease resistance, and superior grain quality (i.e., low percent chalk, cooking, processing and eating). We conducted an advanced yield trial of conventional, herbicide-tolerant Clearfield and conventional aromatic long grains at four locations in Arkansas to identify potential lines to be advanced and possibly released as varieties in the future. We have identified several lines that are comparable or better in grain yield, milling yield, and other agronomic characteristics than existing checks in some or all four locations. These lines will be advanced to another multi-location yield test in the following year to confirm stability across years and locations. [ABSTRACT FROM AUTHOR]

Disease resistance is a valuable trait that rice breeders utilize at the University of Arkansas System Division of Agriculture's Rice Research and Extension Center (RREC) toward selection of preliminary and advanced breeding lines, as well as, in development of new rice varieties. Assessment of rice diseases under field and greenhouse environments is provided by the RREC rice breeding and pathology technical support group. Evaluation for disease resistance starts from early generation lines up to the release of rice varieties. Breeding materials are evaluated for sheath blight under field conditions at RREC with artificial inoculum. Assessment for neck blast is conducted in the field at the University of Arkansas System Division of Agriculture's Pine Tree Research Station (PTRS), while leaf blast testing is conducted in the greenhouse at RREC. Large amounts of inoculum for tested pathogens are prepared in the lab using various protocols and applied to plants using dispersal methods that have explicit protocols. Data generated from screening helps to select lines that are used either to transfer genes for resistance into adapted and high-yielding varieties or to advance entries for further agronomic testing. The breeding and pathology technical support group also assists the extension rice pathology projects in conducting applied research. Various pathogens are also grown for field inoculum to further understand and better manage major prevailing and recently emerging diseases. These endeavors have included collaborative interdepartmental, industry, and multi-state research. [ABSTRACT FROM AUTHOR]

The use of on-farm commercial fields and research stations provides the opportunity to evaluate cultivar performance across a wide range of environmental conditions and management situations. The Arkansas Rice Performance Trials (ARPT) utilize experiment stations and commercial fields throughout the rice-producing regions of Arkansas to evaluate the performance of commercial rice cultivars. These trials provide information on agronomic factors of cultivars such as disease resistance, lodging, plant stand, plant height, grain yield, and milling yield across a range of environmental conditions, growing practices, and soil types. Choosing a cultivar is a critical decision annually for producers. Studies in 2021 were in grower fields in Clay, Desha, Greene, Jackson, Lawrence, and Phillips counties and on research stations in Arkansas, Mississippi, Poinsett, and St. Francis counties. The average grain yield across all 11 trials was 206 bu./ac, with the highest average yielding location being Mississippi County at 227 bu./ac (Table 2). Cultivars that had the highest average grain yield across all locations include RT XP753, RT 7321 FP, RT 7401, RT 7301, RT 7521 FP, DG263L, Taurus, and Ozark. The average milling yield across all cultivars was 58/70 (%HR/%TR), with Jupiter, CLM04, Lynx, PVL02, and Taurus displaying the highest average milling yields. [ABSTRACT FROM AUTHOR]

Sheath blight caused by Rhizoctonia solani AG1-1A is the most prevalent disease in rice fields of Arkansas causing up to 15% grain yield loss. Nearly 57% of rice fields in Arkansas receive at least one fungicide application every year and most of these fungicides are to manage sheath blight. In some commercial rice fields, low application spray volumes used to deliver fungicides to the crop are blamed for the lower efficacy of fungicides used to suppress diseases such as sheath blight and false smut. Field tests for sheath blight suppression were conducted for the 3rd season in 2021 to evaluate two volumes of water (3 and 10 gallons per acre) as a carrier to apply two fungicides (Amistar Top and Quilt Xcel at 15 and 21 fl oz/ac rates, respectively). The sheath blight data analysis showed significant difference in disease suppression and grain yield between the sprayed and unsprayed treatments. However, there was no significant difference in efficacy between Amistar Top and Quilt Xcel in the degree of sheath blight suppression. Sheath blight in unsprayed plots showed most progression throughout the season followed by the plots sprayed with 3 gal/ac. The highest suppression of disease was in plots that received fungicides sprayed using 10 gal/ac of carrier water. In false smut plots, there was no significant differences between the sprayed and unsprayed treatments in the number of galls counted on panicles collected from 8 ft2 or galls counted from 8.8 lb of harvested seed. Effects of both fungicides and the water volumes used to deliver were not significant in suppressing false smut. Although not significant, the unsprayed plots occasionally had lower diseased panicles or gall counts compared to the sprayed check. When visually compared, panicles of secondary tillers in plots that received fungicides appeared greener and carry more false smut galls than the unsprayed plots. The study on false smut is inconclusive and needs repeated study. [ABSTRACT FROM AUTHOR]

