Strawberry Growers Research Articles

‘Florida Radiance’ Strawberry

‘Florida Radiance’ is a strawberry cultivar released from UF/IFAS in 2008. As of 2012, it has become a major cultivar in Florida and other winter and early spring production regions worldwide. In all markets outside the United States and Canada, it is marketed as ‘Florida Fortuna’. In addition to commercial production, it has been tested for many years in field plots at the UF/IFAS Gulf Coast Research and Education Center in Wimauma and the Florida Strawberry Growers Association headquarters in Dover for disease, fruit, and plant traits. This 4-page fact sheet was written by Vance M. Whitaker, Craig K. Chandler, Bielinski M. Santos, and Natalia A. Peres, and published by the UF Department of Horticultural Sciences, June 2013.
 http://edis.ifas.ufl.edu/hs400

Strawberry fields forever? Conflict over neo-productivist Spanish polytunnel technology in British agriculture

This paper uses the example of Spanish polytunnels to demonstrate how the deployment of ‘neo-productivist’ agricultural technologies to meet the demands of food security and sustainability within a globalised food chain is likely to precipitate greater countryside conflict. Field-scale ‘Spanish polytunnels’ for strawberry growing have become a new feature of the British agricultural landscape. This has been driven primarily by supermarkets searching for high quality and quantity supplies of soft fruit. With production becoming industrialised, conflict has ensued in some rural communities where polytunnels have appeared. Interviews with prominent strawberry growers and protestors against polytunnels illuminate a vociferous and embittered wrangle. Within it, land use planners are labelled as ‘strawberry fools’ by both sides for failing, until recently, to provide decisive regulation to prevent conflict and effect its resolution. The paper concludes by drawing attention to the future characteristics of conflicts precipitated as new agricultural technologies are implemented rapidly, impact unevenly and are received acrimoniously.

Strawberry Cultivation under Diverse Agro-Climatic Conditions of India

In India, strawberry performs equally well in climates that are characteristically temperate in the northern latitudes, sub-tropical in the plains, or tropical at high altitude. In spite of attractive fruits and pleasing flavor, strawberry cultivation is still in its infancy in India primarily because of its perishable nature. Recently, some business houses have set up a number of pilot projects for large-scale strawberry production. Farmers in the sub-tropics in the vicinity of an urban center, such as New Delhi, have profitably cultivated strawberries during the winter months using plant material propagated in the hill states of India. Strawberry growers in the hills, thus, have a two-pronged earning potential from strawberry cultivation. Comparison of cultivars and economics of strawberry cultivation is presented.

Strawberry Production in Japan: History and Progress in Production Technology and Cultivar Development

In Japan, there are more than 25,000 strawberry farms totaling 6360 ha. Over 95% of the acreage is in an annual hill culture system and covered with polyethylene plastic to force June-bearing cultivars, such as Tochiotome and Saga-honoka to produce fruit from late fall to early summer. In the late 1960s, a forcing technique was developed that advanced flower bud initiation to late summer and prevented the transplants from becoming dormant in the winter. The new forcing technique involved nitrogen starvation of nursery plants, growing the transplants in walk-in tunnels with no chilling and a long-day photoperiod condition, and applying gibberellic acid before the onset of endodormancy. Until about 1970, strawberry growers in Japan used runner plants produced in waiting-beds, but now most of the transplants are produced in plastic pots to avoid soil-borne diseases. Recently, the use of tray plants produced from hanging runner cuttings has become popular. Most of the strawberries in Japan are grown in soil using the annual hill culture system. To offer better working conditions for plant management and fruit picking, low cost substrate culture systems and bench-top production systems are now used by over 1,800 farmers throughout Japan totaling over 470 ha in production.

