Testing aldicarb as a bird repellent in a sprouting sugar beet field

Temik, the granular formulation of aldicarb [2-methyl-2(methylthio) propionaldehyde 0-(methylcarbamoyl) oxime], was placed together with sugar beet seeds during sowing along the rows, at a rate of 1.4 g/m, in a 1.5-ha experimental area within a 6-ha sugar beet field in an arid area with a long history of bird damage. Thirty-three chukar partridges, a major pest of sprouting crops, were observed foraging in the experimental area throughout the 4-week period between sowing and assessment of damage. Damage was restricted to the borders of the field, with a significant difference in level of damage between treated and control plots located along the borders; the size of damaged areas was about five times smaller in the treated plots than in the control plots. The results were interpreted as reflecting the repellent effect of aldicarb absorbed by the sprouts, and as establishment of a conditioned aversion by the chukars to sugar beet sprouts. The high toxicity of the treated sprouts was demonstrated when adult Japanese quail were fed sprouts collected from treated plots.     

Interactions between a crinivirus, an ipomovirus and a potyvirus in coinfected sweetpotato plants

Novel and severe symptoms of chlorosis, rugosity, leaf strapping and dark green islands, designated as sweetpotato severe mosaic disease (SPSMD), were caused by dual infection of Sweet potato mild mottle virus (SPMMV; Ipomovirus ) and Sweet potato chlorotic stunt virus (SPCSV; Crinivirus ) in three East African sweetpotato cultivars (Tanzania, Dimbuka and New Kawogo). The storage root yield was reduced by ∼80%, as compared with healthy plants under screenhouse conditions in Uganda. Plants infected with SPMMV or SPCSV alone showed nonsignificant or 50% yield reduction, respectively. SPCSV reduced resistance to SPMMV in sweetpotato, similar to the situation with resistance to Sweet potato feathery mottle virus (SPFMV; Potyvirus ) that breaks down following infection with SPCSV, followed by development of sweet potato virus disease (SPVD). In single virus infections with SPMMV and SPFMV or their coinfection, cvs Tanzania and Dimbuka were initially systemically infected, displayed symptoms and contained readily detectable virus titres, but new leaves were symptomless with very low virus titres, indicating recovery from disease. In contrast, cv. New Kawogo remained symptomless and contained low SPMMV and SPFMV titres following graft inoculation. These moderate and high levels of resistance to SPMMV and SPFMV, respectively, were lost and cultivars succumbed to a severe disease following coinfection with SPCSV. The synergistic interactions increased titres of SPMMV and SPFMV RNA by ∼1000-fold as quantified by real-time PCR, whereas SPCSV titres were reduced twofold, indicating an antagonistic interaction. Coinfection with SPMMV and SPFMV caused no detectable changes in virus titres or symptom severity.     

Partial purification of a virus associated with a Spanish isolate of citrus ringspot

A citrus ringspot isolate from Star Ruby grapefruit (RS-SR) was mechanically transmitted to Chenopodium quinoa. RS-SR was partially purified by differential centrifugation, fractionation in a sucrose gradient, and agarose gel electrophoresis of selected fractions. Infectivity of concentrated extracts on C. quinoa was lost in individual fractions of the gradient, but it was recovered by combining a top and a bottom component. Both components contained a 48-kDa protein not found in similar preparations from healthy plants. After further purification the 48 kDa protein was detected at the top edge of the agarose gel. In the initial experiments a 38-kDa protein was found in the same fractions that later contained the 48-kDa protein. An antiserum obtained to the 38 kDa protein reacted in Western blots with both the 38- and the 48-kDa proteins, whereas another antiserum raised to the Florida isolate CRSV-4 (also containing a 48-kDa protein) did not react with the 38-kDa protein, indicating that the latter was probably a degradation product of the 48-kDa protein. Filamentous flexous particles were observed by serologically specific electron microscopy in crude extracts from RS-SR-infected C. quinoa plants. These results indicate that RS-SR is associated with a two-component virus similar to those associated with several psorosis and ringspot isolates, and serologically related to CRSV-4.     