Obtaining disease resistance data is necessary for preliminary and advanced breeding lines and newly developed rice varieties. Disease resistance is a valuable characteristic that rice breeders place a tremendous effort towards at the University of Arkansas System Division of Agriculture's Rice Research and Extension Center (RREC) near Stuttgart, Ark. Assessment of rice diseases under field and greenhouse environments is provided by the RREC rice breeding and pathology technical support group. Evaluation for disease resistance starts from early generation lines up to the release of rice varieties. Breeding materials are evaluated using artificial inoculation for sheath blight at the RREC. Assessment for neck blast is conducted at the University of Arkansas System Division of Agriculture's Pine Tree Research Station (PTRS) near Colt, Ark., while leaf blast testing is conducted in the greenhouse at RREC. Large amounts of inoculum for tested pathogens are prepared in the lab using various dispersal methods that have explicit protocols. Data generated from screening helps in the selection of lines that are used either to transfer genes for resistance into adapted and high-yielding varieties or to advance entries for further agronomic testing. The breeding and pathology technical support group also assists extension plant pathology programs with applied research. Various pathogens are also grown for field inoculum to further understand and better manage major prevailing and recently emerging diseases. These endeavors have included collaborative interdepartmental, industry, and multi-state research. [ABSTRACT FROM AUTHOR]

Reflecting recent changes in the Arkansas rice industry and streamlining the delivery of new and improved rice varieties to Arkansas rice growers, the medium-grain rice breeding project has expanded its research areas and breeding populations to include conventional, Clearfield®, and Provisia® medium-grain and long-grain rice as well as hybrid rice. The newest elite breeding lines/varieties from collaborating programs, as well as lines with diverse genetic origins, will be actively collected, evaluated, and incorporated into current crossing blocks for programmed hybridization. In order to improve the efficiency and effectiveness of the program, maximum mechanized-operation, multiple generations grown in the winter nursery, and new technologies such as genomic selection are vigorously pursued. [ABSTRACT FROM AUTHOR]

The Arkansas Rice Variety Advancement Trials (ARVAT) are conducted each year to evaluate promising experimental lines from the Arkansas rice breeding program compared to commercially available cultivars from public and private breeding programs. The ARVATs are planted on experiment stations and cooperating producer's fields in a diverse range of environments, soil types, and agronomic and pest conditions. The ARVATs were conducted at 6 locations during 2021. Averaged across locations, grain yields were highest for the conventional long-grain hybrid RT XP753, the FullPage long-grain hybrid RT 7521 FP, the conventional medium-grain RU1901033, the MaxAce long-grain RTv7231 MA, the Clearfield medium-grain RU2101234, the Clearfield long-grain RU2001093, the conventional long-grain RU2001185, and the conventional long-grain RU2001125. [ABSTRACT FROM AUTHOR]

The long-grain rice breeding program in the University of Arkansas System Division of Agriculture's Rice Research and Extension Center (RREC) has a long history of successfully developing long- and medium-grain as well as specialty rice cultivars for the Arkansas rice producers and the mid-South. Selections and evaluations are strictly conducted based on the desirable characteristics that need to be improved. These important characteristics include high rough rice yield potential, high milling yields, disease resistance, abiotic tolerance, good plant stature, and superior grain quality (i.e., low chalk, processing, cooking, and eating qualities). In 2021, a total of 1,204 entries entered the yield trials of both initial and advance tests for a total of more than 4,000 yield plots, including plots for seed increases. This report presents the overall results of the 2021 breeding program that includes lines from both initial and advance tests as well as potential lines in the pipeline. [ABSTRACT FROM AUTHOR]

Overall rice acreage in the United States is declining while imports have been rising since the 1980s. Rice imports are mainly driven by the consumption of Jasmine type "aromatic" rice. The aromatic rice breeding program at the University of Arkansas System Division of Agriculture's Rice Research and Extension Center (RREC) is actively developing aromatic varieties that not only have good cooking quality and aroma but also have improved agronomic performance and adaptation to the climatic conditions in the mid-South. In 2021, 20 out of 68 entries had a significantly higher yield than the check varieties in the Stuttgart Initial Test. In the Advanced Yield Trial conducted at the RREC, 23 out of 40 entries had a significantly higher yield over the check varieties. The top 3 entries in both trials had a yield advantage of 50 bu./ac or more over Jazzman 2 or ARoma 17. Furthermore, the Uniform Regional Rice Nursery (URRN) conducted in Arkansas showed the three new aromatic lines also out-yielded the check ARoma 17. Our results showed our current selections of the top elite lines have improved the agronomic performance and can be further tested in multi-environment trials. [ABSTRACT FROM AUTHOR]

