Sugar Beet Yellows Research Articles

Beet luteovirus coat protein sequence variation

SummaryThe sequences of cDNA clones covering the coat protein genes of 29 isolates of beet mild yellowing virus from sugar beet and beet western yellows virus mainly from oilseed rape were compared. The sequences could be partitioned into seven distinct clusters falling into three main groups. Group 1 isolates were found both in oilseed rape and sugar beet mainly from north Europe; group 2 isolates were from hosts other than sugar beet in England and France; group 3 isolates were beet‐specific and found from northern Italy and Iran. The factors affecting this variation and its significance in relation to coat protein‐mediated protection are discussed.

Candidate high spectral resolution infrared indices for crop cover

The sensitivity of near-infrared/red ratio vegetation indices to soil reflectance and plant color result in ambiguous interpretation of plant condition and productivity. Measurements of the reflectance of crop canopies were made at high spectral resolution to investigate candidate vegetation indices, in the near- and middle-infrared (800–2500 nm), for their ability to umambiguously estimate foliage cover independently of the extraneous effects of variations in canopy color and soil background brightness. Reflectances were measured with an IRIS spectroradiometer over plots of sugar beet ( Beta vulgaris L.) sown on different denss and at different densities to produce a wide range in canopy cover. Vegetation color was varied by infecting selected plots with sugar beet yellows virus. Soil brightness was varied by placing trays of peat between the plant rows. Selected narrow-band near- and middle-infrared reflectances were tested for their relationship with canopy cover and their sensitivity to variations in canopy color and soil brightness. The relationship between canopy cover and traditional near-infrared/red ratio indices was f to be sensitive to both canopy color and soil brightness. Most infrared indices were insensitive to the effects of canopy color, but those showing the highest correlations with cover tended to be significantly influenced by soil brightness. The most promising NIR reflectances were those beyond the range (760–900 nm) of near-infrared reflectance detected by current space-borne systems, such as Landsat TM and SPOT HRV.

Using crop diversity to manage pest problems: Some California examples

AbstractModerate to large scale California growers (as well as small scale ones) manipulate cropping patterns in a number of ways to reduce pest problems. Crop rotation, which can be defined as diversifying crops over time, is used to manage selected pests, primarily weeds, pathogens, and nematodes. As a substitute for pesticides, crop rotation has been most rewarding in the control of nematodes; sugarbeet cyst and root knot nematode examples are detailed. Some pests that invade fields from nearby areas can be managed by modifying adjacent cropping patterns or practices; Pierce's disease of grapes, sugarbeet yellows and border harvesting of alfalfa are given as examples. Finally, multiple crops can be grown within a single field or orchard. Although this approach is not widely practiced by many California growers, two examples of systems where intercropping has been shown to limit pest numbers without the use of pesticides are described: intercropping of cotton with alfalfa and companion planting oats when seeding alfalfa. These examples show that using crop diversification to manage pests is feasible, but growers must be strongly motivated to make the necessary changes in cropping patterns. Most of the systems that have been widely adopted are those for which few other economically feasible methods were available.

Effects of the pyrethroid deltamethrin on the acquisition and inoculation of viruses by Myzus persicae

SUMMARYThe pyrethroid, deltamethrin, alone or as an emulsifiable formulation, hindered infection of healthy plants with the persistent beet mild yellowing virus (BMYV) and both acquisition of, and infection with, the non‐persistent potato virus Y (PVY) and the semi‐persistent sugar beet yellows virus (BYV) by Myzus persicae in glasshouse tests.Another pyrethroid, RU‐15525, also protected against infection with PVY. Even sub‐lethal amounts of deltamethrin decreased virus transmission by rapidly incapacitating the aphids, the effect being least with aphids most resistant to organophosphorous insecticides and to certain pyrethroids including deltamethrin. Demeton‐S‐methyl hindered infection only with BMYV. This work shows that deltamethrin restricts transmission of persistent, semi‐persistent and perhaps more importantly of non‐persistent viruses in the glasshouse, and has potential for doing the same in the field.

