Posts Tagged: strawberry yield
Microbial and bioactive soil amendments for improving strawberry crop growth, health, and fruit yields: a 2017-2018 study
In a continuous effort to explore the potential of additive, soil amendment, biostimulant, and other products, a new study was conducted in a conventional strawberry field at the Manzanita Berry Farms in Santa Maria. The following treatments were administered at different times, from planting till the end of production season, as requested by the manufacturer.
- Untreated control: Other than the soil incorporated fertilizers during the field preparation, no other nutrient inputs were added during the study.
- Grower standard: Transplants were dipped in Switch 62.5WG (cyprodinil+fludioxonil, at 5 oz/100 gal) before planting and a proprietary nutrient regimen that included administration of a humic acid-based product was followed.
- Innovak Global regimen: Nutrisorb-L (a blend of polyhydroxy carboxylic acids) at 28 fl oz/ac, starting 2 wk after planting and every 3 wk thereafter through drip. Packhard (carboxylic acids with calcium and boron) at 28 fl oz/ac, starting at the first fruit set (early January) and every 2 wk thereafter as a foliar spray.
- TerraVesco regimen: A microbe-rich Vermi-extract (worm extract) at 10% vol/vol as a transplant dip for 3 hours, followed by application through drip at 7.5 gal/ac after planting, and again in December, 2017 and January, 2018.
- Fertum regimen: Transplant dip in 1% vol/vol of Germinal Plus (a product from marine algae), followed by drip applications of Booster (a biostimulant and a natural organic fertilizer made from seaweed) at 0.5 gal/ac in late November and late December, 201; Silicium PK (a biostimulant and a natural organic fertilizer based on silicon enriched with phosphorus, potassium and seaweed extracts) at 0.5 gal/ac late December, 2017 and once a month starting from mid February to early July, 2018; and Foliar (a biostimulant and a natural organic fertilizer from marine algae) at 0.5 gal/ac in mid and late January.
- Shemin Garden regimen: EcoSil (a silica fertilizer) at 800 ml/ac once a month starting from early December, 2017 to May, 2018 through drip, and at 200 ml/ac in early May and June, 2018 as a foliar spray; ComCat (based on a plant extract) at 20 gr/ac and EcoFlora (a consortium of Azotobacter spp., Bacillus spp., Paenibacillus spp., Pseudomonas sp., Trichoderma spp., and Streptomyces spp.) at 12 oz/ac one week after EcoSil through drip until May, 2018 and ComCat at 10 gr/ac and EcoFlora at 12 oz/ac as a foliar spray in May and June, 2018.
- GrowCentia regimen-low: Yeti containing 1% bacterial culture (of Pseudomonas putida, Citrobacter freundii, Comamonas testosterone, and Enterobacter cloacae) and 2% alfalfa extract applied at 0.6 ml/gal through drip for 90 min weekly from the first drip application.
- GrowCentia regimen-high: Yeti at 1 ml/gal through drip for 90 min weekly from the first drip application.
- NanoChem regimen: EX10, a biodegradable fertilizer additive containing thermal polyaspartate at 1 qrt/ac through first drip after planting with follow up applications in early January (first bloom), mid February, and mid May, 2018. The active ingredient binds with cations such as ammonium, calcium, copper, iron, magnesium, manganese, potassium, and zinc and improves their availability for the plant.
- BiOWiSH regimen 1: Formula 1 at 1.33 oz/gal for transplant dip followed by 3.53 oz/ac through drip starting 2 wk after planting and every 4-5 wk thereafter.
- BiOWiSH regimen 2: Formula 1 at 1.33 oz/gal for transplant dip followed by 3.53 oz/ac as a foliar srpay starting 2 wk after planting and every 4-5 wk thereafter.
- BiOWiSH regimen 3: Formula 1 at 1.33 oz/gal for transplant dip followed by 3.53 oz/ac through drip starting 2 wk after planting alternated with a foliar spray every 4-5 wk.
- BiOWiSH regimen 4: Formula 1 at 1.33 oz/gal for transplant dip followed by BiOWiSH Crop 16-40-0, a microbial consortium (Bacillus amyloliquefaciens, B. lichenoformis, B. pumilus, and B. subtilis)at 3.53 oz/ac through drip starting 2 wk after planting and every 4-5 wk thereafter.
