Strawberry Fruit Production Research Articles

Micorrhizal biotechnology as an alternative to potentialize the strawberry quality

The need to develop and use biotechnology tools to improve management and nutritional techniques in strawberry cultivation are increasing. Based on this, the objective of this study was to test if the mycorrhizal inoculation changes the agronomic and qualitative performance of strawberry fruits. The strawberry daughters plants used were of the cultivar Camarosa. The study was carried out in an agricultural greenhouse, Horticulture Sector of the Faculty of Agronomy and Veterinary Medicine (FAMV) of UPF, in the city of Passo Fundo, Rio Grande do Sul (RS), Brazil. The experiment was developed and maintained from June to December 2015. The treatments consisted of five inoculum: T1 = no inoculum (control); T2 = Acaulospora morrowiae; T3 = Rhizophagus clarus; T4 = mycorrhizal community; T5 = Claroideoglomus etunicatum. The experimental design was a randomized block with four replicates. Each plot consisted of a bag containing 6 plants spaced 0.15 mx 0.15 m. In the pits of the plants, it was applied, with the aid of syringe and water, about 70 infective propagules of the tested inocula. During the conduction of the experiment the temperature and photosynthetically active radiation (PAR) were monitored in the culture environment. It was evaluated the agronomic and qualitative performance of the fruits and the percentage of mycorrhizal colonization of the plants roots. The data were submitted to analysis of variance and the differences between means were compared by the Tukey test at 5% of probability error. The cultivar Camarosa produced more fruits in October. In September, the month before the one with the best agronomic performance, the mean temperature was 17.7 ºC. The mean PAR recorded in the growing environment was low in relation to crop requirements, throughout the growing period. Fruits produced by plants inoculated with A. morrowiae presented higher values of TSS/TTA ratio in September and October. The percentage of mycorrhizal colonization varied from 26.2% for A. morrowiae to 46.2% for R. clarus. The inoculation of arbuscular mycorrhizal fungi does not alter the production of strawberry fruits. However, when the plants are inoculated with A. morrowiae there is an improvement in the fruit flavor.

Effect of Trichoderma Bioactive Metabolite Treatments on the Production, Quality, and Protein Profile of Strawberry Fruits.

Fungi of the genus Trichoderma produce secondary metabolites having several biological activities that affect plant metabolism. We examined the effect of three Trichoderma bioactive metabolites (BAMs), namely, 6-pentyl-α-pyrone (6PP), harzianic acid (HA), and hydrophobin 1 (HYTLO1), on yield, fruit quality, and protein representation of strawberry plants. In particular, 6PP and HA increased the plant yield and number of fruits, when compared to control, while HYTLO1 promoted the growth of the roots and increased the total soluble solids content up to 19% and the accumulation of ascorbic acid and cyanidin 3-O-glucoside in red ripened fruits. Proteomic analysis showed that BAMs influenced the representation of proteins associated with the protein metabolism, response to stress/external stimuli, vesicle trafficking, carbon/energy, and secondary metabolism. Results suggest that the application of Trichoderma BAMs affects strawberry plant productivity and fruit quality and integrate previous observations on deregulated molecular processes in roots and leaves of Trichoderma-treated plants with original data on fruits.

Strawberries at the Crossroads: Management of Soilborne Diseases in California Without Methyl Bromide.

Strawberry production has historically been affected by soilborne diseases such as Verticillium wilt. This disease was a major limiting factor in strawberry production in California in the 1950s and was the main reason that preplant soil fumigation with methyl bromide (MB) was developed in the late 1950s. MB fumigation was so successful that over 90% of the commercial strawberry fruit production in California utilized this technique. However, MB was subsequently linked to ozone depletion, and its use was phased out in 2005. The California strawberry industry was awarded exemption to the full phase-out until 2016, when all MB use in strawberry fruit production was prohibited. MB use continues in strawberry nurseries under an exemption to prevent spread of nematodes and diseases on planting stock. This review examines the impact of the MB phase-out on the California strawberry industry and evaluates the outlook for the industry in the absence of one of the most effective tools for managing soilborne diseases. New soilborne diseases have emerged, and historically important soilborne diseases have reemerged. Registration of new fumigants has been difficult and replacement of MB with a new and effective alternative is unlikely in the foreseeable future. Thus, crop losses due to soilborne diseases are likely to increase. Host plant resistance to soilborne diseases has become a top priority for strawberry breeding programs, and cultivars are increasingly selected for their resistance to soilborne diseases. The intelligent integration of a variety of management tactics is necessary to sustain strawberry production in California.

