Epitrix cucumeris,E. similaris and E. tuberis

Specific scope

This standard describes a diagnostic protocol for adult Epitrix cucumeris, Epitrix similaris and Epitrix tuberis 1 . Note: this protocol focuses on the 3 major North American Epitrix species that can be detected in potato crops.

Specific approval and amendment

Approved in 2011‐09.     

Effect of cutting frequency on above‐ and belowground biomass production of Rumex alpinus,R. crispus,R. obtusifolius and the Rumex hybrid (R. patienta × R. tianschanicus) in the seeding year

Rumex species are important weeds in grasslands and on arable land. The Rumex hybrid (R. patienta × R. tianschanicus; cv. OK‐2, Uteusha) has been planted as a forage and energy crop since 2001 in the Czech Republic, but its ecological requirements and its potential to become a new weedy species have never been investigated. In 2010 and 2011, we performed a pot experiment to investigate the effect of none, one and two cuts per year on biomass production of Rumex OK‐2 and common broad‐leaved Rumex species (Rumex obtusifolius, R. crispus and R. alpinus). The higher cutting frequency can reduce the belowground biomass, but no effect on the aboveground biomass was detected. Flowering in the seeding year was recorded in only 50% of R. obtusifolius plants. Non‐flowering R. obtusifolius plants produced significantly more belowground biomass than flowering plants under no cutting or one cut treatments. The growth response of Rumex OK‐2 to different cutting treatments was very similar to R. crispus. These similarities indicate the weed potential of the hybrid to become a troublesome weedy species, similar to R. crispus.     

L‐P Molleyres,A Rindlisbacher,T Winkler and V Kumar,Insecticidal natural products: new rocglamide derivatives from Aglaia roxburghiana. Pesticide Science 55(4) 494–497 (1999)

The original article to which this Erratum refers was published in Pesticide Science 55 (4) 494–497 (1999)     

Electrophoretic karyotypes of <Emphasis Type="Italic">Rhynchosporium commune,R. secalis and R. agropyri</Emphasis>

Pulsed-field gel electrophoresis was used to generate electrophoretic karyotypes for 15 strains representing the three closely related plant-pathogenic fungi Rhynchosporium commune, R. secalis and R. agropyri. Between 13 and 16 chromosomes ranging in size from 0.9 to 6.4 Mb were found among the strains, leading to estimated genome sizes ranging from 54 to 63 Mb. Southern hybridization was used to identify homologous chromosomes, allowing detection of chromosome-length polymorphisms. There were no obvious differences in genome sizes or structures among the three species. The avirulence gene NIP1 is present on a large chromosome that is not likely to be dispensable. Two strains of R. commune that were proposed in earlier studies to be aneuploid as a result of a parasexual cycle did not possess a larger number of chromosomes. The reported information on genome size and chromosome number will be useful for genome sequencing projects that aim to identify genes involved in speciation and host specialization.     

Electrophysiological and behavioural responses of Pityophthorus pubescens (Coleoptera: Scolytinae) to (E,E)‐α‐farnesene, (R)‐(+)‐limonene and (S)‐(−)‐verbenone in Pinus radiata (Pinaceae) stands in northern Spain

