Residues of aldicarb and its main metabolites in the leaves of sugar beet plants

The residues of aldicarb and of its main metabolites (aldoxycarb, 2-mesyl-2-methylpropionitrile, and 2-mesyl-2-methylpropan-1-ol) were measured, by a gas-liquid chromatographic procedure, in the leaves of ripe sugar beet plants from cultures made by several farmers. The sugar beet plants had been grown in normal fields and treated at sowing with aldicarb at the usual rate of 1 kg ha^?1 in the form of ‘Temik’, the commercial formulation of aldicarb which contains 10% by weight of aldicarb. The samples of sugar beet plants were taken from three fields of different soil types. The residue concentrations, ranged in order of soil type, were: sandy loam > silt loam > clay.     

Distribution of the radioactivity in sugar beet plants treated with [14C]aldicarb

Sugar beet plants were grown in the field, after in-furrow application of [¹⁴C]aldicarb (3 kg of aldicarb ha^?1) at planting. Some plants (the growing plants) were harvested 99 days after sowing and the rest (the ripe plants) 196 days after sowing. The percentages of the weights of [¹⁴C]aldicarb equivalents (the total aldicarb plus aldicarb sulphoxide and sulphone, plus all the other metabolites of [¹⁴C]aldicarb which contain ¹⁴C, expressed as aldicarb equivalents) incorporated into the beet plants, relative to the weight applied to the soil, were 2.8 and 1.8, respectively for the growing and ripe plants. The concentrations of [¹⁴C]aldicarb equivalents (mg kg^?1 fresh weight) in the growing and ripe plants, respectively were: blades of the external leaves, 3.16 and 0.93; blades of the internal leaves, 0.63 and 0.68; petioles of the external leaves, 0.51 and 0.26; petioles of the internal leaves, 0.15 and 0.05; crowns, 0.14 and 0.15; roots, 0.16 and 0.13. The proportions of the extractable aldicarb plus aldicarb sulphoxide and aldicarb sulphone determined by gas-liquid chromatography (expressed as aldicarb equivalents) relative to [¹⁴C]aldicarb equivalents, in the external and internal leaf blades of the growing beets, were 56 and 60%, respectively; these values declined to 25 and 19%, respectively in the ripe plants. The proportion was 21 % or less in all other parts of the growing and ripe plants.     

The metabolism of [14C]aldicarb in the root of sugar beet plants

Sugar beet plants were grown in the field, after in-furrow application of [¹⁴C]- aldicarb (3 kg of aldicarb ha^?1) at planting. The ripe sugar beet plants were harvested, and the roots were analysed. The roots were fractionated according to a procedure similar to the normal beet-sugar manufacturing process. Expressed as a proportion of the total radioactivity incorporated into the root, the pulp contained 29.7%, the lime cake 9.7%, the crystallised sugar 17.7% (which gave, with the radioactivity found in the sugar in the molasses, a total of 20.7% of the radioactivity in the total sugar), and the molasses, 42.9%. A part of the labelled carbon from the radio- active aldicarb and its metabolites had thus been metabolised and incorporated into sugar molecules. Except for the radioactivity in the sugar and in the lime cake from the processing, the proportion of radioactive non-conjugated organosoluble compounds was very low (2.6%), and perhaps partially corresponded to the very low amount of aldoxycarb (aldicarb sulphone) in the root (less than 0.001 mg of [¹⁴C]-aldicarb equivalents kg^?1 fresh weight). Hydrolysis of the molasses yielded free radioactive 2-methyl-2-(methylsulphinyl)propan-1-ol (3.1%), 2-mesyl-2-methyl-propan-I-ol (8.9%) and 2-mesyl-2-methylpropionic acid (12.0%) which had been conjugated to plant constituents in the root. The corresponding concentrations (expressed as mg of [¹⁴C]aldicarb equivalents kg^?1 fresh weight of root) were 0.004, 0.011, and 0.016, respectively. No aldicarb, aldicarb sulphoxide or aldoxycarb (nor the corresponding nitrile, generated from aldicarb during the fractionation procedure) was liberated by the hydrolysis, indicating the absence of conjugates of these compounds in the root.     

