Tolerant Sugar Beet Research Articles

Carboxymethyl Chitosan Improves Sugar Beet Tolerance to Drought by Controlling Enzyme Activity and Stomatal Conductance

Carboxymethyl Chitosan Improves Sugar Beet Tolerance to Drought by Controlling Enzyme Activity and Stomatal Conductance

Aerial low‐altitude remote sensing and deep learning for in‐field disease incidence scoring of virus yellows in sugar beet

AbstractThis study investigates the potential of high‐resolution (<0.5 cm/pixel) aerial imagery and convolutional neural networks (CNNs) for disease incidence scoring in sugar beet, focusing on two important aphid‐transmitted viruses, beet mild yellowing virus (BMYV) and beet chlorosis virus (BChV). The development of tolerant sugar beet cultivars is imperative in the context of increased disease management concerns due to the ban on neonicotinoids in the European Union. However, traditional methods of disease phenotyping, which rely on visual assessment by human experts, are both time‐consuming and subjective. Therefore, this study assessed whether aerial multispectral and RGB images could be harnessed to perform automated disease ratings comparable to those performed by trained experts. To this end, two variety trials were conducted in 2021 and 2022. The 2021 dataset was used to train and validate a CNN model on five cultivars, while the 2022 dataset was used to test the model on two cultivars different from those used in 2021. Additionally, this study tests the use of transformed features instead of raw spectral bands to improve the generalization of CNN models. The results showed that the best CNN model was the one trained for BMYV on RGB images using transformed features instead of conventional raw bands. This model achieved a root mean square error score of 11.45% between the model and expert scores. These results indicate that while high‐resolution aerial imagery and CNNs hold great promise, a complete replacement of human expertise is not yet possible. This research contributes to an innovative approach to disease phenotyping, driving advances in sustainable agriculture and crop breeding.

Genomic characterization of a nematode tolerance locus in sugar beet

BackgroundInfection by beet cyst nematodes (BCN, Heterodera schachtii) causes a serious disease of sugar beet, and climatic change is expected to improve the conditions for BCN infection. Yield and yield stability under adverse conditions are among the main breeding objectives. Breeding of BCN tolerant sugar beet cultivars offering high yield in the presence of the pathogen is therefore of high relevance.ResultsTo identify causal genes providing tolerance against BCN infection, we combined several experimental and bioinformatic approaches. Relevant genomic regions were detected through mapping-by-sequencing using a segregating F2 population. DNA sequencing of contrasting F2 pools and analyses of allele frequencies for variant positions identified a single genomic region which confers nematode tolerance. The genomic interval was confirmed and narrowed down by genotyping with newly developed molecular markers. To pinpoint the causal genes within the potential nematode tolerance locus, we generated long read-based genome sequence assemblies of the tolerant parental breeding line Strube U2Bv and the susceptible reference line 2320Bv. We analyzed continuous sequences of the potential locus with regard to functional gene annotation and differential gene expression upon BCN infection. A cluster of genes with similarity to the Arabidopsis thaliana gene encoding nodule inception protein-like protein 7 (NLP7) was identified. Gene expression analyses confirmed transcriptional activity and revealed clear differences between susceptible and tolerant genotypes.ConclusionsOur findings provide new insights into the genomic basis of plant-nematode interactions that can be used to design and accelerate novel management strategies against BCN.