Association with the Syndrome "Basses Richesses" of Sugar Beet of a Phytoplasma and a Bacterium-Like Organism Transmitted by a Pentastiridius sp

ABSTRACT The syndrome "basses richesses" of sugar beet (SBR) was first observed in 1991 in Burgundy, France. A cixiid planthopper, Pentastiridius beieri, has been proved to be involved in the transmission to sugar beet of a stolbur phytoplasma, which could be detected in some affected plants. In 2000, periwinkle and sugar beet exposed to field-collected cixiids developed symptoms similar to SBR on sugar beet. Use of 4'-6-diamidino-2-phenylindole (DAPI) staining and transmission electron microscopy confirmed the presence of phytoplasma in some of the plants, which were also positive for this pathogen in a polymerase chain reaction (PCR) analysis. A phloem-restricted gram-negative bacteria was seen in all other plants with symptoms but PCR-negative for phytoplasma. Three primer pairs reported as diagnostic for phloem-limited bacteria were tested but only primers specific for 'Candidatus Phlomobacter fragariae' gave a positive signal, which related to the presence of DAPI-stained bacteria-like objects in diseased plants. Although phytoplasma and bacterium-like organisms were associated with the same macroscopic symptoms on sugar beet, histochemical analysis of phloem cells showed that phytoplasma were associated with cell necrosis and cell wall lignification, while bacteria were associated with these same abnormalities as well as deposit of phenolic compounds in the lumen of phloem cells.     

Evolution of a microbial acetyltransferase for modification of glyphosate: a novel tolerance strategy

N-Acetylation is a modification of glyphosate that could potentially be used in transgenic crops, given a suitable acetyltransferase. Weak enzymatic activity (k(cat) = 5 min(-1), K(M) = 1 mM) for N-acetylation of glyphosate was discovered in several strains of Bacillus licheniformis (Weigmann) Chester by screening a microbial collection with a mass spectrometric assay. The parental enzyme conferred no tolerance to glyphosate in any host when expressed as a transgene. Eleven iterations of DNA shuffling resulted in a 7000-fold improvement in catalytic efficiency (k(cat)/K(M)), sufficient for conferring robust tolerance to field rates of glyphosate in transgenic tobacco and maize. In terms of k(cat)/K(M), the native enzyme exhibited weak activity (4-450% of that with glyphosate) with seven of the common amino acids. Evolution of the enzyme towards an improved k(cat)/K(M) for glyphosate resulted in increased activity toward aspartate (40-fold improved k(cat)), but activity with serine and phosphoserine almost completely vanished. No activity was observed among a broad sampling of nucleotides and antibiotics. Improved catalysis with glyphosate coincided with increased thermal stability.     

Ageratum yellow vein China virus Is a Distinct Begomovirus Species Associated with a DNAbeta Molecule

ABSTRACT Ageratum conyzoides plants exhibiting yellow vein symptoms, collected near Haikou, Hainan Province, China, contained begomoviral DNA-A-like molecules. The complete sequences of the molecules from two samples, Hn2 and Hn2-19, were shown to consist of 2,768 and 2,748 nucelotides (nt), respectively. These sequences have more than 97% nucleotide sequence identity, but less than 86% identity with other reported begomovirus sequences. In line with the taxonomic convention for begomoviruses, Hn2 and Hn2-19 are therefore considered to represent isolates of a distinct begomovirus species, for which the name Ageratum yellow vein China virus (AYVCNV) is proposed. Sequence alignment shows AYVCNV has arisen by recombination among viruses related to Ageratum yellow vein virus, Papaya leaf curl China virus, and an unidentified begomovirus. Southern blot analyses revealed that all plants sampled contained molecules resembling DNAbeta. DNAbeta molecules from three samples were 1,323 or 1,324 nt long and had >98% sequence identity but <81% identity with previously reported DNAbeta sequences. Infectious clones of Hn2 and its associated DNAbeta were constructed and agroinoculated to plants. Hn2 alone caused sporadic asymptomatic systemic infection of Nicotiana benthamiana, N. glutinosa, Lycopersicon esculentum, Petunia hybrida, and A. conyzoides but its accumulation was much enhanced in plants co-inoculated with DNAbeta. The co-inoculated N. benthamiana, N. glutinosa, P. hybrida, and L. esculentum plants developed leaf curling or leaf crinkling symptom; those in A. conyzoides were typical of ageratum yellow vein disease. When the DNAbeta molecules associated with four other Chinese begomoviruses were coinoculated with Hn2 to N. benthamiana and N. glutinosa, the DNAbeta molecules were replicated, and the plants developed systemic symptoms of types that were specific for each DNAbeta. This illustrates that there is less specific interaction between monopartite begomovirus and DNAbeta than between the DNA-A and DNA-B of begomoviruses with bipartite genomes.     