Each treatment contained a 165' long 5.7' wide bed and replicated four times in a randomized complete block design. A 15' long plot in the center of the bed was marked and netted for collecting yield and some other parameters that were compared. Strawberry cultivar BG 6-30214 was planted on 7 November, 2017. Other than the untreated control, all other products were administered on top of the grower standard fertility program. However, only the grower standard transplants were dipped in Switch 62.5WG before planting.
Various parameters were measured during the vegetative growth and fruit production periods to evaluate the impact of the treatments on crop growth, health, and yield. Data were analyzed using ANOVA and LSD test was used to separate significant means.
Transplant treatment (above) and drip application (below). Photos by Tamas Zold
Canopy growth: Canopy growth was observed on 11 December, 2017, 7 and 30 January, and 8 February, 2018 by measuring the size of the canopy along and across the length of the bed from 20 random plants per bed and calculating the area. Canopy size significantly (P = 0.0261) different among the treatments only on the last observation date where plants treated with EX10 and the GrowCentia product at the low concentration were larger than those in the grower standard.
Electrical conductivity and temperature of soil: From two random location on each bed, electrical conductivity (EC in dS/m) and temperature (oC) were measured about 3 inches deep from the surface on 12 and 25 January, 7 February, 19 March, 18 April, and 29 May, 2018. Only soil temperature on 25 January significantly (P = 0.0007) varied among treatments where the difference between the highest (untreated control) and the lowest (Vermi-extract) values was 0.8oC.
Dead plants: The number of dead plants represents empty spots in the bed due to the death of transplants. There were no obvious signs of disease or a particular stress factor associated with those plants except that they were randomly distributed within each bed and throughout the field. When counted on 18 April, 2018, BiOWiSH regimen 4, Fertum regimen, GrowCentia product at the high rate, and Innovak Global regimen had
Fruit diseases: Fruit harvested on 12 March, 3 and 13 April, and 17 May, 2018 from each marked plot was incubated at room temperature in dark in plastic containers and the fungal growth was rated 3 and 5 days after harvest (DAH) using a scale of 0 to 4 where 0=no fungal growth, 1=1-25%, 2=26-50%, 3=51-75%, and 4=76-100% fungal growth. Botrytis fruit rot or grey mold was predominant during the first two observation dates and the growth of other fungi (possibly Rhizopus spp.) was also seen during the last two dates. In general, fruit disease occurred at low levels throughout the observation period with
Sugar content in fruit: Sugar content was measured from two harvest-ready berries per bed on 17 May, 2018 using a handheld refractometer. Sugar content varied from 8.06 oBx (Innovak Global regimen) to 9.53 oBx (grower standard).
Fruit firmness: Fruit firmness was measured from eight randomly collected harvest-ready berries from each bed on 28 June, 2018. Firmness varied from 0.82 kgf (Fertum and Shemin Garden regimens) to 0.98 kgf (untreated control).
Fruit yield:Strawberries were harvested from 6 February to 22 June, 2018 on 36 dates. When compared to the grower standard, the marketable berry yield was 16.2, 15.1, 13.7, and 13% higher in Fertum regimen, EX10 treatment, Innovak Global regimen, and BiOWiSH regimen 4, respectively. The marketable berry yield was 9.8, 9, 7.5, and 6.8% higher in those respective treatments over the yield from untreated control.
It took 23 harvest dates in three months (from February to April, 2018) to obtain the first third of the total seasonal yield while the remaining two-thirds were obtained from seven harvest dates in May and six dates in June. Marketable fruit yield was higher than the grower standard in all treatments and higher than the untreated control in most treatments.
In general, fruit yields were higher and the pest and disease pressure was lower than usual during the study period. Aleo, a garlic oil based fungicide, at lower label rates was periodically used for disease management and bug vacuums were operated a few times against the western tarnished plant bug as a standard across all treatments.
This study evaluated some treatment regimens as recommended by the collaborating manufacturers and some of them appear to have a potential for use in strawberry production. These results help the manufacturers fine tune their recommendations for achieving better yields through additional studies.