The metabolism of [14C]aldicarb in the leaves of sugar beet plants

Sugar beet plants were grown in the field, after in-furrow application of [¹⁴C]aldicarb (3 kg of aldicarb ha^?1) at planting. The ripe sugar beet plants were harvested, and the blades and petioles of the leaves were analysed separately. In the whole leaves, 15% of the ¹⁴C (all the percentages of ¹⁴C are relative to the total ¹⁴C incorporated into the whole leaves) was insoluble in ethanol+ water (1+1 by volume), 31% was organo-soluble (and thus unconjugated in the leaves), and 54% was water-soluble (mainly conjugated to plant constituents). The weights and concentrations (as aldicarb equivalents) of various identified metabolites of aldicarb, incorporated into the leaves, were determined; no aldicarb, as such, was detected.     

Evaluation of a pelleted bait containing methyl anthranilate as a bird repellent

No-till agriculture involves the use of granular pesticide formulations, chemically treated seeds, and pelleted baits. Some of these may accidentally kill birds. We have tested whether methyl anthranilate (MA), a known bird repellent, would eliminate consumption of a pelleted bait. In two laboratory experiments and an outdoor aviary trial, cowbirds (Molothrus ater Bodd.) were presented with pellets containing pesticide and MA, pellets containing pesticide but no MA, and carrier pellets without pesticide or MA. Consumption of any formulation was low, but the addition of MA significantly decreased bait loss in the laboratory, and prevented the disappearance of bait in the outdoor trial.     

The efficacy of seed treatment with aldicarb to establish conditioned aversion in birds to sprouting sugar beets

The cotyledons and stems of sugar beet sprouts from seeds each treated with 8 mg Temik granules containing 0.8 mg aldicarb, were noxious to adult Japanese quails (Coturnix coturnix) and to 3-week-old chickens of domestic fowl. Mortality rate, intensity of poisoning situation, and the time interval between feeding and appearance of poisoning signs, corresponded with the number of sprouts fed. The taste of aldicarb residues in the sprouts was discriminable by the birds as well.     

Bait crops and mesurol sprays to reduce bird damage to sprouting sugar beets

The efficacy of two treatments in protecting sugar beet sprouts from damage by birds was tested. Dense sowing of inexpensive sugar beet seeds as an alternative food between the rows of the commercial planting reduced the damage to the commercial crop by about 9%. The same treatment followed by foliar spray (2.25 kg a.i./ha) of Mesurol — a chemical repellent — gave a ～20% reduction in damage, but losses were still heavy. The effects of plot size and of local conditions are discussed.     

Rhizomania disease of sugar beet in England

Rhizomania disease was first detected in the UK in 1987, in a single crop in Suffolk. Affected plants had pale leaves, often upright, narrow and rolled; roots were small, often with constrictions, warty outgrowths, proliferation of fibrous roots, and vascular staining. Disease occurred in strips at right angles to one another, parallel with directions of cultivation, suggesting that the previous beet crop had also been infected. Beet necrotic yellow vein virus was detected by ELISA, by electron microscopy, and by transmission to indicator species. It was sometimes associated with beet soil-borne virus. The affected crop was destroyed with herbicide. No other outbreaks were detected in subsequent surveys of crops in 1987.     

Procedures and potentialities in sugar beet production

Cultivation procedures for the sugar beet crop continue to change considerably in England. The average contract per grower has increased from 3.4 in 1936 to 8.2 ha in 1973. Within the last decade the use of genetic monogerm seed has extended to 65% of the area sown, and pelleted seed to 90%. Seed spacing has doubled and the hand work needed to establish the crop drastically decreased. Much of the crop is now sown in March, instead of April or even May. The average yield of sugar has increased since 1936 from less than 3.6 to over 6 t ha^?1. These changes have been associated with routine usage of fungicide and insecticide on seed and chemical weed control on 90% of the crop in recent years; insecticide, mainly organophosphorus, has been used to control aphids and virus on 36 000 to 125 000 ha of crop annually on the basis of spray warnings; sporadic pesticide control has been used against an abundance of seedling, leaf- and root-eating pests and fungi. The changes in cultural practices have been paralleled by changes in the relative importance of the various pests and diseases—for instance, wide seed spacing and the use of herbicide have intensified seedling pest problems. The extent to which crop losses from weeds, pests and diseases have been assessed as a basis for recommendations for control is discussed, as well as the economics of control by pesticides.     

Resistance to some organophosphorus insecticides in field populations of Myzus persicae from sugar beet in 1974

Following the failure of insecticides to control Myzus persicae on sugar beet, populations from the field were examined for susceptibility to dimethoate. Topical application of discriminating doses of dimethoate showed a 30-fold variation in susceptibility between different populations. After this preliminary screening, clones were established from some populations and their resistance determined by both topical application and a systemic bioassay. This confirmed resistance to dimethoate and demonstrated resistance to demeton-S-methyl. There was no resistance to some other compounds tested. In all populations tested, resistance was associated with increased carboxylesterase activity.     

