Soil disinfestation options in Aydın province,Turkey, strawberry cultivation

Two field experiments were conducted in the two successive seasons of 2005/2006 and 2006/2007 in strawberry-growing areas of Aydin province of Turkey to (a) compare soil solarization and metam sodium (MS) combinations with low-density polyethylene (LDPE) and virtually impermeable film (VIF); and (b) evaluate strawberry fruit yield, soilborne disease and weed control efficacy. Disinfestation treatments were as follows: (i) raised bed solarization for about 6 weeks, (ii) raised bed solarization for 3 weeks, (iii) raised bed solarization for 2 weeks + MS (50 ml m^-2), (iv) MS (50 ml m^-2) with LPDE (v) MS (100 ml m^-2) with LDPE, (vi) MS (50 ml m^-2) with VIF, (vii) MS (100 ml m^-2) with VIF. Results indicated that Macrophomina phaseolina and Fusarium spp. were the major fungal pathogens isolated from the crown of dead or dying plants in both cropping seasons. MS treatment (100 ml m^-2) through the drip irrigation system under LDPE sheet or VIF reduced soilborne diseases significantly while reduced dosage of MS (50 ml m^-2) under LDPE or VIF and in combination with 2-week soil solarization controlled the soilborne diseases to a greater extent than soil solarization treatments. All treatments controlled the following weed species: Portulaca oleracea, Amaranthus spp., Poa annua, Alopecurus myosuroides, Matricaria chamomilla, Digitaria sanguinalis, Raphanus raphanistrum, Seteria verticillata, Chenopodium album, Stelleria media, Capsella bursa-pastoris, Echinochloa cruss-galli, Veronica hederifolia, Lamium amplexicaule and Silybum marianum. None of the treatments provided acceptable control of horseweed (Conyza canadensis). Metam sodium application (100 ml m^-2) significantly increased yields by 18.5% and 14.5% in the 2005/2006 and 21.6% and 18.5% in the 2006/2007 season under LDPE and VIF, respectively, while marketable fruit yield was not significantly increased by soil solarization treatments in either trial. There was no significant difference between MS applications under LDPE and VIF for the weed and disease control, and marketable fruit yield.     

Diversity and spatial distribution of vegetative compatibility types and mating types of <Emphasis Type="BoldItalic">Cryphonectria parasitica</Emphasis> in the Aydın Mountains,Turkey

In this study, the population structure of the chestnut blight fungus Cryphonectria parasitica in the Aydın Mountains was investigated to make inferences about fungal reproduction and population diversity. A total of 213 C. parasitica isolates from eight subpopulations were used to determine vegetative compatibility (vc) and mating types of the population. Furthermore geostatistical analysis was performed to define the spatial structure of the population. The results showed that the isolates were vegetatively compatible with the European vc types of either EU-1 or EU-12. Both vc types were found in almost all subpopulations, but their frequencies varied depending on location. The results of a PCR assay showed that both mating types of C. parasitica (MAT-1 and MAT-2) exist in the population. MAT-1 comprised 65% of the total isolates, and the ratio of mating types was significantly skewed from 1:1. Genotyping based on combined vc and mating type data revealed four genotypes: EU-1/MAT-1 (28.6%), EU-1/MAT-2 (34.7%), EU-12/MAT-1 (36.2%) and EU-12/MAT-2 (0.5%). Geostatistatical analysis indicated that vc types, mating types and vc/mating genotypes were spatially autocorrelated and clustered in their distributions. Results suggested that C. parasitica could have a clonal population structure that is generated by asexual reproduction. Low vc-type diversity suggests that the C. parasitica population in the Aydın Mountains may be highly suitable to hypovirus invasion, thereby providing a high potential for successful biological control. However, co-occurrence of sexually compatible strains of EU-1 and EU-12 at the same locations in close proximity creates a high risk of increase in vc-type diversity.     

