Weed control is one of the most important steps in agricultural production. The sales of herbicides ranks first among the global market share of pesticides. However, the use of a large number of chemical herbicides has caused environmental problems such as water quality degradation and soil pollution, especially the constant occurrence of resistant weeds, which has brought great challenges to agricultural production. According to statistics, as of 2018, a total of 495 cases (biotypes) of resistant weeds have been reported worldwide, involving 255 types of weeds. In China, from the first report of weed resistance in 1992 to 2018, a total of 44 resistance cases have been reported, and the trend of resistant weeds is not optimistic.
With the increase of global environmental awareness and the need for sustainable agricultural development, the development of bio-herbicides with good environmental compatibility, high selectivity and strong biological activity is urgently needed. This trend has become inevitable for the development of contemporary pesticides. Although there are few mature bio-herbicide products on the market, bio-herbicides have become one of the important research and development areas for scientific research institutions and biological pesticide companies. In this article, we hope to help people better understand this market and better grasp the development trend of bio-herbicides by sorting out the current status of the global market, the major bio-herbicide companies and currently available products.
Main categories and characteristics of bio-herbicides
According to a report of MarketsandMarkets, the global market value of bio-herbicides reached $ 800 million in 2016, and will grow at a compound annual growth rate of 14.5%, and is expected to reach $1.5 billion in 2021. This shows the huge market growth potential of bio-herbicides.
According to Wikipedia's definition of bio-herbicide, it refers to a class of natural substances that use biological toxins, pathogenic bacteria, and other microorganisms to control weeds. At present, the common bio-herbicide and the development hotspot are mainly microbial herbicides, which mainly include two types:
1）Living microorganisms: mainly refer to phytopathogenic organisms (fungi, bacteria, and viruses), with the most common one being phytopathogenic fungi;
2) Microbial metabolites: mainly use the toxins and antibiotics produced during the metabolism of these microorganisms, including peptides, terpenes, macrocidins and phenolic resins.
In the field of microbial herbicides, what receive the most studies are fungal bio-herbicides, followed by bacterial herbicides, and viral herbicides are rare.
Among microbial herbicides, fungal herbicides have been most studied. According to research, fungal microorganisms with biological weeding activity mainly involve nine genera such as Colletotrichum, Fusarium, Alternaria, Cercospora, Puccinia, Entyloma, Ascochyta, and Sclerotinia. However, fungal conidial formulations have not brought significant social and economic benefits due to their strict environmental requirements and excessive requirements for technical issues in mass production, formula and storage, etc.
Bacteria with biological weeding potential are mainly rhizobacteria, mainly involve eight genera, i.e., Pseudomonas, Enterobacter, Flavobacterium, Citrobacter, Achromobacter, Alcaligenes, Xanthomonas and Erwinia. These soil microbial formulations can directly act on the seeds and seedlings of the target weeds, and can be used for researching appropriate release technologies, which are two key points of rhizobacteria application in biological weeding practices.
Major bio-herbicides companies and products
At present, companies conducting bio-herbicide-related businesses and R & D are mainly located in North America, which is also related to the relatively mature biological pesticide market in the region. Representative companies include Marrone Bio Innovations (US), Verdesian Life Sciences (US), and Premier Tech (Canada), etc. Since the registration of worldwide first bio- herbicide DeVine in the US in 1981, there have been only more than 20 types of newly registered and launched bio-herbicides in the world for more than 30 years, including BioMal, Biochon and EMERION. These bio-herbicides mainly use living organisms such as fungi and bacteria or natural products.
Emery Oleochemicals (Malaysia): In 2014, its bio-herbicide EMERION™ 7005 was registered by the Canada Pest Management Regulatory Agency (PMRA). EMERION™ 7005 is one of the EMERION™ 7000 series of products that are based on chemicals naturally derived from fats and oils and consist of bioactive ingredients for contact spray control or burn-down of weeds and grasses for food crops, field crops, pastures, landscapes, and lawns, etc. Other products of this series, i.e., EMERION™ 7020, EMERION™ 7030 and EMERION™ 7031, have been approved by the US Environmental Protection Agency (EPA) and listed by Organic Materials Review Institute.
Verdesian Life Sciences (United States): In 2015, Verdesian Life Sciences launched a bio-herbicide in the US with Pseudomonas fluorescens strain D7 as its main active ingredient. Found by the Agricultural Research Service of the U.S. Department of Agriculture, D7 can control downy brome (cheatgrass). For wheat growers who currently control weeds with herbicides that inhibit acetolactate synthase (ALS), D7 will provide an additional mode of action to improve activity and help inhibit the development of resistance. Uniquely, D7 controls weeds by secreting chemicals that selectively inhibit weeds rather than by pathogenic interactions.