Observations of Linked Plant Virus Particles

SUMMARY Two types of plant virus particles, sugar beet yellows virus and pea early-browning virus, show nucleocapsids joined by cross bridges when viewed in the electron microscope. Sugar beet yellows virus particles preferentially aggregate in pairs which are joined by up to ten cross bridges originating from a morphologically different end of the virus particle. The long virus particles of pea early-browning infections were found to possess crystalline aggregates in the plant cytoplasm and many of the virus particles were linked by cross bridges extending the whole length of the virus particle.

Biochemical and serological comparisons between carnation yellow fleck virus and sugar beet yellows virus protein subunits

Carnation yellow fleck virus is serologically related to sugar beet yellow virus. Amino acid analyses and tryptic peptide maps indicate about 50 amino acid differences between the proteins from the two viruses.

Purification and partial characterization of sugar beet yellows virus

A technique was devised for obtaining purified infectious preparations of sugar beet yellows virus (SBYV) particles. As the use of mechanical blending resulted in shearing of particles, infected leaves were hand ground in a mortar; the extracts were clarified with bentonite, concentrated using polyethylene glycol, and further purified by rate zonal and isopycnic gradient centrifugation. The purified particles had a modal length of 1270 nm, sedimented at 110 S, had an unusual ultraviolet absorption spectrum and contained about 5% RNA. The molecular weight of the infectious RNA, estimated by sedimentation and by gel electrophoresis was about 4.3 × 10 6; that of the coat protein subunit was about 23,500. These properties are discussed in relation to the structure of the virus particles and also are compared with the properties of viruses allied to SBYV.

The changes in the titre of the sugar beet yellows virus in sugar beet leaves in the course of the vegetation period

Using the quantitative serological method of double diffusion in agar, the amount of sugar beet yellows virus in the leaves of sugar beet was investigated and the possibility of an accurate serological analysis was examined at certain time periods in the course of vegetation. In sugar beets infected artificially at the beginning of the vegetation period the increase of the titre has a fluctuating course at first. In August, after the intensive growth of plants is over, the virus content maintains on a relatively high degree, increasing further toward the end of vegetation. For a reliable virus analysis the sap can be diluted approximately in the ratio 1/128. The table presented enables one to determine the probable accuracy of the serological analysis at the individual time periods during the vegetation of sugar beet.

Differentiation of strains of sugar beet yellows virus onTetragonia expansa Murr. and other indicator plants

Five different isolates of beet yellows virus were maintained without any changes in their properties onTetragonia expansa Murr. syn.T. tetragonoides Pall. for a long period of time. According to their characteristics and different properties especially in a diploid inbred line of sugar beet the isolates are considered to be strains of BYV and are classified into three groups: group of mild strains (the mild masked and mild strains), normal strains (the common strain) and necrotic strains (the severe necrotic and necrotic strains). The necrotic strains of BYV were relatively easily transmissible manually to sugar beet plants and other indicator species. The common strain can be transmitted to sugar beet,Chenopodium quinoa Willd. but not toC. capitatum L. Asch. Mild strains are transmissible with difficulty andC. quinoa is the only species which develops a larger number of local lesions after inoculation. In contrast to the mild masked and common strains it is manually transmissible toC. capitatum. The mild masked strain can not be transmitted to sugar beet.Nicotiana quadrivalvis Pursh. is not susceptible to mechanical inoculation with BYV. Aphid transmission withMyzus persicae (Sulz.) was positive in experiments with necrotic strains only. Mechanical transmission of BYV was successful also toC. foliosum (Moench) Asch.,C. murale L. andClaytonia perfoliata Donn. The last two species were susceptible to inoculation by aphids as well. Attempts to transmit the virus manually toT. expansa Murr. andC. giganteum Donn. failed.

Electron microscopical proof of the presence of sugar beet yellows virus particles in the roots of sugar beet

The presence of beet yellows virus (BYV) particles was electron microscopically proved in the roots of sugar beet. Specimens for the electron microscopical examination of root sap were prepared by differential centrifugation. It was proved that, contrary to expectations, examinations in spring showed most virus particles in the basal part of the root. At the same time it was found by experiment that the diagnostical BYV antiserum, for which the antigen was prepared from sugar beet leaves, did not react with a purificate of BYV containing virus particles.