Physiological and population genetic analysis of Botrytis field isolates from vineyards in Castilla y León,Spain

Grey mould is reported in the vineyards of Castilla y León, Spain, every year. However, the natural populations of the pathogen have yet to be properly characterized. Vineyards from six wine-producing areas were surveyed in 2002 and 2007, sampling from bunches of grapes with and without symptoms. A total of 283 Botrytis field isolates were selected for physiological and genetic analyses. Botrytis cinerea isolates predominated in the population, although isolates belonging to Botrytis pseudocinerea and Botrytis prunorum were also identified. These two species are recorded for the first time in Spain in this work. In addition, two isolates closely related to Botrytis californica were identified. Physiologically, the B. cinerea population is very diverse, displaying a normal distribution of aggressiveness values in Vitis vinifera leaves, suggesting a quantitative nature for this trait. Several isolates unable to cause infection were identified, most of them belonging to a mycelial morphotype. Population genetic analysis revealed that genotypic diversity is high and that multiple infections of the same bunch of grapes by different genotypes occur frequently. The high genotypic diversity observed, an even distribution of both mating types and the linkage disequilibrium values detected support a mixed mode of reproduction with low levels of clonality. The wine-producing area in which each isolate was collected imposed a low degree of population differentiation, an effect that does not depend solely on the geographic distances but rather on the management practices used by growers and wine producer associations.     

Characterisation of <Emphasis Type="Italic">Phytophthora infestans</Emphasis> isolates collected from potato in Estonia during 2002–2003

A collection of 101 isolates of Phytophthora infestans, obtained from seven sampling sites representing central, east and south-east Estonia during 2002 and 2003 were assessed for several phenotypic and genotypic markers. All 101 isolates were assessed for virulence and resistance to metalaxyl. Virulence to each of the 11 classic resistance genes was found among the tested isolates. The mean number of virulences per isolate was 6.3, with a very low frequency of virulence against resistance genes R5 (5%) and R9 (14%). The most common pathotypes were 1.3.4.7.8.10.11 and 1.3.4.7.10.11, representing altogether 12% of the studied strains. In terms of metalaxyl resistance, 30 resistant, 52 intermediate and 19 sensitive isolates were found. A subgroup of 50 isolates was assessed for mating type, allozymes [glucose-6-phosphate isomerase (Gpi) and peptidase (Pep)], DNA fingerprints with probe RG57 and mtDNA haplotype. Of this subset, 30 were A1 and 20 were A2. Collections from three of the seven fields contained both mating types. Allozyme analysis did not reveal any polymorphism. However, 19 diverse RG57 fingerprints were detected, and two mitochondrial DNA haplotypes, Ia and IIa, were detected. By combining the mating type, mtDNA haplotype and RG57 fingerprint data, 26 multilocus genotypes were identified, of which 18 were detected only once. Genotypic diversity measured by the normalised Shannon diversity index was high (0.76). The large number of multilocus genotypes and the presence of both mating types in some fields indicate that sexual reproduction may take place in Estonian populations of P. infestans.     

Virulence factors analysis of native isolates of Xanthomonas albilineans and Xanthomonas sacchari from Tucumán,Argentina, reveals differences in pathogenic strategies

Xanthomonas albilineans (Xa) and X. sacchari (Xs) are both sugarcane pathogens. Xa is the causal agent of leaf scald disease, but there is limited information about the pathogenicity of Xs. The aim of this work was to study virulence factors of native strains of Xa (Xa32, Xa33, and XaM6) and Xs (Xs14 and Xs15) previously isolated from sugarcane with leaf scald symptoms, to gain insight into the biology of each microorganism. We analysed epiphytic survival, sensitivity to oxidative stress, extracellular degradative enzymes, cell motilities, exopolysaccharide (EPS) characteristics, cell adhesion, biofilm development, and control of stomatal regulation of the five strains. We observed that each species presented similar phenotypes for every factor analysed. Xa strains appeared to be more sensitive to oxidative stress and presented lower epiphytic survival than Xs. All strains presented endoglucanase activity; however, we could only detect protease and amylase activities in Xs strains. Swimming and sliding were higher in Xs, but twitching was variable among species. We also observed that only Xs strains produced a xanthan-like EPS, presented a strong cell adhesion, and structured biofilm. We detected some intraspecific variations showing that higher amounts of EPS produced by Xs14 correlated with its higher sliding motility and its homogenous and more adhesive biofilm. In addition, EPSs of Xs14 and Xs15 presented differences in strand height and acetyl percentage. Finally, we found that strains of both species were able to interfere with stomatal aperture mechanism. All these differences could influence the colonization strategies and/or disease progression in each species.     