BACKGROUND: Some twig beetles in the genus Pityophthorus (Coleoptera: Scolytinae) may vector pitch canker disease Fusarium circinatum (Niremberg & O'Donnell) of Pinus spp. (Pinaceae). Because Pityophthorus pubescens (Marsh.) has been found to be associated with F. circinatum in the Basque Country (northern Spain), various experiments were conducted to assess the beetle's behavioural responses to (E, E)‐α‐farnesene, (R)‐(+)‐limonene and (S)‐(?)‐verbenone to develop a potential inhibitor to host attraction. These experiments comprise electroantennographic and double‐choice olfactometer tests, as well as field assays in Pinus radiata D. Don stands. RESULTS: Both sexes of P. pubescens showed similar electroantennographic responses to different doses (from 1 ng to 1 µg in decadic steps) of each individual compound, with depolarisations to (S)‐(‐)‐verbenone (100 ng) being similar to those of the aggregation pheromone (+)‐trans‐pityol. In olfactometer assays, both sexes were significantly attracted to (+)‐trans‐pityol, but the attraction was reduced when increasing amounts of the chemicals were added to the pheromone. Particularly relevant was the repellent effect induced by (S)‐(?)‐verbenone at 1 ng dose and higher. In the field, (E, E)‐α‐farnesene, (R)‐(+)‐limonene and (S)‐(?)‐verbenone reduced significantly the number of beetles attracted to (+)‐trans‐pityol and racemic trans‐pityol, with (S)‐(?)‐verbenone being the most effective. CONCLUSIONS: (S)‐(?)‐Verbenone showed an interesting potential for use in the protection of P. radiata stands. A potentially effective strategy, which could be implemented in further, more in‐depth studies, could involve the use of this semiochemical as repellent and (+)‐trans‐pityol‐baited traps as attractant in a ‘push‐pull’ strategy. Copyright © 2012 Society of Chemical Industry     

PM 7/21 (2) Ralstonia solanacearum,R. pseudosolanacearum and R. syzygii (Ralstonia solanacearum species complex)

Specific scope

This Standard describes a diagnostic protocol for Ralstonia solanacearum, Ralstonia pseudosolanacearum and Ralstonia syzygii, i.e. phylotype/sequevar strain in the Ralstonia solanacearum Species Complex (RSSC). 1 It should be used in conjunction with PM 7/76 Use of EPPO diagnostic protocols.

Specific approval and amendment

Approved in 2003‐09. First revised in 2018‐02.     

Comparison of induced resistance activated by benzothiadiazole, (2R,3R)‐butanediol and an isoparaffin mixture against anthracnose of Nicotiana benthamiana

Resistance in Nicotiana benthamiana against anthracnose caused by the hemibiotrophic fungus Colletotrichum orbiculare was activated by benzothiadiazole (BTH), (2R,3R)­butanediol or PC1, an isoparaffin‐based mixture. In inoculation experiments, BTH, (2R,3R)­butanediol and PC1 reduced the number of lesions per leaf area caused by C. orbiculare by 98%, 77% and 81%, respectively. Foliar application of BTH induced expression of genes for the acidic pathogenesis‐related (PR) proteins, NbPR‐1a, NbPR‐3Q and acidic NbPR‐5. In contrast, soil application of (2R,3R)­butanediol or PC1 primed expression of genes for the basic PR proteins, NbPRb‐1b, basic NbPR‐2 and NbPR‐5dB. These results are consistent with the activation of salicylic‐acid‐dependent systemic acquired resistance (SAR) by BTH and that of jasmonate/ethylene‐dependent induced systemic resistance (ISR) by (2R,3R)­butanediol or PC1, and show that (2R,3R)­butanediol and PC1 can affect gene expression similarly to plant growth‐promoting rhizobacteria. However, the effects of (2R,3R)‐butanediol and PC1 were not identical. In addition to priming, (2R,3R)‐butanediol induced expression of basic NbPR‐2, whereas PC1 treatment induced expression of both NbPRb‐1b and basic NbPR‐2. Although a number of microbial products, such as (2R,3R)­butanediol, have been shown to produce ISR, this is the first demonstration that an isoparaffin‐based mixture, not derived from a microorganism, can produce ISR.     

<Emphasis Type="Italic">Pseudomonas syringae</Emphasis> pv. <Emphasis Type="Italic">cerasicola</Emphasis>, pv. nov., the Causal Agent of Bacterial Gall of Cherry Tree

