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The aim of this study was to isolate and identify the spoilage fungi from four Australian grown commercial strawberry cultivars, namely Fortuna, Festival, Ruby Gem, and Red Rhapsody, and to investigate their correlation with the studied physicochemical properties in all four cultivars. To further understand the differences in postharvest resistance behavior of strawberries, the correlation between chemical composition, in particular pelargonidin-3-glucoside (the major anthocyanin in strawberry), and fungal decay was studied. Results showed significant differences in (poly)phenolic content between the four investigated cultivars, in particular total phenolics and pelargonidin-3-glucoside. Moreover, the studied strawberries significantly varied (p < 0.05) in other evaluated parameters such as pH, sugars, and ascorbic acid. The Red Rhapsody cultivar with higher contents of total phenolics and pelargonidin-3-glucoside exhibited higher resistance to fungal growth, which was further confirmed by the results of principal component analysis. Findings from this study could benefit the food industry through lessening postharvest spoilage by breeding strawberries with higher polyphenolic content. [ABSTRACT FROM AUTHOR]

Background: The two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), is a major pest of strawberry. It was necessary to control this mite pest that can reducing the quality and quantity of the fruits. In this regard, the effect of ZORO acaricide, Neoseiulus californicus (McGregor) and Amblyseius swirskii Athias-Henriot for suppressing the naturally occurring T. urticae populations on three strawberry cultivars were investigated. Results: The two predatory mites and ZORO treatments significantly suppressed the populations of T. urticae below the control in all tested cultivars. In most cases of the current study, significantly lower numbers of T. urticae were generally observed in ZORO and N. californicus treatments compared to A. swirskii treatment. In all cultivars, the overall mean of reduction percentages of T. urticae populations in N. californicus and ZORO treatments were not statistically different, and all were significantly higher than that in A. swirskii treatment. Conclusion: The present results suggested that the release of N. californicus and the application of ZORO acaricide could be promising strategies for controlling T. urticae on strawberry, although the release of N. californicus appears to be more competent tactic than ZORO acaricide. [ABSTRACT FROM AUTHOR]

Goosegrass is a problematic weed species in Florida vegetable plasticulture production. To reduce costs associated with goosegrass control, a post-emergence precision applicator is under development for use atop the planting beds. To facilitate in situ goosegrass detection and spraying, tiny- You Only Look Once 3 (YOLOv3-tiny) was evaluated as a potential detector. Two annotation techniques were evaluated: (1) annotation of the entire plant (EP) and (2) annotation of partial sections of the leaf blade (LB). For goosegrass detection in strawberry, the F-score was 0.75 and 0.85 for the EP and LB derived networks, respectively. For goosegrass detection in tomato, the F-score was 0.56 and 0.65 for the EP and LB derived networks, respectively. The LB derived networks increased recall at the cost of precision, compared to the EP derived networks. The LB annotation method demonstrated superior results within the context of production and precision spraying, ensuring more targets were sprayed with some over-spraying on false targets. The developed network provides online, real-time, and in situ detection capability for weed management field applications such as precision spraying and autonomous scouts. [ABSTRACT FROM AUTHOR]

The contribution of generalist insect predators to the control of the two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), an herbivorous pest of many crops, is poorly understood. One of the common insect predators in strawberries is the generalist predatory bug Anthocoris nemorum L. (Hemiptera: Anthocoridae), which has the potential to contribute to the control of pest populations. The feeding of adult A. nemorum on T. urticae was assessed by sampling individuals from an organic strawberry field in Denmark, and using PCR gut content analysis to detect remains of T. urticae within their gut. In the lab, we assessed that the DNA half-life detectability was 21.5 h. Significant numbers of field-collected A. nemorum tested positive for T. urticae prey DNA, with very high numbers in June (62.8%) and August (38.8%). This study presents conclusive evidence that the generalist predator A. nemorum can contribute to the decrease of T. urticae densities in strawberry fields, although the actual contribution in the present study is probably limited because predator populations were relatively low compared to T. urticae. The abundance of T. urticae did not increase significantly during the period of sampling, suggesting that a complex of natural enemies can achieve biological control of T. urticae in protected strawberries. [ABSTRACT FROM AUTHOR]

Strawberry anthracnose caused by Colletotrichum gloeosporioides has recently become a major problem in Taiwan, in concurrence with herbicide use by growers. In evaluations of the effects of paraquat, glyphosate and glufosinate on C. gloeosporioides, anthracnose severity and soil microbial communities, paraquat and glyphosate promoted hyphal growth, conidial production and germination, and soil survival of C. gloeosporioides; glufosinate had inhibitory effects. Soil drench with glyphosate, but not paraquat or glufosinate, increased populations of fungi and yeast-like microorganisms. Anthracnose was more severe on leaves after either foliar sprays or drenches with paraquat or glyphosate than on controls without herbicide. Thus, a sudden outbreak of strawberry anthracnose is likely attributable to the stimulatory effects of herbicides on the causal pathogen. To minimize the inoculum potential of C. gloeosporioides and anthracnose severity, strawberry growers should eliminate any plant debris after herbicide treatment. [ABSTRACT FROM AUTHOR]

The strawberry mite, Phytonemus pallidus fragariae (Banks) (Acari: Tarsonemidae), is one of the most important pests of greenhouse grown strawberry plants. Field grown strawberries may also be infested by the pest in high humid conditions. Life tables give the most comprehensive description of the development, survival, stage differentiation, reproduction and consequently population growth of a population, and thus it is an important base of population ecology and pest management. In this study, to provide a comprehensive evaluation of an ecology-based and cost-effective control program, life history and demographic parameters of the strawberry mite were studied. The experiment was conducted under laboratory conditions providing 20 ± 1 °C, 80 ± 10% RH and L16:D8 photoperiod. The data were analyzed based on the age-stage, two-sex life table theory. The population parameters net reproduction rate (R0 = 6.14 offspring), intrinsic rate of increase (r = 0.1317 day−1), and finite rate of increase (λ = 1.1407 day−1) on cv. Aromas were lower than those on the other cultivars tested. Based on the population characteristics, Aromas is a less favorable cultivar for the population growth of strawberry mite. [ABSTRACT FROM AUTHOR]

