- Author: Surendra K. Dara
Integrated pest management, commonly referred to as IPM, is a concept of managing pests that has been in use for several decades. The definition and interpretation of IPM vary depending on the source, such as a university, institute, or a researcher, and its application varies even more widely depending on the practitioner. Here are a few examples of its definitions and interpretations:
“IPM is an ecosystem-based strategy that focuses on long-term prevention of pests or their damage through a combination of techniques such as biological control, habitat manipulation, modification of cultural practices, and use of resistant varieties. Pesticides are used only after monitoring indicates they are needed according to established guidelines, and treatments are made with the goal of removing only the target organism. Pest control materials are selected and applied in a manner that minimizes risks to human health, beneficial and nontarget organisms, and the environment.” UC IPM
“Integrated Pest Management, or IPM, is an approach to solving pest problems by applying our knowledge about pests to prevent them from damaging crops, harming animals, infesting buildings or otherwise interfering with our livelihood or enjoyment of life. IPM means responding to pest problems with the most effective, least-risk option.” IPM Institute of North America
“A well-defined Integrated Pest Management (IPM) is a program that should be based on prevention, monitoring, and control which offers the opportunity to eliminate or drastically reduce the use of pesticides, and to minimize the toxicity of and exposure to any products which are used. IPM does this by utilizing a variety of methods and techniques, including cultural, biological and structural strategies to control a multitude of pest problems.” Beyond Pesticides
“IPM is rotating chemicals from different mode of action groups.” A grower
These definitions and interpretations represent a variety of objectives and strategies for managing pests. IPM is not a principle that can/should be strictly and equally applied to every situation, but a philosophy that can guide the practitioner to use it as appropriate for the situation. For example, varieties that are resistant to arthropod pests and diseases are available for some crops, but not for others. Mating disruption with pheromones is widely practiced for certain lepidopteran and coleopteran pests, but not for several hemipteran pests. Biological control is more readily employed for greenhouse pests, but not to the same extent under field conditions. While chemical pesticides should be used as the last resort, in principle, sometimes they are the first line of defense to prevent damage to the transplants by certain pests or area-wide spread of certain endemic or invasive pests and diseases.
Crop production is an art, science, and business, and by adding environmental and social factors, IPM – an approach used in agriculture – can also be influenced by a number of factors. Each grower has their own strategy for producing crops, minimizing losses, and making a profit in a manner that is acceptable to the society, safe for the consumers, and less disruptive to the environment. In other words, “IPM is an approach to manage pests in an economically viable, socially acceptable, and environmentally safe manner”. Keeping this simple, but loaded, definition in mind and considering recent advances in crop production and protection, communication technology, and globalization of agriculture and commerce, here is the new paradigm of IPM with its management, business, and sustainability aspects.
I. Management Aspect
There are four major components in the IPM model that address the various pest management options, the knowledge and resources the grower has in order to address the pest issue, planning and organization of information to take appropriate actions, and maintaining good communication to acquire and disseminate knowledge about pests and their management.
1. Pest Management:
The concept of pest control has changed to pest management over the years knowing that a balanced approach to managing pest populations to levels that do not cause economic losses is better than eliminating for environmental and economic reasons. Although the term control is frequently used in literature and conversations, it generally refers to management. A thorough knowledge of general IPM principles and various management options for all possible pest problems is important as some are preventive and others are curative. It is also essential to understand inherent and potential interactions among these management options to achieve maximum control. The following are common control options that can be employed at different stages of crop production to prevent, reduce, or treat pest infestations. Each of them may provide only a certain level of control, but their additive effect can be significant in preventing yield losses.
a. Host plant resistance: It involves the use of pest resistant and tolerant cultivars developed through traditional breeding or genetic engineering. These cultivars possess physical, morphological, or biochemical characters that reduce the plant's attractiveness or suitability for the pest to feed, develop, or reproduce successfully. These cultivars resist or tolerate pest damage and thus reduce the yield losses.
b. Cultural control: Changing agronomic practices to avoid or reduce pest infestations and damage refers to cultural control. Adjusting planting dates can help escape pest occurrence or avoid most vulnerable stages. Modifying irrigation practices, fertilizer program, plant or row spacing, and other agronomic practices can create conditions that are less suitable for the pest. Destroying crop residue and thorough cultivation will eliminate breeding sites and control soil-inhabiting stages of the pest. Crop rotation with non-host or tolerant crops will break the pest cycles and reduce their buildup year after year. Choosing clean seed and plant material will avoid the chances of introducing pests right from the beginning of the crop production. Sanitation practices to remove infected/infested plant material, regular cleaning field equipment, avoiding accidental contamination of healthy fields through human activity are also important to prevent the pest spread. Intercropping of non-host plants or those that deter pests or using trap crops to divert pests away from the main crop are some of the other cultural control strategies.
