New Generation Formulations of Agrochemicals

Current Trends and Future Priorities

Tatiana G. Volova, Ekaterina I. Shishatskaya, Natalia O. Zhila, Svetlana V. Prudnikova, Anatoly N. Boyandin, Tatiana G. Volova, Ekaterina I. Shishatskaya, Natalia O. Zhila, Svetlana V. Prudnikova, Anatoly N. Boyandin

• Publisher: Apple Academic Press
• Year: 2019
• Print ISBN: 9781774634288
• eBook ISBN: 9780429782510
• Edition: 1
• Topic: Biological Sciences
• Subtopic: Biochemistry
• Index: Biological Sciences

This important volume provides new research on the design and application of ecologically safe formulations for protecting cultivated crops against pathogen-causing diseases and weeds—that also provide nitrogen fertilizers at the same time. The authors make a significant contribution to the development and agricultural use of environmentally safe and biodegradable new-generation pesticides with targeted and controlled release of active ingredients. They discuss the problems associated with the use and accumulation of xenobiotics in the biosphere and present highlights of modern trends in the design of new-generation formulations.

The authors present their original research results on the properties of herbicides, fungicides, and nitrogen fertilizers deposited in a degradable polymer base and the effectiveness of the use of these formulations in laboratory ecosystems with higher plants infected with fusariosis and weeds. The research provided here provides a new direction for the use of degradable polymers, essential for the creation of ecologically safe agricultural technologies and reducing uncontrolled accumulation and spread of xenobiotics in the biosphere.

CHAPTER 1

AGROCHEMICALS: USAGE AND ASSOCIATED ENVIRONMENTAL ISSUES

The rapid development of chemistry and intensive farming have facilitated the production and use of a vast variety of chemicals intended for protecting crops from weeds, pests, and pathogens. Modern intensive farming is impossible without pesticides. The global losses of potential yields caused by pests reach 37%: 13% of them are due to insects, 12% due to weeds, and 12% due to diseases. The annual losses are assessed at US$2000 billion (Oerke, 2006; Pimentel, 2009). However, pesticide build-up in the biosphere, via accumulation and concentration in the food chains of biota in agroecosystems and natural ecosystems, poses a global environmental threat (Hansen, 2004; Kaplin, 2007). Only a small part of pesticides in the environment reach their goal; the remaining pesticides kill beneficial organisms, accumulate in biological objects, destroy the balance in natural ecosystems, and contaminate soil, water, and air. The scale of pesticide application is very large and keeps on growing.

The Food and Agriculture Organization (FAO) and the World Health Organization (WHO), in the Codex Alimentarius (1963), defined pesticide as any substance intended for preventing, destroying, or controlling any pest, including vectors of human or animal disease, unwanted species of plants or animals, causing harm during or otherwise interfering with the production, processing, storage, transport, or marketing of food, agricultural commodities, wood, and wood products or animal feedstuffs, or substances that may be administered to animals for the control of insects, arachnids, or other pests in or on their bodies. The term includes substances intended for use as a plant growth regulator, defoliant, desiccant, or agent for thinning fruit or preventing the premature fall of fruit. Also used as substances applied to crops either before or after harvest to protect the commodity from deterioration during storage and transport.

By 2016, the global pesticide market had reached US$ 60 billion and exceeded 3 million tons a year. This is about 0.27 kg of pesticides per hectare on the entire Earth’s surface (Ippolito et al., 2015). Up to 40% of all pesticides produced are herbicides, 17% are insecticides, 10% are fungicides, and 33% are other biocides (Popp et al., 2013). Herbicides protecting cereals, soybeans, and corn are important market segments. Herbicides, which constitute up to 55–70% of all pesticides, are the 8^th most harmful pollutants (Kaplin, 2007). Fungicides show the highest growth rates (+11%), outpacing insecticides.