Abstract: Key MessagePowdery mildew resistance in two strawberry mapping populations is controlled by both stable and transient novel QTL of moderate effect. Some low transferability of QTL across wider germplasm was observed.Abstract: The obligate biotrophic fungus Podosphaera aphanis is the causative agent of powdery mildew on cultivated strawberry (Fragaria × ananassa). Genotypes from two bi-parental mapping populations ‘Emily’ × ‘Fenella’ and ‘Redgauntlet’ × ‘Hapil’ were phenotyped for powdery mildew disease severity in a series of field trials. Here, we report multiple QTL associated with resistance to powdery mildew, identified in ten phenotyping events conducted across different years and locations. Six QTL show a level of stable resistance across multiple phenotyping events; however, many other QTL were represented in a single phenotyping event and therefore must be considered transient. Subsequent screening of identified QTL across a validation set determined whether identified QTL remained closely linked to the associated resistance gene in the wider germplasm. Furthermore, a preliminary association analysis identified a novel conserved locus for further investigation. Our data suggest that resistance is highly complex and that multiple, primarily additive, sources of quantitative resistance to powdery mildew exist across strawberry germplasm. Utilisation of the reported markers in marker-assisted breeding or genomic selection would lead to improved powdery mildew-resistant strawberry cultivars, particularly where the studied parents, progeny and close pedigree material are included in breeding germplasm. [ABSTRACT FROM AUTHOR]

Strawberry crinkle disease is one of the major diseases that threatens strawberry production. Although the biological properties of the agent, strawberry crinkle virus (SCV), have been thoroughly investigated, its complete genome sequence has never been published. Existing RT-PCR-based detection relies on a partial sequence of the L protein gene, presumably the least expressed viral gene. Here, we present complete sequences of two divergent SCV isolates co-infecting a single plant, Fragaria x ananassa cv. Čačanská raná. [ABSTRACT FROM AUTHOR]

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Colletotrichum fungi belonging to the Colletotrichum gloeosporioides species complex include a number of economically important postharvest pathogens that often cause anthracnose. Until now, different species within this group could only be distinguished from one another reliably using multigenic phylogenetic analyses. Using a comparative genomics approach, we developed a marker that can differentiate Colletotrichum fructicola, Colletotrichum aenigma and Colletotrichum siamense within the C. gloeosporioides species complex based on PCR amplicon size differences. When we used this marker to classify 115 isolates collected over 20 years from strawberries in Chiba Prefecture, Japan, the isolates were predominantly C. fructicola. To our knowledge, this is the first report characterizing different species of Colletotrichum infecting strawberries in Japan and contributes to our understanding on the diversity of anthracnose pathogens in Japan. [ABSTRACT FROM AUTHOR]

Leaf wetness duration (LWD) plays a key role in disease development and is often used as an input in disease-warning systems. LWD is often estimated using mathematical models, since measurement by sensors is rarely available and/or reliable. A strawberry disease-warning system called 'Strawberry Advisory System' (SAS) is used by growers in Florida, USA, in deciding when to spray their strawberry fields to control anthracnose and Botrytis fruit rot. Currently, SAS is implemented at six locations, where reliable LWD sensors are deployed. A robust LWD model would facilitate SAS expansion from Florida to other regions where reliable LW sensors are not available. The objective of this study was to evaluate the use of mathematical models to estimate LWD and time of spray recommendations in comparison to on site LWD measurements. Specific objectives were to (i) compare model estimated and observed LWD and resulting differences in timing and number of fungicide spray recommendations, (ii) evaluate the effects of weather station sensors precision on LWD models performance, and (iii) compare LWD models performance across four states in the USA. The LWD models evaluated were the classification and regression tree (CART), dew point depression (DPD), number of hours with relative humidity equal or greater than 90 % (NHRH ≥90 %), and Penman-Monteith (P-M). P-M model was expected to have the lowest errors, since it is a physically based and thus portable model. Indeed, the P-M model estimated LWD most accurately (MAE <2 h) at a weather station with high precision sensors but was the least accurate when lower precision sensors of relative humidity and estimated net radiation (based on solar radiation and temperature) were used (MAE = 3.7 h). The CART model was the most robust for estimating LWD and for advising growers on fungicide-spray timing for anthracnose and Botrytis fruit rot control and is therefore the model we recommend for expanding the strawberry disease warning beyond Florida, to other locations where weather stations may be deployed with lower precision sensors, and net radiation observations are not available. [ABSTRACT FROM AUTHOR]

Strawberry is a significantly consumed fruit worldwide, mostly without being subjected to disinfection processes. During the harvest and transfer from farm to consumers as well as where organic farming practises have been employed, the surface of the fruit may become contaminated by pathogenic bacteria. Post-harvest strawberry fruits in punnets available for public consumption were thus screened for the presence of enteric bacteria in the Sunshine Coast region of Queensland, Australia. Some of the tested samples (13 %) were found to carry such bacteria and even in greater numbers if organic amendments were used (69 %). The bacteria were found to belong in the genera of Escherichia, Enterobacter, Raoultella, Klebsiella, Pantoea, Shigella, Citrobacter and Cronobacter within the family Enterobacteriaceae. Some of the isolates were found to adhere to Caco-2 cells representing human gut epithelium as well as carrying virulence and toxin genes. Resistance mostly against sulphafurazole, cefoxitin, ampicillin and nitrofurantoin was found among 14 different antimicrobial agents tested including 100 % resistance to cefoxitin and ampicillin in the genus Pantoea. In the second phase of the study, bacteriophages were isolated against the isolates and were subsequently applied to post-harvest fruits. A significant ( P ≤ 0.001) reduction in the number of enteric bacteria was observed when a high-titre polyvalent bacteriophage suspension (×10 PFU/mL) was applied to the fruit surface. Bacteriophages also decreased the adhesion of the Escherichia coli isolates to Caco-2 cells. Findings might indicate that biological control using bacteriophages might be of significant value for the industry targeting to reduce pathogenic loads of bacteria on the fruit. [ABSTRACT FROM AUTHOR]

