- Author: Surendra K. Dara
The traditional Integrated Pest Management (IPM) model is focused on maintaining ecological balance in the cropping system with some attention to the economics of pest management related to the yield losses. The new model, recently published in the Journal of Integrated Pest Management, is more comprehensive covering the management, business, and sustainability aspects of pest management and discusses various components within (Dara, 2019). IPM, according to the new model, can be defined as an approach to managing pests in an economically viable, socially acceptable, and environmentally safe manner.
New IPM model from Dara, 2019
Based on the information generated by several studies in California and other reports, here is how the new IPM model can be adapted for producing strawberries sustainably.
1. MANAGEMENT ASPECT
A. Pest Management: The term “pest” includes arthropod pests, diseases, and weeds and the management includes the various practices used to suppress them.
- Select varieties that produce good yields while resisting biotic and abiotic stresses.
- Choosing the right mulch and good irrigation and nutrient management contribute to good plant growth and health. Micro-sprinklers save water and hold pest management benefits.
- Explore the potential of beneficial microbes and biostimulants to improve nutrient and water absorption and to maintain crop health. Inoculate the transplants with biostimulants to induce systemic resistance and periodically apply, especially after fumigation, to improve the beneficial microbial activity in the soil.
- Healthy plants resist pest problems and reduce the need for control options. Plant health can be maintained through good cultural practices (biostimulants, nutrients, irrigation, soil conditioning, etc.).
- Predatory mites effectively control twospotted and Lewis mites, but natural enemy populations may not be sufficient to control the western tarnished plant bug.
- Light traps can be useful for managing lepidopteran pests.
- Tractor-mounted vacuums can be a part of the IPM program for managing the western tarnished plant bug, but their pest control efficiency is not necessarily superior to other strategies and are not without some associated risks. For example, operation of vacuums requires fossil fuels and they are used at a much higher frequency than pesticide applications.
- Use botanical, microbial, and chemical pesticides in combination. Combinations can improve pest control efficacy and rotations reduce the risk of resistance development.
- Rotating strawberries with crops such as broccoli can reduce the severity of certain soilborne diseases.
B. Knowledge and Resources:
- Understand pest biology, vulnerable stages of the pest, and appropriate strategies for each pest, different life stages, season, and budget. For example, relying on natural enemies for the western tarnished plant bug control is not effective and can lead to higher pest damage.
- Accurately identify the issue through visual observation or laboratory diagnosis for proper corrective action.
- Try to explore modern technology to monitor crop health.
C. Planning and Organization:
- Regularly monitor crop health for early detection and prevention of potential pest problems. For example, thorough scouting to determine the level of western tarnished plant bug infestation is very important for making the treatment decision. Deformed fruit is not always an indicator for the treatment threshold as nearly 1/3 of the fruit deformity occurs from environmental and other causes not related to the western tarnished plant bug.
- Look for signs of pesticide resistance and use appropriate strategies to reduce the risk.
- Maintain records of pest occurrence, seasonal trends, strategies that worked, and all relevant information, to build institutional knowledge for future use.
- Take the right action at the right time.
- Regularly attend extension events and read research updates. Choose or design practices that are ideal for your farm based on the research updates.
- Periodically provide training to all individuals on the farm who directly or indirectly contribute to good agriculture practices.
- Share good management practices with each other for area-wide improvement of crop production and pest management.
- Try to educate the public so that they make better choices when purchasing produce. For example, good IPM practices can be more sustainable than organically approved practices and well-informed consumers can make a choice among conventional, organic, or sustainably produced grains, fruits, and vegetables. Public education can also help to eliminate otherwise good produce that is discarded because of minor imperfections. In strawberry, fruit deformity is caused due to the feeding of the western tarnished plant bug, genetic factors, poor pollination, or very low temperatures. Although most of the deformed strawberries, especially those from insect damage, have equal quality as marketable strawberries, they are discarded because of their shape. If the consumer market can accept deformed strawberries that still have good taste and nutritional quality, it can significantly reduce the wastage and the amount of pesticides sprayed to control the western tarnished plant bug.
2. BUSINESS ASPECT
- A strong IPM program can help growers produce sustainably while ensuring profitability.
- Consumer choices depend on their knowledge of sustainable agriculture. When they understand that produce with an IPM or Sustainably Produced label is safe for human and environmental health, it will have a major impact on food production systems.
3. SUSTAINABILITY ASPECT
- The current interpretation or perception of sustainability does not reflect true sustainability in terms of environmental health, profitability, food security, social equality, and other elements. A good IPM model can address all these issues to ensure farm productivity, food affordability, and environmental safety.
RESEARCH and OUTREACH
- Research and outreach component is the foundation of IPM to identify pest issues, develop appropriate knowledge for their management, and effectively disseminate the related information. Supporting research and outreach efforts of universities and other entities is essential for continuing IPM.
