The invasion of waterhemp into northern sugarbeet growing regions has prompted producers to re-integrate inter-row cultivation into weed management programs, as no currently registered herbicides can control glyphosate-resistant waterhemp POST in crop. Inter-row cultivation was a common weed control practice in sugarbeet until the release of glyphosate-resistant sugarbeet cultivars in 2008 made the use of inter-row cultivation unnecessary. In the late 2010s, producers began again to use inter-row cultivation to remove weeds that glyphosate did not control, but producers need information on the effectiveness and safety of inter-row cultivation when used with soil-residual herbicide programs. Efficacy and tolerance field experiments were conducted in Minnesota and North Dakota from 2017 to 2019. Results from the efficacy experiment demonstrated that cultivation improved waterhemp control 11% and 12%, 14 and 28 d after treatment, respectively. Waterhemp response to cultivation was dependent on crop canopy and precipitation after cultivation. Cultivation had minimal effect on waterhemp density in three environments, but at one environment, near Galchutt, ND in 2019, waterhemp density increased 600% and 196%, 14 and 28 d after treatment, respectively. Climate data indicated that in 2019 Galchutt, ND received 105 mm of precipitation in the 14 d following cultivation and had an open crop canopy that probably contributed to further weed emergence. Results from the tolerance experiment demonstrated that root yield and recoverable sucrose were not affected by cultivation timing or number of cultivations. In one environment, cultivating reduced sucrose content by 0.8% regardless of date or cultivation number, but no differences were found in four environments. Damage/destruction of leaf tissue from in-season cultivation is probably responsible for the reduction in sucrose content. Results indicate that cultivation can be a valuable tool to control weeds that herbicide cannot, but excessive rainfall and open crop canopy following cultivation can create an environment conducive to further weed emergence.

A prepackaged mixture of desmedipham + phenmedipham was previously labeled for control of Amaranthus spp. in sugarbeet. Currently, there are no effective POST herbicide options to control glyphosate-resistant Palmer amaranth in sugarbeet. Sugarbeet growers are interested in using desmedipham + phenmedipham to control escaped Palmer amaranth. In 2019, a greenhouse experiment was initiated near Scottsbluff, NE, to determine the selectivity of desmedipham and phenmedipham between Palmer amaranth and sugarbeet. Three populations of Palmer amaranth and four sugarbeet hybrids were evaluated. Herbicide treatments consisted of desmedipham and phenmedipham applied singly or as mixtures at an equivalent rate. Herbicides were applied when Palmer amaranth and sugarbeet were at the cotyledon stage, or two true-leaf sugarbeet stage and when Palmer amaranth was 7 cm tall. The selectivity indices for desmedipham, phenmedipham, and desmedipham + phenmedipham were 1.61, 2.47, and 3.05, respectively, at the cotyledon stage. At the two true-leaf application stage, the highest rates of desmedipham and phenmedipham were associated with low mortality rates in sugarbeet, resulting in a failed response of death. The highest rates of desmedipham + phenmedipham caused a death response of sugarbeet; the selectivity index was 2.15. Desmedipham treatments resulted in lower LD50 estimates for Palmer amaranth compared to phenmedipham, indicating that desmedipham can provide greater levels of control for Palmer amaranth. However, desmedipham also caused greater injury in sugarbeet, producing lower LD50 estimates compared to phenmedipham. Desmedipham + phenmedipham provided 90% or greater control of cotyledon-size Palmer amaranth at a labeled rate but also caused high levels of sugarbeet injury. Neither desmedipham, phenmedipham, nor desmedipham + phenmedipham was able to control 7-cm tall Palmer amaranth at previously labeled rates. Results indicate that desmedipham + phenmedipham can only control Palmer amaranth if applied at the cotyledon stage and a high level of sugarbeet injury is acceptable.

The performance of four sequential weed management models that assumed either low or high risk was compared to the performance of two sugarbeet consultants, one who assumed low risk and the other high risk. Weed management recommendations were performed over one growing season at two locations, each with several levels of weed populations. Recommendations for preplant, postemergence, and layby herbicide treatments or late-season handweeding differed among the four weed management levels. The high-risk management level was labor intensive and the low-risk management level was herbicide intensive. Weed populations at harvest, recoverable sucrose, and net return above weed control costs were not different among the four weed management levels. Weeds can be controlled in sugarbeets by employing weed management practices based on bioeconomic modeling.

The performance of a mechanistic simulation model of crop-weed competition was tested with data on the critical period of weed competition in sugarbeets and both seeded and transplanted tomatoes. In general, there was good agreement between simulated and observed yields for different periods of weed interference in each crop. The model was then used to evaluate the influence of weed density, weed height, and weather conditions on timing of the critical period. Simulations suggested that the greater the weed density, the shorter the period of time that the crop could tolerate early-season competition, and the longer the period of time that the crop must be kept weed free to prevent yield losses. Simulations also suggested that the length of time that a crop can tolerate early-season weed competition is related more to the availability of soil moisture, or possibly essential nutrients, than to light limitations.

Bioeconomic sugarbeet weed management models for preplant, postemergence, and layby herbicides, and late-season handweeding decisions are presented. The personal computer/spreadsheet models are based on number of weed seed in soil, field survey of weed populations, growth stages of weeds and sugarbeets, expected yield loss from weeds, herbicide weed control, weed control cost, and sugarbeet price. The models incorporate two producer risk levels. Several weed scenarios were used to verify the models for reasonable recommendations.