Flooded water from considerable acreage of rice fields is drained every year to manage straighthead, incurring additional costs to rice production. The major objectives of this study were to provide growers with updated information on the susceptibility of the new rice varieties and hybrids regarding their reaction to straighthead, to re-evaluate older varieties still in production, to assess the susceptibility of advanced breeding lines prior to release for commercial production, and to test parental lines from the hybrid rice breeding program for their reaction. This paper reports the procedure and results of the 3rd year field test. However, ratings from the previous two years have been included for users to compare and check for consistency. In 2021, four bays were established at the University of Arkansas System Division of Agriculture's Rice Research and Extension Center (RREC), Stuttgart, Arkansas. Each bay had 39 test entries and 5 reference/control entries as hill plots in four replications. Two bays had Monosodium Methanearsonate (MSMA) incorporated in the soil at the rate of 1 gal/ac and the other two bays at 1.5 gal/ac. All were kept flooded up to 4-in. depth starting from the 5-leaf stage through the hard dough stage. Before draining the water, entries were visually examined for straighthead symptoms using the 0 to 9 rating scale. Of 39 entries tested, 16 entries rated from 7 to 9 for susceptibility, 15 rated from 4 to 6, indicating moderate resistance to moderately susceptible response, and the remaining eight entries rated 0 for a high level of tolerance to straighthead and MSMA. When the two rates were compared, the1.5 gal/ac rate showed clear symptoms of straighthead over the 1 gal/ac rate of MSMA. [ABSTRACT FROM AUTHOR]

The cultivar CLL18 is a new and very high-yielding, short-season, long-grain Clearfield® rice cultivar derived from the cross Roy J/CL142-AR. The CLL18 Breeder Head Row seed was released to BASF and Horizon Ag by the University of Arkansas System Division of Agriculture's Arkansas Agricultural Experiment Station to produce breeder and foundation seed in 2022 and 2023, respectively. The major advantages of CLL18 are its very high yield potential, high whole kernel rice milling yield, long kernel length, and low chalk. CLL18 is a non-semidwarf standard height long-grain rice cultivar with lodging resistance similar to Roy J. CLL18 is rated moderately susceptible to rice blast, sheath blight, and bacterial panicle blight, moderately resistant to narrow brown leaf spot, and susceptible to false smut. [ABSTRACT FROM AUTHOR]

The Arkansas Rice Performance Trials (ARPTs) are conducted each year to evaluate promising experimental lines from the Arkansas rice breeding program and commercially available cultivars from public and private breeding programs. The ARPTs are planted on experiment stations and cooperating producer's fields in a diverse range of environments, soil types, and agronomic and pest conditions. The ARPTs were conducted at 4 locations during 2019. Averaged across locations, grain yields were highest for the commercial cultivars RT 7301, RT XP753, RT 7501, RT 7521 FP, DGL263, RT Gemini 214 CL, RT 7321 FP, Jupiter, Titan, and RT CLXL745. Cultivars with the highest overall milling yields during 2019 included: PVL02, CLJ01, Jazzman-2, ARoma 17, Jupiter, CL151, CL153, and CLM04. [ABSTRACT FROM AUTHOR]

On-farm cultivar testing provides the ability to evaluate performance in commercial fields with more unpredictable environments than those at traditional research stations. The Producer Rice Evaluation Program (PREP) utilizes commercial fields throughout the state of Arkansas to evaluate 25 different rice cultivars, including experimental and commercial lines. These on-farm tests are used to analyze different agronomic aspects of cultivars such as disease, lodging, plant stand, plant height, grain yield, and milling yield in diverse environmental conditions, soil types, and growing practices. The most important decision for a producer can be the cultivar that will provide the maximum yield potential for each field. On-farm testing can indicate the cultivars that are best suited for a particular growing situation. Studies were located in grower fields in Craighead, Greene, Lee, Lonoke, Poinsett, Prairie, and Woodruff counties for the 2019 season. The average grain yield across all six locations was 199 bu./ac, and the location with the highest average grain yield average was Woodruff County at 223 bu./ac. The cultivars with the highest average grain yield across all locations were RT XP753, RT Gemini 214 CL, RT 7301, RT 7521 FP, CLL16, RT 7501, Jupiter, RT 7321 FP, Titan, and Diamond. Cultivars with the highest head rice yields were PVL02, CLM04, Jupiter, CLJ01, CL151, CL153, Jazzman-2, ARoma 17, Jewel, Lynx, and PVL01. [ABSTRACT FROM AUTHOR]

Although straighthead has been known to affect only a small percentage of the Arkansas rice acreage, considerable acreage is drained every year to manage straighthead thus incurring additional costs to rice production. The main purposes of this study were to provide growers with updated information on the susceptibility of the new rice varieties and hybrids regarding their reaction to straighthead, to reevaluate the older varieties which are still in production because of their response consistency, and to assess the susceptibility of advanced breeding lines prior to release for commercial production. Three different bays, each with 35 (30 test entries and 5 control) were established in experimental fields of the University of Arkansas System Division of Agriculture's Rice Research and Extension Center, Stuttgart, Arkansas. The 1st two bays received MSMA (monosodium methanearsonate). One of these two bays was kept flooded to at least a 4-inch depth from 5-leaf stage to maturity and the other was flushed intermittently. A third control bay received no MSMA but was kept flooded to at least a 4-inch depth from 5-leaf stage to maturity. The entries were visually examined for straighthead symptoms at dough stage before the flood was drained. None of the control or the test entries showed straighthead symptoms in the MSMA-free bay. The bay that received MSMA and kept with permanent flood showed 7 very susceptible (VS), 3 susceptible (S), 14 moderately resistant (MR), and 4 resistant (R) cultivars indicating clear differences in varietal response to MSMA. Two entries did not emerge and were missing. In the bay that received MSMA and was treated with intermittent flooding, only those that rated VS above showed mild straighthead symptoms on panicles of 2 to 5 tillers which appeared late in the season. The experiment will be repeated in 2020 to include more advanced breeding lines. [ABSTRACT FROM AUTHOR]