Transcriptome Profiles of Strawberry (Fragaria vesca) Fruit Interacting With Botrytis cinerea at Different Ripening Stages.

Gray mold caused by Botrytis cinerea is a major cause of economic losses in strawberry fruit production, limiting fruit shelf life and commercialization. When the fungus infects Fragaria × ananassa strawberry at flowering or unripe fruit stages, symptoms develop after an extended latent phase on ripe fruits before or after harvesting. To elucidate the growth kinetics of B. cinerea on flower/fruit and the molecular responses associated with low susceptibility of unripe fruit stages, woodland strawberry Fragaria vesca flowers and fruits, at unripe white and ripe red stages, were inoculated with B. cinerea. Quantification of fungal genomic DNA within 72 h postinoculation (hpi) showed limited fungal growth on open flower and white fruit, while on red fruit, the growth was exponential starting from 24 hpi and sporulation was observed within 48 hpi. RNA sequencing applied to white and red fruit at 24 hpi showed that a total of 2,141 genes (12.5% of the total expressed genes) were differentially expressed due to B. cinerea infection. A broad transcriptional reprogramming was observed in both unripe and ripe fruits, involving in particular receptor and signaling, secondary metabolites, and defense response pathways. Membrane-localized receptor-like kinases and nucleotide-binding site leucine-rich repeat genes were predominant in the surveillance system of the fruits, most of them being downregulated in white fruits and upregulated in red fruits. In general, unripe fruits exhibited a stronger defense response than red fruits. Genes encoding for pathogenesis-related proteins and flavonoid polyphenols as well as genes involved in cell-wall strengthening were upregulated, while cell-softening genes appeared to be switched off. As a result, B. cinerea remained quiescent in white fruits, while it was able to colonize ripe red fruits.

Impact of Beneficial Microorganisms on Strawberry Growth, Fruit Production, Nutritional Quality, and Volatilome.

Arbuscular mycorrhizal fungi (AMF) colonize the roots of most terrestrial plant species, improving plant growth, nutrient uptake and biotic/abiotic stress resistance and tolerance. Similarly, plant growth promoting bacteria (PGPB) enhance plant fitness and production. In this study, three different AMF (Funneliformis mosseae, Septoglomus viscosum, and Rhizophagus irregularis) were used in combination with three different strains of Pseudomonas sp. (19Fv1t, 5Vm1K and Pf4) to inoculate plantlets of Fragaria × ananassa var. Eliana F1. The effects of the different fungus/bacterium combinations were assessed on plant growth parameters, fruit production and quality, including health-promoting compounds. Inoculated and uninoculated plants were maintained in a greenhouse for 4 months and irrigated with a nutrient solution at two different phosphate levels. The number of flowers and fruits were recorded weekly. At harvest, fresh and dry weights of roots and shoots, mycorrhizal colonization and concentration of leaf photosynthetic pigments were measured in each plant. The following fruit parameters were recorded: pH, titratable acids, concentration of organic acids, soluble sugars, ascorbic acids, and anthocyanidins; volatile and elemental composition were also evaluated. Data were statistically analyzed by ANOVA and PCA/PCA-DA. Mycorrhizal colonization was higher in plants inoculated with R. irregularis, followed by F. mosseae and S. viscosum. In general, AMF mostly affected the parameters associated with the vegetative portion of the plant, while PGPB were especially relevant for fruit yield and quality. The plant physiological status was differentially affected by inoculations, resulting in enhanced root and shoot biomass. Inoculation with Pf4 bacterial strain increased flower and fruit production per plant and malic acid content in fruits, while decreased the pH value, regardless of the used fungus. Inoculations affected fruit nutritional quality, increasing sugar and anthocyanin concentrations, and modulated pH, malic acid, volatile compounds and elements. In the present study, we show for the first time that strawberry fruit concentration of some elements and/or volatiles can be affected by the presence of specific beneficial soil microorganisms. In addition, our results indicated that it is possible to select the best plant-microorganism combination for field applications, and improving fruit production and quality, also in terms of health promoting properties.