Greenhouse and field experiments were conducted to determine whether PRE-applied ethofumesate increased POST spray retention and weed control with glyphosate. In greenhouse studies, ethofumesate was applied PRE at rates from 0 to 224 g ai ha−1 followed by POST treatment with either water or glyphosate (840 g ae ha−1) to which a red dye had been added. Plants were immediately washed and spray retention determined spectrophotometrically. Common lambsquarters retained more glyphosate solution compared to water, regardless of PRE ethofumesate rate. Increasing the rate of PRE ethofumesate increased the POST spray retention of both water and glyphosate. PRE application of ethofumesate increased POST spray retention of water by 114% and glyphosate solution by 18% compared to no ethofumesate treatment as determined by nonlinear regression. Ethofumesate rates of 90 g ha−1 increased POST spray retention to at least 95% of the total observed response. In field studies, common lambsquarters, redroot pigweed, and hairy nightshade densities were all reduced by ethofumesate, although the duration of ethofumesate effect varied by species and ethofumesate application timing. PRE ethofumesate had no significant effect on hairy nightshade density until after POST glyphosate was applied, whereas common lambsquarters densities were most affected by PRE ethofumesate early in the season. Late-season redroot pigweed density was reduced by ethofumesate regardless of application timing.

An integrated approach based on the use of bioinformatics and gene expression analysis tools was carried out to evaluate the organ-specific transcription modulation of nine genes relevant to sugar metabolism of Beta vulgaris L. plantlets of the autumn cv. Franca and spring cv. Bianca, in response to low-temperature (LT) treatments. Different growth cycles imply different plant capability to adapt to the environment that includes variations in gene expression of key metabolic enzymes. The transcriptional response was evaluated by quantitative PCR analysis before, during and after the LT treatments. The results were correlated with the LT-induced electrolyte leakage measure and the carbohydrate content. Stress-induced transcript level alterations were detected in the two cultivars, suggesting a modulation of sucrose synthesis and carbohydrate partitioning. Cold stress induced deep changes in the autumn cultivar, especially in fructose-1,6-biphosphatase gene expression, irrespective of temperature or exposure time. These differential features of expression profiles constitute first clues on the molecular basis of the differential LT response of sugarbeet autumn and spring cultivars.

The basic B-subunit of the seed storage protein 11-S globulin (an 11-S-legumin type protein) is the major polypeptide in soluble protein extracts from primed sugarbeet (Beta vulgaris L.) seeds. In contrast, only a small amount of this protein is present in corresponding extracts from untreated dry mature seeds. Here, and as for all 11-S globulins described so far, the B-chain is linked to other polypeptide(s), corresponding most presumably to an acidic A-chain, through the formation of disulphide bridge(s). Polyacrylamide gel electrophoretic analyses of total and soluble protein extracts from untreated and primed seeds strongly indicate that this priming-induced solubilization of the B-chain resulted from an endoproteolytic attack on the A-chain. Microscopical immunolocalization showed a uniform distribution of the 11-S globulin B-chain over the protein bodies of the embryonic cells from the untreated seeds. For the primed seeds, however, the B-subunit of 11-S globulin diffused out of the protein bodies and invaded the cytosolic compartment. This phenomenon occurred independently of the manner of priming, being observed with hydroprimed and osmoprimed seeds, as well as with sugarbeet seeds that had been primed by a prehydration treatment. Quantitative analyses of the amounts of soluble 11-S globulin B-chain have enabled the priming of sugarbeet seeds to be optimized.

Priming of sugarbeet (Beta vulgaris L.) seeds induces increased solubilization of the basic B-subunit of 11-S globulin (a major seed storage protein in sugarbeet). Using a sensitive single-seed ELISA, the soluble and total B-subunit contents of individual untreated and primed sugarbeet seeds were measured. With the untreated seeds, there was a 160-fold range of the soluble B-subunit content among individual seeds. The individual primed seeds also exhibited large variations in their soluble B-subunit content, yet only over a five-fold range. Furthermore, the frequency distributions of soluble B-subunit content were markedly different for the primed and untreated seed populations; the primed seed population exhibited a substantially higher median than that for the untreated seed population. In marked contrast, and as expected from results with pooled seed samples, the distributions of total B-subunit content were superimposed when comparing untreated and primed seed populations.

The relationship between initial mobilization of 11-S globulin storage protein (leading to solubilization of its B-subunit) and germination performance after priming was studied in sugarbeet (Beta vulgaris L.) seeds. Priming was conducted for 2 d either in water (hydropriming) or in –2.0 MPa polyethylene glycol-8000 (osmopriming), at various temperatures ranging from 5 to 40°C and oxygen concentrations in the atmosphere ranging from 0 to 21%. For both types of pre-treatments, the range of temperatures and the concentrations of oxygen which were effective in priming were very similar to those which allowed solubilization of the B-subunit of 11-S globulin, supporting the robustness of this protein marker for optimization of sugarbeet seed priming. Furthermore, the temperature and oxygen dependence of priming efficiency closely paralleled that for germination of the untreated seeds, reinforcing the finding that the beneficial effect of priming corresponded to the advancement of germination sensu stricto (i.e. phase II of the germination process). For priming times longer than 2 d, particularly for osmopriming, there was a very dramatic decrease in germination of the treated seeds. For instance, following a 14 d osmopriming at 25°C as much as 60% of the pre-treated seed population failed to germinate when transferred to water. This loss in germination performance quite closely paralleled degradation of LEA (late embryogenesis abundant) proteins, notably a heat-stable seed-specific protein of about 60 kDa and a seed-specific biotinylated LEA protein.