Acknowledgments: We thank the planting and harvest crew at Manzanita Berry Farms for their help with the crop production aspects, Chris Martinez, Tamas Zold, and Maria Murrietta for their technical assistance, Sumanth Dara for statistical analysis, and the support of the industry collaborators who funded the study.
Influence of weather on strawberry crop and development of a yield forecasting model
California offers ideal weather conditions for both nursery plant and strawberry fruit production. Variations in weather conditions in three strawberry production regions in California complement fruit production from each other and help avoid market glut. The warmer Oxnard area, the milder Santa Maria area, and the colder Watsonville area with minimal overlapping of their peak fruit production seasons allow yearlong strawberry production.
Weather influences on strawberry have been well documented in various strawberry producing regions across the world (Palencia et al., 2013; Li et al., 2010; Waister et al., 1972). Examples of key weather parameters correlated with strawberry yield include temperature, precipitation, solar radiation, relative humidity, and wind speed. Crop growth is weather dependent, thus, it is a common practice to estimate fruit yield based on weather variables. Since strawberry production spreads across 4–5 months, evaluating relationships between meteorological parameters and strawberry yield can provide valuable information and early indications of yield estimations that growers can utilize to their advantage. Objective of this research was to evaluate correlations of meteorological parameters on strawberry yield for Santa Maria region and to develop weather based statistical yield forecasting models for strawberries.
Strawberry yield data
Daily strawberry yield data for the Santa Maria region was obtained from published sources (California Strawberry Commission). This information is publically available and is originally compiled from the United States Department of Agriculture Market News/Fruits & Vegetables website. Daily strawberry yield data for the month of April through July were aggregated to weekly values. For this analysis we used weekly strawberry yield data for 2009 through 2015.
Weather data
Weather data were obtained from the California Irrigation Management Information System (http://www.cimis.water.ca.gov/), a network of over 145 automated weather stations in California. Specific meteorological parameters used in this study were net radiation, air temperature (minimum and maximum), relative humidity (minimum and maximum), dew point temperature, soil temperature (minimum and maximum), vapor pressure (minimum and maximum), reference evapotranspiration, and average wind speed.
Correlation analysis
Weekly values of meteorological parameters from October of the year prior to harvest to February of current year of strawberry harvest were correlated with weekly strawberry yield from April through July and tested for significance. Each meteorological variable was correlated with strawberry yields from April to July. This thorough correlation analysis was done in order to understand influence of meteorological parameters on strawberry yield on a more detailed basis.
Fall and winter weather conditions during the vegetative growth period of strawberry have a significant influence on the fruit yields in the following spring and summer for the Santa Maria region. Results show that net radiation, relative humidity, vapor pressure, wind speed, and temperature showed significant correlations with strawberry yields at various temporal scales. In general, it was evident that many meteorological parameters during the early stages of strawberry growth and development phase exhibit statistically significant correlation with strawberry yields during the peak fruit production period. This finding is consistent with the findings of Lobell et al. (2006) for strawberry and other crops in California.
Table 1. Correlation matrix of monthly meteorological parameters and strawberry yields that were statistically significant.
Statistical yield model
Weather parameters that showed significant correlations were used to develop strawberry yield forecasting model. Instead of using weather parameters as explanatory variables, they were transformed into principal components to develop yield–forecasting models.
Figure 1 shows observed versus predicted yields for April (top) and June (bottom)
It is important to note that there are limitations on how much variability in yield data that can be explained by meteorological parameters as many other factors such as management practices, pests, diseases, varieties, other stress factors can also influence yield variability. Additionally, historic strawberry yield data provided an average estimate for the region and might not represent accurate observations.
These results demonstrate the potential to predict strawberry yield using weather variables relevant to the Santa Maria strawberry growing region. In order to make these results usable for decision–making, it could be refined to be utilized at the field scale. Additionally, skills of these models can be further improved by combining weather parameters and relevant physiological parameters of strawberry at the field scale.