In addition to the below references, there are several articles in this eJournal on crop production and protection topics related to strawberry.
- Download “Biology and management of spider mites in strawberry” in English and Spanish at http://ucanr.edu/spidermiteguide or scan the QR code. Information about different species of spider mites and predatory mites is available in this guide.
- Efficacy of botanical, chemical, and microbial pesticides on twospotted spider mite and their impact on predatory mites http://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=18553
- Entomopathogenic fungi can endophytically colonize strawberry plants when applied to the soil and negatively impact twospotted spider mite infestations http://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=16821
- How to detect resistance to miticides in twospotted spider mite populations and strategies to reduce the resistance development http://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=22097
- Comparison between the twospotted spider mite and the Lewis mite http://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=5771
- An overview of lygus bug biology, damage, and management in strawberries http://cesantabarbara.ucanr.edu/files/75473.pdf
- Lygus biology, monitoring, and management videos http://ucanr.edu/SDYouTube
- Fruit deformity in strawberry from lygus bug and other factors http://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=19630
- Potential of a solar-powered UV light trap as a pest management option in strawberry http://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=25307
- IPM tools for controlling western tarnished plant bug in strawberry https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=19641
- Entomopathogens (pathogens of insects, mites, and ticks), their modes of infection, and how they can be used as a powerful tool in IPM http://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=24119
- Biopesticides and IPM https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=25912
- Lygus bug and natural enemy populations in organic and conventional strawberries https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=14030
- Microbial and bioactive soil amendments for improving strawberry health and yields (2017-2018 study) https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=27891
- Beneficial microbe-based products for strawberry health and yield (2016-2017 study)
- Beneficial microbes and entomopathogenic fungi for strawberry health and yield (2015-2016 study) https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=22709
- Entomopathogenic fungi antagonizing Macrophomina phaseolina https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=28274
- Entomopathogenic fungi and other biologicals against Fusarium oxysporum
- Micro-sprinklers in strawberry https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=19699
- Author: Surendra K. Dara
Botrytis fruit rot or gray mold, caused by Botrytis cinerea, is common fruit disease in California strawberries (Koike et al. 2018). Botrytis cinerea has a wide host range infecting several commercially important crops including blueberry (Saito et al. 2016), grapes (Saito et al., 2019), and tomato (Breeze, 2019). Fungal infection can cause flower or fruit rot. Fruit can be infected directly or through a latent infection in the flowers. Moist and cool conditions favor fungal infections and increased sugar content in the ripening fruit can also contribute to the disease development. Initial symptoms of infection appear as brown lesions and a thick mat of gray conidia is characteristic symptom in the later stages of infection. As chemical fungicides are primarily used for gray mold control, fungicide resistance is a common problem around the world (Panebianco et al., 2015; Liu et al., 2016; Stockwell et al., 2018; Weber and Hahn, 2019). In strawberry, cultural control options such as removing diseased plant material or using cultivars with traits that can reduce gray mold infections may not be practical when the disease is widespread in the field or cultivar choice is made based on other factors. Non-chemical control options are necessary to help reduce the risk of chemical fungicide resistance, prolong the life of available chemical fungicides, achieve desired disease control, and to maintain environmental health. Although there are several botanical and microbial fungicides available for gray mold control, limited information is available on their efficacy in California strawberries. A study was conducted in the spring of 2019 to evaluate the efficacy of several chemical, botanical, and microbial fungicides in certain combinations and rotations to help identify effective options for an integrated disease management strategy.
Strawberry cultivar San Andreas was planted late November, 2018 and the study was conducted in April and May, 2019. Each treatment had a 20' long strawberry plot with two rows of plants replicated in a randomized complete block design. Plots were maintained without any fungicidal applications until the study was initiated. Table 1 contains the list of treatments, application rates and dates of application, and Table 2 contains the type of fungicide used and their mode of action. Beauveria bassiana and Metarhizium anisopliae s.l. are California isolates of entomopathogenic fungi, isolated from an insect and a soil sample, respectively. These fungi are pathogenic to a variety of arthropods and some strains are formulated as biopesticides for arthropod control. However, earlier studies in California demonstrated that these fungi are also known to antagonize plant pathogens such as Fusarium oxysporum f.sp. vasinfectum Race 4 (Dara et al., 2016) and Macrophomina phaseolina (Dara et al., 2018) and reduce the disease severity. To further evaluate their efficacy against B. cinerea, these two fungi were also included in this study alternating with two chemical fungicides.