Statistical data on pesticide use in different countries are often lacking. The total annual amount of pesticides used now is between 2 and 3 million tons (Atwood, Paisley-Jones, 2017). They are used mainly in Europe (45%) and U.S. (25%); India uses 4% and the rest of the world 26% (De et al., 2014). Almost 50% of the pesticides are sold in Latin America and Asia. The study of the global pesticide production market states that by 2019, global pesticide production is to reach 3.2 million tons, versus 2.3 million tons in 2013. Thus, the compound annual growth rate between 2014 and 2020 should reach 6.1%. Although North America is the most extensive pesticide producer, the Asia-Pacific region is expected to show the most significant annual growth rate, reaching 7.9% in 2014–2020. As reported by OECD and Eurostat, over the past decade, the amounts of pesticides used in the number of West European countries have been reduced. Between 2000 and 2010, the amounts of pesticides used by farmers decreased from 5 to 3.3 kg/ha in France, from 3.5 to 2.8 kg/ha in Great Britain, and from 20 to 13 kg/ha in Malta (FAOSTAT, 2014). In 2010, the most significant amounts of pesticides (16.0–17.8 kg/ha) were used in Israel, India, and China (FAOSTAT, 2014). In Russia, in 2013, the market of pesticides reached US$ 1.3 billion. According to other sources, about 71.36 billion RUB were used for plant protection measures in Russia in 2013. A total of 53.9 thousand tons of pesticides were used in Russia in 2013, including 31.1 thousand tons of herbicides, 8.4 thousand tons of fungicides, 5.5 thousand tons of insecticides, 4.9 thousand tons of seed protectants, and 3 thousand tons of desiccants. Over the past three years, the pesticide market has been increasing by 10–12% every year.

Environmental effects of pesticides are radically different from the effects of other types of chemicals, as pesticides are artificially synthesized compounds, which are intentionally introduced into the environment. Pesticides pose a severe threat to terrestrial and aquatic ecosystems, with their long-term effects remaining insufficiently understood (Boatman et al., 2007; Mineau, Whiteside, 2013; Grung et al., 2015). Moreover, the application of several pesticides may aggravate their adverse impacts or result in an antagonistic effect. For example, triazine herbicides can increase the toxic effect of organophosphorus insecticides or decrease the toxicity of the fungicide prochloraz, which is harmful to human health (Hernández et al., 2013). Moreover, pesticide degradation products can intensify the toxicity of the original pesticide. For instance, the herbicide glyphosate and the main product of its degradation, aminomethylphosphonic acid (AMPA), are often found in freshwater ecosystems (Székács, Darvas, 2012). Glyphosate interferes with the shikimate pathway of aromatic amino acid synthesis in plants (Steinrücken, Amrhein, 1980), which is not found in animal cells. Yet, very low concentrations of glyphosate cause apoptosis of animal cells, and the presence of AMPA substantially aggravates the toxic effect (Benachour, Séralini, 2009).

Pesticides are chemical compounds of various types, which are used to control harmful organisms in agriculture, medicine, industry, oil production, and other areas. Over 900 chemical compounds are used as ingredients of 1300 commercial pesticides, herbicides constituting 31%, insecticides 21%, fungicides 17%, acaricides 9%, and rodenticides 2%. The other 20% of pesticides include various biocides to control snails (molluscicides), algae (algicides), and nematodes (nematicides) as well as plant growth regulators (6%) and natural or artificial pheromones (5%). Further, 610 products, including organochlorine insecticides, which were used in the past, have been banned because of their high toxicity or low efficacy, due to development of resistance in target organisms (Sánchez-Bayo et al., 2011).