Nonlinear regression for description of strawberry (Fragaria x ananassa) production

ABSTRACTThe aim of this study was to select growth models to describe strawberry (Fragaria x ananassa)fruit production. To do this, data on 16 treatments (combination of 2 cultivars [Albion and Camarosa], 2 origins [National and Imported], and 4 organic substrates mixed [70% crushed sugar cane residue + 30% organic compost, 70% crushed sugar cane residue + 30% commercial substrate, 70% burnt rice husk + 30% organic compost, and 70% burnt rice husk + 30% commercial substrate]) conducted in a Randomized Complete Block Design (RCBD) with 4 replicates were used. Different parameterizations of the Logistic, Gompertz, and von Bertalanffy models were adjusted for number and weight of fruits per plant (g) accumulated in multiple harvests. The model adjustment and parameter estimation were obtained by ordinary least squares, using a Gauss Newton algorithm. The selection of the best model was chosen by intrinsic and parametric nonlinearity. Among the adjusted nonlinear models, the best adjustment for both variables was achieved by the parameterization 2 of the Logistic model and parameterization 1 of the Gompertz model, because they had lower results with less parametric and intrinsic nonlinearity. However, care should be taken when using the Gompertz model because it tends to overestimate the production estimate and may cause misunderstandings in interpretation.

Fitness, Competitive Ability, and Mutation Stability of Isolates of Colletotrichum acutatum from Strawberry Resistant to QoI Fungicides.

Quinone-outside inhibitor (QoI) fungicides are used to manage anthracnose of strawberry, caused by Colletotrichum acutatum. However, selection for resistance to QoI fungicides was first reported in 2013 in Florida and, subsequently, in strawberry nurseries and production areas across the United States and Canada. C. acutatum resistance to QoIs is associated with the G143A point mutation in the cytochrome b gene. This mutation is known to be associated with field resistance even at high rates of QoI. In this study, we investigated the relative fitness and competitive ability of QoI-resistant and -sensitive C. acutatum isolates. A fitness comparison did not indicate any difference between resistant and sensitive isolates in aggressiveness, spore production, and mycelial growth at different temperatures. Additionally, in the absence of selection pressure, resistant and sensitive isolates were equally competitive. Cultivation of QoI-resistant and QoI-sensitive isolates for four culture cycles in vitro in the absence of azoxystrobin showed that QoI resistance was stable. The observed lack of fitness penalties and stability of the G143A mutation in QoI-resistant C. acutatum populations suggest that the interruption and further reintroduction of QoI fungicides might not be an option for strawberry nurseries and fruit production areas. Further investigation of alternative chemical and nonchemical C. acutatum control practices, in addition to the integration of multisite fungicides, is needed to reduce the occurrence and distribution of QoI-resistant populations in strawberry fields.

Pest categorisation of Anthonomus bisignifer.

The Panel on Plant Health performed a pest categorisation of the strawberry blossom weevil, Anthonomus bisignifer Schenkling, (Coleoptera: Curculionidae), for the EU. Anthonomus bisignifer is a well‐defined and distinguishable species, recognised as an occasional pest of strawberry (Fragaria) fruit production in Japan where it is also feeds on Rubus and Rosa spp. Adults clip developing buds, preventing fruit development and reducing yield. Losses are variable and are likely to depend on the cultivars attacked. Severe damage to Fragaria spp. has been reported but is rare. Flowers of ornamental garden Rosa spp. are more commonly damaged. Anthonomus bisignifer is not known to occur in the EU. A. bisignifer is listed in Annex IIAI of Council Directive 2000/29/EC. Host plants for planting could provide a pathway although only a few non‐EU countries can export Fragaria plants for planting to the EU and A. bisignifer is not known to occur in any of them. However, Rubus and Rosa plants for planting could provide a potential pathway to introduce A. bisignifer. Considering climatic similarities of the region where A. bisignifer occurs and where hosts occur in the EU, A. bisignifer has the potential to establish within the EU. There would be one generation per year, as in Japan. Impacts could be expected on field grown and protected Fragaria, field grown Rubus and garden Rosa spp. There is uncertainty regarding which other hosts exist within Rosaceae, hence impacts could potentially be seen on other species too. Phytosanitary measures are available to reduce the likelihood of introduction of A. bisignifer. All criteria assessed by EFSA for consideration as a potential Union quarantine pest are met. As A. bisignifer is not known to occur in the EU, this criterion assessed by EFSA to consider it as a Union regulated non‐quarantine pest is not met.