c. Biological control: Natural enemies such as spiders, predators, and parasitic wasps can be very effective in causing significant reductions in pest populations in certain circumstances. Periodical releases of commercially available natural enemies or conserving natural enemy populations by providing refuges or avoiding practices that harm them are some of the common practices to control endemic pests. To address invasive pest issues, classical biological control approach is typically employed where natural enemies from the native region of the invasive pest are imported, multiplied, and released in the new habitat of the pest. The release of irradiated, sterile insects is another biological control technique that is successfully used against a number of pests.
d. Behavioral control: Behavior of the pest can be exploited for its control through baits, traps, and mating disruption techniques. Baits containing poisonous material will attract and kill the pests when distributed in the field or placed in traps. Pests are attracted to certain colors, lights, odors of attractants or pheromones. Devices that use one or more of these can be used to attract, trap or kill pests. Pheromone lures confuse adult insects and disrupt their mating potential, and thus reduce their offspring.
e. Physical or mechanical control: This approach refers to the use of a variety of physical or mechanical techniques for pest exclusion, trapping (in some cases similar to the behavioral control), removal, or destruction. Pest exclusion with netting, handpicking or vacuuming to remove pests, mechanical tools for weed control, traps for rodent pests, modifying environmental conditions such as heat or humidity in greenhouses, steam sterilization or solarization, visual or physical bird deterrents such as reflective material or sonic devices are some examples for physical or mechanical control.
f. Microbial control: Using entomopathogenic bacteria, fungi, microsporidia, nematodes, and viruses, and fermentation byproducts of microbes against arthropod pests, fungi against plant parasitic nematodes, and bacterial and fungal antagonizers of plant pathogens generally come under microbial control.
g. Chemical control: Chemical control typically refers to the use of synthetic chemical pesticides, but to be technically accurate, it should include synthetic chemicals as well as chemicals of microbial or botanical origin. Although botanical extracts such as azadirachtin and pyrethrins, and microbe-derived toxic metabolites such as avermectin and spinosad are regarded as biologicals, they are still chemical molecules, similar to synthetic chemicals, and possess many of the human and environmental safety risks as chemical pesticides. Chemical pesticides are categorized into different groups based on their mode of action and rotating chemicals from different groups is recommended to reduce the risk of resistance development. Government regulations restrict the time and amount of certain chemical pesticides and help mitigate the associated risks.
The new RNAi (ribonucleic acid interference) technology where double-stranded RNA is applied to silence specific genes in the target insect is considered as a biopesticide application. Certain biostimulants based on minerals, microbes, plant extracts, seaweed or algae impart induced systemic resistance to pests and diseases, but are applied as amendments without any claims for pest or disease control. These new products or technologies can fall into one or more abovementioned categories.
As required by the crop and pest situation, one or more of these control options can be used throughout the production period for effective pest management. When used effectively, non-chemical control options delay, reduce, or eliminate the use of chemical pesticides.
2. Knowledge and Resources:
The knowledge of various control options, pest biology and damage potential, and suitability of available resources enables the grower to make a decision appropriate for their situation.
a. Pest: Identification of the pest, understanding its biology and seasonal population trends, damaging life stages and their habitats, nature of damage and its economic significance, vulnerability of each life for one or more control options, host preference and alternate hosts, and all the related information is critical for identifying an effective control strategy.
b. Available control options: Since not all control options can be used against every pest, the grower has to choose the ones that are ideal for the situation. For example, systemic insecticides are more effective against pests that mine or bore into the plant tissue. Pests that follow a particular seasonal pattern can be controlled by adjusting planting dates. Commercially available natural enemies can be released against some, while mating disruption works well against others. Entomopathogenic nematodes can be used against certain soil pests, bacteria and viruses against pests with chewing mouthparts such as lepidoptera and coleopteran, and fungi against sucking pests.
c. Tools and technology: A particular pest can be controlled by certain options, but they may not all be available in a particular place, for a particular crop, or within the available financial means. For example, the release of natural enemies may be possible in high-value speciality crops, but not in large acreage field crops. A particular pesticide might be registered against a pest on some crops, but not on all. Use of netting or tractor-mounted vacuums can be effective, but very expensive limiting their availability to those who can afford.
This is a critical component where diagnostic and preventive or curative decisions are made based on available and affordable control options.