SUSCEPTIBILITY OF SOME STARWEBERRY CULTIVARS TO THE INFESTATION OF TETRANYCHUS URTICAE KOCH

The relative susceptibility of six strawberry cultivars (Chandler sweet charll Branko, style , Helda and Almont) to the infestation with the two spotted mite Tetranychus urticae Koch was studied in Al kanater Research station Qualubia Governorate , through two successive seasons (2010/2011) and (2011/2012) . Evaluation of mite infestation was estimated according to the other mean number of eggs and immature stages, results showed that the population dynamics of spider mites infestation in the six cultivars appear in few numbers during the period from October until February. The infestation increased during March and reaches until February the infestation increased during march and reaches the maximum during April and decreases. The results also showed that sweetcharll and Chandler are the least preferable varieties, while Almont and Helda where the most preferable varieties to spider mite infestation . Based on these conclusions, Sweetcharll and Chandler varieties are recommended for the strawberry growers in order to depress the population density of the mite T. urticae in the strawberry fields in Egypt.

GROWTH, YIELD, AND ION RELATIONS OF STRAWBERRY IN RESPONSE TO IRRIGATION WITH CHLORIDE-DOMINATED WATERS

Strawberry is listed as the most salt sensitive fruit crop in comprehensive salt tolerance data bases. Recently, concerns have arisen regarding declining quality of irrigation waters available to coastal strawberry growers in southern and central California. Over time, the waters have become more saline, with increasing sodium (Na+) and chloride (Cl−). Due to the apparent extreme Cl− sensitivity of strawberry, the rising Cl− levels in the irrigation waters are of particular importance. In order to establish the specific ion causing yield reduction in strawberry, cultivars ‘Ventana’ and ‘Camarosa’ were grown in twenty-four outdoor sand tanks at the ARS-USDA U. S. Salinity Laboratory in Riverside, CA and irrigated with waters containing a complete nutrient solution plus Cl− salts of calcium (Ca2+), magnesium (Mg2+), Na+, and potassium (K+). Six salinity treatments were imposed with electric conductivities (EC) = 0.835, 1.05, 1.28, 1.48, 1.71, and 2.24 dS m−1, and were replicated four times. Fresh and dry weights of ‘Camarosa’ shoots and roots were significantly higher than those of ‘Ventana’ at all salinity levels. Marketable yield of ‘Camarosa’ fruit decreased from 770 to 360 g/plant as salinity increased and was lower at all salinity levels than the yield from the less vigorous ‘Ventana’ plants. ‘Ventana’ berry yield decreased from 925 to 705 g/plant as salinity increased from 0.835 to 2.24 dS m−1. Relative yield of ‘Camarosa’ decreased 43% for each unit increase in salinity once irrigation water salinity exceeded 0.80 dS m−1. Relative ‘Ventana’ yield was unaffected by irrigation water salinity up to 1.71 dS m−1, and thereafter, for each additional unit increase in salinity, yield was reduced 61%. Both cultivars appeared to possess an exclusion mechanism whereby Na+ was sequestered in the roots, and Na+ transport to blade, petiole and fruit tissues was limited. Chloride content of the plant organs increased as salinity increased to 2.24 dS m−1 and substrate Cl increased from 0.1 to13 mmolcL−1. Chloride was highest in the roots, followed by the leaves, petioles and fruit. Based on plant ion relations and relative fruit yield, we determined that, over the range of salinity levels studied, specific ion toxicity exists with respect to Cl−, rather than to Na+ ions, and, further, that the salt tolerance threshold is lower for ‘Camarosa’ than for ‘Ventana’.

Strawberry production in forced and protected culture in Europe as a response to climate change

Neri, D., Baruzzi, G., Massetani, F. and Faedi, W. 2012. Strawberry production in forced and protected culture in Europe as a response to climate change. Can. J. Plant Sci. 92: 1021–1036. In Europe, the production of strawberry for fresh market in forced and protected conditions is increasing. These techniques were initially aimed at enhancing the earliness of June-bearing short day varieties. Nowadays, the objective is to have year-round fruit availability, forcing and preserving strawberry crops against adverse weather conditions. The new high-quality low-chilling varieties widely expanded winter–spring strawberry production in the Mediterranean climate with autumn planting, while the diffusion of day-neutral ever-bearing varieties increased spring–summer yields in more continental climates, avoiding the extremely cold winter with spring planting. Finally, the use of tray-plants significantly increased late summer–fall strawberry production with summer programmed planting. The present review analyzes the recent evolution of strawberry cultivars and cultivation systems under plastic tunnels and in greenhouses. The physiological effects on plant architecture and propagation are discussed. In conclusion, we can affirm that strawberry growers are facing climate change with innovations in cultivated varieties and cultural techniques, and by the integration of the different production areas, with their specific optimum yield seasons, to continuously fulfill the demands of the European market.