Pesticides are mostly used in agriculture for controlling arthropods (insecticides and acaricides), nematodes (nematicides), fungal (fungicides) and bacterial (bactericides) diseases of animals and plants, as well as for weed control (herbicides). By now, 227 weed species have been identified, which are responsible for damaging 90% of the crop yield; 18 of them are considered as the most lethal ones in the world. Pesticides are used as wettable aerosols, powders, emulsions, dusts, and granules. The “fate” of these compounds in the environment is determined by a combination of physical, chemical, and biological factors. The type of soil, its mineral and organic composition, moisture content, oxygen content, and temperature influence the rate of pesticide degradation, which is the result of oxidation, adsorption, hydrolysis, catalytic decomposition, and processing by soil microorganisms. Most pesticides are toxic to a wide range of plants and animals. Thus, the names insecticide, fungicide, herbicide are often misleading, as they disguise the actual effects of these compounds. Pesticides affect all living organisms and are very toxic to warm-blooded and poikilothermic vertebrates. The effect of pesticides is not dependent on the population density, but they are used only against large populations, i.e., their application is density dependent.

In pest control, the actual amount of pesticides applied is usually larger than the amount needed to kill the pest. Vast areas are treated with pesticides, which inevitably results in harmful effects. The harmfulness of pesticides is aggravated by their persistence in the soil for months or even years. They are also spread far beyond the regions where they are applied. Over 50% of the active ingredients of the pesticides applied become air-borne instantly. The pesticide may also be transported from foliage to soil by wind or rain. Soil application of several herbicides results in high residual herbicide contents. The residue that remains in the field after a crop is harvested may be another, though minor, the source of pesticides in soil. Pesticides resuspended in the air may be transported to the soil by wind or rain. No more than 25–50% of the pesticide sprayed from aircraft reaches its aim; the remaining part lands around the crop fields. Establishment of the unsprayed buffer areas can considerably decrease the drift to the adjacent regions. The effects of the sprays on non-target objects may decrease by 41% for herbicides, 21% for insecticides, and 14% for fungicides compared to the effects in the preceding years (Siebers et al., 2003; de Jong et al., 2008).

Herbicides are applied at rather high rates, which are toxic, although over time, in the soil, toxicity decreases to concentrations below the minimum efficacy level, and the treatment needs to be repeated. Not all pesticides will reach their target. On the soil surface, the pesticide may undergo chemical and/or biological degradation as well as photodegradation. Pesticide losses may also be caused by washout and leakage.

Residual amounts of pesticides are detected in water, soil, and air in all geographical regions, including areas very far away from the application site: oceans, deserts, and Polar Regions. The presence of pesticides has been detected at all levels of the food chain: from plankton to whales and Arctic wildlife. Most of the species accumulate these compounds, and their concentrations increase from link to link in the food chain. People are not protected from pesticides, which have been detected in various tissues and excretions of humans, even those living in areas far away from the pesticide application site. Studies conducted in the 1980s and 1990s showed that these substances had caused 1.0–1.5 million cases of severe intoxication in humans. The U.N. data show that every year, almost one million people are diagnosed with pesticide poisoning, and about 40,000 of them die.

The use of fungicides in plant protection is not safe either, as they change the structure of microbiota, which plays a significant role in processing organics in the soil. For instance, copper fungicides are toxic to earthworms and other soil animals. The ubiquitous use of herbicides causes loss of plant biomass and impoverishes the biodiversity of ecosystems. Insecticides are toxic to most soil invertebrates, birds, and small mammals, considerably decreasing their populations and disrupting the trophic structure of the communities. Persistent pesticides (DDT, etc.) accumulate in soil and groundwater and concentrate in the food chain, producing sublethal effects (Ribeiro et al., 2007; Sánchez-Bayo et al., 2011; Sopeña et al., 2009).

Thus, the environmental consequences of using pesticides are caused by their high toxicity. Chemical pesticides have the following drawbacks:

• phytotoxicity (inhibition of plant growth and fruiting);

• fruit drop risk;

• lowering plant resistance to pathogens;

• development of specific group resistance of pest populations to chemical pesticides;

• environmental pollution;

• unpredictable interactions between residues of various chemicals in the soil;

• eradication of beneficial insect fauna and, hence, development of outbreaks of the previously economically insignificant pests; and

• adverse effects on insect pollinators.