Invasive African boneseed and a native shrub support similar faunal assemblages in a heavily infested landscape

Invasive weeds may provide habitat for wildlife in altered landscapes. We compare fauna within three types of sites in You Yangs Regional Park in central Victoria, Australia, that is, sites with an invasive shrub understory (African boneseed, Chrysanthemoides monilifera subsp. monilifera (DC.) T. Norl.), native shrub understory (snowy mintbush Prostanthera nivea), and sites without an understory (open sites). Sites with an understory dominated by boneseed provided habitat for avian species and an introduced small mammal, comparable with sites with mintbush as the understory. Species-specific models of common species suggest vegetation structure, rather than composition, drove this effect. Open sites differed in terms of avifaunal assemblage, and the abundance of three common native birds and one common invasive small mammal. Boneseed additionally showed phenological differences in fruiting and flowering and differences in flowering abundance when compared with mintbush, comparably offering resources to wildlife. Transitioning vegetation communities to more natural states should consider wildlife already depending on weeds, a dependency likely driven by a paucity of alternative native vegetation.     

Herbicide safeners: a review

Herbicide safeners selectively protect crop plants from herbicide damage without reducing activity in target weed species. This paper provides an outline of the discovery and uses of these compounds, before reviewing literature devoted to defining the biochemical and physiological mechanisms involved in safener activity. Emphasis is placed on the effects of safeners on herbicide metabolism and their interactions with enzyme systems, such as cytochrome P₄₅₀ mono-oxygenases and glutathione-S-transferases. Attention is drawn to the potential wide-ranging applications of safeners and, in particular, their use as powerful research tools with which to identify and manipulate those mechanisms which contribute to herbicide selectivity and resistance. © 1999 Society of Chemical Industry     

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.     

Genetic Structure and Temporal Dynamics of a Colletotrichum graminicola Population in a Sorghum Disease Nursery

ABSTRACT Restriction fragment length polymorphisms (RFLPs) were used to study the population genetics of Colletotrichum graminicola (= C. sublineolum), the causal agent of sorghum anthracnose. Screening of 80 anonymous probes from a genomic library detected polymorphisms in 81% of 299 probe-enzyme combinations among nine international isolates. Seven single- or low-copy probes were used to study a collection of 411 isolates sampled during 1991 to 1993 from a sorghum disease nursery in Georgia. Nei's gene diversity was moderately high, with = 0.215 on average, while genotypic diversity was extremely low with an average genotypic diversity value of G = 1.513. Only nine multilocus haplotypes were identified, with one haplotype being present at a frequency of approximately 80% each year. Two other haplotypes were found at significant frequencies (4 to 10%). Allele and haplotype frequencies did not differ over the 3 years, indicating that this population was stable. Our findings suggest that genetic drift and gene flow were not major contributors to genetic structure, while asexual reproduction had a significant effect.     

Distribution of a juvenogen and its metabolites in a laboratory system during juvenogen-induced caste differentiation in a termite, Reticulitermes santonensis (Isoptera: Rhinotermitidae)

BACKGROUND: Juvenoids and juvenogens have been for many years considered promising candidates for control of pest insect species including termites. Their use as termite pest management agents requires the generation of knowledge concerning their degradation and distribution in time and space. Groups of 40 Reticulitermes santonensis de Feytaud workers were provided with wood impregnated with a juvenogen, ethyl cis-N-{2-[4-(2-butyryloxycyclohexylmethyl)phenoxy]ethyl}carbamate, labelled with tritium in the benzene ring (305 GBq mmol(-1)). After 14 days the radioactivity was determined in all elements of the experimental system. RESULTS: The majority of the input activity was detected in the wood, only about 1% in the bodies of surviving termites and 1% in the substrate. A considerable part of the input activity was probably lost as gaseous termite metabolites. The activity in workers was significantly higher than in presoldiers, which had differentiated under the influence of the labelled juvenogen. A stable value of radioactivity was detected on the body surfaces. CONCLUSIONS: The results suggest good stability of the compound in the wooden carrier and low contamination of the environment with non-gaseous residuals, together with the desired biological impact on termite caste differentiation.     

RU-15525, a new pyrethroid with a very strong knockdown effect

(E)-5-Benzyl-3- furylmethyl (1-R),3-S)-2,2-dimethyl-3-(2,3,4,5-tetrahydro-2-oxothien-3-ylidenemethyl)cyclopropanecarboxylate or RU-15525 is a new pyrethroid. The action of this compound was tested on Musca domestica and Aedes aegypti and a very strong knockdown effect was observed in comparison with the knockdown effect of allethrin, bioallethrin and (S)-bioallethrin.     