3. Planning and Organization:
This component deals with the management aspect of the of the new IPM model for data collection, organization, and actual actions against pest infestations.
a. Pest monitoring: Regularly monitoring the fields for pest infestation and spread is a basic step in crop protection. Early detection in many cases can help address the pest situation by low-cost spot treatment or removal of pests or infected/infested plant material. When pest infestations continue to grow, regular monitoring is necessary to assess the damage and determine the time to initiate farm-wide control. Monitoring is also important to avoid calendar-based pesticide applications especially at lower pest populations that do not warrant treatments.
b. Managing information: A good recordkeeping about pests, their damage, effective treatments, seasonal fluctuations, interactions with environmental factors, irrigation practices, plant nutrition, and all related information from year to year will build the institutional knowledge and prepares the grower to take preventive or curative actions.
c. Corrective actions: Taking timely action is probably the most important aspect of IPM. Even with all the knowledge about the pest and availability of resources for its effective management, losses can be prevented only when corrective actions are taken at the right time. Good farm management will allow the grower to take timely actions. These actions are not only necessary to prevent damage on a particular farm, but also to prevent the spread to neighboring farms. When pest management is neglected, it leads to area-wide problems with larger regulatory, social, and economic implications.
4. Communication:
Good communication to transfer the individual or collective knowledge for the benefit of everyone is the last component of the new IPM model. Modern and traditional communication tools can be used for outreach as university and private researchers develop information about endemic and invasive pests, emerging threats, and new control strategies.
a. Staying informed: Growers and pest control professionals should stay informed about existing and emerging pests and their management options. Science-based information can be obtained by attending extension meetings, webinars, or workshops, reading newsletter, trade, extension, or scientific journal articles, and keeping in touch with researchers and other professionals through various communication channels. Well-informed growers can be well prepared to address pest issues.
b. Communication within the group: Educating farm crew through periodical training or communication will help with all aspects of pest management, proper pesticide handling, ensuring worker safety, and preventing environmental contamination. Knowledgeable field crew will be beneficial for effective implementation of pest management strategies.
c. Communication among growers: Although certain crop production and protection strategies are considered proprietary information, pests do not have boundaries and can spread to multiple fields when they are not effectively managed throughout the region. Sharing knowledge and resources with each other will improve pest control efficacy and benefit the entire grower community.
In addition to these four components with an IPM model, factors that influence profitable, safe, and affordable food production at a larger scale and their implications for global food security should also be included. There are two layers surrounding these four components addressing the business and sustainable aspects of food production.
II. Business Aspect:
Consumers want nutritious, healthy, and tasty produce that is free of pest damage at affordable prices. Growers try to meet this demand by producing food that meets all the consumer needs, while maintaining environmental and human safety and still being able to make a profit. Sellers evaluate the market demand and strategize their sales to satisfy consumers while making their own profit to stay in the business. In an ideal system, consumer, producer, and seller would maintain a harmonious balance of food production and sale. In such a system, food is safe and affordable to everyone, there will be food security all over the world, and both growers and sellers make a good profit with no or minimal risk to the environment in the process of food production. However, this balance is frequently disrupted due to i) consumers' misunderstanding of various food production systems, their demand for perfectly shaped fruits and vegetables at affordable prices or their willingness to pay a premium price for food items that are perceived to be safe, ii) growers trying to find economical ways of producing high quality food while facing with continuous pest problems and other challenges, and iii) sellers trying to market organic food at a higher price as a safer alternative to conventionally produced food. If growers implement good IPM strategies to produce safe food and consumers are aware of this practice and gain confidence in food produced in an IPM system, then sellers would be able to market what informed-consumers demand.
III. Sustainability Aspect:
As mentioned earlier, IPM is an approach to ensure economic viability at both consumer and producer level (seller is always expected to make a profit), environmental safety through a balanced use of all available pest control options, and social acceptability as food is safe and affordable.
While organic food production is generally perceived as safe and sustainable, the following examples can explain why it is not necessarily true. Organic food production is not pesticide-free and some of the pesticides used in an organic system are as harmful to humans and non-target organisms as some chemical pesticides. Certain organically accepted pesticides have toxins or natural chemical molecules that are very similar to those in synthetic pesticides. In fact, some synthetic pesticides are manufactured imitating the pesticidal molecules of natural origin. Mechanical pest control practices such as vacuuming or tilling utilize fossil fuels and indirectly have a negative impact on the environment. For example, diesel-powered tractors are operated for vacuuming western tarnished bug in strawberry 2-3 times or more each week while a pesticide application typically requires the use of tractor once every 7-14 days. To control certain pests, multiple applications of organic pesticides might be necessary with associated costs and risks, while similar pest populations could be controlled by fewer chemical pesticide applications. It is very difficult to manage certain plant diseases and arthropod pests through non-chemical means and inadequate control not only leads to crop losses, but can result in their spread to larger areas making their control even more difficult. Many growers prefer a good IPM-based production to an organic production for the ease of operation and profitability. However, they continue to produce organic food to stay in business.