A full version of this article (Pathak et al., 2016) can be viewed at: https://www.hindawi.com/journals/amete/2016/9525204/
References
Palencia, P., F. Marti´nez, J.J. Medina, and J. Lo´pez– Medina. 2013. Strawberry yield efficiency and its correlation with temperature and solar radiation. Hortic. Bras.31(1): 93–99
Li, H., T. Li, R.J. Gordon, S.K. Asiedu, and K. Hu. 2010. Strawberry plant fruiting efficiency and its correlation with solar irradiance, temperature and reflectance water index variation. Environ. Exp. Bot. 68, 165–174.
Waister, P. D. 1972. Wind as a limitation on the growth and yield of strawberries. hort. Sci. 47: 411 – 418.
Lobell, D.B., K. Cahill, and C. Field. 2006. Weather–based yield forecasts developed for 12 California crops. California Agriculture, 60(4): 211–215.
Pathak, T.B., Dara, S.K., Biscaro, A. 2016. Evaluating correlations and development of meteorology based yield forecasting model for strawberry. Advances in Meteorology, vol. 2016, article ID 9525204. doi:10.1155/2016/9525204
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Evaluating beneficial microbe-based products for their impact on strawberry plant growth, health, and fruit yield
Various soilborne, fruit and foliar diseases can affect strawberry crop and fruit yields. Chemical fumigants and a variety of fungicides are typically used for managing the disease issues. In addition to the environmental and human health concerns with chemical control options there is a need to improve current disease management with alternatives that include beneficial microbes. Previous studies showed some promise with some of the treatments, but additional studies are required to evaluate the efficacy, which is more evident especially when there is disease incidence.
A study was conducted in summer-planted conventional strawberries in 2016 at Manzanita Berry Farms to evaluate the impact of various beneficial microbial treatments on plant growth, health, and fruit yield. Untreated control and the grower standard practice (Healthy Soil treatment) were compared with MycoApply EndoMaxx (Glomus intraradices, G. aggregatum, G. mosseae, and G. etunicatum), Actinovate AG (Streptomyces lydicus WYEC 108), and Inocucor Garden Solution (Saccharomyces cerevisiae and Bacillus subtilis) applied in the following treatments:
1. Untreated control
2. Grower Standard-Healthy Soil; transplant dip in Switch 62.5WG 5 oz in 100 gal
3. MycoApply EndoMaxx 2 gpa transplant dip (TD)
4. MycoApply EndoMaxx 2 gpa drip at planting (DrP)
5. MycoApply EndoMaxx 2 gpa transplant dip + 2 gpa drip at planting
6. MycoApply EndoMaxx 4 gpa transplant dip
7. MycoApply EndoMaxx 4 gpa drip at planting
8. MycoApply EndoMaxx 4 gpa transplant dip + 4 gpa drip at planting
9. Actinovate AG 6 oz/ac transplant dip + 6 oz drip at planting + 6 oz drip monthly (DrM)
10. Inocucor Garden Solution 1 gpa drip at planting + 1 gpa drip monthly
Transplanting was done on 21 May, 2016 with appropriate treatments administered at the time of planting and thereafter. Study had two blocks of 10 strawberry beds (300' long) and treatments were randomly applied to a bed within each block. Two 15' long plots were marked within each bed for sampling. Canopy growth was measured on June 21, July 5 and 20; powdery mildew severity on August 3, September 1, October 10 and November 16; botrytis severity 3 and 5 days after harvest (DAH) for berries harvested on September 13 and 27, and October 11 and 18; and dead and dying plants were counted on September 16 and October 23. Yield data were collected from August 20 to November 18. Powdery mildew and botrytis fruit rot severity was measured on a scale of 0 to 4 where 0=No disease, 1=1-25%, 2=26-50%, 3=51-75%, and 4=76-100% severity. Data were analyzed and means were separated using LSD test.
Strawberry field and plots on June 9 (above) and August 31 (below).
Two sampling plots were set up within each bed to collect plant growth, health, and yield data.
Canopy growth: MycoApply EndoMaxxat 2 gpa either as a transplant dip with or without drip application at planting appeared to promote significantly higher growth (P <0.0001) than MycoApply EndoMaxx at 2 and 4 gpa as drip at planting, untreated control, and grower standard. Inoculating the entire transplant with Glomus spp. through a dip appears to be better than application through drip irrigation system.