High‐temperature‐induced reductions in cropping in everbearing strawberries (Fragaria × ananassa) are associated with reduced pollen performance

Heat‐induced short‐term reductions in cropping (often referred to as ‘thermodormancy’ by UK strawberry growers) occur frequently in extended‐season everbearing strawberry production in the UK. A 2‐year study evaluated the effects of high temperatures on the performance of pollen in two everbearing strawberry cultivars (cvs ‘Everest’ and ‘Diamante’). Pollen from both cultivars lost its ability to germinate following exposure to a period of high temperature (30/20°C day/night). However, after termination of the high‐temperature episode, germination capacity recovered to levels similar to control plants that were not exposed to high temperature. High temperature also resulted in slower rates of pollen tube growth. As a result, only a small proportion of high‐temperature‐affected flowers developed into fruits. These results suggest that heat‐induced reductions in cropping in everbearing strawberries are associated with reduced pollen performance.

살균제 살포횟수 감소를 위한 딸기 탄저병 방제프로그램

The effect of various fungicides on anthracnose of strawberry, caused by Colletotrichum gloeosporioides, was determined in vitro, and in greenhouse and field trials. The values of benomyl were clearly different between two sensitive and resistant groups of isolates. Iminoctadine tris had lower values than mancozeb and propineb as protective fungicides and the response of mancozeb, propineb and azoxystrobin was variable depending on the isolate. In the greenhouse, pre- and post- inoculation fungicide applications significantly reduced disease compared to the non-treated control. Propineb, mancozeb and azoxystrobin were effective in controlling the disease when applied prior to inoculation. Metconazole and prochloraz-Mn treatments as ergosterol biosynthesis-inhibiting fungicides had the lowest incidence of anthracnose. In the nursery field trials in 2009 and 2010, the reduced fungicide spray program provided similar levels of disease control compared to the calendar-based applications with captan. A reduced spray program based on efficacious fungicides such as prochloraz-Mn will be useful for strawberry growers and provide more options for controlling anthracnose in Korea.

REDES DE INNOVACIÓN EN EL SISTEMA PRODUCTIVO FRESA EN ZAMORA, MICHOACÁN

The objectives of this work were to characterize strawberry growers in Zamora, Michoacan, Mexico, and to identify factors limiting produc¬tion with the methodology of innovation networks. The state of Michoacan is the largest strawberry producer in Mexico, but production is extensive and disorganized. The productive system network of strawberry has a large number of nodes, but dispersion is high. This fact is reflected in the scarce number of links (265), a low density and an elevated standard deviation (12.47 %). The centralization index is 18.36 %, in part because decision-making and access to system information in the web are concentrated in only two actors; one of them is a final buyer and the other is a local lender. The strawberry agribusinessmen from Michoacan interviewed had a mean yield of 24.44 t•ha-1. Their per hectare income was $ 9,208 USCy, but with a cost of production of $11,867 USCy and an index of innovation adoption of 55.56 %. The adoption of organizational innovations is limited. All these factors originate low macro competitiveness. It is necessary to enhance innovation to increase the competitiveness.

Cultural Practices for Vegetable and Small Fruit Crops: Using Kaolin Clay to Reduce Sprinkler Irrigation for Strawberry Transplant Establishment

Because of the current limitations on water usage for strawberry growers in the Plant City area of Hillsborough County, researchers at the UF/IFAS Gulf Coast Research and Education center have been looking for inexpensive ways to reduce the amount of sprinkler irrigation in strawberry production. This 3-page fact sheet presents research results on the effect of kaolin clay application on sprinkler irrigation volumes applied to newly transplanted strawberries. It was written by Bielinski M. Santos, Teresa P. Salame-Donoso, Craig D. Stanley, Alicia J. Whidden, Crystal A. Snodgrass, and Mary B. Henry, and published by the UF Department of Horticultural Sciences, December 2010.