Implementation of a herbicide simulation model in a geographical information system with an example of a site-specific application

A Geographical Information System (GIS) was combined with a model for simulating leaching and degradation of herbicides. The model uses first–order kinetics to simulate degradation, and a cascade model to simulate transport. This system was tested with data from a 16 km² research catchment in northern Germany. Geometrical, topological, and soil data of this area were stored in a GIS. For the whole area, divided into small homogeneous sites (ecotopes), model runs were carried out. The system is able to handle data for all ecotopes automatically and to present calculated results on the behaviour of herbicides as distributed over time and depth for the area. An application of ethofumesate made in sugar–beet in spring and recropping of winter wheat after beet harvest was modelled. Degradation/sorption parameters were estimated from similar soils. Simulation results showed slower degradation in the sandy sites of the catchment, compared to the more loamy regions. Residues of herbicide remaining after beet harvest were greater than 20% of the applied dose in the sandy soils after 150 days. Hence, high risk of damage to the following crop of winter wheat was predicted. At the other sites residues remaining were between 2% and 20% of the applied dose. Einbindung eines Simulationsmodells zum Herbizidverhalten in ein Geographisches Informationssystem–Beispiel zur schlagspezifischen Anwendung Ein Geographisches Informationssystem (GIS) wurde mit einem Simulationsmodell für Herbizidabbau und –einwaschung kombiniert. Grundlage der Abbausimulation ist eine Kinetik 1. Ordnung, der Transport im Boden wird mit Hilfe eines Kaskadenmodells berechnet. Das System wurde in einem Intensiv–Untersuchungsgebiet (16 km²) in Norddeutschland getestet. Geometrische und topologische Daten der Fläche sowie Bodendaten sind im GIS gespeichert. Für die gesamte Fläche, die in kleine homogene Teilflächen (Ökotope) aufgeteilt wurde, wurden Simulationsberechnungen durchgeführt. Das System ist in der Lage, Daten für alle Ökotope automatisch bereitzustellen und die Ergebnisse zum Einwaschungs– und Abbauverhalten für die gesamte Fläche in ihrer Verteilung über Zeit und Tiefe darzustellen. Als Szenario wurde die Applikation von Ethofumesat in Zuckerrüben im Frühjahr mit einem Nachbau von Winterweizen nach der Rübenemte gewählt. Abbauund Sorptionsparameter waren in ähnlichen Böden ermittelt worden. Die Simulationsergebnisse zeigten einen langsameren Abbau in den sandigen Böden verglichen mit den lehmigen. In den sandigen Böden lagen die Rückstandsgehalte nach 150 Tagen übe 20 % der Ausgangskonzentration, wodurch ein hohes Nachbaurisiko für Winterweizen prognostiziert wurde. Für den Rest der Fläche lagen die Rückstände zwischen 2% und 20% der Ausgangskonzentration.     

Fungal biodegradation of a phenylurea herbicide,diuron : structure and toxicity of metabolites

Microbial degradation, organic synthesis and ecotoxicology were used to investigate the fate of diuron after spreading on soils. Quantitative biodegradation assays were performed with fungal strains, showing that diuron was degraded but not entirely mineralized. The modifications observed consisted in demethylation of the terminal nitrogen atom. The identified metabolites were synthesized in sufficient amounts to confirm their structures and determine their non‐target toxicity using four biotests. The two metabolites exhibited higher effects than parent diuron. This limited biodegradability and potential aquatic toxicity suggest that diuron is of higher environmental concern than previously recognized. © 2000 Society of Chemical Industry     

There has never been a better time or a greater need for resistance management

Integrated pest management (IPM) and sustainable agriculture benefit from selective and environmentally benign crop-protection products. The performance of these products, however, is threatened by resistance. If it is to be prevented from standing in the path of progress, resistance must be managed. As agricultural practices move towards IPM and sustainable crop protection, selection pressure will be concentrated on products which are compatible with these systems. Producers, researchers, government and extension workers cannot solve these complex problems alone. The key to success is collaboration. The Insecticide Resistance Action Committee (IRAC) was set up by the crop-protection industry in 1984 to promote and co-ordinate its contribution to resistance management. Today, it is collaborating with research institutes, government organisations and extension services to combat resistance. IRAC focuses on research and communication projects which reduce selection pressure, organising workshops in ‘resistance hot spots’ and providing input to draft legislation. Selected examples of IRAC's collaborative work are described. ©1997 SCI     

Inhibition of acetyl-coenzyme a carboxylase by coenzyme a conjugates of grass-selective herbicides