To reflect the recent changes of the Arkansas rice industry and streamline the delivery of new and improved rice varieties to Arkansas rice growers, the medium-grain rice breeding project has expanded its research areas and breeding populations to include both conventional and Clearfield medium- and long-grain rice as well as hybrid rice. The newest elite breeding lines/varieties from collaborating programs, as well as lines with diverse genetic origins will be actively collected, evaluated, and incorporated into current crossing blocks for programmed hybridization. To improve the efficiency and effectiveness of the program, maximum mechanized-operation, multiple generations grown in the winter nursery, and new technologies such as molecular marker-assisted selection (MAS) are rigorously pursued. [ABSTRACT FROM AUTHOR]

The Arkansas Rice Performance Trials (ARPTs) are conducted each year to evaluate promising experimental lines from the Arkansas rice breeding program and commercially available cultivars from public and private breeding programs. The ARPTs are planted on experiment stations and cooperating producer's fields in a diverse range of environments, soil types, and agronomic and pest conditions. The ARPTs were conducted at five locations during 2018. Averaged across locations, grain yields were highest for the commercial cultivars RT 7801, RT 7501, RT Gemini 214 CL, RT XP753, RT XP760, RT 7521 FP, RT 7321 FP, RT 7311 CL, Diamond, and Jupiter. Four advanced experimental lines, CLXAR19, CLX-1030, ARX7-1121, and CLX6-1111 also outperformed many current commercial cultivars. Cultivars with the highest overall milling yields during 2018 included: CL153, CL172, ARX7-1087, ARoma 17, and CLX6-1111. [ABSTRACT FROM AUTHOR]

Sheath blight disease of rice caused by Rhizoctonia solani AG1-1A is one of the major diseases of rice in Arkansas. Fungicides are often recommended if the established threshold levels are reached and the disease progresses into the upper canopy during the later growth stages. The economic benefit of these applications must periodically be reevaluated based on changes in cultivars, management practices, and fungicide efficacy. The effect of fungicide application timing was evaluated on the cultivars LaKast and Jupiter at two seeding rates. The fungicide applications at panicle differentiation and boot split were compared with the untreated controls. All plots were artificially inoculated with R. solani AG1-1A. Both fungicide application timings resulted in reduced sheath blight incidence and higher grain yields when compared to the untreated control. However, mean monetary gains were variable based on trial location and fungicide application timing. With the adequate nitrogen fertilization applied and less differences in canopy, seeding rates seemed to have less impact in the disease or grain yield in this study. These results suggest the current recommended fungicide application timing of panicle differentiation through heading is generally most appropriate for use in Arkansas. [ABSTRACT FROM AUTHOR]

The response is reported of nearly 285 rice entries, 222 from the Uniform Regional Rice Nursery (URRN) and 63 from the Arkansas Rice Performance Test (ARPT) evaluated by artificially inoculating with a bacterial suspension under field conditions. The entries were planted in two plantings, early and late, taking into consideration the differences in maturity and the possible variability in responses due to varied weather factors across the season. Twenty-three URRN entries were grouped as moderately resistant (MR) and 47 as moderately susceptible (MS) in both the early and late planted entries. Thirty one entries showed MR response in early planted and MS in the late planted. The remaining 111 entries were grouped into different categories. Twelve entries showed MR response in early planted and S (susceptible) or VS (very susceptible) in the late planted URRN set. Contrarily, 12 other entries responded as MS in early planted and MR in the late planted URRN set. There were 8 entries which were S in early planted and MR in the late planted sets. Among the ARPT, five were grouped as MR and 11 as MS in both early and late planted. Eleven entries showed MR response in early and MS in the late planted. The remaining 36 entries were grouped in various categories. Four entries showed MR response in early and S or VS in the late planted ARPT set. Ten other entries responded as MS in early planted and S or VS in the late planted ARPT set. There were 22 entries that showed S or VS in both plantings. The three entries (RU1701176, RU1701179 and, RU1401105) that rated MR in 2017 responded MR, MS, MS, respectively, in the early planted set and all showed a susceptible response in late planted sets suggesting the importance of variability in weather factors in enhancing bacterial panicle blight (BPB) severity. Among the 243 URRN entries evaluated under natural conditions in the University of Arkansas System Division of Agriculture's Rice Research and Extension Center rice breeder's field, 133 entries did not show any visual symptom of BPB. Twenty-four entries responded as resistant (R) (1), 34 as MR (2), 27 as MS (3), 16 as S (4) and 1 as VS (5) and 8 missing. [ABSTRACT FROM AUTHOR]