The effects of pesticides on undesirable biota can be divided into two categories: demo-ecological and ecosystemic effects. The effects of the first (demo-ecological) category are at the level of populations of the species that are sensitive to a pesticide. The effect may be immediate, killing the undesirable object, or the pesticide may gradually accumulate in food chains, or it may cause a decrease in the biotic potential, resulting in fecundity reduction or infecundity of individuals. The other (ecosystemic) category is more complicated. For example, the population density of a species that either is insensitive or shows low sensitivity to the effect of a given pesticide may decrease because of extermination of plants or animals this species feeds on. Another ecosystemic effect of pesticides may be an increase in the population density of a previously scarce species because of the death of the competing species or predators and parasites.

Pesticides are capable of migrating in the natural environment. They are transported from soil to the water of surface and subsoil flows, bottom sediments, and air. Humans receive them with plant- and animal-derived foods. In the areas where pesticides are used routinely, changes are observed in the population densities and species compositions of insects, birds, mammals, and soil inhabitants.

Most pesticides are cumulative poisons, whose toxic effects are determined not only by their concentrations but also by the exposure time. According to their toxicity to humans and warm-blooded animals, pesticides are classified as strong toxic agents (LD₅₀ up to 50 mg/kg), highly toxic agents (LD₅₀ up to 200 mg/kg), moderately toxic agents (LD₅₀ up to 1000 mg/kg), and low-toxic agents (LD₅₀ above 1000 mg/kg). A number of pesticides with mutagenic and carcinogenic properties pose a threat to the health when getting into the human body with food, as they can cause neuropathy and dysfunction of endocrine system and affect reproductive function (Giri et al., 2002; Olgun et al., 2004; Perez-Martinez et al., 2001; Damalas, Eleftherohorinos, 2011). Health effects of pesticides may be acute – nausea, headache, skin, and eye irritation – or chronic – cancer, neurological disorders, diabetes mellitus, reproductive dysfunction, congenital abnormalities, and cardiovascular diseases (Mostafalou, Abdollahi, 2013). Pesticides are especially dangerous for infants in case of chronic intoxication of the child’s organism by micro-doses of certain pesticides contained in food and household chemical goods (Weiss et al., 2004). Pesticides have a number of properties that make them more harmful than other chemicals. Thus, more effective tools and approaches need to be found, which would not adversely affect humans and the environment (MacDougall et al., 1992).

Science and industry have put considerable effort into developing new types of pesticides and increasing their production, as the use of chemicals in agriculture is an effective way to increase crop yields. Hence, pesticide production and usage increase, too (MacDougall et al., 1992; Popp et al., 2013). New types of pesticides, which are being progressively used, control harmful organisms and weeds more effectively than previously used compounds. Recently there has been considerable research to create new pesticide formulations and study their behavior in the environment. The aim of this research is to produce less toxic and more selective pesticides and to decrease their application rates. Modern herbicides include sulfonylurea formulations for different regions and with different persistence and phenoxyphenoxy propionic and phenoxybenzoic acid derivatives, which are effective against a wide range of weeds, including monocotyledons. Important broad-spectrum herbicides are glyphosate and glyphosinate, which decompose in th...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• About the Authors
• Table of Contents
• Abbreviations
• Preface
• Introduction
• 1. Agrochemicals: Usage and Associated Environmental Issues
• 2. Polyhydroxyalkanoates: Natural Degradable Biopolymers
• 3. Biodegradation Behavior of Polyhydroxyalkanoates
• 4. Experimental Formulations of Herbicides and Evaluation of Their Efficacy
• 5. Characterization of Experimental Formulations of the Fungicide Tebuconazole and Their Efficacy
• 6. Slow-Release Formulations of Nitrogen Fertilizers and Evaluation of Their Efficacy
• Conclusion
• Index