Greenhouse and field experiments were conducted to evaluate the effectiveness of site-specific tactics for management of the twospotted spider mite, Tetranychus urticae Koch, a major pest of greenhouse and field-grown strawberries ( Fragaria x ananassa Duchesne). Two site-specific (spot) treatments, the miticide bifenazate (Acramite) and the predatory mite Neoseiulus californicus McGregor, were compared with whole-plot treatments of bifenazate or N. californicus to determine whether T. urticae could be effectively managed in field-grown strawberry using only site-specific tactics. Additionally, the cost of site-specific tactics was compared with whole-plot treatments to determine the economic value of using site-specific management tactics for T. urticae in strawberries. In the greenhouse, all treatments equivalently reduced the number of T. urticae below control. In the field during the 2011-2012 season, more T. urticae eggs and motiles were in the whole-plot treatments of both N. californicus and bifenazate in the mid-season and late season, respectively, compared with the spot treatments. With the exception of site-specific N. californicus during the 2011-2012 field season, there were no differences in marketable yields between plots with site-specific treatments and whole-plot management. An economic analysis demonstrated a significant cost savings (75.3 %) with site-specific treatments of N. californicus compared with whole-plot application of N. californicus. Similarly, a 24.7 % reduction in cost was achieved in using site-specific bifenazate compared with whole-plot application of bifenazate. The findings indicate that site-specific treatments with N. californicus and bifenazate are competitive alternatives to whole-field application for T. urticae management in strawberries. [ABSTRACT FROM AUTHOR]

We developed a loop-mediated isothermal amplification (LAMP) assay for detecting Colletotrichum gloeosporioides, which causes anthracnose, in strawberry plants. Primer sets targeted the region from the gene encoding 5.8S ribosomal RNA to internal transcribed spacer 2, which is highly conserved in 25 Colletotrichum species in GenBank. Our results indicated that the LAMP assay, which uses template DNA prepared using microwave irradiation, is a simple and sensitive tool for detecting C. gloeosporioides in infected strawberry plants. Further, our results showed that the LAMP assay could differentiate Colletotrichum species such as C. acutatum, C. aenigma, and C. siamense. [ABSTRACT FROM AUTHOR]

The effect of aromatic plants on number of twospotted spider mite (TSSM), Tetranychus urticae Koch, when intercropped with strawberry were assessed in the field. During the first year, chives ( Allium schoenoprasum L.), coriander ( Coriandrum sativum L.), fennel ( Foeniculum vulgare Mill.), garlic ( Allium sativum L.), oregano ( Origanum vulgare L.), or sweet marjoram ( Origanum majorana L.) were intercropped with strawberry. Assessments were performed on TSSM populations by taking six samples from July 20 to September 20, 2012. During the second year, garlic plants were intercropped between rows of strawberry at three densities in greenhouse and field. Mobile forms and eggs numbers (only in field) of TSSM were evaluated from April 18 to June 05 (greenhouse) and June 06 to August 14, 2013 (field). It was found that intercropping with garlic caused a greater reduction of TSSM (up to 52 %) in strawberry plants when higher populations of TSSM occurred in the field. TSSM reduction was found in one sample when fennel and chives were intercropped with strawberries (42 and 50 % reduction, respectively); this also occurred when populations of TSSM were higher. The three densities of garlic plants (one, two and three rows among the strawberry rows) reduced TSSM mobile forms by 49, 53 and 60 % (greenhouse) and 44, 51 and 65 % (field), and eggs by 38, 43 and 64 % (field), respectively. The results suggest that intercropping garlic plants between strawberry rows is a promising strategy to reduce TSSM populations. [ABSTRACT FROM AUTHOR]

Polyphenols are secondary metabolites widely present in plants which benefit to human health. In the present study we analyzed the changes of polyphenol contents during strawberry fruit development as well as changes of polyphenol oxidase (PPO). The results depicted that the polyphenol content showed a decreasing trend with the fruit development. The pH value impacts the PPO activity, and in strawberry fruit the optimal pH for the PPO activity was 4.5. Meanwhile, PPO activity kept decreasing with the development of the fruit flesh and achenes. The damaged fruit enhanced the PPO activity. We found four PPO genes encoding the PPO in the strawberry that had different expression levels in tissues. The overexpression of the FaPPO1 genes improved the PPO activity in strawberry fruit and delays the fungus infection process. The FaPPO1 gene expression changes had affected the pathogen-related gene expression, such as PAL, SOD, POD, BG, and Chitinase genes. The fruit damage induced the FaPPO1 gene expression, and the abscisic acid and methyl jasmonic were also involved in the regulation of FaPPO1 gene expression. The FaPPO1 and FaPPO2 gene expressions were regulated both by abiotic stresses of low temperature, NaCl, and HO and biotic stresses of powdery mildew and gray mold. Understanding the regulation mechanism of PPO will be helpful and provide meaningful ideas in future for strawberry breeders. [ABSTRACT FROM AUTHOR]

The methods recently applied for decontamination of fruits and vegetables are not always efficient, human and ecologically friendly. In this context, photosensitization might serve as really promising tool. Obtained data indicated that Botrytis spp. was susceptible to photosensitization and its growth inhibited 14 % and reduced 18 % rotten strawberries. The following evaluation of shelf life of treated strawberries indicated some extension in comparison with control ones. The examination of nutritional quality of treated strawberries revealed that total antioxidant activity, amount of phenols and anthocyanins did not change in comparison with control. No effects on berry color were observed, just a slight reduction (10 %) of fruit firmness found in treated ones. In conclusion, photosensitization has potential as bio-fungicide, since inactivates Botrytis spp. on the surface of strawberry without impact on their nutritional properties or visual quality. [ABSTRACT FROM AUTHOR]

