The effect of D–D, chloropicrin and previous crops on numbers of migratory root-parasitic nematodes and on the growth of sugar beet and barley

Thirty-three gal D–D or chloropicrin/acre (371 l/ha) injected during winter into well-drained, sandy soils controlled Longidorus attenuatus, Trichodorus spp. and other migratory root-parasitic nematodes and resulted in greatly increased yields of sugar beet for at least 3 years; 2 years of bare fallow was less effective than soil fumigation. Trichodorus spp. multiplied more on sugar beet than on barley, whereas L. attenuatus multiplied more on barley and clover than on sugar beet.     

Needle nematodes (Longidorus spp.) and stubby-root nematodes (Trichodorus spp.) harmful to sugar beet and other field crops in England

Longidorus attenuatus produces galls at the tips of roots of field crops, including sugar beet, growing in alkaline, sandy soils in eastern England. L. elongatus produces similar, but often larger, galls on the roots of sugar beet and other crops in sandy soils in the W. Midlands and in Fen peats. Trichodorus spp. cause ‘stubby root’ of sugar beet and can feed on many field crops. Seven species of Trichodorus were found in sandy soils in eastern England. L. attenuatus, L. elongatus and Trichodorus spp. aggregate around roots and stunt sugar beet and other crop plants. L. attenuatus is commoner below plough depth than in the topsoil, whereas T. cylindricus, T. pachy-dermus and T. anemones are more abundant in the topsoil. These nematodes cause some forms of ‘Docking disorder’.     

Fumigation with D-D or Telone on soils prone to Docking disorder

The liquid fumigants dichloropropane-dichloropropene mixture (D-D) or dichloropropenes (Telone), when applied at 64 or 43 1/ha respectively in bands 15–20 cm below the lines of the crop rows before sugar beet was sown on land with a history of Docking disorder, often led to appreciable increases in sugar yield; this occurred even in seasons that were not conducive to the development of the disorder, particularly in East Anglia. Treatment often increased yield economically but the crop response could not be forecast at the time of fumigant application. The effect of fumigation in Lincolnshire and Yorkshire was more variable, sometimes being favourable and occasionally unfavourable, whilst the same treatment in Nottinghamshire seldom increased and sometimes decreased the yield of sugar. Yields of barley grain in the years following the sugar-beet crops in Yorkshire and Nottinghamshire were not increased by the band application of nematicide but were sometimes increased by it when applied overall.     

The effect of nematicides, applied to the seed rows in spring, on growth and yield of sugar beet in Docking-disorder-affected fields

Both Trichodorus spp. and Longidorus spp. damage roots of sugar-beet seedlings in sandy soil, causing Docking disorder. Trials in infested fields between 1969 and 1972 tested the effects of fumigation along the rows with different amounts of D-D or Telone applied either two weeks before sowing or immediately before sowing, application of the systemic nematicide aldicarb (Temik) in the furrow with the seed during sowing, and top-dressing with nitrogen. Seedling establishment was often decreased by fumigation immediately before sowing, especially when followed by excessive rainfall, but only rarely by earlier fumigation or by aldicarb; differences in numbers of roots harvested were smaller because hand-singling removed excess seedlings. There was usually little difference between the yield increases given by the most effective treatments, which were aldicarb at 1·12 kg active ingredient/ha and 2·2–6·6 ml D-D or Telone/m of row at either time of application. Nitrogen top-dressing never affected sugar yield significantly. Longidorus spp. and Trichodorus spp. were both controlled well in the fumigated row but much less well at 13 cm, and not at all at 25 cm from the row (i.e. mid-way between two treated rows).     