Energy and economic analysis of greenhouse strawberry production in Tehran province of Iran

The aims of this study were to determine energy use pattern, to investigate the energy use efficiency, and to make an economical analysis in greenhouse strawberry production in Iran. Data used in this study were obtained from 25 greenhouse strawberry growers using a face to face questionnaire method. The results indicate that greenhouse strawberry production consumed a total energy of 121891.33 MJ ha −1. About 78% of this was generated by diesel fuel, 10% from chemical fertilizers, and 4.5% from electricity. Energy ratio, specific energy, net energy and energy intensiveness of greenhouse strawberry production were 0.15, 12.55 MJ kg −1, −683488.37 MJ ha −1 and 8.18 MJ $ −1, respectively. Determination of the efficient allocation of energy resources were modeled by Cobb–Douglas production function. Econometric model evaluation showed the impact of human labor, fertilizers, installation of equipment and transportation costs for strawberry production were all significant at 1% level. The elasticity estimates indicated that among the cost inputs, transportation is the most important input (−0.75) that influences total cost of production, followed by labor (0.31), fertilizers (0.18) and installation of equipments (0.22). The benefit–cost ratio and net return were obtained as 1.74 and 151907.91 $ ha −1, respectively.

Estimating the Energy Indices and Profitability of Strawberry Production in Kamyaran Zone of Iran

Problem statement: The aim of this research is to determine the energ y indices and to make a cost analysis of strawberry grown in open fi eld in Kamyaran zone of Iran. Approach: The data used in the study were obtained from 35 local strawberry growers by using a face-to-face questionnaire in August-September 2009. Results: Total energy input for strawberry production was calculated to be 36822.9 MJ.ha -1 . The Energy ratio was 0.48 and energy productivity was found to be 0.25 kg.MJ -1 . About 74.5% of the total energy inputs used in st rawberry production was non- renewable while only about 25.5% was renewable. The share of 56.6% of the total energy input was depended on the indirect form, whereas 43.4% of the total energy input was in the direct form. Specific energy was 3.96 MJ.kg -1 . Economic analyses showed that profit/cost ratio a nd net profit were 1.49 and 4616.9 $.ha -1 , respectively. Conclusion: The net energy in the study area was negative. This means that the amount of output ener gy is less than input energy and production in this situation is irrational, thus efficient use of reso urces and proper land management is needed.

Strawberry Bruising Sensitivity Depends on the Type of Force Applied, Cooling Method, and Pulp Temperature

Strawberry (Fragaria ×ananassa Duch.) fruit are very susceptible to mechanical injury and for this reason are normally field-packed. Fruit of three cultivars (Chandler, Oso Grande, Sweet Charlie) were subjected to forced-air or hydrocooling to reach pulp temperatures between 1 and 30 °C and then individually subjected to compression and impact forces representative of commercial handling operations. Strawberries with a pulp temperature of 24 °C exhibited sensitivity to compression but greater resistance to impacts. As pulp temperature decreased, fruit were less susceptible to compression as shown by up to 60% reduction in bruise volume. In contrast, strawberries at 1 °C pulp temperature had more severe impact bruising with up to 93% larger bruise volume than at 24 °C depending on the cultivar. Strawberries also showed different impact bruise susceptibility depending on the cooling method. Impacted fruit that were forced-air cooled had larger bruise volumes than those that were hydrocooled. The impact bruise volume for strawberries forced-air cooled to 1 °C was 29% larger than for fruit hydrocooled to 20 °C, 84% higher than those forced-air cooled to 20 °C, and 164% higher than those hydrocooled to 1 °C. Because incidence and severity of impact and compression bruises are temperature-dependent, strawberry growers should consider pulp temperature for harvest scheduling and for potential grading on a packing line. Hydrocooling shows promise to rapidly cool strawberry fruit while reducing weight loss and bruising sensitivity.