Ethofumesate applied at greater than labeled rates postemergence to sugarbeet

AbstractEthofumesate is a broad-spectrum, soil-applied herbicide used to control broadleaf and grass weeds in sugarbeet crops. Ethofumesate is commonly applied preemergence at rates ranging from 1.25 to 4.2 kg ai ha−1, or applied postemergence (POST), up to 0.38 kg ai ha−1. The Generic Crop Science company has developed a new Ethofumesate 4SC label that has increased ethofumesate POST rates up to 4.48 kg ha−1 in sugarbeet with more than two true leaves per plant. Field and greenhouse experiments were conducted in 2018 and 2019 to evaluate sugarbeet tolerance and herbicide efficacy. Field tolerance experiments indicated sugarbeet stature from ethofumesate applied POST at 0.28, 0.56, and 1.12 kg ha−1 was the same as that of the nontreated control, but ethofumesate at 2.24 kg ha−1 reduced sugarbeet stature, although that rate did not affect yield components. Ethofumesate applied POST at 4.48 kg ha−1 reduced sugarbeet stature and affected sugarbeet yield components. Ethofumesate applied alone POST provided weed control of up to 85%, 76%, and 84% on common lambsquarters, redroot pigweed, and waterhemp, respectively, in field efficacy experiments. Mixing ethofumesate at 1.12 kg ha−1 with glyphosate does not provide a second effective herbicide for POST control of common lambsquarters or redroot pigweed, but it does provide residual control of these weeds when at least one-half inch of penetrating rainfall occurs, following application. In greenhouse experiments, ethofumesate alone or ethofumesate plus glyphosate applied to common lambsquarters, redroot pigweed, or waterhemp at heights of less than 2.5 cm provided the best combination of burndown and soil residual control compared with weeds that were 2.5 to 5 cm tall. Ethofumesate applied POST at 1.12 kg ha−1 plus glyphosate provided the best combination of tolerance and efficacy, especially on waterhemp.

Genome-wide analysis of WD40 protein family and functional characterization of BvWD40-82 in sugar beet.

Sugar beet is one of the most important sugar crops in the world. It contributes greatly to the global sugar production, but salt stress negatively affects the crop yield. WD40 proteins play important roles in plant growth and response to abiotic stresses through their involvement in a variety of biological processes, such as signal transduction, histone modification, ubiquitination, and RNA processing. The WD40 protein family has been well-studied in Arabidopsis thaliana, rice and other plants, but the systematic analysis of the sugar beet WD40 proteins has not been reported. In this study, a total of 177 BvWD40 proteins were identified from the sugar beet genome, and their evolutionary characteristics, protein structure, gene structure, protein interaction network and gene ontology were systematically analyzed to understand their evolution and function. Meanwhile, the expression patterns of BvWD40s under salt stress were characterized, and a BvWD40-82 gene was hypothesized as a salt-tolerant candidate gene. Its function was further characterized using molecular and genetic methods. The result showed that BvWD40-82 enhanced salt stress tolerance in transgenic Arabidopsis seedlings by increasing the contents of osmolytes and antioxidant enzyme activities, maintaining intracellular ion homeostasis and increasing the expression of genes related to SOS and ABA pathways. The result has laid a foundation for further mechanistic study of the BvWD40 genes in sugar beet tolerance to salt stress, and it may inform biotechnological applications in improving crop stress resilience.

Allantoin, a purine metabolite, confers saline–alkaline tolerance to sugar beet by triggering a self-amplifying feedback loop comprising jasmonic acid and nitric oxide

Saline–alkaline (SA) soil inhibits plant growth and development. A few plants have evolved strategies to combat SA stress, but the underlying mechanisms remain elusive. In the current study, we performed a combined proteome and metabolome profiling to capture the major pathways and specified metabolites involved in the sugar beet tolerance to SA stress. Protein abundance and metabolite accumulation in purine metabolism were altered to favour allantoin accumulation under SA stress. Exogenous allantoin alleviated the oxidative damage caused by SA stress, whereas inhibition of allantoin biosynthesis weakened SA tolerance. Transcriptome analysis revealed that allantoin altered the expression patterns of genes involved in jasmonic acid (JA) and nitric oxide (NO) biosynthesis to elevate their levels under SA stress. Inhibition of allantoin biosynthesis completely abolished the JA and NO accumulation. The application of JA and NO promoted the accumulation of each other, and both enhanced SA tolerance. Inhibition of JA biosynthesis completely abolished allantoin-induced SA tolerance and NO accumulation and weakened sodium nitroprusside (SNP, a donor of NO) -induced SA tolerance, whereas inhibition of NO biosynthesis only attenuated allantoin-induced SA tolerance and JA accumulation and JA-induced SA tolerance. Our results suggest that allantoin accumulation is assisted under SA stress, promoting JA accumulation and consequently NO biosynthesis. Subsequently, NO in turn assists JA biosynthesis, forming a self-amplifying feedback loop, in which JA and NO synergistically improve SA tolerance. The current study provides a novel insight into SA tolerance in sugar beet and preliminary reveals the regulatory role of allantoin in SA tolerance.