Pest categorisation of Anthonomus signatus.

The Panel on Plant Health performed a pest categorisation of the strawberry bud weevil, Anthonomus signatus Say, (Coleoptera: Curculionidae), for the EU. A. signatus is a well‐defined and distinguishable species, recognised as a pest of strawberry (Fragaria) fruit production in eastern North America where it is also a pest of Rubus. There are reports of A. signatus associated with non‐rosaceous plants such as Mentha, Nepeta, Rhododendron and Solidago although whether such plants are true hosts is uncertain. This pest categorisation focuses on Fragaria and Rubus as hosts. Anthonomus signatus is not known to occur in the EU. It is listed in Annex IIAI of Council Directive 2000/29/EC. The international trade in Fragaria and Rubus plants for planting provides a potential pathway to introduce A. signatus from North America. Considering climatic similarities between North America and the EU, the thermal biology of A. signatus and host distribution in the EU, A. signatus has the potential to establish within the EU. There would be one generation per year, as in North America. As a pest of field grown Fragaria and Rubus, A. signatus would not be expected to establish in EU glasshouses. In North America, adults clip developing buds, preventing fruit development and reducing yield. Losses are variable and depend on the cultivars attacked. Severe crop losses have been reported. However, some Fragaria cultivars can compensate the loss of buds, e.g. by increasing the weight of fruits developing on remaining buds. Phytosanitary measures are available to reduce the likelihood of introduction of A. signatus from North America. All criteria assessed by EFSA for consideration as a potential Union quarantine pest are met. As A. signatus is not known to occur in the EU, this criterion assessed by EFSA to consider it as a Union regulated non‐quarantine pest is not met.

Properties of New Strawberry Lines Compared with Well-Known Cultivars in Winter Planting System Conditions

In Southern Italy and Sicily, strawberry cultivation is dominated by international cultivars such as ‘Candonga Sabrosa’, ‘Florida Fortuna’, ‘Sabrina’ and ‘Sant Andreas’. The primary objective of our study was to compare the field performance of two experimental lines and four established cultivars in a Sicilian representative strawberry production area. The second objective was to compare the fruits physic-chemical nutraceutical characteristics of these genotypes in response to different postharvest fruit storage temperatures. A supporting genetic analysis, via SSR markers, was also performed in order to establish genotype correlations. Our study confirmed the high result of ‘Florida Fortuna’ in terms of earliness and productivity and the high performance of ‘Candonga Sabrosa’ in terms of total soluble content and fruit firmness. The new lines ‘PA1’ and ‘PA2’ showed satisfying results. However, the new line ‘PA2’, might deserve particular attention by growers involved in strawberry early fruit production in Mediterranean areas both for its yield performance and fruit quality characteristics. This study also showed that a 4 °C fruit storage temperature treatment for 36 hours positively affects the physical and chemical quality properties of strawberry fruits, whereas overall quality declines at 20 °C storage. According to the genetic characterization, ‘PA2’ was closely related to ‘Candonga Sabrosa’ and ‘Florida Fortuna’.

Chitosan and plant probiotics application enhance growth and yield of strawberry

Abstract Strawberry is a newly introduced fruit crop in Bangladesh, which gained considerable interests from both growers and consumers. Resource poor growers of the country will need alternate production technology to keep the cost under control as well as minimize health hazard by reducing use of synthetic pesticides. This study evaluated and compared the performance of plant probiotic bacteria, chitosan and fungicides on growth and fruit yield of strawberry. Application of two plant probiotic bacteria, Bph-4 and BTLK6a to strawberry plants significantly increased vegetative growth and fruit yield compared to non-treated control. Further investigation on these bacteria revealed that they possessed indole acetic acid production and/or antagonistic properties to phytopathogenic microbes. The Bph-4 and BTLK6a were identified as Stenotrophomonas sp. and Ochrobacterum sp., respectively through 16S rRNA gene sequencing. Chitosan @ 250–500 ppm and BTLK6a application on tissue-cultured plants of cv. Strawberry Festival produced 56% and 43% higher fruit yield, respectively, compared to non-treated control. Out of two different plant types tested, tissue-cultured plants responded to chitosan and probiotics better than runner grown plants for percentage of yield increase. Fungicide treatment did not provide any yield advantage likely due to the absence of targeted diseases. These results suggest that chitosan and plant probiotic bacteria could be used as natural bioregulators for safe production of strawberry fruits in Bangladesh.