This study is focused on the novel approaches to enhance the inactivation of the Gram (−) food pathogen Salmonella enterica and harmful molds in vitro and on the surface of strawberries using the chlorophyllin–chitosan complex. Salmonella enterica (∼1 × 107 CFU mL−1) was incubated with chlorophyllin 1.5 × 10−5 M (Chl, food additive), chitosan 0.1% (CHS, food supplement) or the chlorophyllin–chitosan complex (1.5 × 10−5 M Chl–0.1% CHS) and illuminated with visible light (λ = 405 nm, light dose 38 J cm−2) in vitro. Chlorophyllin (Chl)-based photosensitization inactivated Salmonella just by 1.8 log. Chitosan (CHS) alone incubated for 2 h with Salmonella reduced viability 2.15 log, whereas photoactivated Chl–CHS diminished bacterial viability by 7 log. SEM images indicate that the Chl–CHS complex under these experimental conditions covered the entire bacterial surface. Significant cell membrane disintegration was the main lethal injury induced in Gram (−) bacteria by this treatment. Analysis of strawberry decontamination from surface-inoculated Salmonella indicated that photoactivated Chl–CHS (1.5 × 10−5 M Chl–0.1% CHS, 30 min incubation, light dose 38 J cm−2) coatings diminished the pathogen population on the surface of strawberries by 2.2 log. Decontamination of strawberries from naturally distributed yeasts/molds revealed that chitosan alone reduced the population of yeasts/molds just by 0.4 log, Chl-based photosensitization just by 0.9 log, whereas photoactivated Chl–CHS coatings reduced yeasts/molds on the surface of strawberries by 1.4 log. Electron paramagnetic resonance spectroscopy confirmed that no additional photosensitization-induced free radicals have been found in the strawberry matrix. Visual quality (color, texture) of the treated strawberries was not affected either. In conclusion, photoactive Chl–CHS exhibited strong antimicrobial action against more resistant to photosensitization Gram (−) Salmonella enterica in comparison with Gram (+) bacteria in vitro. It reduced significantly the viability of strawberry surface-attached yeasts/molds and inoculated Salmonella without any negative impact on the visual quality of berries. Experimental data support the idea that photoactivated Chl–CHS can be a useful tool for the future development of edible photoactive antimicrobial coatings which can preserve strawberries and prolong their shelf-life according to requirements of “clean green technology”. [ABSTRACT FROM AUTHOR]

A new species of Neopestalotiopsis based on both morphological and molecular characteristics is described. Neopestalotiopsis iranensis sp. nov. isolated from rotted strawberry ( Fragaria ananassa) fruits as well as from stolon and leaf lesions in Kurdistan province, Iran. Initially, light tan and sunken spots developed on fruits and resulted in a soft decay of the fruit flesh. The new species is morphologically distinguished from similar species with different conidium size and by possessing longer apical appendages, as well as some knobbed basal appendages. Phylogenetic analyses (Bayesian inference, maximum likelihood and maximum parsimony analyses) based on internal transcribed spacer, β-tubulin, and partial translation elongation factor 1-alpha combined gene sequences also indicated that this species is phylogenetically distinct from others. Moreover, strawberry crop is introduced here as a new host for N. mesopotamica. [ABSTRACT FROM AUTHOR]

Crown and leather rot of strawberry caused by Phytophthora spp. are major soil diseases of cultivated strawberry ( Fragaria × ananassa) in Poland. In this study, in total 45 isolates of Phytophthora spp. from plants of cultivars Elsanta, Honeoye, Florence, Camarosa, Roxana, Onebor, Alba, Elegance, Albion, Senga Sengana and Malwina originating from crowns (20 isolates) and fruits (25 isolates) as well as 25 soil samples from the same fruiting strawberry plantations located in central, north-eastern, and south-eastern regions of Poland were identified. Among them, 44 isolates from plant organs and eight from soil samples were identified as Phytophthora cactorum and from one plant and one soil sample as P. citricola; of those remaining from the soil, one was identified as P. citrophthora and one as P. cryptogea. Identifications were based on morphological characteristics and DNA analyses. Species-specific polymerase chain reaction confirmed the presence of Phytophthora spp. in all positive examined plant and soil samples and confirmed that P. cactorum is predominantly responsible for crown and leather rot diseases of strawberry in monitored regions of Poland. Pathogenicity tests showed that all isolates of Phytophthora spp. originating from soil derived from strawberry plantations were pathogenic both to strawberry and to raspberry. [ABSTRACT FROM AUTHOR]

Wild vegetation surrounding crops may provide temporary habitat and potential food sources for phytoseiids in different seasons. Monthly vegetation samples of wild plants adjacent to strawberry plants and wild plants in a vegetation strip close to the crop were taken. The frequency of Neoseiulus californicus, Tetranychus urticae and other mites and insects was recorded. In addition, in a laboratory assay, the survival, developmental time and fecundity of females fed on pollen of strawberry and pollen of wild plants where N. californicus was recorded during their flowering, were estimated. Pollen from Urtica urens, Lamium amplexicaule, Convolvulus arvensis, Sonchus oleraceous, Galega officinalis, and Fragaria x ananassa (strawberry) allowed development of N. californicus to adult, but not reproduction. Survival was 70-80 % when fed on pollen from S. oleraceus, G. officinalis and C. arvensis, 80-90 % when fed on pollen from U. urens and F. x ananassa, and more than 90 % when fed on T. urticae and on pollen from L. amplexicaule. In autumn and winter, U. urens, L. amplexicaule and S. oleraceous could promote the persistence of N. californicus when prey density in strawberry is low, offering T. urticae, thrips and pollen. In summer, pollen of C. arvensis and G. officinalis would contribute to the persistence of N. californicus when the strawberry crop is ending and offers scarce food resources. Although the pollen of these plants would not enable the predator population to increase, the presence of these plants in the vicinity of strawberry could contribute to the persistence of N. californicus population and help to limit T. urticae growth when this pest begins to colonize the crop. [ABSTRACT FROM AUTHOR]