Biological Suppression of Populations of Heterodera schachtii Adapted to Different Host Genotypes of Sugar Beet.

Productivity of sugar beet and brassica vegetable crops is constrained by the nematode Heterodera schachtii worldwide. In sugar beet cropping areas of Central Europe and North America, H. schachtii is managed by crop rotation, and cultivation of resistant brassica cover crops. The recently released nematode-tolerant sugar beet cultivars suffer less damage than susceptible cultivars at high initial population densities of H. schachtii. Many tolerant cultivars allow for less nematode reproduction than susceptible cultivars. Monoculture of susceptible hosts can facilitate the evolution of suppressive soil. Objectives of this study were to determine if susceptible hosts are required for this process, and if monoculture with sugar beet genotypes of different host status (susceptible, resistant, tolerant) impact this capacity. Additionally, we tested if amending soil with the cyst nematode pathogens Pasteuria nishizawae or Hyalorbilia sp. strain DoUCR50 favored the establishment of soil suppressiveness. In 4-year microplot studies with H. schachtii Schach0 or Schach1, one susceptible, one Schach0-resistant, and one tolerant sugar beet genotype were monocultured. In 2010, plots were amended with P. nishizawae or DoUCR50, the last being introduced into non-treated soil for Schach0, and into previously biocide-treated soil for Schach1. In 2011, respective Schach0 plots received a second amendment with DoUCR50. Nematode population densities and growth and yield parameters were determined annually. Effects of P. nishizawae and DoUCR50 on populations of H. schachtii were limited and not consistent. Starting in the second year of the monoculture, eggs of both H. schachtii pathotypes became diseased. Up to 90% of the total eggs were encumbered by the third cropping cycle, under the susceptible, resistant, and tolerant cultivar. In all years, the tolerant genotype produced the highest and most stable white sugar yields while yields of the other cultivars slowly improved during the monoculture. Results of this study suggested the presence of egg-infecting factors in this sugar beet monoculture that dramatically increased the proportions of diseased eggs. The tolerant cultivar allowed establishment of soil suppressiveness without the initial yield decline observed when susceptible sugar beet genotypes are grown in monoculture.

Environment influences sugarbeet tolerance to S-metolachlor

AbstractHerbicides used in sugarbeet are commonly adapted from other row crops and may cause injury and yield loss often associated with environmental and edaphic factors. Glyphosate-resistant waterhemp in sugarbeet requires a PRE herbicide, such as S-metolachlor, for its control. The objectives of this research were to evaluate sugarbeet tolerance to PRE S-metolachlor, including air temperature and soil water content interactions with soil series in field and growth chamber experiments. Results from field experiments conducted in 12 environments in 2015, 2016, and 2017 indicated 2.16 or 4.32 kg ai ha−1S-metolachlor applied PRE reduced sugarbeet density and stature but did not reduce root yield, sucrose content, or recoverable sucrose compared with the untreated control in environments with soils with less than 3.5% organic matter (OM) and receiving greater than 40-mm cumulative rainfall within 14 d after planting. In the growth chamber, sugarbeet density and shoot fresh weight following S-metolachlor application was influenced by soil moisture content, air temperature, and soil series but not by S-metolachlor rate. Sugarbeet density and shoot fresh weight were reduced 15% and 106%, respectively, when S-metolachlor was applied to a Glyndon sandy loam (2.6% OM, 9.5% clay) at 100% field capacity (FC) and 14 C compared with S-metolachlor application to a Fargo silty clay (7.7% OM and 54% clay) at 100% FC and 21 C. It is concluded that field selection, rather than herbicide rate, is an important criterion for managing sugarbeet tolerance with S-metolachlor.