Bacterial gall on trunks and twigs of cherry trees (Prunus × yedoens, Someiyoshino) was found in Miyazaki and Saga prefectures, Japan. The surface of young galls are relatively smooth and light brown, but they become rough and dark brown. Characteristics of the bacterium isolated from galls on trunks or twigs are similar to those of Pseudomonas syringae pathovars, i.e., pv. actinidiae, pv. daphniphylli, pv. dendropanacis, pv. Morsprunorum, pv. myricae, pv. rhaphiolepidis, pv. syringae and pv. tremae. This bacterium produced galls on cherry and apricot, but not on 66 other species of plants belonging to 39 families. From these results, this bacterium was classified as a new pathovar of Pseudomonas syringae, and the name Pseudomonas syringae pv. cerasicola, pv. nov., is proposed. Strain M9501(ICMP 13926) was designated as the pathotype strain. Received 10 September 1999/ Accepted in revised form 24 December 1999     

PM 7/62 (2) ‘Candidatus Phytoplasma mali’, ‘Ca. P. pyri’ and ‘Ca. P. prunorum’

Specific scope

This Standard describes a diagnostic protocol for ‘Candidatus Phytoplasma mali’, ‘Ca. P. pyri’ and ‘Ca. P. prunorum’. This Standard should be used in conjunction with PM 7/76 Use of EPPO diagnostic protocols

Specific approval and amendment

Approved as PM 7/62 Candidatus Phytoplasma mali and PM 7/63 Ca. P. pyri in 2006. Revised in 2017‐02 as a single Standard as PM 7/62 (2) with the addition of ‘Ca. P. prunorum’.     

PM 9/9(1): Heracleum mantegazzianum,H. sosnowskyi and H. persicum

Specific scope

This standard describes national regulatory control systems for Heracleum mantegazzianum, Heracleum sosnowskyi and Heracleum persicum. In the text the three species are referred to as Heracleum spp. in order to reduce repetitions.

Specific approval and amendment

First approved in 2009–09.

     

Competition between Solanum nigrum and pepper in the presence of Meloidogyne incognita

The influence of the root-knot nematode Meloidogyne incognita (Kofoid & White) Chitwood on the competitive relationships between pepper (Capsicum annuum L.) and Solanum nigrum L. (black nightshade) was investigated in a glasshouse experiment. Seven competition treatments were set up: two intraspecific for the crop and the weed and five interspecific treatments in which the emergence of S. nigrum plants was progressively delayed with respect to that of the pepper. Nematodes reproduced in every inoculated plant and their multiplication rates were high in both pepper and S. nigrum. The parasite reduced all growth and yield parameters of the crop, but did less harm to the weed. The negative effect of S. nigrum on pepper peaked in the treatment in which the weed and pepper plants emerged together. S. nigrum was a stronger competitor than pepper under both nematode-infested and nematode-free conditions. The effect of nematodes on pepper yield was less than that of competition, but both appeared to be additive.     

Enantioselective catalysis for agrochemicals: synthetic routes to (S)-metolachlor, (R)-metalaxyl and (αS,3R)-clozylacon

The application of enantioselective catalytic methods for the technical preparation of chiral agrochemicals is illustrated for three active ingredients of the acylanilide type. The key step for the technical synthesis of the herbicide (S)-metolachlor is the enantioselective hydrogenation of an imine intermediate using a novel iridium ferrocenyldiphosphine catalyst with an unprecedented high activity and 80% ee. (R)-metalaxyl and (αS,3R)-clozylacon were synthesized via the enantioselective hydrogenation of corre-sponding enamide precursors with Rh and Ru/binap catalysts with >95% and 99% enantiomeric purity, respectively. © 1998 Society of Chemical Industry     

Resistance to benzimidazole can be caused by changes in β-tubulin isoforms

The summary reports work that indicates that resistance in Rhynchosporium secalis to benzimidazole fungicides could result from substitution of the normal wild-type benA β-tubulin gene by other β-tubulin isoforms. © 1999 Society of Chemical Industry     

Genomic Variation within Monilinia laxa, M. fructigena and M. fructicola, and Application to Species Identification by PCR