A total of 146 samples of different kinds of cheeses produced in Spain were analysed in order to ascertain the specific contamination pattern. The organochlorine compounds studied were those most commonly investigated in previous surveys: α-HCH, β-HCH, γ-HCH (lindane), γ-HCH, chlordane, aldrin, dieldrin, endrin, heptachlor, heptachlor epoxide, and the isomers and metabolites of DDT. α-HCH, β-HCH, γ-HCH, chlordane, p,p′, DDT, and p,p′-DDE were found in more than 76% of samples; p,p′-DDE and γ-HCH were the most frequently detected, with frequencies of 100 and 97.9% respectively. γ-HCH, aldrin, dieldrin, heptachlor, heptachlor epoxide, o,p′-DDT, p,p′-DDD and o,p′-DDD were observed at lower frequencies. No residues of endrin were detected in any sample. Insecticides exceeding the maximum residue limits (MRLs) were chlordane, β-HCH, α-HCH and γ-HCH, with 42, 20, eight and six samples respectively. Mean residues of organochlorines found were as follows (μ kg^?1 butterfat): α-HCH = 46.3; β-HCH = 46.5; γ-HCH = 54.2; δ-HCH = 16.9; aldrin = 16.7; dieldrin = 9.7; heptachlor = 15.9; heptachlor epoxide = 14.8; chlordane = 50.2; o,p′-DDT = 5.1; p,p′-DDT = 12.4; o,p′-DDT = 19.6; p,p′-DDD = 46.7; o,p′-DDE = 6.9; p,p′-DDE = 40.7 (.DDT = 55.0). Estimated dietary intakes (EDIs) from cheese consumption were compared to acceptable daily intakes (ADIs) for the pesticides where residues exceeded the MRL. EDIs calculated were in all cases below ADIs, and, therefore, based on the ADIs, there is no health risk involved in the consumption of cheese from Spain arising from organochlorine residues.     

Application of a mathematical function for a temperature optimum curve to establish differences in growth between isolates of a fungus

A function that approximates the curve of the growth rate of the mycelium of the imperfect fungusSphaeropsis sapinea in relation to temperature is proposed. This function contains three free parameters, representing maximum growth rate, optimum temperature and shape of the curve. It was applied to data from an experiment with 27 isolates, in which the growth rate was measured in two replications at ten temperatures ranging from ?2 °C to 45 °C. Fitting the function to data from each isolate in each replication resulted in estimates of three parameters in which the information about the curve contained in the ten original observations is compressed. The estimates of the optimum temperature and of the shape were used in a further statistical analysis aimed at comparing the isolates and at ascertaining whether they could be divided into a few distinct groups, possibly related to different strains. The latter proved not to be the case.     

A stochastic optimization method to estimate the spatial distribution of a pathogen from a sample

Information on the spatial distribution of plant disease can be utilized to implement efficient and spatially targeted disease management interventions. We present a pathogen-generic method to estimate the spatial distribution of a plant pathogen using a stochastic optimization process which is epidemiologically motivated. Based on an initial sample, the method simulates the individual spread processes of a pathogen between patches of host to generate optimized spatial distribution maps. The method was tested on data sets of Huanglongbing of citrus and was compared with a kriging method from the field of geostatistics using the well-established kappa statistic to quantify map accuracy. Our method produced accurate maps of disease distribution with kappa values as high as 0.46 and was able to outperform the kriging method across a range of sample sizes based on the kappa statistic. As expected, map accuracy improved with sample size but there was a high amount of variation between different random sample placements (i.e., the spatial distribution of samples). This highlights the importance of sample placement on the ability to estimate the spatial distribution of a plant pathogen and we thus conclude that further research into sampling design and its effect on the ability to estimate disease distribution is necessary.     

利用编码harpin蛋白的基因遗传改良生防荧光假单胞菌2P24

荧光假单胞菌Pseudomonas fluorescens 2P24是根围促生细菌（PGPR）,具有Ⅲ型分泌系统（T3SS）。为了在2P24中表达植物过敏反应激发子harpin,赋予生防菌诱导抗病性能力,本文选择可在2P24中表达的来自Pseudomonas syringae pv.tomato DC3000的avrPto1基因启动子与水稻细菌性条斑病菌Xanthomonasoryzae pv.oryzicola harpin蛋白编码基因hpa1进行融合,实现了harpin蛋白在2P24的表达。重组菌株通过T3SS分泌harpin蛋白,可激发烟草产生过敏反应（HR）,激活HR途径的HIN1基因和HRS203J基因以及病程相关蛋白PR1a基因的转录表达。harpin重组菌株与2P24一样,对小麦赤霉病菌Fusarium graminearum和棉花枯萎病菌F.oxysporum f.sp.vasinfectum具有抑制作用。这为利用植物-病原物互作中激发植物产生抗病性的激发子来遗传改良生防微生物奠定了理论和实践基础。