The influence of Siberian strains of bacteria Bacillus spp. on the strawberry gray mold causative agent and plant resistance to the disease in three seasons differing in growing conditions has been studied. Bacterial strains B. subtilis, B. amyloliquefaciens, and B. licheniformis suppress the development of the phytopathogenic fungus B. cinerea in vitro and in vivo. In addition to the antifungal action, bacterial strains show a positive effect on the growth and development of strawberry plants, indicating multifunctional properties of Siberian strains Bacillus spp. [ABSTRACT FROM AUTHOR]

Pesticide use is pervasive and intensive in agricultural production. Certain food activists, producers, and public health researchers contest pervasive pesticide use on the basis that it is unsustainable for human health, the environment and the control of pests in growing food. In Australia government has largely left the resolution of this contestation to consumer choice. Yet the use of pesticides is barely visible to those consuming the products. This paper uses the example of strawberries to trace back how consumption choices are framed by regulatory choices in which consumers have little engagement. Strawberries have traditionally been a highly pesticide-intensive crop. The results highlight the limits of consumer choice as a method of deliberative democratic engagement with issues of agrifood sustainability. [ABSTRACT FROM AUTHOR]

The twospotted spider mite (TSSM), Tetranychus urticae Koch, is one of the main pests on strawberry crops in Brazil. TSSM can be difficult to control due to acaricide resistance. The objective of this work was to compare the effect of conventional and integrated strawberry production (ISP) systems on mite abundance and acaricide resistance. The control of TSSM in ISP was based on the release of Neoseiulus californicus (McGregor) or application of a selective acaricide (propargite), when TSSM monitoring indicated the timing for the release of predaceous mites (1-3 mites per leaflet on 30 % leaflets) or chemical intervention (>10 mites per leaflet). Only acaricides (abamectin, fenpyroximate) were applied in the conventional system. Integrated control of TSSM were sufficient to maintain a significantly lower pest infestation level, resulting in a sixfold reduction in the frequency of acaricide applications, and consequently, a lower selection pressure for acaricide resistance. Strategies for the management of TSSM in strawberry fields are described and discussed. [ABSTRACT FROM AUTHOR]

Key message: Diploid strawberry and potato transformed with a transposon tagging construct exhibited either global (strawberry) or local transposition (potato). An activation tagged, compact-sized strawberry mutant overexpressed the gene adjacent to Ds. Abstract: As major fruit and vegetable crops, respectively, strawberry and potato are among the first horticultural crops with draft genome sequences. To study gene function, we examined transposon-tagged mutant strategies in model populations for both species, Fragaria vesca and Solanum tuberosum Group Phureja, using the same Activation/ Dissociation ( Ac/Ds) construct. Early somatic transposition during tissue culture occurred at a frequency of 18.5 % in strawberry but not in potato transformants. Green fluorescent protein under a monocot promoter was a more reliable selectable marker in strawberry compared to potato. BASTA (gluphosinate herbicide) resistance served as an effective selectable marker for both species (80 and 85 % reliable in strawberry and potato, respectively), although the effective concentration differed (0.5 % for strawberry and 0.03 % for potato). Transposons preferentially reinserted within genes (exons and introns) in both species. Real-time quantitative PCR revealed enhanced gene expression (670 and 298-fold expression compared to wild type in petiole and leaf tissue, respectively) for an activation tagged strawberry mutant with Ds inserted about 0.6 kb upstream from a gene coding for an epidermis-specific secreted glycoprotein EP1. Our data also suggested that endopolyploid (diploid) cells occurring in leaf explants of monoploid potato were the favored targets of T-DNA integration during transformation. Mutants obtained in these studies provide a useful resource for future genetic studies. [ABSTRACT FROM AUTHOR]

A new disease of rose was noticed in Chiba Prefecture of Japan in 1968, and the pathogen was initially identified as Phytophthora megasperma based on morphological characteristics. Similar Phytophthora isolates have since been collected from rose plants in Chiba, Kanagawa, and Shizuoka Prefectures. In 2005, several Phytophthora isolates were recovered from crowns of strawberry plants in Hokkaido Prefecture. These were considered to be members of a new species. In this study, we re-examined all these isolates using morphological and physiological studies and a multilocus phylogenetic analysis. The rose and strawberry isolates were mostly similar morphologically and physiologically, with some exceptions. The rose isolates differed significantly from P. megasperma sensu stricto and other related Phytophthora species. The rose and strawberry isolates had external proliferation of sporangia, characteristic funnel-shaped oogonia, predominantly paragynous antheridia, and fast growth rates of 10.5 mm/24 h at an optimum temperature of 28 °C. In the multilocus phylogenetic tree constructed using sequences from the rDNA ITS regions, rDNA LSU, and the translation elongation factor 1-α, β-tubulin and coxI genes, they formed a distinct monophyletic group in clade 7 with strong bootstrap support. The rose and strawberry isolates separated into two distinct groups. The results indicate that the rose and strawberry isolates constitute two separate species, designated here as Phytophthora nagaii and P. fragariaefolia. [ABSTRACT FROM AUTHOR]