Efficacy of mating disruption technique against carob moth,Apomyelois ceratoniae Zeller (Lepidoptera: Pyralidae) in pomegranate orchards in Southeast Turkey (Şanlıurfa)

Carob moth, Apomyelois (=Ectomyelois) ceratoniae Zeller (Lepidoptera: Pyralidae) is a key pest in pomegranate orchards in Southeast of Turkey. The pest causes significant damage and reduces marketability of fruits, and is difficult to control with insecticides. Therefore, it is imperative to develop environmentally sound effective alternative management approaches. In this study, we aimed to evaluate the mating disruption technique and determine the appropriate application dose for the management of the pest. The study was carried out in Central and Suruç districts of ?anl?urfa province (Turkey) in 2011 and 2012. SPLAT EC (Specialized Pheromone-Lure Application Technology) trade named dispenser containing 2% Z7, E9-11-dodecatrienyl formate pheromone mimic was applied at 500, 625 and 750 g/ha in three pomegranate orchards in each district. Results indicated that mating disruption technique significantly reduced the pest populations. But effectiveness of the method was less in terms of the damage rate on fruits. Pheromone applied at 500 g/ha was not effective. However, application at 625 g/ha reduced the pest populations to an acceptable level. Thus, the concentration could be considered an appropriate dose for the less abundant pest population within integrated pest management while higher population would require combining the mating disruption method with a bio-insecticide.     

Tachinid parasitoids (Diptera: Tachinidae) of<Emphasis Type="Italic">Spodoptera exigua</Emphasis> in cotton fields in Diyarbakır,Turkey

Tachinid parasitoidsExorista xanthaspis (Wiedemann),Nemorilla maculosa (Meigen),Palesisa maculosa (Villeneuve) andDrino imberbis (Wiedemann) were obtained fromSpodoptera exigua (Hübner) (Noctuidae) larvae collected from cotton fields in Turkey.S. exigua is a new host record forN. maculosa, andP. maculosa is recorded from Turkey for the first time. http://www.phytoparasitica.org posting July 14, 2004.     

Factors influencing growth,sporulation and virus transfer in <Emphasis Type="Italic">Cryphonectria parasitica</Emphasis> isolates from Castilla and León (Spain)

Biological control with Cryphonectria hypovirus CHV1 of the chestnut blight, caused by the fungus Cryphonectria parasitica, has reduced the impact of the disease in Europe. The virus reduces the virulence of the fungus so that it causes non-lethal cankers, thus enabling the chestnut trees to overcome the disease. The virus can be transmitted horizontally by hyphal anastomosis or vertically to the conidia. In this study, we investigated growth and sporulation of the fungus as well as rates of horizontal transmission of the virus at different temperatures. We used fungal isolates of the vegetative compatibility types (vc types) that are most prevalent in Castilla and León (central northern Spain) to evaluate the effects of fungal strain on the parameters tested. In addition, we infected four isolates of C. parasitica with hypovirus subtypes CHV1-F1 and CHV1-I, to determine the influence of virus subtype on growth, sporulation and virus transfer. We assessed growth of fungal colonies and horizontal transmission of the virus at 15 °C and 25 °C. Colony growth was affected by an interaction between fungal isolates included in vc type EU1 or EU11 and virus at both 15 °C and 25 °C. However, horizontal transmission of the virus was only influenced by the fungal genotype of isolates included in vc type EU1 or EU11, and spore production was only affected by the virus subtype. Vertical transmission was also influenced by the fungal isolate and virus subtype. Growth of the fungal isolates varied depending on the virus subtype with which they were infected. This supports the theory that fungal host and virus subtype influence transmission and dissemination of hypovirulence. The fungal genotype affects colony growth and horizontal transmission of the virus. It is common to expect a good dissemination of the hypovirus with a low vc type diversity but the selection of the best combination of hypovirus and fungal isolate is crucial for the success of biological control not only for small areas but in larger chestnut populations as well.