‘Florida Radiance’ Strawberry

‘Florida Radiance’ is a strawberry cultivar released from UF/IFAS in 2008. As of 2012, it has become a major cultivar in Florida and other winter and early spring production regions worldwide. In all markets outside the United States and Canada, it is marketed as ‘Florida Fortuna’. In addition to commercial production, it has been tested for many years in field plots at the UF/IFAS Gulf Coast Research and Education Center in Wimauma and the Florida Strawberry Growers Association headquarters in Dover for disease, fruit, and plant traits. This 4-page fact sheet was written by Vance M. Whitaker, Craig K. Chandler, Bielinski M. Santos, and Natalia A. Peres, and published by the UF Department of Horticultural Sciences, June 2013. http://edis.ifas.ufl.edu/hs400

Sensitivity of Podosphaera aphanis isolates to DMI fungicides: distribution and reduced cross-sensitivity

Management of strawberry powdery mildew, Podopshaera aphanis (Wallr.), requires numerous fungicide treatments. Limiting epidemics is heavily dependent on sterol demethylation inhibitors (DMIs) such as myclobutanil or penconazole. Recently, a noticeable reduction in the efficacy of these triazole fungicides was reported by strawberry growers in France. The goal of this study was to investigate the state of DMI sensitivity of French P. aphanis and provide tools for improved pest management. Using leaf disc sporulation assays, sensitivity to myclobutanil and penconazole of 23 isolates of P. aphanis was monitored. Myclobutanil EC(50) ranged from less than 0.1 to 14.67 mg L(-1) and for penconazole from 0.04 to 4.2 mg L(-1). A cross-analysis and a Venn diagram showed that there was reduced sensitivity and a positive correlation between the less sensitive myclobutanil and penconazole isolates; 73.9% of isolates were less sensitive to a DMI and 47.8% exhibited less sensitivity to both fungicides. The results show that sensitivity to myclobutanil and, to a lesser extent, penconazole has become less efficient in strawberry powdery mildew in France. Therefore, urgent action is required in order to document its appearance and optimise methods of control.

BIOLOGICAL CONTROL OF APHIDS WITH CHRYSOPERLA CARNEA ON STRAWBERRY

Aphids cause considerable damage in strawberry crops and massive applications of insecticides have come to a limit with the appearance of plant pathogens resistance. Aphid species such as Rhodobium porosum and Aphis gossypii are resistant to all chemical molecules approved on strawberry crops in France. The large variety of aphid species encountered on the strawberry crop, requires the use of non specific beneficial organisms such as lacewings. The lacewing Chrysoperla carnea is widely known as a natural beneficial insect against aphids. However, its effective use as a predator introduced in strawberry crops has still to be confirmed. The experiment carried out in the year 2007 intended to assess its efficiency as a predator on strawberry plants. In this experiment, various treatments were compared on soil- and soilless-grown everbearing strawberry crops: 1 lacewing per plant, 5 lacewings per plant, and, in the soil-grown crop only, a control treatment without lacewing. The treatments were repeated every two weeks starting from planting date. The results show that aphid infestations were successfully limited by the use of lacewings. The absence of chemical treatment during the release of lacewings was quite encouraging. Control of pest populations differed according to the amount of lacewings introduced, with 5 lacewings per plant, the predatory action could be characterised as both preventive and curative. With 1 lacewing per plant, the increase in aphid populations was limited but it is suggested that several treatments might be necessary to stop this increase. These experiments confirm that lacewings can be used as predators of aphid populations in strawberry crops. Further studies are now required to develop control strategies using lacewings introduction that may be adopted by strawberry growers.