While middle and upper-class consumers may be willing to pay higher prices for organically produced food, many of the low-income groups in developed and underdeveloped countries cannot afford such food. Organic food production can lead to social inequality and a false sense of wellbeing for those can afford. Food security for the growing world population is necessary through optimizing input costs, minimizing wastage, grower adoption of safe and sustainable practices, and consumer confidence in food produced through such practices. IPM addresses all the economic, environmental, and social aspects and provides safe and affordable food to the consumers and profits to producers and sellers, while maintaining environmental health.
- Author: Surendra K. Dara
- Author: Dave Peck, Manzanita Berry Farms
Experimental plots in mid January, 2018. Photo by Surendra Dara
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
Tamas Zold taking canopy measurements. Photo by Surendra Dara
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
Areas where transplants did not establish. Photo by Surendra Dara
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.
- Author: Christian Nansen, Elvira de Lange, Alison Stewart, Department of Entomology and Nematology, UC Davis
- Author: Mark Edsall, California Strawberry Commission
- Author: Surendra K. Dara
The western tarnished plant bug (or lygus bug) and different species of spider mites are major arthropod pests in California strawberries. While predatory mite releases are very popular for controlling spider mites in both organic and conventional fields, a significant amount of chemical pesticides are used for arthropod pest management in conventional fields. Nearly 280,000 pounds of active ingredient of at least 30 chemical and botanical pesticides were used in 2016 in California strawberries (USDA-NASS, 2016; CDPR, 2017) and malathion, bifenazate, naled, acequinocyl, and fenpropathrin were the most common of about 79,000 pounds of chemical pesticides. A uniform and thorough coverage of pesticide sprays is essential for effective pest management and also for reducing excessive pesticide use that could lead to resistance and environmental health issues (Shi et al., 2013). Evaluation of pesticide spray applications and their performance will help improve current pest management strategies in strawberry as they did in other crops (Nansen et al., 2011; Nansen et al., 2015).
Several factors such as the tractor speed, spray nozzles, spray volume, boom height, adjuvants, pressure, canopy characters, micro and macroclimatic conditions influence the spray coverage. A better understanding of these factors will help improve the pesticide use and efficacy, optimize the cost, and reduce pesticide drift and other associated risks (Nansen and Ridsdill-Smith, 2013).
A study was conducted during 2016 and 2017 to evaluate multiple spray configurations under varying weather conditions where more than 4000 data points were collected. Data for only two spray configurations, using Albuz ATR 80 Lilac and Albuz ATR 80 Green nozzles, are shown here.
Collecting the spray cards for evaluating the spray coverage (above). Photo by Elvira de Lange.
Water-sensible spray card in the strawberry canopy (above) and determining the spray coverage with the help of SnapCard app (below). Photos by Elvira de Lange.
Configuration 1: Albuz ATR 80 Lilac nozzles were used in 144 experimental applications delivering 32-80 gallons of spray volume per acre. Water-sensitive spray cards (TeeJet, Wheaton, IL) were clipped to the petioles of strawberry leaves in horizontal and vertical orientation (1 card per application for each orientation). They were placed in the strawberry canopy prior to spray applications and the coverage was determined based on the pattern on the cards using the SnapCard smartphone application. Data suggested that spray volume does not always translate into a good spray coverage (Fig. 1). There was a wide variation in the coverage that ranged from 0-55% at 33 gpa and 5-80% at 80 gpa suggesting the influence of other factors. Taking the operational and weather conditions into account, a multiple linear regression analysis was conducted to measure the relationship between predicted and observed spray coverage which appeared to have a linear correlation (Adjusted R2=0.27; F+52.6; P < 0.001) (Fig. 2). Wind speed, wind gust, ambient temperature, pressure, and tractor speed were used as explanatory variables in this analysis. Based on this regression model, four possible scenarios were developed with predicted spray coverage values (Table 1). A 2 mph increase in the wind speed from 6 mph to 8 mph could reduce the spray coverage from 61 to 45% when the tractor runs at 1 mph or from 30 to 13% when the tractor runs at 2 mph.