Powdery mildew: Disease incidence and severity was low during the observation period. When the average of four observations period was compared, the grower standard, MycoApply Endomaxx at 2 and 4 gpa as drip at planting, and the Actinovate treatments had the lowest incidence (P = 0.0271).
Botrytis fruit rot: There was no difference (P >0.05) among the treatments on botrytis when the mold growth on fruit was compared 3 and 5 days after harvest.
Unknown issue: Some wilting and dead plants were found throughout the field during the study. Although symptoms suggested some kind of wilt, laboratory testing did not identify any pathogens. The total number of dead and dying plants was the lowest in Actinovate treatment, but it was significantly different (P = 0.0429) only from the grower standard Healthy Soil treatment.
*Means followed by the same or no letter are not significantly different at the P value indicated in the table.
Fruit yield: There were no statistically significant difference among the treatments and the seasonal total of marketable yield varied between 66 lb/plot in the grower standard and about 76 lb/plot in MycoApply EndoMaxx applied as a transplant dip at 4 gpa.
Total and marketable berry yields and their proportion among different treatments.
We need to continue to evaluate beneficial microbial products and their potential benefit in improve crop health and yields.
Acknowledgements: Thanks to Chris Martinez and Tamas Zold for technical assistance, and Valent USA and Inocucor Technologies for the financial support of the study.
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Improving strawberry yield with a recycled food waste-based liquid compost
Synthetic or chemical or inorganic fertilizers are commonly used in many conventional crop production systems providing essential nutrients necessary for optimal plant growth and yields. While these fertilizers provide plants with readily available nutrients, excessive application could lead to leaching into the ground water or increase the attractiveness of plants to pests and diseases. Organic fertilizers, on the other hand, are generally made from plant or animal sources. Compared to synthetic fertilizers where nutrients are readily available, nutrients are slowly released from organic fertilizers and thus have a lower risk of nutrient leaching. Organic fertilizers add organic matter to the soil, which improves soil structure, water holding capacity, and root growth. Organic matter also supports beneficial microbial communities in the soil that improve nutrient availability to the plant and protect plants from plant pathogens and other stress factors.
Organic fertilizers, especially those made from food waste, have a significant environmental benefit by recycling valuable nutrient and energy resources that would have, otherwise, been wasted (Senesi, 1989). Several studies emphasized the importance of soil organic matter and its positive impact on soil fertility, crop productivity, and environmental sustainability (Tisdall and Oades, 1982; Baldock and Nelson, 2000; Johnston et al., 2009). However, a balanced used of both synthetic and organic fertilizers is a good strategy both to meet plant needs and environmental sustainability (Chen, 2006).
In the United States, food waste at consumer and retail levels was estimated to be about 30% of the food supply, which is equal to 133 billion pounds valued at $161 billion (USDA-ERS, 2016). Food waste is the largest part what goes into landfills and is the third largest source of methane in the United States. Converting food waste into a fertilizer will have a major impact on agriculture and environment.
To evaluate the efficacy of a recycled food waste-based liquid compost on strawberry yield, a study was conducted during the spring of 2013 on a conventional strawberry field at DB Specialty Farms, Santa Maria.
Materials and Methods
Harvest-to-Harvest (H2H), made by hydrolysis of freshly expired produce, meat, and other food items collected from grocery stores, was evaluated alone and in combination with the grower standard. The formulation of H2H used in the study had NPK at 1-1-0, 5-7% of amino acids, 6-8% of lipids, 8-10% carbohydrates, and 20-25% organic matter according to the label. Treatments included i) Grower standard or GS (proprietary fertilizer regimen), ii) H2H at 73 gallons/acre, and iii) H2H:GS at 50:50. H2H was administered through the drip irrigation system 28 March, 9 and 18 April. Each treatment had a block of about 1.6 acre that were adjacent to each other. On six randomly selected beds within each block, a 40-plant section was marked as a sampling plot. Yield data were collected from these plots from 4 April to 20 May on 10 sampling dates following grower's harvest schedule.
Data were analyzed using analysis of variance and significant means were separated using Tukey's HSD test.
AndresTapia administering treatments through a special pump built by JoeCoelho (above) and observation plots (below).