Inoculation of tissue-cultured plants of strawberry cultivar Ichigochukanbohon-Nou2gou (Nou-2) with the anthracnose pathogen ( Glomerella cingulata) results in wilting and plant death, whereas inoculation of strawberry runners grown in greenhouses results in leaf spots, not wilting or death. When tissue-cultured Nou-2 plants were acclimated for 3, 9 or 15 days, plant resistance to anthracnose increased as the acclimation period increased, suggesting that the resistance of Nou-2 may be induced by external factors. To clarify the mechanisms of resistance, we used cDNA microarray analyses to compare gene expressions among tissue-cultured and acclimated plants of the resistant cultivar Nou-2 and the susceptible cultivar Tochiotome. As a result, we identified 18 cDNA clones that were upregulated during acclimation in Nou-2 but not in Tochiotome. In a real-time RT-PCR of the 18 clones, the expression levels of three were significantly higher in acclimated plants of Nou-2. Two of the three clones showed close homology to enzymes related to flavonoid biosynthesis, i.e., leucoanthocyanidin dioxygenase (LDOX, ANS) and UDP-glucosyltransferase, putative (3-GT). The clones spotted onto the cDNA microarrays were rechecked, and 23 nonredundant cDNA clones of 13 enzymes were estimated to be flavonoid biosynthetic enzymes. Most of these clones were upregulated by acclimation in Nou-2. [ABSTRACT FROM AUTHOR]

This is the first report of the genetic diversity within ilarvirus subgroup 1 from eastern Australia. It supports the separation of tobacco streak virus (TSV) strains from parthenium ( Parthenium hysterophorus) and crownbeard ( Verbescina encelioides) based on serology and host specificity. It has confirmed one previously described strain of TSV as a member of the species Strawberry necrotic shock virus and another as a new subgroup 1 ilarvirus, ageratum latent virus (AgLV), from Ageratum houstonianum. A multiplex RT-PCR showed that the genetically distinct strains of TSV and AgLV were commonly found in symptomless infections in virus-specific alternative weed hosts growing over a wide geographical range in eastern Australia. TSV has been one of the most damaging viruses in Australian oilseed and pulse crops in recent years, and this study has provided the taxonomic knowledge essential for the development of control programs for these viruses. [ABSTRACT FROM AUTHOR]

Background and aims: Azospirillum brasilense REC3 is a plant growth-promoting and siderophore-producing bacterium isolated from strawberry. Colletotrichum acutatum M11 is the causal agent of anthracnose, an important disease in strawberry crop. The aim of this study was to characterize at the biochemical and molecular level, the systemic resistance induced by A. brasilense on pathogen-challenged strawberry plants. Methods: Phytopathological tests were performed; the content of phenolic compounds was determined spectrophotometrically; callose depositions in leaves by aniline blue staining; salicylic acid (SA) content in leaves by HPLC; and defense-related gene expression [pathogenesis-related proteins (FaPR1), chitinases (FaChi2-1; FaChi2-2) and glucanase (FaBG2-2)] by RT-PCR. Results: A. brasilense REC3 reduced anthracnose symptoms on pathogen-challenged plants, and the effect became greater as the elapsed time between bacterial inoculation and fungal infection increased. Biochemical and transcriptional studies revealed a transient accumulation of SA and the induction of defense-related genes, suggesting further that this response is related to structural cell wall modifications as consequence of the observed increase in phenolic compounds and callose deposition. Conclusions: The plant growth-promoting bacterium A. brasilense REC3 participates actively in the induction of systemic protection on strawberry plants against anthracnose disease caused by C. acutatum M11. [ABSTRACT FROM AUTHOR]

The oomycete Phytophthora cactorum can cause economically important diseases on numerous host plants worldwide, such as crown rot on strawberry. To explore the molecular mechanisms underlying the pathogenicity of P. cactorum on strawberry, transcriptional analysis of P. cactorum during strawberry infection and cyst germination was performed by applying suppression subtractive hybridization (SSH) and effector-specific differential display (ESDD) techniques. Two SSH cDNA libraries were generated, enriched for P. cactorum genes expressed during infection or during cyst germination, respectively, and 137 unique differentially expressed genes were identified. To specifically select RxLR effector genes from P. cactorum, ESDD was performed using RxLR and EER motif-based degenerate primers. Eight RxLR effector candidate genes as well as 67 other genes were identified out of 124 selected fragments. The expression levels of 20 putatively up-regulated genes were further analyzed using real-time RT-PCR, showing that, indeed 19 of these 20 genes were up-regulated during at least one of the studied developmental stages or during strawberry crown invasion, relative to the mycelium. This study provides a first overview of P. cactorum genes that are up-regulated immediately prior to or during strawberry infection and also provides a novel method for selecting RxLR effector genes from the unsequenced genome of P. cactorum. [ABSTRACT FROM AUTHOR]

nthracnose, caused by the fungus Colletotrichum acutatum is one of the most important diseases in strawberry crop. Due to environmental pollution and resistance produced by chemical fungicides, nowadays biological control is considered a good alternative for crop protection. Among biocontrol agents, there are plant growth-promoting bacteria, such as members of the genus Azospirillum. In this work, we demonstrate that under iron limiting conditions different strains of A. brasilense produce siderophores, exhibiting different yields and rates of production according to their origin. Chemical assays revealed that strains REC2 and REC3 secrete catechol type siderophores, including salicylic acid, detected by thin layer chromatography coupled with fluorescence spectroscopy and gas chromatography-mass spectrometry analysis. Siderophores produced by them showed in vitro antifungal activity against C. acutatum M11. Furthermore, this latter coincided with results obtained from phytopathological tests performed in planta, where a reduction of anthracnose symptoms on strawberry plants previously inoculated with A. brasilense was observed. These outcomes suggest that some strains of A. brasilense could act as biocontrol agent preventing anthracnose disease in strawberry. [ABSTRACT FROM AUTHOR]

In 2012-2015, a new fungal pathogen was isolated from fruits and leaves of strawberry from strawberry productive regions of Iran. The pathogen was identified as Pilidium concavum on the basis of morphology and ITS sequence analysis. A pathogenicity test was performed on fruit and leaf and P. concavum was re-isolated confirming Koch's postulates. This is the first report of P. concavum as the cause of Tan-brown Rot on Strawberry in Iran. [ABSTRACT FROM AUTHOR]

Based on inoculation experiments and morphological and molecular phylogenetic studies, Cylindrocladium damping-off of strawberry and Cylindrocladium blight of coral bells in Japan were demonstrated to be caused by Cylindrocladium canadense. This is the first report of a disease on strawberry and coral bells caused by this fungus. [ABSTRACT FROM AUTHOR]