Protecting fungicide chemistry used in Australian strawberry production for more sustainable control of powdery mildew and leaf blotch

Powdery mildew (caused by Podosphaera aphanis) and leaf blotch (caused by Gnomoniopsis fructicola) are important diseases of strawberry in nursery and fruit production regions of Australia. Myclobutanil, trifloxystrobin and penthiopyrad are registered for control of powdery mildew in Australia, but are not restricted to either nursery or fruit production. Due to the specific mode of action of these fungicides against P. aphanis, their repeated use over the successive stages of strawberry runner and then fruit production may increase the risk of fungicide resistance in the pathogen. Currently, there is no fungicide registered for control of G. fructicola in strawberry in Australia. A series of field trials in Queensland and Victorian strawberry nurseries over two seasons (2013/14 to 2014/15) evaluated the efficacy of 19 fungicide and biorational products, applied alone or as part of a program (in combination with other products), against powdery mildew and leaf blotch. Our aim was to manage the risk of fungicide resistance by developing disease control programs specifically for use in the strawberry runner nurseries with different activity groups to the fungicides used in strawberry fruit production. Treatments were applied weekly using a knapsack sprayer starting December/January for approximately 16 weeks until prior to harvest of runners in March/April. Runners were randomly selected and rated for the incidence of powdery mildew and leaf blotch prior to harvest. Where single fungicide treatments were applied (2013/14), the field trial results identified bupirimate, cyflufenamid, quinoxyfen, proquinazid, azoxystrobin + difenoconazole, as equally or more effective in controlling powdery mildew as the industry standard program of sulphur, myclobutanil and trifloxystrobin. Field trials in 2014/15 assessed spray programs that were based on sulphur in different combinations with quinoxyfen, bupirimate, cyflufenamid and/or with reduced applications of myclobutanil and trifloxystrobin. All programs were as effective against powdery mildew as the industry standard program. Azoxystrobin + difenoconazole, prochloraz, and chlorothalonil were the most effective against leaf blotch in trials in 2013/14 and 2014/15. It is anticipated that the coordinated use of different chemistries across the strawberry nursery and fruit industries will reduce the risk of fungicide resistance developing in pathogen populations, and increase the sustainability of disease protection across strawberry crops.

EFFECT OF IRRIGATION SCHEDULING AND PLANT DENSITY ON PRODUCTIVITY AND QUALITY OF STRAWBERRY GROWN IN WATER CULTURE

The experiment was carried out at the experimental site of Arid Land Agricultural graduate studies and Research Institute (ALARI), Faculty of Agriculture, Ain Shams University, Qalyobia Governorate during the two successive seasons of 2013/2014 and 2014/2015. Fresh bare root strawberry (Fragaria x ananassa) transplants cv. Festival were used in this experiment.The aim of the study was to determine the best irrigation scheduling and better strawberry density to get the best production and quality of strawberry fruits grown in A-shape NFT system. Five irrigation schedules (24 hours (control), ¼ / ½ hour (Sched 1), ¼ / 1 hour (Sched 2), ¼ / 2 hours (Sched 3), ¼ / 3 hours (Sched 4) and two plant density per square meter (21 plants / m2 “PD-1”,32 plants / m2 “PD-2”) and the combinations among them were tested in this experiment. The EC of the nutrient solution was adjusted at the range of 2.0 – 2.5 m.mhos-2 and pH was maintained at the range of 5.5-6.0 throughout the experimental time. The measurements recorded were as follows: number of leaves, % of fruit set, early and total yield and mean fruit weight. Quality measurements included total soluble solids (TSS) (the percentage of TSS was determined by using hand refractometer), ascorbic acid (vitamin C), and fruit acidity. Results indicated that irrigating plants for 15 min every ½ hour increased productivity (mean fruit weight, early yield and total yield) and quality (TSS) but reduced vitamin C and fruit acidity of strawberry. While the irrigating plants every 1 hour reduced number of leaves, set %, early & total yield, mean fruit weight, TSS.