Brown rot and twig canker of fruit trees are caused by Monilinia laxa, M. fructigena and M. fructicola. The Internal Transcribed Spacer (ITS) between the 18S and the 28S rRNA genes of four M. laxa and four M. fructigena isolates collected in France was amplified by Polymerase Chain Reaction (PCR) using universal primers and sequenced. Multiple alignment of the ITS sequences and comparison with published sequences revealed very little intraspecific variation and a low interspecific polymorphism clustered in two regions. Species-specific PCR primers were designed to amplify a 356bp fragment for each of the three species. The specificity of the three primer pairs was successfully tested with a collection of 17 M. laxa, 18 M. fructigena and 6 M. fructicola isolates collected from different hosts and different countries, unequivocally confirming the identification of each isolate based on morphological and cultural traits. Using stringent PCR conditions, no cross-reaction was observed with any of the isolates tested. The specificity of the PCR assays was also successfully confirmed with DNA extracted from different fungal species, either phylogenetically close to the genus Monilinia or commonly found on diseased fruits. Using this new reliable technique, doubtful isolates can be directly identified in a single PCR run. Moreover, detection and identification of the Monilinia species were successfully achieved directly on diseased fruits. This simple and rapid method can be particularly useful to detect M. fructicola which is a listed quarantine fungus in all European countries.     

Dynamics of above‐ground and below‐ground biomass of Rumex crispus,Rumex obtusifolius and the new weedy species Rumex hybrid cv. OK‐2 (R. patientia x R. tianschanicus) in the seeding year

Docks can be serious weeds of arable land and permanent grasslands where they can persist through well‐established root systems. A Rumex hybrid (R. patientia x R. tianschanicus; cv. OK‐2, Uteusha) has been planted as a forage and energy crop since 2001 in Czechia and has now become a new weed species. As its ecological characteristics are unknown, there is a need for improved knowledge for developing control measures and strategies. In 2010 and 2011, we performed a tube pot experiment to investigate above‐ground and below‐ground biomass growth dynamics and below‐ground biomass allocation of Rumex OK‐2. We compared the hybrid with Rumex crispus and Rumex obtusifolius during the vegetation season in the seeding year. Above‐ground and below‐ground biomass of Rumex species tended to increase from July to September. In the seeding year, flowering was recorded only for one plant of Rumex OK‐2 and 27.5% of R. obtusifolius plants, whereas R. crispus did not flower. The proportion of below‐ground biomass of Rumex species in the upper 30 cm was about 70–80%. The growth dynamics and allocation of below‐ground biomass of Rumex OK‐2 were more like R. crispus than to R. obtusifolius. These similarities indicate the potential of Rumex OK‐2 to become a troublesome weedy species, comparable with R. crispus.     

Response of tomato rootstocks carrying the <Emphasis Type="Italic">Mi</Emphasis>-resistance gene to populations of <Emphasis Type="Italic">Meloidogyne arenaria,M. incognita and M. javanica</Emphasis>

The response of four Mi-resistance gene tomato rootstocks to seven populations of Meloidogyne was determined in pot tests conducted in a glasshouse. Rootstocks PG76 (Solanum lycopersicum × Solanum sp.) and Brigeor (S. lycopersicum × S. habrochaites) and resistant cv. Monika (S. lycopersicum) were assessed against one population of M. arenaria, three of M. incognita, and three of M. javanica. Rootstocks Beaufort and Maxifort were assessed against one population of M. arenaria, two of M. incognita and two of M. javanica. Rootstock PG76 was highly resistant (reproduction index <10%) to all the populations, whereas rootstock Brigeor and cv. Monika were highly to moderate resistant. Rootstocks Beaufort and Maxifort showed reduced resistance or inability to suppress nematode reproduction, and their responses varied according to the population tested. Beaufort and Maxifort were susceptible to the two populations of M. javanica as Maxifort was to one of M. incognita. The reproduction index of the nematode was higher (P < 0.05) on Maxifort than Beaufort for all root-knot nematode populations.     