Bacterial panicle blight (BPB) is one of the most threatening diseases for rice production in Arkansas and other southern rice-producing states. The disease is caused largely by Burkholderia glumae and possibly other Burkholderia species. One of the objectives in 2018 was to evaluate the effect of moisture in association with severity and incidence of BPB in the field, greenhouse, and shaded areas of the field along tree lines as part of a short-term strategy to manage BPB. Greenhouse, tree-line shade, and other field tests mostly agreed that the incidence of BPB disease increased with moisture. In the greenhouse when Jupiter and Bengal were spray inoculated at the flowering developmental stage, only 27.2% of the florets were infected when no dew was present. However, rice plants incubated in a dew chamber for 24 hours and 48 hours showed 92% and 98%, respectively, floret infection. In 2017, the west side tree shade had more BPB symptomatic panicles than the east side unlike what was observed in 2016 and again in 2018. On the other hand, the field test in 2018 on mist and no mist application showed variable results compared to the last two years. Overall, infected panicle counts were significantly higher in spray inoculated plots than seed inoculated and non-inoculated plots. The intensity of panicle blight, however, was not severe enough to show significant differences between the inoculation treatments. Moreover, the late-season rains after spray inoculation lowered the effect of the mist treatment. There was no significant effect on infected panicle counts between the misted plots and non-misted plots in 2018 unlike the previous years. The dew and tree-line shade test results agreed with years of field tests and observations suggesting moisture in the form of dew, mist, fog, or shade favors BPB development and spread within a rice plant or between plants. [ABSTRACT FROM AUTHOR]

Autumn decline, also referred to as akiochi, shows black root rotting usually with stunted and yellowish rice foliage starting as early as two weeks following establishment of the permanent flood. In severe conditions, root crowns rot and are invaded by opportunistic fungi rendering a dark brown discoloration. Rotting of root crowns specifically is referred to as autumn decline/akiochi and hinders the rice plant's ability to translocate nutrients up from the roots. The root mass blackening is often caused by iron sulfide (FeS) which further leads to hydrogen sulfide toxicity (HST). Research objectives in 2018 included: 1) to search for practical methods to prevent or correct the root blackening and rotting; 2) to evaluate the degree of resistance or tolerance of common rice cultivars to these complex problems under field conditions; and 3) to evaluate the interaction of infested residue and well water collected from a field with a history of these problems. When Spectrum PC, Spectrum PTB, Calcium Oxide (CaO), Zinc Oxide (ZnO) and the combination of CaO and ZnO were tested in the greenhouse, all treatments appeared to have similar root mass discoloration. Crown rot ratings were lower with CaO and the Spectrum formulations. Cultivar evaluation from the field showed the mean percentage of root blackening ranged from 40% to 70% and crown rotting ranged from 0 to 9 on a 0 to 9 scale where 0 = no discoloration and 9 = total discoloration of the crown. There were clear indications that field soil and well water by themselves or together caused root mass discoloration regardless of residue amounts. [ABSTRACT FROM AUTHOR]

Disease resistance in rice is one of many goals rice breeders and pathologists work on at the University of Arkansas System Division of Agriculture's Rice Research and Extension Center (RREC) near Stuttgart, Arkansas. The breeding and pathology support group evaluates preliminary and advanced breeding lines against major diseases of economic importance in both the greenhouse and field. At RREC, preliminary and advanced breeding materials are evaluated using artificial inoculation for sheath blight in the field and blast diseases in the greenhouse. Advanced breeding materials are tested in the field for blast resistance with artificial inoculation at the University of Arkansas System Division of Agriculture's Pine Tree Research Station (PTRS) near Colt, Arkansas. Large amounts of disease inocula are prepared in the laboratory and applied to rice plants following specific protocols. The rice breeders utilize these data to make selections. The breeding program advanced yield plots are also evaluated in the field for diseases including the rice blast, sheath blight, bacterial panicle blight, kernel smut and false smut. Selected lines are used either to transfer genes for resistance into adapted and high yielding varieties or to advance entries for further agronomic testing. The evaluation of preliminary breeding materials helps breeders eliminate extremely susceptible materials, thus saving time and resources. The breeding and pathology technical support group is fully involved in extension plant pathology programs with applied research on bacterial panicle blight, including collaborative interdepartmental, industry, and multi-state research endeavors. [ABSTRACT FROM AUTHOR]

To reflect the recent changes of the Arkansas rice industry and streamline the delivery of new and improved rice varieties to Arkansas rice growers, the medium-grain rice breeding project has expanded its research areas and breeding populations to include both conventional and Clearfield medium- and long-grain rice as well as hybrid rice. The newest elite breeding lines/varieties from collaborating programs, as well as lines with diverse genetic origins will be actively collected, evaluated, and incorporated into current crossing blocks for programmed hybridization. To improve the efficiency and effectiveness of the program, maximum mechanized-operation, multiple generations grown in the winter nursery, and new technologies such as molecular marker-assisted selection (MAS) are rigorously pursued. [ABSTRACT FROM AUTHOR]