Development of herbicide resistance in weeds in a crop rotation with acetolactate synthase‐tolerant sugar beets under varying selection pressure

SummaryThe development of acetolactate synthase (ALS) tolerant sugar beet provides new opportunities for weed control in sugar beet cultivation. The system consists of an ALS−inhibiting herbicide (foramsulfuron + thiencarbazone‐methyl) and a herbicide‐tolerant sugar beet variety. Previously, the use of ALS‐inhibitors in sugar beet was limited due to the susceptibility of the crop to active ingredients from this mode of action. The postulated benefits of cultivation of the ALS‐tolerant sugar beet are associated with potential risks. Up to now, with no relevant proportion of herbicide‐tolerant crops in Germany, ALS‐inhibitors are used in many different crops. An additional use in sugar beet cultivation could increase the selection pressure for ALS‐resistant weeds. To evaluate the impact of varying intensity of ALS‐inhibitor use on two weed species (Alopecurus myosuroides and Tripleurospermum perforatum) in a crop rotation, field trials were conducted in Germany in two locations from 2014 to 2017. Weed densities, genetic resistance background and crop yields were annually assessed. The results indicate that it is possible to control ALS‐resistant weeds with an adapted herbicide strategy in a crop rotation including herbicide‐tolerant sugar beet. According to the weed density and species, the herbicide strategy must be extended to graminicide treatment in sugar beet, and a residual herbicide must be used in winter wheat. The spread of resistant biotypes in our experiments could not be attributed to the integration of herbicide‐tolerant cultivars, although the application of ALS‐inhibitors promoted the development of resistant weed populations. Annual use of ALS‐inhibitors resulted in significant high weed densities and caused seriously yield losses. Genetic analysis of surviving weed plants confirmed the selection of ALS‐resistant biotypes.

VARIETAL TOLERANCE OF SUGAR BEET (BETA VULGARIS L.) TO WATER STRESS

Two field experiments were conducted in the experimental farm, faculty of Agriculture, Cairo university, Giza, Egypt during 2014/2015 and 2015/2016 seasons to evaluate the tolerance of two monogerm sugar beet varieties: Puma and Palace cevek, and two multigerm varieties: Monte Bianko and Ninagri to water depletion levels (25, 50 and 75% of the available soil moisture). Puma variety was the most tolerant sugar beet variety according to stress tolerance index (STI) along with recorded the highest leaf area index (LAI) and plant dry weight at 150, 175 and 200 days after sowing as well as the highest root and sugar yields, followed by Monte Bianko, Ninagri and Palace cevek variety throughout the growing seasons, while the highest sucrose, purity and sugar recovery (SR) percentages resulted from Palace cevek variety. Increasing water depletion level from 25 up to 75% negatively affect beet growth traits and decreased root yield by 17.45 and 17.44% and sugar yield by 11.63 and 9.94% in the first and second seasons, respectively. On the contrary, sucrose, purity and SR significantly increased as water depletion increased, in addition to, the water use efficiency (WUE) increased by 48.3 and 40.1% in the 1st and 2nd seasons, respectively. Puma variety irrigated with 25% water depletion produced the highest LAI, plant dry weight, potassium and sodium content as well as root and sugar yields.

Nematode-tolerant sugar beet varieties – resistant or susceptible to the Beet Cyst Nematode Heterodera schachtii?