Treatments were applied with a CO2-pressurized backpack sprayer using 66.5 gpa spray volume. Five days before the first spray application and 3 days after each application, all ripe fruit were harvested from each plot and incubated at the room temperature in vented plastic containers. The level of gray mold on fruit from each plot was rated using a 0 to 4 scale (where 0=no disease, 1=1-25% fruit with fungal infection, 2=26-50% infection, 3=51-75%, and 4=76-100%) 3 and 5 days after each harvest (DAH). Due to the rains, fruit could not be harvested after the 3rd spray application for disease rating, but was harvested and discarded after the rains to avoid cross infection for the following week's harvest. Data were analyzed using analysis of variance using Statistix software and significant means were separated using Least Significant Difference separation test.
Gray mold occurred at low to moderate levels during the study period. Along with B. cinerea, there were a few instances of minor fungal infections from Rhizopus spp. (Rhizopus fruit rot) and Mucor spp. (Mucor fruit rot). Pre-treatment disease ratings were statistically not significant (P = 0.6197 and 0.5741) 3 and 5 DAH. While the chemical standard treatment with the rotation of Captan, Merivon, Switch, and Pristine (treatment 2) appeared to result in the lowest disease rating throughout the observation period, treatments 3 and 5 after the 1st spray application, treatments 5 and 11 along with 3, 4 and 6 after the 2nd spray application, and treatments 3 and 5 along with 11 after the 4th spray application also had similar disease control at 3 DAH. When disease at 5 DAH was compared, the lowest rating was seen in treatment 2 after the 1st and 2nd spray applications, and treatments 2, 3, and 11 after the 4th application. Several other treatments also provided statistically similar control during these days.
When the average disease rating for the three post-treatment observation events was considered, treatment 2, 3, 5, and 11 had the lowest disease at both 3 and 5 DAH. Treatments 4 and 12 at 3 DAH also had a statistically similar level of disease control to treatment 2.
In general, most of the treatments provided moderate to high control compared to the disease in untreated control when the post-treatment averages were considered. Only treatment 7 and 13 had lower control at 3 DAH.
This study compared a variety of registered and developmental products along with two entomopathogenic fungi in managing B. cinerea. Considering the fungicide resistance problem in B. cinerea in multiple crops, having multiple non-chemical control options is very important to achieve desirable control with integrated disease management strategies. Since the active ingredients in the botanical and bacterial fungicides used in this study are not public, discuss will be limited on their modes of action and efficacy at this point. Similarly, the active ingredient of WXF-17001 is also not known, however, an earlier study by Calvo-Garrido et al. (2014) demonstrated that a fatty acid-based natural product reduced B. cinerea conidial germination by 54% and disease severity in grapes by 96% compared to untreated control. The product used by Calvo-Garrido et al. (2014) is thought to be fungistatic and reduce the postharvest respiratory activity and ethylene production in fruits.
While chemical fungicides have a specific mode of action, biological and other products act in multiple manners either directly antagonizing the plant pathogen or by triggering the plant defenses. For example, amending the potting medium with biochar resulted in induced systemic resistance in tomato and reduced B. cinerea severity by 50% (Mehari et al., 2015). Luna et al. (2016) also showed that application of β-aminobutyric acid and jasmonic acid promoted seed germination and long-term resistance to B. cinerea in tomato. Burkholderia phytofirmans, beneficial endophytic bacterium, offered protection against B. cinerea in grapes by mobilizing carbon resources (callose deposition), triggering plant immune system (hydrogen peroxide production and priming of defense genese), and through antifungal activity (Miotto-Vilanova et al. 2016). Similarly, entomopathogenic fungi such as B. bassiana are also known to induce systemic resistance against plant pathogens (Griffin et al. 2006). Compared to other options evaluated in the study, entomopathogenic fungi have an advantage of controlling both arthropod pests and diseases, while also having plant growth promoting effect (Dara et al. 2017).
Rotating fungicides with different mode of actions reduces the risk of resistance development and using some combinations will also maintain control efficacy. This study provided the efficacy of multiple control options and their combinations and rotations for B. cinerea. This is also the first study demonstrating the efficacy of entomopathogenic fungi against B. cinerea in strawberry.
Acknowledgements: Thanks to Sipcam Agro and Westbridge for funding the study, technical assistance of Hamza Khairi for data collection, and the field staff at the Shafter Research Station for the crop maintenance.
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Dara, S.S.R., S. S. Dara, and S. K. Dara. 2018. Preliminary report on the potential of Beauveria bassiana and Metarhizium anisopliae s.l. in antagonizing the charcoal rot causing fungus Macrophomina phaseolina in strawberry. UC ANR eJournal of Entomology and Biologicals https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=28274
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Weber, R.W.S. and M. Hahn. 2019. Grey mould disease of strawberry in northern Germany: causal agents, fungicide resistance and management strategies. Appl. Microbiol. Biotechnol. 103: 1589-1597.
- Author: Surendra K. Dara
- Author: Dave Peck, Manzanita Berry Farms
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.