Configuration 2: Albuz ATR 80 Green nozzles were used in 276 experimental applications delivering 180-440 gallons of volume per acre. Since the droplet size from the Green nozzle is much larger than that from the Lilac nozzle, a better coverage is expected with the presumption of lesser sensitivity to environmental and operating conditions. However, data from the spray cards indicated a poor relationship between the spray volume and coverage under this configuration as well (Fig. 3). For example, both 200 and 350 gpa had a similar spray coverage. Multiple linear regression analysis, using strawberry canopy characteristics (plant height and width, dry weight, and canopy coverage), operating and weather conditions as explanatory variables, showed a significant linear correlation (Adjusted R2=0.45; F=199.5; P < 0.001) between observed and predicted spray coverages (Fig. 4). A prediction model under this configuration showed nearly 20% decline in spray coverage when the tractor speed increased from 1 to 2 mph (Table 2). Wind speed appeared to have a minimal impact, probably due to the droplet size.
Fig. 3. Spray coverage related to the volume using the Albuz ATR 80 Green nozzle.
Fig. 4. Modeling spray coverage under different conditions using the Albuz ATR 80 Lilac nozzle.
This study demonstrates the importance of weather and operating conditions on spray coverage. Additional data will be collected in 2018 to expand our understanding of the factors that influence spray coverage. These studies will be useful to determine appropriate operating conditions such as the spray volume, tractor speed, and types of nozzles and identify weather conditions that are ideal to achieve good coverage. A free smartphone application is under development for the growers and PCAs to input weather and operating conditions to predict the spray coverage. This information will ultimately improve the pest control efficacy and contribute to sustainable pest management practices.
Acknowledgments: We thank the financial support of the California Strawberry Commission and the collaboration of several growers. We also thank the technical assistance of Daniel Olivier, Marianna Castiaux, and Ariel Zajdband, California Strawberry Commission and Robert Starnes, Jessie Liu, Laurie Casebier, Haleh Khodaverdi, and Isaac Corral, UC Davis.
References
CDPR. 2017. Summary of pesticide use report data 2016: California Department of Pesticide Regulation, p. 909.
Nansen C, Ferguson JC, Moore J, Groves L, Emery R, Garel N and Hewitt A. 2015. Optimizing pesticide spray coverage using a novel web and smartphone tool, SnapCard. Agronomy for Sustainable Development: 1-11. DOI: 10.1007/s13593-015-0309-y.
Nansen C & Ridsdill-Smith TJ (2013) The performance of insecticides – a critical review: Insecticides (ed. by S Trdan) InTech Europe, Croatia, pp. 195-232.
Nansen C, Vaughn K, Xue Y, Rush C, Workneh F, Goolsby J, Troxclair N, Anciso J, Gregory A, Holman D, Hammond A, Mirkov E, Tantravahi P and Martini X (2011) A decision-support tool to predict spray deposition of insecticides in commercial potato fields and its implications for their performance. Journal of Economic Entomology 104: 1138-1145. DOI: 10.1603/EC10452.
Shi M, Collins PJ, Ridsdill-Smith TJ, Emery RN and Renton M. 2013. Dosage consistency is the key factor in avoiding evolution of resistance to phosphine and population increase in stored-grain pests. Pest Management Science 69: 1049–1060. DOI: 10.1002/ps.3457.
USDA_NASS. 2016. Quick stats.
- Author: Melissa O'Neal, Marrone Bio Innovations
- Author: Surendra K. Dara
The biopesticides market has been experiencing a rapid growth in recent years; however, plant- and microorganism-based biopesticides have been used for centuries for controlling pests. According to 17th century records, plant extracts such as nicotine were some of the earliest agricultural biopesticides used to control plum beetles and other pests (BPIA, 2017). Experimentation involving biological controls against lepidopteran pests were performed as early as 1835, during Agostine Bassi's efficacy demonstrations of the white muscardine disease caused by a fungus now known as Beauveria bassiana against lepidopteran pests (BPIA, 2017). Further, the use of mineral oils as plant protectants was cited in experiments during the 19th century (BPIA, 2017).
In the early 20th century, an increasing number of studies involving biopesticides emerged during the rapid institutional expansion of agricultural research (Stoytcheva, 2011). The bacterium Bacillus thuringiensis (Bt) was the initial biopesticide and has the most widespread use to this day. In 1901, Bt was isolated from a diseased silkworm by Japanese biologist Shigetane Ishiwata. Ten years later, German researcher Ernst Berliner rediscovered it in a diseased flour moth caterpillar (BPIA, 2017). Other commercial success stories from the 1980s and 1990s involve the use of Agrobacterium radiobacter to prevent crown gall on woody crops (Escobar and Dandekar, 2003) as well as utilizing Pseudomonas fluorescens for the prevention of fire blight in orchards with streptomycin-resistant pathogen populations (Stockwell et al., 2010).