In choice test experiments on strawberry leaf disc arenas the phytoseiid mites Neoseiulus californicus and N. cucumeris were more effective than Typhlodromus pyri as predators of the phytophagous mites Tetranychus urticae and Phytonemus pallidus. There were no preferences shown for either prey by any of these predators. In multiple predator leaf disc experiments both Phytoseiulus persimilis and N. cucumeris significantly reduced numbers of T. urticae eggs and active stages; this effect was seen when the two species were present alone or in combination with other predator species. Neoseiulus californicus was less effective at reducing T. urticae numbers, and T. pyri was not effective; no interaction between predator species was detected in these experiments. When T. urticae alone was present as prey on potted plants, P. persimilis and N. californicus were the only phytoseiids to significantly reduce T. urticae numbers. These two predator species provided effective control of T. urticae when P. pallidus was also present; however, none of the predators reduced numbers of P. pallidus. There were no significant negative interactions when different species of predators were present together on these potted plants. In field experiments, releases of both P. persimilis and N. cucumeris significantly reduced T. urticae numbers. However, there was a significant interaction between these predator species, leading to poorer control of T. urticae when both species were released together. These results show the importance of conducting predator/prey feeding tests at different spatial scales. [ABSTRACT FROM AUTHOR]

The mode of action of soluble silicon against strawberry powdery mildew ( Sphaerotheca aphanis var. aphanis) was investigated in four experiments. First, silicon-treated leaves from plants grown with silicate (Si+) and control leaves were excised, inoculated with conidia, and subsequent germination and formation of appressoria in a petri dish was assessed after 24 h. The germination rate was 49.7% on Si+ leaves, and was 67.2% on control leaves ( t-test, P < 0.01). Second, we soaked cellulose membranes in various solvents and then placed the membranes on 4% water agar, dusted the membranes with conidia, and examined after 12 h. No difference was apparent between any treatment and the control (distilled water). Third, strawberries growing hydroponically with additional silicon in the medium were inoculated with conidia, and leaves were observed with a scanning electron microscope 1–2 days after inoculation. Germ tubes and secondary hyphae were shorter and had fewer branches on Si+ leaves than on the control. Moreover, penetration appeared to be inhibited. Fourth, the cuticle was separated from leaves from plants grown as in the third experiment, placed on water agar, and dusted with conidia. Germination of conidia, observed with a light microscope, on Si+ leaves was suppressed markedly to 40%–60% of that of the control. These results suggested that soluble silicon induced physiological changes in the cuticle layer after absorption by the plant. In addition, soluble silicate reduced germination of conidia, formation of appressoria, and possibly the penetration of powdery mildew. [ABSTRACT FROM AUTHOR]

Black root rot is an important disease of strawberry caused by a complex of fungi that includes species of Rhizoctonia. In this study, a modified MIDI method (Microbial Identification System) was investigated for its utility to differentiate isolates of the three different anastomosis groups (AGs) of binucleate Rhizoctonia spp., associated with strawberry black root rot complex representing AG-A, AG-G, and AG-I. A total of 11 fatty acids were detected, and the FAME profiles for isolates of the three different AGs of Rhizoctonia spp. varied quantitatively and qualitatively. Moreover, the modified MIDI method will be a useful discriminatory tool for fungal identification and classification of the AGs of binucleate Rhizoctonia spp. associated with strawberry black root rot complex. [ABSTRACT FROM AUTHOR]

Gnomonia fragariae has been occasionally listed among the fungi associated with diseased strawberry plants. However its pathogenicity has not been established. During the investigation on strawberry decline in Latvia and Sweden, a fungus was repeatedly recovered from discoloured root and crown tissues of severely stunted plants. Attempts to induce sporulation of the isolates grown on several agar media resulted in the formation of mature ascomata only on potato carrot agar and oatmeal agar. On morphological grounds and comparisons with reference herbarium specimens these isolates were identified as Gnomonia fragariae. The pathogenicity of the fungus was evaluated initially in the detached leaf assay and subsequently in three bioassays on strawberry plants. All the bioassays showed that G. fragariae was pathogenic on strawberry and capable of causing severe root rot and petiole blight. The symptoms that developed in the greenhouse experiments closely resembled those observed in the fields. The fungus did not cause rapid plant death but growth and development of inoculated strawberry plants was severely affected. To our knowledge this is the first time when pathogenicity of G. fragariae as a root rot pathogen has been clearly established. Our study shows that G. fragariae is one of the serious pathogens involved in the root rot complex of strawberry in Latvia and Sweden. [ABSTRACT FROM AUTHOR]

Powdery mildew of strawberry is caused by the obligate pathogenic fungus Sphaerotheca macularis f. sp. fragariae. The disease affects the leaves, flowers and fruit of this crop. This study examined the effects of different environmental factors on disease cycle components (germination, conidiation and survival) in strawberry to determine which conditions limit the progress of the disease. The optimal environmental conditions for conidial germination and conidial germ tube length ranged between 15 and 25 °C with relative humidity (RH) higher than 75%, but less than 98%. High light intensity reduced germination and hyphal growth. The viability of conidia on infected leaves was examined at temperatures ranging from 15 to 35 °C at 80–85% RH. Conidia survival declined over time, but a certain percentage of conidia remained active after 5 months incubation. The rate of conidial germination was significantly higher on young leaves than on older leaves. This observation was consistent across all four tested cultivars. Conidiation at 70–75% RH was similar to that at 80–85%, but greater than that at ≥95% RH. The shortest time from inoculation to appearance of the first disease symptoms was 4 days, at 20 and 30 °C with RH above 75%. In growth chambers, temperatures of 10 and 30 °C, RH above 95%, radiation of 7000 lux and the use of a more tolerant cultivar were all detrimental to disease development. In general, the environmental conditions required for germination and dispersal of powdery mildew are conducive to disease progress under strawberry production conditions in Israel. Furthermore, viability and survival of the pathogen during and between seasons appears to be dependent on asexual inoculum production. [ABSTRACT FROM AUTHOR]