The beet cyst nematode Heterodera schachtii (BCN) is an important parasite compromising yield of sugar beet. Standard sugar beet varieties are susceptible to BCN and strongly support BCN reproduction. Another type of variety is resistant to BCN. Although resistance leads to reduced nematode infestation levels, the yield potential of available resistant varieties is low. Tolerant varieties form a third type; high yield is produced with and without BCN infestation. However, so far it has remained unknown whether tolerant sugar beet varieties support or reduce BCN infestation and reproduction under field conditions. In order to address this question, the impact of five tolerant beet varieties on BCN population levels was investigated at 15 locations during a period of three years and compared to a resistant and a susceptible variety. The results demonstrate that all tolerant varieties led to population levels that ranged between that of the susceptible and that of the resistant variety. According to the respective BCN reproduction, the different varieties were classified as moderately susceptible (MS) or highly susceptible (HS) or as moderately resistant (MR) or highly resistant (HR). Tolerant varieties differed in their host status but tended to respond moderately resistant. In conclusion, it is suggested to include the analysis of resistance level either in the official registration procedure for BCN-tolerant sugar beet varieties or to perform this analysis for all registered varieties as a kind of risk assessment.

The mRNA sequence polymorphisms of flowering key genes in bolting sensitive or tolerant sugar beet genotypes

The mRNA sequence polymorphisms of flowering key genes in bolting sensitive or tolerant sugar beet genotypes

Quantitative reproductive potential of Heterodera schachtii on weeds typical for late summer fallow in sugar beet rotations

SummaryIn Europe, sugar beet is often produced in a 3‐year rotation with cereals, leaving stubble fields fallow from cereal harvest until primary tillage in autumn in the year prior to sugar beet production. The weed flora on such fields could include host plants of Heterodera schachtii that is one of the most important pests of sugar beet. Crop sequences with non‐hosts and cover cropping with resistant cruciferous hosts during this period have been crucial for its management. Availability of resistant and tolerant sugar beet cultivars could entice growers to forego cover cropping, exacerbating weed problems during the fallow period. The objective of this study was to determine the reproductive potential of H. schachtii on weeds that develop during this period. Under glasshouse conditions, reproduction on 39 plant species was compared with that on oilseed radish and sugar beet of differing nematode host status. In 2 years in field microplots, 18 previously tested species were grown in H. schachtii‐infested soil during the typical fallow period at 60 plants m−2, and nine of these species were also grown at 180 plants m−2. There were variable results between years after 8 weeks of growth, but most weeds allowed lower reproduction (<10%) than the susceptible sugar beet; only Stellaria media at 180 plants m−2 and Thlaspi arvense at both plant densities increased nematodes. Such weed densities may seldom occur under commercial conditions; thus, weed management for nematological considerations during the stubble period may have limited importance.

Growth analysis of rhizomania infected and healthy sugar beet

Viral disease of rhizomania is one of the most important diseases of sugar beet all over the world. The disease significantly has reduced the yield and quality of sugar beet, and has imposed high economic loss to farmers. Long-term breeding programs to introduce tolerant cultivars are the only chance of avoiding further yield losses. This study tried to measure and analyze the growth of shoots and roots of rhizomania-tolerant and -susceptible sugar beet with the aim of providing information for modeling of the rhizomania effects on the growth of sugar beet. Growth indices were used for analyzing, quantification, and time-course of sugar beet growth under infested and non-infested soils conditions. A 2-year experiment was conducted using four sugar beet cultivars in 2010 and 2011 in Mashhad, Iran. The results of this study showed that under infested soils, root dry matter and leaf area index of the susceptible cultivars in comparison to tolerant cultivars were lower by 57 and 24%, respectively. In addition, crop growth rate and net assimilation rate of susceptible cultivars were affected by rhizomania and were lower than in tolerant cultivars. On non-infested soil, the difference between dry matter and growth indices of susceptible and tolerant sugar beet cultivars was not significant. Rhizomania decreased green area and photosynthesis capacity and led to lower growth rate and dry matter production. Our study quantified the growth of rhizomania-infested sugar beet plants in comparison with non-infested plants and provided information to be used for modeling of the rhizomania effects on the growth of sugar beet.