Resurgence in academic and industrial research for biopesticide development occurred in response to rising costs associated with the overuse of synthetic chemicals. Increasing biopesticide adoption has resulted, in part due to rapid expansion of organic agriculture during the past decade (Eze et al., 2016). As a result, the development of new biopesticides has continued to increase since the mid-1990s. Over 100 active ingredients have been registered with the United States Environmental Protection Agency (USEPA) Biopesticides Division since 1995 (EPA, 2017). The increasing cost of developing chemical pesticides (Fig. 1) could also have contributed to the rise in biopesticide registration (McDougall, 2016).
Fig. 1. Costs to discover and develop a synthetic agricultural chemical. (Based on McDougall 2016)
Biopesticides currently represent approximately 5% of the total pesticide market (Olson, 2015). However, the biopesticides market is experiencing rapid growth of about three times the rate associated with conventional agricultural chemicals (Chandler et al., 2011). The trend toward the use of biopesticides is growing stronger for two major reasons; the first is the fact that biologicals alone and in combination with chemicals have the potential to provide superior yields and quality (Yadav et al., 2013; Dara, 2015 & 2016; BPIA, 2017;). Secondly, increasing regulatory restriction on chemicals has established restrictive barriers to bringing new products to market while countries such as Europe simultaneously are eliminating pesticide active ingredients at a rapid rate (Erbach, 2012) (Fig. 2).
Fig.2. Numbers of new agricultural chemical leads and launches from 1995-2010 (Based on data from Ag Chem New Compound Review, 2010).
Over 200 biopesticide products are currently sold in the US, in comparison to only 60 comparable products in the European Union. Overall, more than 225 microbial biopesticides are presently manufactured within 30 countries that belong to the Organization for Economic Cooperation and Development. Approximately 45% of the total biopesticide use occurs in USA, Canada, and Mexico, whereas Asia uses around 5% of biopesticides sold globally (Kumar & Singh, 2016).
According to Berkshire Hathaway, the global biopesticides market is projected to reach a value of $8.8 billion by 2022, representing annual average growth of 17% from 2016 (Brzoskiewicz, 2018). Primary growth factors affecting the biopesticides market include growth in crop production, ease of application, increase the in need for organic food, and growing preference for sustainable pest control methods. Although biopesticides currently account for approximately 2% of the plant protectants used globally, the growth rate indicates an increasing trend during the past two decades, wherein the global use of biopesticides is increasing steadily by 10% every year (Brzoskiewicz, 2018).
Biostimulants are a recent emergent area within which functionality and regulatory guidelines may not be as well-defined as those for biopesticides. A plant biostimulant is defined as “any substance or microorganism applied to plants with the aim to enhance nutrition efficiency, abiotic stress tolerance and/or crop quality traits, regardless of its nutrients content” (du Jardin, 2015, p. 3). Chatzikonstantinou (2017) regarded fertilizers and biostimulants as being a part of the same family, with reasoning based in their similarities for helping plants to simulate nutrients, boosting tolerance to abiotic stress factors, and increasing the quality of crops. There are currently no federal statutory definitions for biostimulants in the US, and uncertainty exists in both federal and state regulatory agencies in terms of how to develop guidelines for plant biostimulant categories (Russell, 2015).
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Literature cited
Ag Chem New Compound Review. 2010. Vol 28.
(BPIA). Biological Products Industry Alliance. 2017. History of biopesticides. http://www.bpia.org/history-of-biopesticides/
Brzoskiewicz, R. 2018. Biopesticides market: Global forecast to 2022. http://www.satprnews.com/2018/01/15/biopesticides-market-global-forecast-to-2022/
Chandler, D., A. Bailey, G.M. Tatchell, G. Davisdon, J. Greaves, et al. 2011. The development, regulation and use of biopesticides for integrated pest management. Phil Trans R Soc B 366: 1987–1998.
Chatzikonstantinou, L. 2017. Why biostimulants and fertilizers are part of the same family. http://www.biostimulants.eu/2017/05/why-biostimulants-fertilizers-are-part-of-the-same-family/
du Jardin, P. 2015. Plant biostimulants: Definition, concept, main categories and regulation. Sci Hort 196: 3–14.
Dara, S. K. 2015. Root aphids and their management in organic celery. CAPCA Adviser 18(5): 65-70.
Dara, S. K. 2016. IPM solutions for insect pests in California strawberries: efficacy of botanical, chemical, mechanical, and microbial options. CAPCA Adviser 19(2): 40-46.