Results and Discussion
Compared to the yield in GS plots, marketable strawberry yield was significantly higher (P < 0.05) for H2H treatment on four of the harvest dates and for GS:H2H combination on two of the harvest dates (Table 1). The average marketable berry yield was significantly higher (P = 0.0003) in both H2H and GS:H2H treatments compared to the GS treatment (Fig. 1). There was no difference (P = 0.283) in the weight of unmarketable berries and their proportion of the total yield was 18.7, 15.5, and 16.2 for GS, H2H, and GS:H2H, respectively.
Table 1. Marketable berry yield on different harvest dates. Means followed by the same letter within the same column are not statistically different based on Tukey's HSD test.
Fig. 1. Average marketable and unmarketable yield during the observation period.
This first commercial field study using H2H shows promising results in improving strawberry yield with recycled food waste. Manufacturer made changes to the H2H formulation and recommendation rates after the study was conducted. Additional studies in different fields with different application rates from the beginning of the production season are essential to make valid conclusions. Soil conditions and nutrient management practices vary among various fields and additional studies will add value to the results obtained in this preliminary study.
Acknowledgements: Thanks to Daren Gee for the collaboration, California Safe Soils for financial support, and Joe Coelho and Andres Tapia for their technical assistance.
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References
Baldock, J. A. and P. N. Nelson. 2000. Soil organic matter. In: Sumner, M. E. (Ed.) Handbook of Soil Science. CRC Press, Boca Raton, FL, USA, pp. B25-B84.
Chen, J.-H. 2006. The combined use of chemical and organic fertilizers and/or biofertilizer for crop growth and soil fertility. International workshop on sustained management of the soil-rhizosphere system for efficient crop production and fertilizer use. Vol. 16. p. 20. Land Development Department Bangkok, Thailand.
Johnston, A. E., P. R. Poulton, and K. Coleman. 2009. Soil organic matter: its importance in agriculture and carbon dioxide fluxes. Adv. Agronomy 101: 1-57.
Senesi, N. 1989. Composted materials as organic fertilizers. Science of the Total Environment 81: 521-542.
Tisdall, J. M. and J. M. Oades. 1982. Organic matter and water-stable aggregates in soils. European J. Soil Sci. 33: 141-163.
United States Department of Agriculture Economic Research Service (USDA-ERS). 2016. US Food Waste Challenge FAQ's. Accessed on 9 December, 2016 from http://www.usda.gov/oce/foodwaste/faqs.htm
Impact of entomopathogenic fungi and beneficial microbes on strawberry growth, health, and yield
Six-month old strawberry field.
Under the soil is a complex and dynamic world of moisture, pH, salinity, nutrients, microorganisms, and plant roots along with pests, pathogens, weeds and more. A good balance of essential nutrients, moisture, and beneficial microorganisms provides optimal plant growth and yield. These factors also influence natural plant defenses and help withstand stress caused by biotic and abiotic factors.
Several beneficial microbe-based products are commercially available to promote plant growth and improve health, yield potential and quality. Some of them improve nutrient and water absorption while others provide protection against plant pathogens or improve plant defense mechanism. In addition to the macronutrients such as nitrogen, phosphorus, and potassium, several micronutrients are critical for optimal growth and yield potential. Some of the micronutrient products are also useful in promoting beneficial microbes. Understanding the plant-microbe-nutrient interactions and how different products help crop production are helpful for making appropriate decisions.
Mycorrhizae (fungi of roots) establish a symbiotic relationship with plants and serve as an extended network of the root system. They facilitate improved uptake of moisture and nutrients resulting in better plant growth and yield (Amerian and Stewart, 2001; Wu and Zou, 2009; Bolandnazar et al., 2007; Nedorost et al., 2014). Mycorrhizae can also help absorb certain nutrients more efficiently than plants can and make them more readily available for the plant. With increased moisture and nutrient absorption, plants can become more drought-tolerant. Mycorrhizae also help plants to withstand saline conditions and protect from plant pathogens. A healthy root system can fight soil diseases and weed invasion. Additionally, mycorrhizae increase organic matter content and improve soil structure.