The Arkansas rice breeding program has the ongoing goal to develop new long- and medium-grain cultivars as well as specialty cultivars including aromatics and Japanese quality short-grains. Cultivars are evaluated and selected for desirable characteristics. Those with desirable qualities which require further improvement are utilized as parents in future crosses. Important components of this program include: high-yield potential, excellent milling yields, pest and disease resistance, improved plant type (i.e., short stature, semidwarf, shorter maturity, erect leaves), and superior grain quality (i.e., low chalk, cooking, processing and eating). New cultivars are continually being released to rice producers for traditional Southern U.S. markets as well as for emerging specialty markets, which are gaining in popularity with rice consumers. This report describes the progress of the long-grain and specialty rice pure-line rice breeding efforts at the University of Arkansas System Division of Agriculture. [ABSTRACT FROM AUTHOR]

Development of disease resistant rice is one of many goals rice breeders work on at the University of Arkansas System Division of Agriculture's Rice Research and Extension Center (RREC) near Stuttgart, Arkansas The center's plant pathology group assists by screening preliminary to advance breeding entries for disease reaction under greenhouse and field conditions. Breeding materials are evaluated after using artificial inoculum for sheath blight at the RREC and blast disease at the RREC and the University of Arkansas System Division of Agriculture's Pine Tree Research Station (PTRS) near Colt, Arkansas. Both sheath blight and blast inocula are produced in the laboratory and applied to plants using specific protocols for each disease. Sheath blight is screened under field conditions, but blast screening utilizes both greenhouse and field environments. The major objectives of this technical support are to provide data that not only helps breeders remove the most susceptible lines early in their program, but also to support advancement of lines or transfer of genes for resistance into adapted and high yielding varieties. The breeding and pathology technical support group assists extension plant pathology programs with applied research to manage diseases that prevail in rice fields, as well as, collaborative interdepartmental, industry, and multi-state research endeavors. [ABSTRACT FROM AUTHOR]

Rice sheath blight, caused by the soilborne fungal pathogen Rhizoctonia solani AG-1A, is an economically important disease in rice. Nearly 57% of Arkansas rice fields receive fungicides to suppress one or more rice diseases including sheath blight. Disease control using chemicals leads to increased risk to our environment. As an alternative option, biological control methods have gained interest in modern agriculture. As a result, several species in genus Trichoderma are known to be effective against fungal plant diseases. In this preliminary study, an experiment was designed in 2019 to test an isolate of Trichoderma atroviride (TM17) for seed dressing, and as a pre- and post-inoculation treatment to suppress sheath blight of rice. Seeds of long-grain rice, CL163 were soaked in a suspension of TM17, adjusted to 109 per ml spore concentration and dried under a sterile hood overnight before planting. Pre-inoculation treatment was sprayed on foliage at panicle initiation a week before R. solani AG-1A was inoculated. The post-inoculation treatment was applied a week after inoculation with 109 per ml spore concentration as in the seed treatment. Results showed that disease ratings were lower in foliage treated plots (pre- and post-inoculation treatments) than in the untreated control plots. Grain yields were also significantly higher in these plots than the untreated check. Plots planted with treated seeds showed a slightly lower incidence of disease than the control plots. Nevertheless, yield differences were not significantly different. The experiment should be repeated, refining the seed dressing method and on methodologies, particularly towards establishing TM17 in rice canopy throughout the season. [ABSTRACT FROM AUTHOR]

Jewel is a new short season, high yielding, long-grain rice cultivar with the Pi-ta gene for blast resistance and the Cheniere cook type developed from a complex cross with many parents, some of which are: Katy, Newbonnet, Drew, Lebonnet, Starbonnett, LaGrue, Lemont, Wells, Radiated Bonnet 73, short strawed Starbonnet, Dawn, and Bluebonnet 50. Jewel has been approved for release, by the University of Arkansas System Division of Agriculture's Arkansas Agricultural Experiment Station, to qualified seed growers for the summer of 2020. The major advantages of Jewel are its blast tolerance, yield potential, high whole kernel rice milling yield, long kernel length, low chalk and L-202 cook type. Jewel is a non-semidwarf standard long-grain rice cultivar with lodging resistance approaching that of Roy J. Jewel is rated moderately susceptible to rice blast, sheath blight and false smut, and rated susceptible to bacterial panicle blight. [ABSTRACT FROM AUTHOR]

On-farm testing provides researchers the opportunity to evaluate cultivars in a more unpredictable environment than that of the experiment stations or traditional test plots. The Producer Rice Evaluation Program (PREP) utilizes commercial rice fields throughout the state to evaluate experimental lines and various commercial cultivars for disease, lodging, grain yield potential, and milling yield in diverse growing conditions, soil types and farming practices. For producers, knowing the optimum cultivar for each field is their biggest and most important tool. On-farm testing can indicate which cultivars are suited for a particular growing situation. Field studies were located in Craighead, Drew, Lafayette, Lawrence, Phillips, Poinsett, Prairie, and White counties during the 2017 growing season. Twenty cultivars were selected for evaluation in the on-farm tests. The average grain yield across all locations was 211 bu/acre and the mean milling yield, percent head rice and percent total white rice (%HR/%TR), was 59/70. The cultivars with the highest grain yields averaged across locations were RT XP753, RT 7311 CL, RT 7812 CL, Titan, RT XP760, RT Gemini 214 CL, Jupiter, and Diamond. Cultivars CL172, CL153, CL111, and RT 7812 CL had the highest milling yields averaged across locations. [ABSTRACT FROM AUTHOR]