Fumigant Use for Strawberry Production in Europe: The Current Landscape and Solutions

ABSTRACTThe impact of methyl bromide (MB) phase-out on important fruit and nursery industries in the EU (2005/2008) has been significant. Under EU Regulation 1107/2009, MB fumigant alternatives 1,3-dichloropropene and chloropicrin were also phased out (in 2010 and 2013, respectively) while dazomet, metam sodium, and potassium were re-approved with crucial restrictions of rates and years of application. However, currently an EU Member State may authorize use of these phased-out fumigants for 120 days/year. This exemption has been used for strawberry (fruit and nursery production) and other crops in Spain, Italy, Belgium, France, UK, Cyprus, Malta, and Greece in recent years. To provide an update of the current situation, a comprehensive survey of 41 European and other industries has been completed. Most of them use crop rotation as the main pest management solution. Non-chemical solutions, in particular soilless cultivation, are important in the UK, Ireland, France, the Netherlands, and Belgium. Chemical fumigation is still important in Spain, Italy, Morocco, Turkey, France, and Belgium.

Evaluating Correlations and Development of Meteorology Based Yield Forecasting Model for Strawberry

California state is among the leading producers of strawberries in the world. The value of the California strawberry crop is approximately $2.6 billion, which makes it one of the most valuable fruit crops for the state and nation’s economy. California’s weather provides ideal conditions for strawberry production and changes in weather pattern could have a significant impact on strawberry fruit production. Evaluating relationships between meteorological parameters and strawberry yield can provide valuable information and early indications of yield forecasts that growers can utilize to their advantage. Objectives of this paper were to evaluate correlations of meteorological parameters on strawberry yield for Santa Maria region and to develop meteorology based empirical yield forecasting models for strawberries. Results showed significant correlation between meteorological parameters and strawberry yield and provided a basis for yield forecasting with lead time. Results from empirical models showed that cross-validated yields were closely associated with observed yield with lead time of 2 to 5 months. Overall, this study showed great potential in developing meteorology based yield forecast using principal components. This study only looked at meteorology based yield forecasts. Skills of these models can be further improved by adding physiological parameters of strawberry to existing models for strawberry.

Characteristics of growing media mixes and application for open-field production of strawberry (Fragaria ananassa)

Growing media are widely used for strawberry production in protected environments. Due to increasing restrictions on the use of soil fumigants, there is a need to investigate production of strawberry fruits in open fields using substrate media. The objectives of the study were to characterize chemical and hydraulic properties of a number of selected growing media mixes and to evaluate them in a two-year field study for strawberry production in open fields. The growing media mixes were 100% coconut coir, a peat–perlite (PP) mix, a peat-rice hull (PR) mix, and a peat–coir–rice hull (PCR) mix. Results indicated that major macro- and micro nutrient element concentrations, pH, and salinity found in these growing media, after supplemental fertilization, were in recommended ranges for strawberry production. Compared to field soil, higher water content values were found for these growing media mixes at saturation and after free drainage. Among these media mixes, 100% Coir showed the highest water content values at saturation (0.95cm3cm−3) and after free drainage (0.51cm3cm−3). The field study also demonstrated the most vigorous vegetative growth in Coir by showing higher values in plant canopy size and biomass dry weight. In year 1 field experiment, marketable strawberry fruit yields from Coir, PP, and PR averaged 41,640kgha−1 which was not significantly different from the soil beds. Marketable strawberry yields from the year 2 Coir and PP treatments averaged 48,520kgha−1, which was also not significantly different from the grower standard practice in field soils. The year 2 yield was higher than year 1 because of longer harvesting season and more favorable weather conditions for strawberry growth. The study demonstrated that certain growing media mixes such as PP or the 100% Coir possess the needed chemical and hydraulic properties for plant growth and the 100% Coir could be used as a promising substrate material for open-field production of strawberries. Additional work is needed to optimize the irrigation and fertilization regimes to reduce the volume of growing media needed per plant and to evaluate the reuse of the substrate media to reduce production cost.