Considering an increasing need for fumigation alternatives to address soilborne pathogens in strawberry, mycorrhizae and other beneficial microbes could be potential tools in maintaining plant health. Additionally, recent studies suggest that entomopathogenic fungi such as Beauveria bassiana, Metarhizium brunneum, and Isaria fumosorosea form mycorrhiza-like and endophytic relationships with various species of plants and could help with plant growth and health (Behie and Bidochka, 2014; Dara et al., 2016). These fungi are currently used for pest management, but their interaction with plants is a new area of research. Understanding this interaction will potentially expand the use of the biopesticides based on these fungi for improving plant growth and health. A study was conducted at Manzanita Berry Farms, Santa Maria in fall-planted strawberry crop during the 2014-2015 production season to evaluate the impact of beneficial microbes on strawberry growth, health, mite infestations, powdery mildew, botrytis fruit rot, and yield.
Methodology:
List of treatments, their application rates and frequencies:
- Untreated control: Received no supplemental treatments other than standard grower practices.
- HealthySoil: NPK (0.1-0.1-0.1).
- BotaniGard ES: Entomopathogenic fungus Beauveria bassiana strain GHA. Rate - 1 qrt in 50 gal for a 30 min transplant dip and 1 qrt/ac every 15 days until January and once a month thereafter until April, 2015.
- Met52: Entomopathogenic fungus Metarhizium brunneum strain F52. Rate – 16 fl oz in 50 gal for a 30 min transplant dip and 16 fl oz/ac every 15 days until January and once a month thereafter until April, 2015.
- NoFly: Entomopathogenic fungus Isaria fumosorosea strain FE9901. Rate – 11.55 oz in 50 gal for a 30 min transplant dip and 11.55 oz/ac every 15 days until January and once a month thereafter until April, 2015.
- Actinovate AG: Beneficial soilborne bacterium Streptomyces lydicus WYEC 108. Rate – 6 oz in 50 gal for a 30 mintransplant dip and 6 oz/ac every month.
- TerraClean 5.0: Hydrogen dioxide and peroxyacetic acid. Rate – 1:256 dilution for a 1 min root dip followed by 2 gal/ac 10 days after planting and then 2 and 1 gal/ac alternated every 15 days until April, 2015.
- TerraGrow: Humic acids, amino acids, sea kelp, glucose based carriers, bacteria – Bacillus licheniformis, B. subtilis, B. pumilus, B. amyloliquefaciens, and B. magaterium, and mycorrhizae – Trichoderma harzianum and T. reesei. Rate – 1.13 g in 10 gal for a 1 min root dip followed by 1.5 lb/ac 10 days after planting and once every month until April, 2015.
- TerraCelan and TerraGrow: Same as individual treatments at the time of planting, but TerraClean at 2 gal/ac and TerraGrow at 1.5 lb/ac 10 days after planting followed by monthly treatments until April, 2015.
- O-MEGA: NPK (0.2-1.0-0.5), bacteria – Azotobacter chroococcum, Azospirillum lipoferum, Lactobacillus acidophilus, Pseudomonas fluorescens, Cellulomonas cellulans and the fungus Aspergillus niger. Rate – 20 ml in 1 gal sprinkled on transplants 30 min before planting followed by 1 qrt/ac every week rest of the season.
Strawberry transplants (variety BG-6.3024) were treated at the time of planting on 6 November, 2014 and treatments are also administered periodically through the drip irrigation system following the abovementioned schedule. Each treatment had two 330' long beds each with four rows of plants. Treatments were randomly arranged in two blocks and two sampling plots (20' long) were established within each bed in a block. The impact of the treatments on plant growth (canopy size), health, spider mite populations, botrytis and powdery mildew severity, and yield were monitored periodically. Plant growth was determined by measuring the canopy size. Plant health was rated on a scale of 0 to 5 where 0=dead, 1=weak, 2=moderate low, 3=moderate high, 4=good, and 5=very good. Powdery mildew severity was determined by observing leaf samples under microscope and rating the severity on a scale of 0 to 4 where 0=no infection, 1=1-25%, 2=26-50%, 3=51-75%, and 4=76-100% of leaf area with powdery mildew. Twenty plants or leaf samples per plot were used for these observations. To monitor botrytis fruit rot, a box of fruits from each plot were held at room temperature and disease was rated 3 and 5 days after harvest on a scale of 0 to 4 where 0=no infection, 1=1-25%, 2=26-50%, 3=51-75%, and 4=76-100% of fruit with botrytis. Yield data were also collected from the plots throughout the production season using grower's harvesting schedule. Mite counts were also taken periodically.