The Arkansas Rice Performance Trials (ARPTs) are conducted each year to evaluate promising experimental lines from the Arkansas rice breeding program and commercially available cultivars from public and private breeding programs. The ARPTs are planted on experiment stations and cooperating producer's fields in a diverse range of environments, soil types, and agronomic and pest conditions. The ARPTs were conducted at five locations during 2017. Averaged across locations, grain yields were highest for the commercial cultivars XP753, XP760, RT7812CL, RTGemini214CL, RT7311CL, Diamond, and Jupiter. Two advanced experimental lines, AREX7-1084 and AREX7-1124 also outperformed many current commercial cultivars. Cultivars with the highest overall milling yields during 2017 included: CL153, CL163, CL172, and Roy J. [ABSTRACT FROM AUTHOR]

The Arkansas rice breeding program has the ongoing goal to develop new long- and medium-grain cultivars as well as specialty cultivars including aromatics and Japanese quality short-grains. Cultivars are evaluated and selected for desirable characteristics. Those with desirable qualities which require further improvement are utilized as parents in future crosses. Important components of this program include: high-yield potential, excellent milling yields, pest and disease resistance, improved plant type (i.e. short stature, semidwarf, shorter maturity, erect leaves), and superior grain quality (i.e. low chalk, cooking, processing and eating). New cultivars are continually being released to rice producers for the traditional Southern U.S. markets as well as for the emerging specialty markets, which are gaining in popularity with rice consumers. This report describes the progress of the long-grain and specialty rice pure line rice breeding effort at the University of Arkansas System Division of Agriculture. [ABSTRACT FROM AUTHOR]

Bacterial panicle blight (BPB), caused mainly by the bacterial pathogen Burkholderia glumae posed a higher level of threat to rice production worldwide in recent years. Here, we report the response of over 290 rice entries evaluated by artificially inoculating with a bacterial suspension under field conditions. From the Uniform Regional Rice Nursery (URRN) field screening, nearly 10 percent and 6 percent of the entries showed a resistant and moderately resistant reaction, respectively. A subset of 10 entries showed lower BPB disease in both the URRN and Arkansas Rice Performance Trials (ARPT). From 60 symptomatic samples screened on semi-selective medium, 52 were further evaluated by molecular test. Among these, 45 isolates were confirmed as B. glumae. The remaining seven were bacteria other than B. glumae and none of these seven isolates matched to B.gladioli. The three methods of inoculation (clip, direct injection and panicle) tested showed distinct disease phenotypes between cultivars that traditionally have been considered resistant or moderately resistant. Direct injection of bacterial inoculum into the sheath caused pathogen-related necrotic spots around the site of inoculation but not in sheaths injected with water alone. The genes Os1g32460, Os05g30500, Os11g31190, Os11g12340, Os11g12330, Os11g12040, Os11g12300, Os11g12000 and Os08g25050 were tested to determine if they are differentially expressed between the moderately resistant cultivar Jupiter and the susceptible cultivar Bengal after inoculation with B. glumae. While several of the genes were found to be upregulated after pathogen infection, none of the genes tested were differentially expressed between resistant and susceptible cultivars and the results were highly variable depending on the time of inoculation. Therefore, more optimization is needed. [ABSTRACT FROM AUTHOR]

Bacterial panicle blight (BPB) is one of the most threatening diseases for rice production in Arkansas and other southern rice producing states. The disease is caused by Burkholderia glumae and possibly other Burkholderia species. As part of a short term strategy to manage BPB, two objectives were addressed in this study. 1) to evaluate survival of B. glumae from infected rice residues, inoculated soil, and "overwintering rice" 2) to evaluate the effect of dew associated with severity and incidence of BPB in the field, greenhouse, and shaded areas of the field along tree lines. Despite the high initial population density in artificially inoculated soils, B. glumae appeared to be short lived. In 2015, no colonies of B. glumae were recovered from soil that had been inoculated a month earlier and left on the surface of the field or buried. In 2016, a two weeks sampling time was included and B. glumae was recovered at a much smaller population density compared to the initial time point. In 2017, a similar trend of declining number of positive florets was observed. Based on these results B. glumae appeared less important in the overwintering infection of new rice plants. When tested using infected panicles placed on the soil surface or buried in the field, none of the florets tested positive after a month in 2015 for BPB in either case. In 2016, no BPB infected kernel/chaff was obtained from the panicles on the surface. A similar declining B. glumae recovery was observed in 2017. However, a low number but positive recovery of BPB extended into February when artificially inoculated rice plants were left as volunteers to overwinter, the number of positive seeds dropped from 34% to 4% by January. The field mist test, greenhouse dew test, and the tree line shade test agreed on increment of incidence of BPB disease. In 2017, tree shade on the west side rendered more BPB symptomatic panicles than that of the east side unlike what was observed in 2016. The mist, dew and tree line shade test results were in agreement with years of field observation suggesting moisture in a form of dew, mist, fog, shade favor BPB development and spread within a rice plant or between plants. [ABSTRACT FROM AUTHOR]