Evaluation of biosolarization for the control of charcoal rot disease (Macrophomina phaseolina) in strawberry

Macrophomina phaseolina, the causal agent of charcoal rot, is a primarily soil-borne pathogen. Charcoal rot has become increasingly troublesome in strawberry (Fragaria × ananassa Duch.) in Spain, where it was reported for the first time in 2006, and worldwide. After the phase out of methyl bromide, some authors have associated the changes in the fumigation products used and methods of applying them prior to planting strawberries with the establishment of M. phaseolina. Moreover, in developed countries, the majority of useful chemical alternatives are futureless, because of regulatory restrictions. Among the non-chemical alternatives for strawberry fruit production is soil biosolarization, a new technique that combines soil biofumigation and soil solarization. In this study, we compared the efficacy of several biosolarization treatments to control M. phaseolina for three successive seasons in a non-chemical treated field near Moguer, Huelva (southwestern Spain). The influence of these treatments on M. phaseolina soil population, charcoal rot development, and strawberry yield was assessed each year. Soil was biofumigated by amendment of fresh chicken manure at 12,500 kg/ha with or without Trichoderma spp (TUSAL®) at 3.5 kg/ha; fresh chicken manure at 25,000 kg/ha; Brassica spp. pellets (BIOFENCE®) at 2000 kg/ha and 15,000 kg/ha; dried olive pomace at 12,500 kg/ha or sugar beet vinasse at 15,000 kg/ha. Soil was then solarized for 30 days by covering with a clear plastic mulch. A control that received fermented manure remained uncovered. The treatments reduced or stabilized M. phaseolina sclerotia populations in soil compared to the untreated control. Treatments which combined biosolarization with chicken manure at 25,000 kg/ha or sugar beet vinasse at 15,000 kg/ha significantly reduced the incidence of charcoal rot compared to the untreated control. Furthermore, yields obtained by amendment with fresh chicken manure (59,319–89,421 kg/ha) were also similar to the yields previously reported for the standard chemical fumigation with 1,3-dichloropropene:chloropicrin. Therefore, biosolarization with fresh chicken manure could be a promising and sustainable option for strawberry crops grown in warm temperate climate areas.

First Report of Fusarium solani Causing Crown and Root Rot on Strawberry Crops in Southwestern Spain

Spain is the fourth largest strawberry (Fragaria × ananassa) producing country in the world. Since April 2010, stunted and dead strawberry plants have been detected in four strawberry fruit production fields in Huelva (southwestern Spain) affecting less than 1% of plants. Symptoms consisted of foliage wilt, plant stunting and drying, and death of older leaves. Internal vascular and cortical tissues of plant crowns showed an orange to brown discoloration. Crowns and roots of symptomatic plants were surface sterilized in 1% sodium hypochlorite for 2 min, rinsed in sterile distilled water for 2 min, and air-dried in a laminar flow cabinet. Small disinfested pieces were transferred to petri dishes containing potato dextrose agar (PDA) and incubated for 10 days at 25°C with a 12-h photoperiod. Cultures derived from single spores were obtained, and morphological characterization was performed by microscopic examination. White to pale cream colonies developed after 10 days of incubation. Unbranched monophialides with microconidia in false heads, micro- (0 to 3 septa) and macroconidia (5 to 7 septa) wide and robust in shape, and chlamydospores were consistent with descriptions of Fusarium solani (Martius) Appel & Wollenweber emend. Snyder & Hansen (2). In addition, the fungus was isolated from asymptomatic runner plants from nurseries by the same method described above, and from soil samples from six fruit-producing fields. Soil samples were analyzed by dilution plating on Fusarium-selective agar medium (1). Genomic DNA from three isolates (FPOST-81 from dead plant 'Sabrina,' TOR-11 from runner plant 'Camarosa,' and TOR-1 from soil) was obtained with a DNA extraction kit (Isolate Plant DNA MiniKit, Bioline). A portion of the translation elongation factor-1 alpha (EF-1α) gene was sequenced using EF-1/-2 primers (3) (GenBank Accession Nos. KF275032, KF275033, and KF275034). The sequence comparison revealed a 99 to 100% match with F. solani sequences in GenBank and Fusarium-ID databases. To confirm the pathogenicity of the fungi, runner strawberry plants 'Camarosa' were inoculated by dipping crowns and roots into a conidial suspension (106 to 107 conidia per ml) for 30 min (8 plants per F. solani isolate) or into sterile distilled water for the controls. Plants were potted in 13-cm diameter pots with peat and maintained at 25/18°C and 70/40% relative humidity (day/night) in a growth chamber with a daily 16-h photoperiod of fluorescent light. Three plants inoculated with isolates TOR-11 and FPOST-81, and four plants inoculated with isolate TOR-1, died within 10 days after inoculation. After 8 to 12 weeks, all of the remaining inoculated plants were stunted and developed symptoms similar to those observed in the field. Production of new feeder roots was lacking or scarce. Control plants remained healthy and formed feeder roots. All plants inoculated with isolates TOR-1 and FPOST-81, and 50% of plants inoculated with TOR-11, showed brown discoloration in the crown. F. solani was re-isolated from symptomatic plants at frequencies of 100% and 80 to 100% from root and crown tissues, respectively. Although F. solani has been reported as a pathogen in other crops, to our knowledge, this is the first report of the occurrence of F. solani causing disease in strawberry plants in Spain.