The effect of small doses of nematicides on migratory root-parasitic nematodes and on the growth of sugar beet and barley in sandy soils

Smaller amounts of D–D (6–12 gal/acre) (68–135 1/ha) or ethylene dibromide (9 gal/acre) (100 1/ha) than are customarily used to disinfest field soils killed many root-parasitic nematodes (Trichodorus, Pratylenchus, Tylenchorhynchus and Longidorus attenuatus) when injected 6–8 in (15–20 cm) deep during early autumn in rows 10 in (25 cm) apart in well-drained sandy soils. They also increased the yield of sugar beet grown in fields infested with Trichodorus or Longidorus attenuatus, without affecting sugar percentage or juice purity of the roots, and in some places increased the yield of barley grown after the beet. D–D was much less effective when injected 8–12 in deep during late autumn or winter. Increasing nitrogen dressings to the seedbed from 1·5 to 3 cwt/acre (188 to 376 kg/ha) increased sugar beet yield in one field, decreased it in another and decreased juice purity in both. In two other experiments extra nitrogen did not affect sugar beet yield. Even smaller amounts of the nematicides ‘placed’ in the rows, before or after sowing sugar beet in them, killed many of the nematodes and also increased sugar yield. Phytotoxic nematicides can be placed in the rows during autumn, winter or spring but placement is simpler during spring, when the treated rows are indicated by the position of the marks of the tractor wheels left when the nematicide was applied. When applied during autumn or winter, the rows need to be indicated by drilling wheat or grass.     

Cytoplasmic male sterility in hybrids of sterile wild beet (Beta vulgaris ssp. maritima) and O-type fertile sugar beet (Beta vulgaris L.): molecular analysis of mitochondrial and nuclear genomes

The organization of the mitochondrial genome of B3, B4 and B5generations of hybrids created by backcrossing sterile wild beet Betamaritima with a fertile O-type sugar beet line was studied usingrestriction fragment length polymorphism (RFLP) analysis. Random amplifiedpolymorphic DNA (RAPD) analysis was used to study restoration of the fertile(O-type) sugar beet genotype in hybrids after multiple backcrossings.Restriction of mtDNAs from the cytoplasm of B. maritimaandhybrids revealed BamHI, EcoRI andXhoI restriction patterns different from those for sterileand fertile sugar beet lines. The most conspicuous feature of our accession ofsterile wild beet mtDNA was the absence of the 10.7-kbEcoRI fragment detected in the cytoplasm of S-type sterileB. maritima and sugar beet. The hybridization of digestedmtDNAs with coxII, atpA andatp6 homologous probes revealed alterations within thesegene loci that distinguished wild beet and hybrids from sugar beets.Characteristic hybridization profiles for the wild beet and B3, B4 and B5hybrids were observed for all probes regardless of the restrictase used todigest mtDNA. Notable changes in atpA andatp6 genes resulted when probes that comprised the5flanking sequences of these genes and a small part of the coding sequences wereused. RFLP analysis of the sterile B. maritimamitochondrial genome further supported the unique character of this source ofwild beet sterility. The genotypic differences between hybrids and parentalaccessions were determined by scoring PCR-RAPD reaction products for nineselected primers. The diversity of the B. maritimagenotyperesulted in a lower genetic similarity index in comparison with hybrids,sterileand fertile lines of sugar beet. The dendrogram obtained after cluster analysisdistinguished hybrids as a group that differed from wild beet and themaintainersugar beet line used for backcrossing. These results may indicate incompleterestoration of the fertile sugar beet genotype in hybrids.     

Populations of Rhizoctonia solani in soil under crops in rotation with sugar beet

Using a soil debris isolation method, populations of Rhizoctonia solani were monitored over a 4 -yr period in four fields which were initially cropped to sugar beet and in which four areas of Rhizoctonia crown rot diseased beets (DA) and four areas of apparently healthy beets (AH) had been selected and precisely located. Soil from these areas was assayed during the subsequent crops, which included sugar beet, tomato, cucumber, maize and soybean. No significant differences in colony counts were found between the soils in DA and AH on any of 30 sampling dates. R. solani population counts were, in general, quite low, except under sugar beet and following tomato harvest. Areas of diseased beet and high R. solani soil populations that developed in subsequent sugar beet crops did not necessarily coincide with the previously selected diseased areas. High R. solani populations developed from parasitic activity on sugar beet or saprophytically on tomato crop residues. Of the other crops, both maize and soybean may have slightly increased the low R. solani residual populations in soil. The monitoring of R. solani populations in the season prior to, and during the early season of sugar beet cropping did not provide a basis for forecasting disease in fields or sites within fields. The initiation of disease patches in these sugar beet fields was therefore governed by factors other than inoculum density.     