New insights into virus yellows distribution in Europe and effects of beet yellows virus,beet mild yellowing virus,and beet chlorosis virus on sugar beet yield following field inoculation

Beet yellows virus (BYV), beet mild yellowing virus (BMYV), beet chlorosis virus (BChV), and beet mosaic virus (BtMV) cause virus yellows (VY) disease in sugar beet. The main virus vector is the aphid Myzus persicae. Due to efficient vector control by neonicotinoid seed treatment over the last decades, there is no current knowledge regarding virus species distribution. Therefore, Europe-wide virus monitoring was carried out from 2017 to 2019, where neonicotinoids were banned in 2019. The monitoring showed that closterovirus BYV is currently widely spread in northern Europe. The poleroviruses BMYV and BChV were most frequently detected in the northern and western regions. The potyvirus BtMV was only sporadically detected. To study virus infestation and influence on yield, viruses were transmitted to sugar beet plants using viruliferous M. persicae in quadruplicate field plots with 10% inoculation density simulating natural infection. A plant-to-plant virus spread was observed within 4 weeks. A nearly complete infection of all plants was observed in all treatments at harvest. In accordance with these findings, a significant yield reduction was caused by BMYV and BChV (−23% and −24%) and only a moderate reduction in yield was observed for BYV (−10%). This study showed that inoculation at low densities mimics natural infection, and quick spreading induced representative yield effects. Within the background of a post-neonicotinoid era, this provides the basis to screen sugar beet genotypes for the selection of virus tolerance/resistance and to test the effectiveness of insecticides for the control of M. persicae with a manageable workload.     

Identification of sugar beet germplasm EL51 as a source of resistance to post-emergence Rhizoctonia damping-off

Resistance of sugar beet seedlings to Rhizoctonia damping-off caused by Rhizoctonia solani has not been described. A series of preliminary characterisations using a single susceptible host and four different R. solani isolates suggested the disease progression pattern was predictable. Two AG-4 isolates and a less virulent AG-2-2 isolate (W22) showed a comparable pattern of disease progression in the growth chamber where disease index values increased for the first 5–6 days, were relatively constant for the next 7–8 days, and declined thereafter. Seedlings inoculated with a highly virulent AG-2-2 isolate (R-1) under the same conditions showed similar patterns for the first 4 days post-inoculation; however disease index values continued to increase until seedling death at 13–14 days. Similar results were observed in the greenhouse, and a small expanded set of other germplasm lines were screened. One tested germplasm accession, EL51, survived seedling inoculation with R. solani AG-2-2 R-1, and its disease progress pattern was characterised. In a field seedling disease nursery artificially inoculated with R. solani AG-2-2 R-1, seedling persistence was high with EL51, but not with a susceptible hybrid. Identification of EL51 as a source of resistance to Rhizoctonia damping-off may allow investigations into the Beta vulgaris–Rhizoctonia solani pathosystem and add value in sugar beet breeding.     

Soil metabolism of the herbicide napropamide in cereals, maize, sugar beet and vegetable field replacement crops

The metabolism of the herbicide napropamide has been studied in the field in the soil of replacement crops (cereals, corn, sugar beet, potato and several vegetables). Napropamide was soil applied in the autumn and the soil left fallow during the winter. Crops were sown in April of the following year and simulated the replacement crops that are grown in the event of failure of the first autumn-sown crop. Trials were made twice, i.e. during the 1987-1988 and 1988-1989 crop seasons. The soil metabolism of napropamide was also studied in a rose nursery. Napropamide was transformed by microbiological processes in the soil into the corresponding monoethylamide and acid. These compounds did not generally accumulate in the soil, and their individual concentrations did not exceed that of residual napropamide during the observed growing seasons. The kinetics, metabolic pathways and agricultural implications of the herbicide are briefly discussed.     