Sheath blight disease of rice caused by Rhizoctonia solani AG1-1A is one of the major diseases of rice in Arkansas. Fungicides are often recommended if established threshold levels are reached and the disease progresses into the upper canopy during reproductive growth stages. The economic benefit of these applications must periodically be reevaluated based on changes in cultivars, management practices, and fungicide efficacy. The effect of fungicide application timing was evaluated on the cultivars LaKast and Jupiter at two seeding rates. Fungicide timings consisted of an untreated control and applications at panicle differentiation or boot split. All plots were artificially inoculated with the sheath blight fungus. Similar to 2016, both fungicide application timings resulted in reduced sheath blight incidence and higher grain yields compared to the untreated control. However, mean monetary gains were variable based on trial location and fungicide application timing. [ABSTRACT FROM AUTHOR]

Hydrogen sulfide toxicity or autumn decline, also referred to as akiochi, shows black root rotting usually with stunted and yellowish rice foliage starting as early as two weeks following establishment of the permanent flood. In severe conditions, root crowns rot and are invaded by opportunistic fungi rendering dark brown discoloration. Rotting of root crowns specifically is referred to as autumn decline/akiochi and hinders the rice plant's ability with upward nutrient translocation from the roots. This paper reports on progress for two project objectives: 1) to search for practical methods to prevent or correct the root blackening and rotting associated with autumn decline; 2) to evaluate the degree of resistance or tolerance of common rice cultivars to autumn decline under greenhouse or field conditions. A field with a history of hydrogen sulfide toxicity and autumn decline was identified in Humphrey, Ark. for the purpose of conducting the following three tests. Two formulations of anoxygenic phototrophic bacteria products namely, spectrum PC and Spectrum PTB were tested in micro-plots (half barrels). At the same time, pot experiments were established to test cultivar tolerance differences and a greenhouse test was conducted to evaluate the effects of water temperatures, soil, and water sources on symptom development. The products PC and PTB were not effective in reducing the percent of root mass discoloration which was consistent with previous year's experiments. Spectrum PC did reduced root crown rot by 20% while Spectrum PTB lowered the damage by 40%. From the cultivar evaluation test, those that showed crown root rot above 3 on the 0-9 scale fell in the category of susceptible regardless of the intensity of root mass discoloration. Nearly 75% of the cultivars showed less than 35% root mass discoloration.Only 55% of the cultivars showed root crown damage that ranged from 5% to 30%. Root crown damage among the cultivars ranged from 0.5 to 9. The greenhouse test showed water temperature for flooding had much lower impact on hydrogen sulfide toxicity symptom or autumn decline than soil and water sources. Soil from a field with a history produced symptoms with either well water or chlorinated city water. However, the greenhouse soil with no history of toxicity or autumn decline showed no disease symptoms with the city water. Instead, it showed the autumn decline symptom with the well water. [ABSTRACT FROM AUTHOR]

Development of disease resistant rice is one of many goals rice breeders work on at the University of Arkansas System Division of Agriculture's Rice Research and Extension Center (RREC) near Stuttgart, Ark. The center's plant pathology group assists by screening preliminary to advance breeding entries against rice diseases under greenhouse and field conditions. Breeding materials are evaluated using artificial inoculation for sheath blight and blast diseases at the RREC and University of Arkansas Systems Division of Agriculture's Pine Tree Research Station (PTRS) near Colt, Ark. Large amounts of disease inocula are prepared in the laboratory and applied to plants using specific protocols. Sheath blight is screened under field conditions, but blast screening utilizes both greenhouse and field environments. The breeding programs utilize these data to make selections. Selected lines are used either to transfer genes for resistance into adapted and high yielding varieties or to advance entries for further agronomic testing. The breeding and pathology technical support group also assists extension plant pathology programs with applied research to manage major prevailing and newly emerging diseases, including collaborative interdepartmental, industry, and multi-state research endeavors. [ABSTRACT FROM AUTHOR]

ARoma 17, a new high yielding Jasmine-type aromatic, mid-season, long-grain rice cultivar, originated from the cross 'Jazzman'/PI 597046. The aromatic line has been approved for release for the 2018 growing season. ARoma 17 offers a Jasmine-type rice adapted to Arkansas growing conditions for rice producers who want to serve that consumer market. [ABSTRACT FROM AUTHOR]

To reflect the recent changes of the state rice industry and streamline the delivery of new and improved rice varieties to the Arkansas rice growers, the new medium-grain rice breeding project will expand its research areas and breeding populations to include both conventional and Clearfield medium- and semidwarf long-grain rice, as well as hybrid rice. Newest elite breeding lines/varieties from collaborating programs, as well as lines with diverse genetic origins will be actively collected, evaluated, and incorporated into the current crossing blocks for the programmed hybridization. To improve the efficiency and effectiveness, maximum mechanized-operation, multiple generations of winter nursery, and new technologies such as molecular marker-assisted selection (MAS) will also be rigorously pursued. [ABSTRACT FROM AUTHOR]