Vertical Distribution of Heterodera schachtii under Susceptible, Resistant, or Tolerant Sugar Beet Cultivars.

Heterodera schachtii is managed by rotation with non-hosts, resistant cover crops, and resistant and tolerant sugar beet cultivars. Microplots 60 cm deep and 30 cm in diameter containing steamed field soil were (i) noninfested or infested with 550 H. schachtii eggs per 100 g at (ii) 0 to 60 cm, (iii) 0 to 30 cm or (iv) 30 to 60 cm in depth. Plots were planted to susceptible, resistant, and tolerant sugar beets. Five weeks later, the sugar beet canopy was largest in condition i, smallest in condition ii, and intermediate in conditions iii and iv. White sugar yield (WSY) was highest in condition i, second in condition iv, lowest in condition ii, and intermediate in condition iii. Cultivar-specific final nematode numbers were independent of the level of infestation. In two experiments utilizing 1-m2 microplots, naturally occurring H. schachtii populations were suppressed with fosthiazate at depth layers in reverse to those infested in the first experiment, and planted to susceptible, resistant, and tolerant sugar beets. In one experiment, WSY was highest in soil treated with fosthiazate at 0 to 60 cm in depth, lowest in nontreated, unaffected in soil treated at 30 to 60 cm in depth, and somewhat lower in soil treated at 0 to 30 cm in depth. In all cultivars, early root penetration predicted canopy diameter; only in the susceptible cultivar did the canopy diameter predict WSY. Deep-occurring H. schachtii can impact productivity in sugar beet cropping.

Using a selective fast turn-around bioassay for population density determination of Heterodera schachtii

In Central Europe, Heterodera schachtii is kept below threshold levels by cover-cropping with resistant crucifers and crop rotation with non-hosts. Determining population densities of H. schachtii in soil is critical when implementing resistant and tolerant sugar beet cultivars in integrated pest management (IPM) programmes. Soil extraction of the cysts followed by egg counts or extraction of the second-stage juveniles (J2) facilitated by the chemical stimulant acetox can be unsatisfactory in mixed field populations of cyst nematodes. In contrast to H. schachtii, nematodes typically present in sugar beet soils, e.g., Globodera pallida, G. rostochiensis, H. avenae, H. filipjevi, Meloidogyne hapla, M. incognita and Pratylenchus penetrans, rarely penetrated radish roots. In this bioassay, equivalents of 50 g of soil dry weight were adjusted to 10-20% moisture, seeded with Raphanus sativus cv. Saxa 3, and incubated at a day-night (16:8 h) cycle of 28/23°C for 4 days before J2 in radish roots were enumerated. In different soil types, penetration by H. schachtii reflected the inoculation levels. When inoculated with mixes of H. schachtii with H. avenae or H. filipjevi, counts of H. schachtii were similar to those in soils with H. schachtii only. When comparing three methods in three soils spiked with H. schachtii cysts, the bioassay and the extraction method were lightly impacted by the soil texture but results of the acetox method varied with texture. When implemented for field samples from Franconia, the radish bioassay and the acetox method provided results related to cyst and egg extraction data. The radish bioassay provided a quick and easy method for quantifying H. schachtii in the presence of other nematode species in a wide range of soil types. Including this assay in IPM programmes may serve as an alternative to standard methods and will improve the decision making in sustainable production systems.

Bred for Europe but grown in America: the case of GM sugar beet

In 2007, a genetically modified herbicide tolerant (GMHT) sugar beet (Beta vulgaris L.) tolerant against glyphosate, a commonly used broad spectrum herbicide, was commercialised in the USA and Canada. The speed of uptake of GMHT sugar beet by farmers has no precedent. While it took the hitherto most successful GM crop in the USA 15 years to reach an adoption rate of 95%, GMHT sugar beet achieved this figure after only 2 years. This paper traces the history of GMHT sugar beet which started at the European continent and describes the economic and environmental impact of its introduction in the USA. The results suggest that the rapid adoption is economically sound with adopter rents averaging $257/ha. Moreover the adoption has a high potential to reduce the environmental impact of sugar beet production. Will these experiences bring GMHT sugar beet back to its roots in Europe?