Differential sensitivity of Atriplex patula and Chenopodium album to sugar beet herbicides: a possible cause for the upsurge of A. patula in sugar beet fields

In the last decade, the prevalence of Atriplex patula as a weed in the Belgian sugar beet area has increased. Possible reasons for its expansion in sugar beet fields, besides a poor implementation of the low‐dose phenmedipham/activator/soil‐acting herbicide (FAR) system, might be low sensitivity or evolved resistance to one or more herbicides used in sugar beet. Dose – response pot bioassays were conducted in the glasshouse to evaluate the effectiveness of five foliar‐applied sugar beet herbicides (metamitron, phenmedipham, desmedipham, ethofumesate and triallate) and three pre‐plant‐incorporated herbicides (metamitron, lenacil, dimethenamid‐P) for controlling five Belgian A. patula populations. Local metamitron‐susceptible and metamitron‐resistant populations of Chenopodium album were used as reference populations. Effective dosages and resistance indices were calculated. DNA sequence analysis of the photosystem II psbA gene was performed on putative resistant A. patula populations. Overall, A. patula exhibited large intraspecific variation in herbicide sensitivity. In general, A. patula populations were less susceptible to phenmedipham, desmedipham, ethofumesate and triallate relative to C. album populations. Two A. patula populations bear the leucine‐218 to valine mutation on the chloroplast psbA gene conferring low level to high level cross‐resistance to the photosystem II inhibitors phenmedipham, desmedipham, metamitron and lenacil. In order to avoid insufficient A. patula control and further spread, seedlings should preferentially be treated with FAR mixtures containing higher‐than‐standard doses of metamitron and phenmedipham/desmedipham and no later than the cotyledon stage.     

Resistance against rhizomania disease via RNA silencing in sugar beet

Rhizomania is one of the most damaging and widely spread diseases in major sugar beet growing regions of the world. The causal agent, beet necrotic yellow vein virus (BNYVV), is transmitted via the fungus Polymyxa betae, which retains it in the field for years. In this study, an RNA silencing mechanism was employed to induce resistance against rhizomania using intron‐hairpin RNA (ihpRNA) constructs. These constructs were based on sequences of the BNYVV 5′‐untranslated region of RNA‐2 or the flanking sequence encoding P21 coat protein, with different lengths and orientations. Both transient and stable transformation methods produced effective resistance against rhizomania correlated with the transgene presence. Among the constructs, those generating ihpRNA structures with small intronic loops produced the highest frequencies of resistant events. The inheritance of transgenes and resistance was confirmed over generations in stably transformed plants.     

甜菜NBS-LRR家族基因的鉴定与分析

为明确甜菜中由抗性基因R编码的包含富亮氨酸重复序列（leucine-rich repeat,LRR）和核苷酸结合位点（nucleotide-binding site,NBS）的家族成员及其功能,基于甜菜基因组全长序列,利用HMMER、TBtools、Pfam、NCBI等软件和在线程序对甜菜NBS-LRR家族成员进行筛选和鉴定,采用生物信息学方法对鉴定到的成员进行亚家族分类、染色体定位、结构域分析、进化树构建、顺式元件分析和同源序列筛选。结果显示,从甜菜基因组中最终筛选鉴定到267条NBS-LRR家族基因序列,占甜菜基因组的0.614%,通过对267条基因序列进行结构域预测并进行分类,分属于N型、NL型、CNL型、TNL型和RNL型5个亚家族,分别包含110、25、128、3和1条序列。甜菜NBS-LRR家族基因大多位于2号、3号、4号和7号染色体上,根据基因簇划分原则发现有73.25%的基因以基因簇形式存在。经Clustal Omega和MEME在线程序对CNL型亚家族中具有完整卷曲螺旋（coiled-coil,CC）、NBS和LRR结构域的24条基因序列进行结构域保守性分析,共发现7个保守性较高的基序,基于CNL型亚家族128条基因序列构建的进化树显示CNL型亚家族的系统进化受CC、NBS和LRR结构域的影响较大。甜菜NBS-LRR家族基因含有大量植物激素相关顺式元件和多种胁迫响应元件,部分序列含有植物生理响应元件。甜菜NBS-LRR家族基因与菠菜和藜麦的抗病蛋白同源性较高。     

Fluorescent staining of resting spores of Polymyxa betae as a fungal vector of rhizomania disease of sugar beet in soil

When the resting spores of Polymyxa betae were pretreated with 2% sodium dodecyl sulfate (SDS) and then stained with various fluorochromes including 3,3′-dihexyloxacarbocyanine iodide [DiOC6(3)], calcofluor, and a fluorescein isothiocyanate (FITC)-conjugated lectin, such as wheat germ lectin (WGA) or caster bean lectin, most spores fluoresced brightly. FITC-WGA mainly stained the cell surface, while DiOC6(3) stained the cytoplasm. After pretreatment with SDS and addition of FITC-WGA or DiOC6(3) to a soil suspension containing resting spores, the resting spores were distinguishable from the soil particles. This staining method is easy to use for the detection of resting spores in the soil.