The Spray Warning Scheme for Control of Sugar Beet Yellows in England Summary of Results between 1959–66

SUMMARYSugar beet growers in England have been advised since 1959 to spray their crops with systemic insecticide to control spread of yellows viruses when infestation with the vector aphids (mainly Myzus persicae Sulz.) in May and June reaches 0.25 aphids/plant. The data collected up to 1966 show that aphid infestation at any one time is not proportionally related to eventual yellows incidence. Graphs of mean aphid infestation and yellows incidence in different areas are presented, which are a guide to issuing spray warnings.

Relation of beet yellows virus to the phloem and to movement in the sieve tube.

In minor veins of leaves of Beta vulgaris L. (sugar beet) yellows virus particles were found both in parenchyma cells and in mature sieve elements. In parenchyma cells the particles were usually confined to the cytoplasm, that is, they were absent from the vacuoles. In the sieve elements, which at maturity have no vacuoles, the particles were scattered throughout the cell. In dense aggregations the particles tended to assume an orderly arrangement in both parenchyma cells and sieve elements. Most of the sieve elements containing virus particles had mitochondria, plastids, endoplasmic reticulum, and plasma membrane normal for mature sieve elements. Some sieve elements, however, showed evidence of degeneration. Virus particles were present also in the pores of the sieve plates, the plasmodesmata connecting the sieve elements with parenchyma cells, and the plasmodesmata between parenchyma cells. The distribution of the virus particles in the phloem of Beta is compatible with the concept that plant viruses move through the phloem in the sieve tubes and that this movement is a passive transport by mass flow. The observations also indicate that the beet yellows virus moves from cell to cell and in the sieve tube in the form of complete particles, and that this movement may occur through sieve-plate pores in the sieve tube and through plasmodesmata elsewhere.

Control of sugar beet yellows

Control of sugar beet yellows

The control of the sources of virus yellows of sugar-beet

The means whereby sugar-beet yellows viruses and their predominant vector, Myzus persicac (Sulz.), overwinter in Britain are reviewed. M. persicae overwinters mainly on cultivated secondary host plants that are not associated with the viruses: the viruses overwinter principally in the mangold and sugar-beet seed crops, which are the main source of infection in the following summer; mangold clamps may be a minor source and weeds seem unimportant.Despite autumn certification of first-year sugar-beet seed crops, visible infection within them in the following June is never negligible, and rapid spread of virus within these crops during their second year can cause a high proportion of the plants therein to be infective, although still symptomless. The many aphids that may leave these crops and the uncertified seed crops are an important source of infection for the root crop.It is suggested as a new control measure that seed crops of beet and mangolds should be grown in Britain in alternate years only. Consideration of the low frequencies of winds of a speed and direction suitable for carrying viruliferous aphids from Continental beet-growing areas to Britain, and of the low incidence of virus yellows in areas of Britain that are free of seed crops and comparable, in distance and direction relative to the main British beet-growing areas, with those of the latter in relation to the Continent, suggests that the effectiveness of the proposed measure is unlikely to be nullified by intrusion of infected aphids from the Continent.

Spread of Yellows Virus by Myzus persicae in Sugar Beet Crops

WINGLESS Myzus persicae were reared on sugar beet plants (provided by Dr. G. E. Russell, Plant Breeding Institute, Cambridge) infected with sugar beet yellows virus (SBYV), sugar beet mild yellows virus (SBMYV)1, or both viruses. Eight widely separated plants in a 7¼-acre field of sugar beet each received three adult and six young aphids from these cultures on May 31, 1962, and nearby plants were examined for aphids and virus symptoms at weekly intervals thereafter.

Do aphids carry transmissible sugar beet yellows virus via their stylets?—Evidence from ultraviolet irradiation

To celebrate the sixtieth anniversary of Virology a survey is made of the plant viruses, virologists and their institutions, and tools and technology described in the first decade of plant virus publications in Virology. This was a period when plant viruses increasingly became tools of discovery as epistemic objects and plant virology became a discipline discrete from plant pathology and other life sciences.