Biochemical analysis of drought tolerant sugarbeet mutants induced with gamma radiation

Biochemical analysis of drought tolerant sugarbeet mutants induced with gamma radiation

Effect of Chlorimuron-Ethyl on Biochemical Mechanism in Tolerant Sugar Beet

Effect of chlorimuron-ethyl on biochemical mechanism in tolerant sugar beet was investigated to provide basic data on using the tolerant genotype properly. Tolerant sugar beet was used to analyze its biochemical mechanism under chlorimuron-ethyl stress with frame culture in field and water culture. Glutathione S-transferase (GST) activity of leaves in tolerant sugar beet was remarkably increased as chlorimuron-ethyl was preemergence applicated at 0.5 and 1.5 g a.i. ha -1, at the same time glutathione (GSH) content increased 50.0-490.1 μg g -1. GST activity of sensitive sugar beet decreased 122.6 U mg -1 min -1 compared with tolerant sugar beet and GSH content only increased to 7.4 μg g -1 at chlorimuron-ethyl 0.5 g a.i. ha -1 in sensitive sugar beet. The higher GST activity and GSH content conjugated chlorimuron-ethyl absorbed in tolerant sugar beet and made it lost activity. Acetolactate synthases (ALS) activity of the tolerant sugar beet increased to 62.5 and 70.6%, respectively in seedling and leaf growth period, at the same time ALS activity of the sensitive variety was decreased to 36.8 and 64.8%, respectively. The rapidly increased GST activity, GSH content, and ALS, the target enzyme activity were the important pathways for enduring chlorimuron-ethyl in tolerant sugar beet.

Optimizings-Metolachlor and Dimethenamid-P in Sugarbeet Microrate Treatments

Field trials were conducted in East Lansing, MI in 2004 and 2005 and in St. Charles, MI in 2004, 2005, and 2006 to compare weed control and sugarbeet tolerance from microrate herbicide treatments that includeds-metolachlor and dimethenamid-P. Treatments included the base microrate treatment alone and with full- and split-application rates ofs-metolachlor at 1.4 kg/ha or dimethenamid-P at 0.84 kg/ha at the various microrate application timings. All treatments injured sugarbeet. In 2004 and 2006, full rates of boths-metolachlor and dimethenamid-P applied PRE or in the first microrate application injured sugarbeet more than the base microrate treatment. Whens-metolachlor or dimethenamid-P were split-applied between PRE and the third microrate application or between the first and the third microrate applications, injury was still greater than from the base microrate treatment. Furthermore, applying dimethenamid-P at one-fourth the full rate in all four microrate applications injured sugarbeet more than the base microrate treatment. A full rate ofs-metolachlor or dimethenamid-P applied in either the third or fourth microrate applications or splitting the applications between the second and fourth microrate treatments did not increase sugarbeet injury compared with the base microrate treatment. Control of common lambsquarters and giant foxtail from all treatments containings-metolachlor or dimethenamid-P, regardless of the time of application, was greater than from the base microrate treatment at all locations. Pigweed spp. control was 94% or greater from all treatments. In 2004, late-season control of giant foxtail was greater from all treatments that includeds-metolachlor or dimethenamid-P compared with the base microrate treatment. In 2005, the only treatments that did not improve late-season giant foxtail control compared with the base microrate treatment were the treatments that included a full rate ofs-metolachlor or dimethenamid-P applied in the fourth microrate application. Even though some herbicide treatments that includeds-metolachlor or dimethenamid-P injured sugarbeet more than the base microrate treatment, recoverable sucrose per hectare was similar among treatments.