Erbach, G. 2012. Pesticide legislation in the EU: Towards sustainable use of plant protection products. Library briefing, Library of the European Parliament 120291REV1: 1-6.
(EPA). U.S. Environmental Protection Agency. 2017. Biopesticide active ingredients. https://www.epa.gov/ingredients-used-pesticide-products/biopesticide-active-ingredients
Escobar, M.A. and A.M. Dandekar. 2003. Agrobacterium tumefaciens as an agent of disease. Trends Pl Sci. 8(8): 380-396.
Eze, S.C., C.L. Mba, and P.I. Ezeaku. 2016. Analytical review of pesticide formulation trends and application: The effects on the target organisms and environment. Int Jour Sci Env Tech 5(1): 253-266.
Kumar, S., and A. Singh. 2015. Biopesticides: Present status and the future prospects. J Fertil Pestic 6: e129. doi:10.4172/2471-2728.1000e129
McDougall, P. 2016. A consultancy study for CropLife International, CropLife America and the European Crop Protection Association. https://croplife.org/wp-content/uploads/2016/04/Cost-of-CP-report-FINAL.pdf
Olson, S. 2015. An analysis of the biopesticide market now and where it is going. Outlk Pest Mgmt 26: 203-206. DOI: 10.1564/v26_oct_04
Jones, R. 2015. Biostimulants: An OPP perspective. Association of American Pesticide Control Officials SFIREG Meeting Proceedings, Arlington, VA (September 2015). https://aapco.files.wordpress.com/2015/10/russ_jones_epa_biostimulants_sfireg_draft_09-2015.pdf
Stockwell, V.O., K. B. Johnson, D. Sugar, and J. E. Loper. 2010. Control of fire blight by Pseudomonas fluorescens A506 and Pantoea vagans C9-1 applied as single strains and mixed inocula. Phytopath 100(12): 1330-1339.
Stoytcheva, M (ed.). 2011. Pesticides: Formulations, effects, fate. Intech, Rijeka, Croatia.
Yadav, S.K, S. Babu, M. K. Yadav, K.Singh, G. S. Yadav, and S. Pal. 2013. A review of organic farming for sustainable agriculture in northern India. Int Jour Agr 2013: 1-8. http://dx.doi.org/10.1155/2013/718145
- Author: Melissa O'Neal, Marrone Bio Innovations
- Author: Surendra K. Dara
Biopesticides are based on naturally occurring microorganisms, plant extracts or other materials and are regulated by the United States Environmental Protection Agency (EPA)'s Biopesticide Division. Biopesticides have been safely used for over 63 years and are generally subjected to reduced regulation compared to conventional chemical pesticides.
Biopesticides can be developed from plant extracts or entomopathogenic microorganisms. Graphic: Surendra Dara
The active ingredient in microbial pesticides consists of a microorganism, such as a bacterium, fungus, nematode, protozoan or virus. While microbials are capable of assisting in the management of many different types of pests, each type of microorganism tends to be relatively specific for a target pest or group of pests. Biochemical pesticides are based on naturally occurring substances, which function by providing pest management through non-toxic mechanisms. Biochemical pesticides may function by disrupting or interfering with mating, such as in the case of insect sex pheromones or various plant extracts which serve as insect attractants used with traps. Conventional pesticides, by contrast, are generally synthetic materials that directly kill or inactivate the pest (Leahy et al., 2014).
Biopesticide development
Typically, samples of microorganisms or infected arthropods are collected from natural environments. Samples are taken to the laboratory and plated on media; thereafter, various colonies form from the collected samples. Individual colonies of interest may be selected, suspended, and examined for pesticidal activity during laboratory bioassays (Taylor, 1988). As part of the laboratory bioassay process, researchers screen candidates against a number of potential targets, which may vary widely, depending upon institutional goals and availability.
A key initial task is identification and characterization of the pesticidal compounds sourced from the plants or microbes collected in natural settings (Strobel and Daisy, 2003). Part of this process involves isolating and eliminating any compounds which have potential human health implications or may negatively impact non-targets organisms (USDA, 2017b). Additionally, analytical assays based on bioactive chemistry are developed to ensure quality control during the manufacturing process (Strobel and Daisy, 2003).
Several steps are involved with product and process development. First, user-friendly formulations are developed in both lab and pilot facilities. Next, manufacturing processes are developed and scaled in arenas including lab, pilot, and manufacturing facilities (Strobel and Daisy, 2003). Thereafter, field studies are conducted and data are gathered for the regulatory submissions which support product registration (USDA, 2017a).