Ensiled sugar beets as dietary component and their effect on preference and dry matter intake by goats

This study examines the influence of ensiled sugar beets (Beta vulgaris ssp. vulgaris) on preference and short-time dry matter (DM) intake of goats. Whole sugar beets were ensiled either without any silage additive (sugar beet silage (SBS)) or with a chemical additive (6 l/t) containing 85% formic and propionic acids (treated sugar beet silage (TBS)) and were chopped after ensiling. The influence of different proportions of SBS (0%, 6.25%, 12.5%, 18.75% and 25% of dietary DM) and TBS (0%, 5%, 10%, 15% and 20% of DM) in partial mixed rations on short-time DM intake by goats (adult Saanen type wethers; n = 10) was studied in two separate, independent trials. Preference behaviour was investigated by offering the goats two different experimental diets per day and offer each possible combination of them (n = 10) once throughout the trial. On this basis, the mean DM intake (within 30 min and 3 h) of each experimental diet was determined. Both sugar beet silages showed good fermentation quality with low pH. By using the chemical silage additive, the production of ethanol was reduced and considerable amounts of sugar were preserved. In the short-term preference experiment, increasing concentrations of sugar beet silage in the ration increased DM intake (p < 0.05) in a linear way with a strong preference for those diets containing high amounts of sugar beet silage. Initial DM intake after 30 min was 4–5 fold increased for diets containing the highest beet concentration. It is assumed that the preference was positively influenced by sugar and sweet taste or the associated higher concentration of metabolisable energy.     

The control of Alternaria species on leaves of sugar beet infected with yellowing viruses

Leaves of virus-free sugar-beet plants rarely became infected with Alternaria spp. in two field experiments at Cambridge in 1965. Infection with beet yellows virus (BYV) increased susceptibility of plants to Alternaria only slightly but infection with beet mild yellowing virus (BMYV) increased it greatly. There was a close association between the severity of Alternaria symptoms, shown by different breeding lines and varieties of sugar beet, and the losses of sugar yield which they sustained after infection with BYV and BMYV. Many lines and varieties were resistant to Alternaria even when infected with BMYV and their resistance seemed to be inherited as a dominant character. Individual plants of any one line or variety differed greatly in resistance to Alternaria, suggesting that selection should improve the present level of resistance. Spraying the foliage of Alternaria-susceptible varieties with fungicides had little effect on the severity of Alternaria symptoms or on sugar yield. This was probably because the wet summer of 1965 was ideal for the spread of Alternaria and because rain washed the fungicide deposits from the sprayed leaves.     

Growth and photosynthetic efficiency promotion of sugar beet (<Emphasis Type="Italic">Beta vulgaris</Emphasis> L.) by endophytic bacteria

Very little is known about the physiological interactions between plants and endophytic bacteria. We investigated the impact of three endophytic bacteria, Bacillus pumilus 2-1, Chryseobacterium indologene 2-2, and Acinetobacter johnsonii 3-1, on the photosynthetic capacity and growth of sugar beet. Endophyte-free plants were obtained first and infected with the bacteria. Measurements of total chlorophyll content revealed very significant differences between endophyte-free beet plants and some infected by endophytic bacteria. The maximum photochemical yield (Fv/Fm) was used to determine any photosynthetic effect on plants caused by biotic or abiotic factors. After 30 days of growth, there was significantly higher Fv/Fm for endophyte-infected than endophyte-free plants. The light response curves of beet showed that photosynthetic capacity was significantly increased in endophyte-infected plants. Photosynthesis of endophyte-free plants was saturated at 1,300 μmol m⁻² s⁻¹, whereas endophyte-infected plants were not saturated at the irradiance used. The effect seemed to be due to promotion of electron transport in the thylakoid membranes. Promotion of photosynthetic capacity in sugar beet was due to increased chlorophyll content, leading to a consequent increased carbohydrate synthesis. It is possible that the increased maximum yield of photosynthesis in sugar beet was promoted by phytohormones and produced by the bacteria.     

Genetic localization of four genes for nematode (Heterodera schachtii Schm.) resistance in sugar beet (Beta vulgaris L.)