Effects of non-chemical soil fumigant treatments on root colonisation with arbuscular mycorrhizal fungi and strawberry fruit production

The effects of biofumigation and soil heating on arbuscular mycorrhizal fungi (AMF) colonisation, strawberry growth and strawberry yield in pot experiments compared with untreated soil and chemical fumigation with dazomet were tested. Three different Brassicaceae species (Brassica juncea, Eruca sativa, Sinapis alba) were used as biofumigant plant green manure and soil heating was applied to simulate soil solarisation. Half of the plants were inoculated with indigenous arbuscular mycorrhizal fungi inoculum. With one exception (E. sativa) among the uninoculated plants, the treatments significantly decreased the mycorrhizal colonisation parameters compared with the untreated control. Dazomet displayed the greatest inhibitory effects on AMF establishment. In addition, the intensity and number of bands corresponding to Glomus spp. obtained with temporal temperature-gradient gel electrophoresis were lower for strawberry plants from biofumigant treatments than from the control. For the inoculated plants, there were almost no significant differences among the mycorrhizal colonisation parameters. The mass of leaves for the uninoculated and inoculated plants was higher for almost all non-chemical soil fumigant treatments compared with the control, except for heating of the uninoculated treatments. The number of strawberry fruits for the uninoculated biofumigant treatments was the highest, being higher than the values observed for the heating treatments, the chemical disinfection treatments and the control. There were no significant differences among the inoculated treatments. Biofumigation with Brassicaceae species resulted in higher soil organic matter and mineral nutrients and had a relatively small effect on AMF colonisation (F% = 59.0, 80.3, 47.3 for Bj, Es and Sa, respectively) compared with uninoculated controls (F% = 84.3). Despite the reduced AMF colonisation, biofumigation resulted in a higher fruit number and mass of leaves. Therefore, it represents a non-chemical soil fumigation method that should be applied in sustainable strawberry production.

Gypsum as a source of sulfur for strawberry crops

De uma maneira geral, diversos são os estudos sobre a resposta das plantas ao enxofre (S), porém poucos são específicos para a cultura do morangueiro. A exigência por nutrientes e o estado nutricional é um atributo particular de cada espécie e deve ser levada em conta na determinação da demanda nutricional. O objetivo deste trabalho foi avaliar a influência da aplicação de doses S e fósforo (P) no desenvolvimento e produtividade do morangueiro. Foi conduzido um experimento em casa de vegetação, em vasos de 2 Kg de solo (Latossolo Bruno), em Guarapuava-PR. O experimento constituiu-se de um fatorial 6 x 2, delineado em blocos ao acaso, com três repetições, sendo seis doses de S: 0, 10, 20, 30, 40 e 50 mg kg-1, na forma de gesso agrícola e duas doses de P: 300 e 600 mg kg-1 de P2O5. Nos vasos foram transplantadas mudas de morango variedade Albion, cultivadas por 170 dias. Os frutos foram colhidos e pesados ao longo do experimento e a parte aérea ao final do experimento. A parte aérea e os frutos foram secos, pesados, moídos e analisados em relação ao teor de S, Ca e P. A produção de frutos de morango foi influenciada pelas doses de S, sendo que a maior produtividade foi alcançada na dose de 60 mg kg-1 de S com aplicação de 300 mg kg-1 de P e na aplicação de 600 mg kg-1 de P combinada com a dose de 37 mg kg-1 de S.