Biopesticide registration process
A special committee has been established within the EPA due to the fact that it is often challenging to determine whether a substance meets the criteria for classification as a biochemical pesticide (Leahy et al., 2014). The Biopesticide Pollution Prevention Division (BPPD) of the EPA is charged with data review required for registration. Requirements for registration include acute studies consisting of oral, inhalation, intravenous, and dermal tests, in addition to eye and skin studies in rodents. A product chemistry review involving a five-batch analysis is also required by BPPD. Microbiology and quality control investigations assure that material is free of human pathogens. Ecological effects, including impact on non-target birds, fish, Daphnia, honeybees, lacewings, ladybeetles, and parasitic wasps is additionally determined. The review process is taken one step further during the endangered species review. Finally, the matter of the Exemption from Tolerance Petition for Food Use is addressed (EPA, 2017). It should be noted that efficacy data are required in addition to the aforementioned topics when attempting to register a new biopesticide in California (CDPR, 2017). There are several examples of successful pesticides which are sourced from natural products and registered as chemical pesticides (Fig. 1).
Fig. 1. Chemical pesticides developed from natural sources. Graphic: Melissa O'Neal
Abamectin is an insecticide/miticide derived from Streptomyces avermitilis, a microorganism found in soil. Its mode of action involves interference with neurotransmission (CDPR, 1993). Tebufenozide is an insect growth disruptor which interferes with insect molting hormones (Smagghe et al., 2012). The spinosyns are a family of chemicals produced by fermentation of Saccharopolyspora bacteria which are toxic due to disruption of neurotransmitters in both target and non-target organisms (Kirst, 2010). Azoxystrobin is a synthetic material derived from phytotoxic compounds which naturally occur in the mushrooms Oudemansiella mucida and Strobilurus tenacellus. Its mode of action is disruption of energetic reactions involving ATP synthesis (AgChemAccess, 2015). Finally, pyrethrins are naturally occurring materials derived from the chrysanthemum (Chrysanthemum cinerariaefolium) flowers and acts as a contact nerve poisons (Extoxnet, 1994).
The following tables 1-5 provide an overview of some of the commercial biopesticides currently registered in the US and other countries for controlling insects, mites, plant pathogenic fungi, and plant parasitic nematodes.
Table 1. Microbial insecticides andacaracides.
Table 2. Plant extract and oil insecticides and acaricides.
Table 3. Microbial fungicides.
Table 4. Non-microbial fungicides.
Table 5. Bionematicides.
References
AgChemAccess. 2015. Azoxystrobin. http://www.agchemaccess.com/Azoxystrobin.
(CDPR). California Department of Pesticide Regulation. 1993. Abamectin Avert Prescription Treatment 310 (Section 3 Registration) Risk Characterization Document. http://www.cdpr.ca.gov/docs/risk/rcd/abamectin.pdf
(CDPR). California Department of Pesticide Regulation. 2017. How to apply for pesticide product registration. http://www.cdpr.ca.gov/docs/registration/instructions.htm
(EPA). U.S. Environmental Protection Agency. 2017. Biopesticides. https://www.epa.gov/pesticides/biopesticides#what
Extoxnet. 1994. Pesticide information profile: Pyrethrins. http://pmep.cce.cornell.edu/profiles/extoxnet/pyrethrins-ziram/pyrethrins-ext.html
Kirst, H.A. 2010. The spinosyn family of insecticides: realizing the potential of natural products research. J Antibiot 63(3): 101-11. doi: 10.1038/ja.2010.5.
Leahy, J., M. Mendelsohn, J. Kough, R. Jones, and N. Berckes. 2014. Biopesticide oversight and registration at the U.S. Environmental Protection Agency. In Biopesticides: State of the Art and Future Opportunities; Coats, et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2014.
Smagghe, G., L.E. Gomez, and T.S. Dhadialla. 2012. Insect growth disruptors. Adv Ins Phys 43: 1-552.
Strobel, G. and B. Daisy. 2003. Bioprospecting for microbial endophytes and their natural products. Microbiol Mol Bio Rev 67(4): 491-502.
Taylor, J.K. 1988. Quality assurance of chemical measurements. Chelsea, MI: Lewis.
(USDA). United States Department of Agriculture. 2017a. About AMS.
https://www.ams.usda.gov/about-ams/programs-offices/national-organic-program
(USDA). United States Department of Agriculture. 2017b. USDA FY 2016 avoiding harm from invasive species (USDA Do No Harm 2016 Report, Part 2). https://www.invasivespeciesinfo.gov/docs/resources/usdanoharm20170119.docx