Sugar beet (Beta vulgaris L.) is highly susceptible to the beet cyst nematode (Heterodera schachtii Schm.). Three resistance genes originating from the wild beets B. procumbens (Hs1 ^pro-1) and B. webbiana (Hs1 ^web-1, Hs2 ^web-7) have been transferred to sugar beet via species hybridization. We describe the genetic localization of the nematode resistance genes in four different sugar beet lines using segregating F₂ populations and RFLP markers from our current sugar beet linkage map. The mapping studies yielded a surprising result. Although the four parental lines carrying the wild beet translocations were not related to each other, the four genes mapped to the same locus in sugar beet independent of the original translocation event. Close linkage (0–4.6 cM) was found with marker loci at one end of linkage group IV. In two populations, RFLP loci showed segregation distortion due to gametic selection. For the first time, the non-randomness of the translocation process promoting gene transfer from the wild beet to the sugar beet is demonstrated. The data suggest that the resistance genes were incorporated into the sugar beet chromosomes by non-allelic homologous recombination. The finding that the different resistance genes are allelic will have major implications on future attempts to breed sugar beet combining the different resistance genes.     

Phenotypic polymorphism and allele differentiation of isozymes in fodder beet,multigerm sugar beet and monogerm sugar beet

Summary Thirteen enzymes (MDH, SDH, LAP, PGM, PX, IDH, GPI, 6PGD, APH, GOT, GDH, ME and SOD) of 3 cultivated beet (B. vulgaris L.) gene pools, comprising 12 accessions of fodder beet, 11 of old multigerm sugar beet and 10 of modern monogerm sugar beet, were investigated using horizontal starch gel electrophoresis. Eleven accessions of primitive or wild B. vulgaris were also included for the comparison of isozymes. Variation in isozyme phenotypes was investigated to detect diversity in the three cultivated forms of beet. Phenotypic variation was observed in all except ME and SOD, which were monomorphic. A high degree of phenotypic polymorphism (Pj) was found in GDH, PGM, IDH, APH and MDH. Differences in phenotypic polymorphism in MDH, GPI and PX were recognized between fodder beet and both sugar beet groups. Average polymorphism for 13 enzymes in both sugar beets was significantly higher than that in fodder beet. For 13 enzymes, the existence of high isozyme diversity in both sugar beet gene pools was revealed. Allele frequencies in 13 alleles of five enzyme-coding loci, Lap, Px-1, Aph-1, Got-2 and Gdh-2, were investigated. New alleles, Px-1 ¹ and Got-2 ¹, were found in fodder beet accessions. No significant differences of average allele frequencies of five loci between fodder beet and both sugar beets were recognized. Several unique alleles and different isozyme phenotypes were observed in the accessions of B. vulgaris ssp. macrocarpa and ssp. adanensis. Future utilization of cultivated beet gene pools for sugar beet breeding is discussed from the viewpoint of genetic resources.     

Helicotylenchus vulgaris and its association with damage to sugar beet

Severe and irregular stunting of sugar beet has been associated with Helicotylenchus vulgaris but little is known of the pathogenicity of this nematode. A survey was made at 10 sites in East Anglia on calcareous soils (Wantage series) on which the original damage was reported. Numbers were usually maintained under a variety of crops, despite fluctuations during the period. In field trials, aldicarb treatment did not improve the yield of either sugar beet or winter wheat on land infested with H. vulgaris. In pot tests growth of sugar beet was stimulated by low nematode inocula; this effect diminished as numbers inoculated increased. Sugar beet grown at 10 °C and 15 °C with H. vulgaris grew markedly better in sterilised soil than in untreated field soil, especially at the higher temperature early in the experiment. It is concluded that though H. vulgaris may damage sugar beet it requires an atypical combination of external conditions to cause significant yield loss.     

Bodenbewohnende Schädlinge und Seitenwurzelfäule der Zuckerrübe in Abhängigkeit von der Rotation – Ergebnisse eines Fruchtfolgeversuches