ASSESSING THE POSSIBLE CAUSES FOR THE "STRAWBERRY DRIED CALYX DISORDER" IN FLORIDA AND SPAIN

Several preliminary assays and surveys were conducted in Huelva, Spain, and Florida, USA to characterize the possible causes of the dried calyx (SDCD). Field surveys performed in both locations suggest that certain strawberry cultivars might be more susceptible than others to the appearance of SDCD. At both locations, several cultivars are planted concurrently under equal irrigation, fertilization and pest management programs. Field observations indicated the cultivars 'Strawberry Festival', 'Camino Real' and 'Palomar' showed the SDCD earlier and more severely than others. SDCD symptoms consistently developed after exposure to stressful conditions, such as low temperatures and/or light. The symptoms appeared to be associated with high electric conductivity (EC; salt concentration) of hydroponic solutions or soils. A greenhouse study conducted in Florida with 6 cultivars showed salt injury developed after 30 days of treating 'Strawberry Festival' and 'Camino Real' plants with a fertilizer solution of EC of 1.2 mS/cm, whereas other cultivars did not show visible injury until 45 to 55 days after initial treatment with solutions of EC equal to 1.2 and 2.4 mS/cm, indicating that these cultivars appeared to be more sensitive to high-EC fertilizer solutions than others. Circumstantial evidence seems to eliminate biotic entities as the causal agents because: a) symptoms comparable to SDCD were developed under pathogen-free greenhouse conditions; b) none of analyzed calyx samples from Florida and Spain has yielded positive pathogen results; c) SDCD tends to disappear during the growing season when either fertigation practices are modified or stressful conditions disappear; and d) SDCD distribution in high tunnels and fields seems to be more accentuated in rows closer to entrances and at the end of drip lines. Until the nature of this disorder is fully understood, strawberry growers should exercise caution on their fertilization and irrigation programs during stressful environmental conditions for susceptible cultivars. Reducing the fertilization rates during the days before an expected freeze, while maintaining regular irrigation programs, appears to help to minimize the incidence of SDCD.

RULE BASED PREDICTION SYSTEM TO OPTIMIZE FUNGICIDE APPLICATIONS FOR CONTROL OF PODOSPHAERA APHANIS

UK strawberry growers are under pressure from retailers to produce high quality fruit while reducing the amount of pesticides applied to control pathogens. Since strawberry growers started to use polythene tunnels to provide favorable conditions for strawberry production Podosphaera aphanis (strawberry powdery mildew) has become the major pathogen of UK strawberries. A rule based prediction system had been developed previously to identify when the P. aphanis inoculum present at a site poses the highest risk of developing into an epidemic. Sensitivity analysis was carried out on the parameters that describe the conditions within a tunnel to determine which of the parameters would have the smallest and greatest effects on the prediction of high risk days. The sensitivity analysis showed that the least sensitive parameters were maximum germination temperature, maximum growth temperature and leaf wetness. Changes in the growth temperature threshold had the greatest effect on the amount of predicted high risk days. The prediction system was tested in two commercial sites in the 2007 season where the growers managed half a field as they would have normally and the other half of the field had fungicides applied as predicted by the rule based system, for high risk days, for the development of P. aphanis. Results showed that the prediction system resulted in comparable control of P. aphanis on commercial sites with fewer fungicide applications.

STRAWBERRY INDUSTRY IN CHINA

Due to recent industry expansion, China is a leading strawberry producing country: in 2005, crop area and production were estimated at 84,300 hectares and 1.95 million MT, respectively. Strawberry is produced in nearly all regions of the country, with Hebei, Shandong and Liaoning Provinces accounting for 60% of total production. Production derives from two production systems: open field (OF) and protected culture (PC). The OF system uses large-scale plantings to produce processing fruit, while PC uses plastic-covered structures to produce fruit mainly for fresh market production. The PC system uses annual plantings of fresh-dug plants, raised beds and polyethylene bed mulch, whereas OF production uses perennial plantings, furrow irrigation and bare soil. Harvest season varies with production area and system, with PC plantings producing fruit November-May, and OF plantings producing fruit April-June. Nearly all fresh-market fruit is consumed within China while nearly all processed strawberries are exported. Japanese cultivars are used for fresh-market production while US and European cultivars are used for processing. Poor plant quality is a serious limitation and there are few nurseries that produce certified disease-free plants. Research in breeding is conducted by a number of Chinese universities and research institutes, but few cultivars have been commercialized. On-farm propagation, poorly-adapted cultivars, the lack of refrigeration, and inefficient post-harvest handling systems limit fruit production and quality. A major challenge is the effective delivery of educational programs for hundreds of thousands of Chinese strawberry growers.