Effect of keeping viruliferous aphids on plants or glass on their transmission of sugar beet yellows virus

A rapid and simple protocol for preparing viral RNA from aphids (Myzus persicae) and potato (Solanum tuberosum L.) tissue (leaves, sprouts, and tubers) for reverse transcription–polymerase chain reaction (RT–PCR) was developed. The four-step method involves: (1) preparing plant crude sap or aphid macerates in a buffered detergent (Triton XL-80N) solution; (2) immobilizing clarified sap on a nitrocellulose membrane; (3) performing reverse transcription using eluted water extract from cut-out spot from membrane; and (4) amplifying cDNA through PCR. The entire procedure from tissue grinding to RT–PCR can be completed within 6 h. The protocol was applied successfully for the detection of individual potato viruses: carlavirus Potato virus S (PVS), potexvirus Potato virus X (PVX), potyvirus Potato virus Y (PVY), and polerovirus Potato leafroll virus (PLRV). PLRV was also detected from individual viruliferous aphids or composites of viruliferous and healthy aphids. PVY and PLRV were detected from extracts immobilized on nitrocellulose membranes, stored for more than 65–273 days at room temperature (25 °C). The protocol was companed with the ‘long protocols’ involving enzyme and phenol extraction for aphids or sodium sulfite and phenol extraction for tubers. The simplified protocol was found comparable in sensitivity to these long procedures, and is especially suitable for those regions where specialized PCR laboratories are only available in centralized locations. Viral RNA immobilized membranes can be mailed out for detection by RT–PCR to these centralized laboratories from remote areas of the country.

Effect of treating stylets of aphids with formalin on the transmission of sugar beet yellows virus

Formalin treatment of exposed stylets of anesthetized Myzus persicae (Sulzer) apterae or nymphs, which had fed on Swiss chard plants infected with sugar beet yellows virus, resulted in a depression in virus transmission; but it also depressed frequency and depth of stylet penetration during the first few hours of inoculation access time to test plants. Because of the treatment-feeding interaction, it was not possible to determine whether or not this semipersistent aphid-borne virus is stylet-borne or internally translocated prior to transmission.

The use of rainfall, temperature, and actual transpiration in some crop-weather investigations

This paper reports various investigations of the effects of meteorological factors on the yields of crops in England and Wales. The investigations were undertaken primarily with the objects of seeing (a) whether variations in temperature had any direct effect on yields, and (b) whether Penman's concept of actual transpiration gave a better measure of the overall effect of rainfall than the use of a multiple regression on variates representing total rainfall and its distribution.The effect of temperature and its seasonal distribution on the yields of wheat on various plots of the classical wheat experiment on Broadbalk field at Rothamsted was studied in conjunction with rainfall and its seasonal distribution, using the regression method devised by Fisher. Variations in temperature were found to show no effects on the final yields.The relationship between actual transpiration and yield was investigated for the Broadbalk field and for sugar beet and potatoes, using average yields determined by sampling methods, for various districts in England and Wales. For sugar-beet virus yellows infection, and for potatoes blight attack, were also taken into account.No relationship between actual transpiration and wheat yields on Broadbalk field was found, but sugar beet and potatoes both showed a positive association between actual transpiration and yield except for sugar beet in the Spalding area, where there is a high-water table. Actual transpiration was in general more effective than a regression on total rainfall and its distribution accounting for variations in yield. As might be expected virus yellows and blight also account for a good deal of the variation in yield.

Aphid Control Trials on Sugar Beets and Virus Yellows Disease in Kern County, California

The economic feasibility of the use of systemic pesticides (either demeton or Di-Syston® ( O-O -diethyl S- 2(ethylthio)ethyl phosphorodithioate) for the suppression of aphid vectors of the sugar beet yellows viruses was indicated from the results obtained on replicated plots conducted in Kern County. California, during the spring of 1960. In terms of tons of beets per acre, a preplant application of Di-Syston granules at a rate of approximately l pounds of actual toxicant per acre was found to be better than no treatment, but inferior to any other treatment schedule whether it involved one or two treatments. The best treatment combination used was a preplant treatment with Di-Syston granules followed by an application of a demeton spray (applied at a rate of 8 ounces of actual toxicant per acre in 44 gallons of water) when sampling indicated that the number of infested plants approached 50%. Under conditions of a multi-treatment test, however, increased yields were also found with a single treatment schedule of either a demeton spray or a topical application or a side dressing of Di-Syston granules (at a rate of approximately 1 pound actual toxicant per acre). Because of the inherent difficulty in predicting the development of aphid populations and the relative slowness with which a side dressing becomes effective, it would probably offer the least reliability of the various treatment schedules tried, with the exception of the single preplant treatment.