Soil inhabiting pests and rot of feeding roots of sugar beet depending on rotation - Results of a long-term trial Over a period of 17 years a trial was carried out with sugar beet, cereals and oilseed rape in different crop rotations on a field near Göttingen (Lower Saxony). The frequency of sugar beet in the rotation was 17, 25, 33 and 67 %. In absence of beet nematodes, root and sugar yield of the beet decreased after repeated growing of sugar beet in short rotations compared to variants with long rotations. Sugar content and beet quality were only slightly influenced. By applying a bioassay (BW-Test) with young beet plants in the greenhouse it was shown that increasing infections on the tips of rootlets of the beet plants were the cause for decreasing beet yield in close rotations. Mortality of young beet plants and progress of infection in the test indicated roughly the quantity of pathogenic fungi in the soil. In the roots of the bait platits the parasitic fungus Aphanomyces cochlioides predominated. Rate of infection and yield reduction in the field were decisively influenced by weather conditions. Differences in yield between sugar beet grown in a three-year and a four-year rotation, however, were not significant. An occurrence of beet pests depending on crop rotation was stated only for Atomaria linearis and this only in a few years.     

Chemical control of beet cyst-nematode, Heterodera schachtii, in some peaty loam soils

In peaty loam soils, aldicarb or oxamyl mixed with the top 15 cm of the soil in spring before sugar beet seeds were sown, minimised invasion of the roots by larvae of the beet cyst-nematode, Heterodera schachtii, so preventing injury to the seedlings, and greatly increased sugar yields in heavily infested soil. Small amounts of both compounds were often as effective as larger amounts. Nematode increase on sugar beet roots was slow. Aldicarb or oxamyl lessened nematode increase in four years out of five. Fumigating predetermined row positions with dichloropropene mixtures (D-D, Telone) or incorporating aldicarb or methomyl shallowly in soil, later occupied by the roots of sugar beet seedlings, did not control the nematode, although sugar yields were sometimes increased.     

Field performance of chitinase transgenic silver birches (<Emphasis Type="Italic">Betula pendula</Emphasis>): resistance to fungal diseases

A field trial of 15 transgenic birch lines expressing a sugar beet chitinase IV gene and the corresponding controls was established in southern Finland to study the effects of the level of sugar beet chitinase IV expression on birch resistance to fungal diseases. The symptoms caused by natural infections of two fungal pathogens, Pyrenopeziza betulicola (leaf spot disease) and Melampsoridium betulinum (birch rust), were analysed in the field during a period of 3 years. The lines that had shown a high level of sugar beet chitinase IV mRNA accumulation in the greenhouse also showed high sugar beet chitinase IV expression after 3 years in the field. The level of sugar beet chitinase IV expression did not significantly improve the resistance of transgenic birches to leaf spot disease. Instead, some transgenic lines were significantly more susceptible to leaf spot than the controls. The level of sugar beet chitinase IV expression did have an improving effect on most parameters of birch rust; the groups of lines showing high or intermediate transgene expression were more resistant to birch rust than those showing low expression. This result indicates that the tested transformation may provide a tool for increasing the resistance of silver birch to birch rust.     

The Absence of TIR-Type Resistance Gene Analogues in the Sugar Beet (Beta vulgaris L.) Genome

The majority of known plant resistance genes encode proteins with conserved nucleotide-binding sites and leucine-rich repeats (NBS-LRR). Degenerate primers based on conserved NBS-LRR motifs were used to amplify analogues of resistance genes from the dicot sugar beet. Along with a cDNA library screen, the PCR screen identified 27 genomic and 12 expressed NBS-LRR RGAs (nlRGAs) sugar beet clones. The clones were classified into three subfamilies based on nucleotide sequence identity. Sequence analyses suggested that point mutations, such as nucleotide substitutions and insertion/deletions, are probably the primary source of diversity of sugar beet nlRGAs. A phylogenetic analysis revealed an ancestral relationship among sugar beet nlRGAs and resistance genes from various angiosperm species. One group appeared to share the same common ancestor as Prf, Rx, RPP8, and Mi, whereas the second group originated from the ancestral gene from which 12C1, Xa1, and Cre3 arose. The predicted protein products of the nlRGAs isolated in this study are all members of the non-TIR-type resistance gene subfamily and share strong sequence and structural similarities with non-TIR-type resistance proteins. No representatives of the TIR-type RGAs were detected either by PCR amplification using TIR type-specific primers or by in silico screening of more than 16,000 sugar beet ESTs. These findings suggest that TIR type of RGAs is absent from the sugar beet genome. The possible evolutionary loss of TIR type RGAs in the sugar beet is discussed. These authors (Yanyan Tian, Longjiang Fan) contributed equally to this work.