Data were analyzed using analysis of variance and significant means were separated using Tukey's HSD means separation test.
Treating the transplants with different treatment materials and planting in respective beds
Newly transplanted experimental plots.
Chris Martinez (center, front row) and rest of the field crew at Manzanita Berry Farms
Results:
Canopy size: Significant differences (P = 0.002) among treatments were seen only on the first observation date on 26 January, 2015 where TerraClean-treated plants were smaller than some of the treatments. There were no significant differences (P > 0.05) in treatments on the following observations in February and March, however TerraClean-treated plants recovered and plants were larger in some of the treatments.
Size of the plant canopy on three observation dates.
Plant health: Treatments did not have a significant (P > 0.05) impact on plant health. Health ratings varied from 4.2 for TerraClean to 4.6 for untreated, BotaniGard, Actinovate, and O-Mega treatments in January. In February, TerraGrow-treated plants had 4.5 rating and BotaniGard and O-Mega treatments had 4.8. March ratings varied between 4.8 and 4.9 in all the treatments. As there were no soilborne diseases during the study period, the impact of the treatments could not be determined, which was the main objective of the study.
Plant health ratings on three observation dates.
Powdery mildew: Disease severity did not differ among treatments (P > 0.05) on 16 April and 16 June, but significant (P = 0.008) differences were observed on 26 June where BotaniGard-treated plants had the lowest. When data were compared for the three observation dates, severity rating varied from 1.8 for BotaniGard to 2.24 for TerraClean.
Powdery mildew severity on individual observation dates (top) and combined for three observations (bottom)
Botrytis fruit rot: There were no significant (P > 0.05) differences among treatments on any of the four observation dates or when data were combined for all observations. In general, fruit rot was less severe 3 days after harvest than 5 days after during the first three observation dates. When data were combined for the observation dates, HealthySoil treatment had a rating of 1 followed by Met52, NoFly, Actinovate, and TerraClean+TerraGrow with a 1.3 rating for 3 days after harvest.
Severity of botrytis fruit rot 3 and 5 days after harvest on individual observation dates (above) and when data were combined (below).
Spider mites: Mite populations were very low in all the plots during observation period and data were not included.
Fruit yield: While the seasonal yield of total, marketable, or unmarketable berries was not significantly (P > 0.05) different for any of the treatments marketable yields had a wider range than unmarketable yields among treatments. The lowest marketable fruit yield was seen in TerraClean (35.6 kg or 79.4 lb) and HealthySoil (35.8 kg or 79.8 lb) while the highest yield was seen in Actinovate (40.1 kg or 89.4 lb) followed by untreated control (39.4 kg or 87.9 lb), O-Mega (39.3 kg or 87.6 lb), Met52 (39.2 kg or 87.4 lb), and NoFly (38.7 kg or 86.3 lb) treatments.
Seasonal yields of total, marketable, and unmarketable strawberries per plot.
This is the first field study evaluating the impact of three popular entomopathogenic fungi along with multiple beneficial microbes on strawberry plant growth, foliar and fruit diseases, and yield. While differences among treatments were not pronounced, it appeared that some had a positive impact on some of the parameters measured. It is interesting to note that yields were higher (although not statistically significant) than the grower standard, HealthySoil. Compared to the grower standard, marketable yield was higher in many other treatments. Since an untreated situation is not common in a commercial field, using beneficial microbes can be useful. Although previous field studies evaluated the impact of with the entomopathogenic fungus B. bassiana in strawberries (Dara, 2013; Dara, 2016), a positive impact on plant growth or yield by I. fumosorosea and M. brunneum in commercial strawberries has never been reported earlier.
Additional studies with different application rates would be useful to understand how beneficial microbes could be exploited more.
Acknowledgments: Thanks to Dave Peck, Manzanita Berry Farms for the collaboration and industry partners for the financial support. Thanks to Chris Martinez and rest of the field crew at Manzanita Berry Farms and Fritz Light and Tamas Zold for the technical assistance.
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