Moisture content and dormancy in Striga asiatica seeds

Freshly harvested Striga asiatica L. seeds will germinate in response to a stimulant only after the passage of time, an after-ripening period, and exposure to moisture at a suitable temperature, a conditioning period. To investigate the role of seed moisture content in the regulation of the after-ripening period, seeds were placed in chambers having specific relative humidity of 6%, 14%, 33%, 75% and 91% for 30, 60, 90 and 150 days. The seeds were then conditioned and germination percentage, response to tetrazolium and seed moisture contents were measured. Seeds at moisture contents less than 10% at the start of conditioning had germination of greater than 93%. Seeds at moisture contents over 10% at the start of conditioning could germinate between 60% and 3%, with germination decreasing as seed moisture content at the start of conditioning increased. The highest moisture content (17%) and lowest germination percentage (3%) occurred in seeds stored at 91% relative humidity for 150 days. There was a linear relationship of a high degree of correlation (0.997) between a positive tetrazolium test and germination capacity. Germination capacity of seeds could be changed from 90% to 3% by prolonged storage in water (dilute benomyl solution), causing `wet dormancy', then returned to 90% germination by returning to dry storage. Seed moisture content at the beginning of conditioning appears to control the responsiveness of the seeds to germination stimulants. The implications of these findings to the control of the parasite are discussed.     

Red Stripe of Rice Is Caused by a Bacterium <Emphasis Type="Italic">Microbacterium</Emphasis> sp.

In an etiological study to identify the causal agent of red stripe of rice, white bacterial colonies were consistently isolated from all diseased leaf samples collected in Indonesia. All the bacterial isolates were pathogenic to rice and caused symptoms similar to red stripe. The bacterial infection in rice leaves was confirmed histologically. Bacterial masses were observed in the lumina of xylem vessels in the lesion area, especially in those of connecting strands. Analysis of the 16S rDNA of the causal bacterium gave best matches to the 16S rDNA sequence of Microbacterium spp. of Microbacteriaceae which includes Clavibacter. Received 9 September 1999/ Accepted in revised form 16 November 1999     

Population dynamics of Rumex obtusifolius under contrasting lucerne cropping systems

The population dynamics of Rumex obtusifolius L. was analysed in a lucerne:winter cereal crop rotation by means of a matrix population model that takes into consideration two crop rotation periods: the lucerne (Medicago sativa L.) cropping period and the cereal cropping period. Several transition matrices based on life-cycle stages were calculated for each cropping period using experimental data and were used in the construction of a model that analyses the population dynamics of R. obtusifolius under different harvest dates and lengths of lucerne cropping periods. Model projections showed that populations of R. obtusifolius increased during the lucerne cropping period regardless of harvest date and decreased during the cereal cropping period. Under a late harvest date, populations decreased at each crop rotation when lucerne was grown for 3 years, remained close to the equilibrium when lucerne was left to grow for 5 years, and increased for longer lucerne cropping periods. In contrast, populations of R. obtusifolius decreased even with a lucerne cropping period of 9 years under an early harvest date. The significance of these results in relation to the biology and the non-chemical control of the species is discussed.     

Resistance against uprooting in carrots ( Daucus carota) and annual weeds: a basis for selective mechanical weed control

Trials were carried out in order to investigate ways in which to achieve selectivity in mechanical weed control. The influence of soil type, uprooting angle and development stage on the uprooting force of some annual weeds and carrot was studied. Spergula arvensis L., Urtica urens L., Chenopodium album L. and carrot (Daucus carota L.) were sown in soil bins filled with four different soil types. The plants were uprooted when they had two true leaves. Soil type significantly influenced the uprooting force needed by all four species. The forces required to uproot U. urens and C. album differed significantly between peat and loamy sand. In loamy sand, Capsella bursa-pastoris (L.) Med., Stellaria media (L.) Vill, Chamomilla suaveolens (L.) Pursh Buch. and Viola arvensis Murr. could all be uprooted by less force than it took to uproot carrot. The uprooting angle (0°, 45° and 90°) had no significant influence on the uprooting force for carrot at the studied developmental stage. C. album, S. arvensis, U. urens, Matricaria inodora, Thlaspi arvense L. and carrot could all be uprooted by less than 1 N when they had two true leaves. Carrots required a greater uprooting force than the weeds at the three early developmental stages studied. This indicates that it should be possible to develop selective mechanical weed control methods.