A mixed model approach was used to estimate variance components and heritabilities for resistance to powdery mildew, a wind-borne disease in strawberry. In order to improve precision in the statistical computations, spatial error control effects were included to account for systematic environmental variations in the large field trials. Pedigree information was included where feasible. Seedling families obtained from an incomplete 63-by-63 diallel cross were grown at six locations and scored subjectively for mildew attack three times during the growing season. The 63 parents included both European and American cultivars as well as advanced selections from various breeding programmes. A total of 298 full-sib families were realized, including 26 reciprocal families. No reciprocal differences were found. On a plot-mean basis, the broad-sense heritability was found to be intermediate, H2=0.44−0.50, depending on whether the pedigree information was included in the model or not. The increase was mainly due to a substantial increase in the additive variance component. Likewise, the narrow-sense heritability increased from h2=0.39 to h2=0.45 when the pedigree information was included, while the ratio of the specific combining ability variance to the general combining ability variance fell from 13% to 10%. The predicted breeding values of the 63 parents demonstrate that important cultivars such as Elsanta and Korona are unlikely to produce progenies with a high degree of resistance. On the other hand, the Norwegian cultivar Solprins, the Canadian cultivar Kent and the Italian cultivar Patty appeared to give highly resistant progeny. At the full-sib level, the estimated disease scores ranged from 1.15 (Kent × Induka) to 4.19 (Cavendish × Avanta), revealing a huge range of variation for powdery mildew resistance available for selection. [ABSTRACT FROM AUTHOR]

From 1996 to 1997, potassium silicate (SiO2) was tested at 0, 25, 50, and 100 mg l-1 in hydroponics to control powdery mildew. Other elements were added in the usual amounts, and the strawberries were cultivated hydroponically in a greenhouse for 4 months (from October to January). The powdery mildew spread in the control plot, but little mildew developed in the plot with 25 mg l-1 silicate, and none in plots with more than 50 mg l-1 silicate. The suppressive effect lasted for about 4 months on fruits and even longer on leaves. On analysis of mineral content in the leaves, only the silicate content differed markedly between the control and treated plants. Nitrogen, phosphate, potassium, and calcium contents did not differ greatly. The maximum silicate content was about 24 times that of the control, and disease severity decreased significantly when the content was more than 1.5% in the leaves. The hardness of the strawberry leaves, measured by a creep meter, was increased by the silicate treatment. [ABSTRACT FROM AUTHOR]

A modified method for detecting amplified fragment length polymorphism (AFLP) has been developed for species with small genomes. We successfully used a combination of primers with a reduced number of selective bases to differentiate and fingerprint isolates of Colletotrichum acutatum, the causative agent of strawberry black spot, an important strawberry disease. [ABSTRACT FROM AUTHOR]

Focuses on the use of predatory phytoseiid mite Typhlodromus pyri (T.pyri) for biological control of the two-spotted spider mite Tetranychus urticae on strawberries. Efficacy T.pyri in controlling spider mites in strawberries grown in glasshouse.

This article presents an abstract of the paper "Integrated Disease Management of Strawberry Anthracnose and Development of a New Biopesticide," which was presented by a winner of the Society Fellowship at the 2013 Annual Meeting of the Phytopathological Society of Japan in Gifu.

Phytophthora crown rot (PhCR) caused by Phytophthora cactorum is a destructive disease of the allo-octoploid cultivated strawberry (Fragaria ×ananassa Duch). Many major strawberry cultivars grown worldwide are susceptible to PhCR. Resistance is conferred by the recently-discovered FaRPc2 locus, but high-throughput markers are not yet available for marker-assisted breeding. In the current study, we developed DNA markers for two haplotypes at the FaRPc2 locus associated with resistance, H2 and H3. Marker validation and marker-assisted selection were performed in University of Florida (UF) breeding population. Seven single nucleotide polymorphism-based high resolution melting (HRM) markers linked to H2 and four HRM markers for H3 were developed. One HRM marker, RPCHRM3 linked to H3, was converted to a Kompetitive Allele Specific PCR (KASP) marker. To further examine the utility of the markers, they were screened in University of California Davis cultivars with known phenotypes as well as in 20 diverse accessions with phenotypes that are reported in the literature and that are preserved at the USDA-ARS National Clonal Germplasm Repository, in Corvallis, Oregon. The most informative markers for FaRPc2 resistance are being implemented in the UF strawberry breeding program to improve PhCR resistance. [ABSTRACT FROM AUTHOR]

An abstract on the study relating to the genetic diversity and aggressiveness of colletotrichum acutatum species related to strawberry in England is presented.

Colletotrichum acutatum is the primary causal agent of strawberry (Fragaria x ananassa) anthracnose causing severe economic losses to the crop. This fungal pathogen infects white fruits at pre-harvest unripe stage and remains quiescent during ripening causing anthracnose symptoms only on ripe fruits. In a previous microarray experiment a lectin gene was found overexpressed in white fruits inoculated with C. acutatum. For establishing weather this gene plays any role in the low susceptibility of white unripe fruits, an experiment was designed for silencing and overexpressing the lectin gene in white and red strawberry fruits, respectively, using Agrobacterium-mediated transient transformation. Exploiting the potential of plant species to silence genes when they recognize intron-containing constructs encoding self-complementary 'hairpin' RNA (ihpRNA), a construct containing the partial sense and corresponding antisense sequence of the lectin gene separated by an intron was generated to transform white fruits. On the other hand, to overexpress the gene on the red fruits, a vector containing the lectin gene under the control of 35S promoter was constructed. The timing for lectin gene silencing in white fruits was determined by qRT-PCR whereas, for monitoring transient lectin overexpression in red fruits, a DsRed fluorescent protein was used as reporter in microscopy analysis. [ABSTRACT FROM AUTHOR]