Marrone Bio Innovations Inc. (USA): In 2018, Marrone Bio Innovations (MBI) submitted the registration package for its first bioherbicide, MBI-014, to the US Environmental Protection Agency (EPA), which brings prospect to the market. It is understood that MBI-014 is a water-dispersible microbial herbicide made from a new species of heat-killed bacteria, Burkholderia rinojensis (strain A396), and has a new mode of action. It has post-emergent herbicidal activities across a range of weeds, especially weeds in the pigweed family. At present, the company is still conducting a series of studies on its optimal dose, adjuvant package needed and further expansion of the spectrum of targeted weeds. The product is expected to be available around 2020.
Bioherbicides Australia Pty Ltd. (Australia): In 2013, BioHerbicides registered its first bio-herbicide Di-Bak Parkinsonia in Australia for Parkinsonia aculeate control. The active ingredient of this bioherbicide is a natural fungus that was derived from resurrected trees by a professor at University of Queensland in 2004.
Certis USA (United States): In 2019, Certis USA launched Homeplate® in the United States. Homeplate® is a non-selective, broad-spectrum, fatty acid, burndown herbicide with the active ingredients of palm oil and coconut oil (44% caprylic acid and 36% capric acid). It works as a foliar contact spray to control a wide variety of weeds in all crops. In addition to burndown, Homeplate is flexible with labeled uses in direct and shielded sprays, pre-plant applications, post-harvest sprays, as a harvest aid and desiccant, for sucker control and as a pruning and trimming aid. Homeplate is currently registered in 45 states of the U.S.
Premier Tech (Canada): In 2017, Premier Tech signed a license agreement with Agriculture and Agri-Food Canada (AAFC) to finalize the development and commercialization of a bio-herbicide which is formulated from an indigenous fungus, Phoma macrostoma. Over the past 10 years, the federal department invested millions of dollars in research on this fungus and its compounds (macrocidins), which can eliminate broadleaved weeds, particularly dandelions. This breakthrough discovery has been patented in several countries and commercially registered in the U.S. and Canada.
Plant Advanced Technologiest (France): Plant Advanced Technologies (ALPAT) announces that the joint project associating Institut National de la Recherche Agronomique (INRA) and ITEIPMAI, entitled HerbiScan, enters the category "Innovative Agriculture", and aims to discover and develop new herbicides of plant origin, which will be in adequacy with the stakes of the current agriculture. So far, the company has not yet launched any product.
Koppert (Netherlands): The Dutch company Koppert was approved for the official registration of its bio-herbicide Biochon in 1997. The herbicide is a rotting agent for woody weeds that is produced by Chondrostereum purpureum, and can control the germination and growth of wild black cherry and a variety of woody weeds. The successful development of this product proves the activities of microbial herbicides against woody weeds.
Philombios (Canada): The herbicide BioMal developed by Philombios has the active ingredient of Colletotrichum gloeosporioides f.sp.malvae (Cgm), which is used to control Malva rotundifolia L. Biomal was registered in 1992 and is used in wheat and other crop fields in the grassland region of Canada and the northern plain region of the US. This product is the first fungal bio-herbicide registered in Canada. However, due to technical and economic concerns, it has not been sold in large quantities.
Upjohn (USA): Collego, a bio-herbicide developed by Upjohn in collaboration with the University of Arkansas, was launched in the US in 1992. The active ingredient of this herbicide is Colletotrichum gloeosporioides f.sp.aeschynomene (Cga). It is understood that the product has a 100% control effect on seedlings of Virginia Aeschynomene indica in rice and soybean fields; its commercial preparations are routinely used in the field, with control effect more than 90%. From 1982 to 1991, the bacterial herbicide was used in 5,000-10,000 hectares of rice fields in the US each year.
Mycogen (USA): Camperico, a bio-herbicide jointly developed by Mycogen and Japan Tobacco (“JT”), was officially registered in Japan in 1997. With the active ingredient being Xanthomonas campstris pv. Poae (JT-P482), Camperico is a bacterial bio-herbicide that can be used to control bluegrass on golf courses. Generally, it is difficult for bacteria to invade weeds. However, the bacteria in Camperico can invade through the sections of trimmed bluegrass when sprayed during lawn mowing. Then, they multiply in the vascular system and block it, causing the death of the weeds.
Tifton Innovation Corporation (USA): In 1987, the company registered its bio-herbicide Dr.Biosedge in the US which is an urediospore preparation of Puccinia canaliculata. Available in powders and granules, it can be used to control Cyperus esculentus in rice fields. Its control effect can reach 90%-98% when used at single application. It can be used in combination with chemical herbicides such as Bentazone and Bensulfuron-methyl to control various weeds. Due to its high cost of production, however, the product is not available on the market.
Abott (United States): In 1981, Abott Laboratories of Illinois registered its mycoherbicide DeVine in the US. DeVine is a suspension concentrate prepared from chlamydospores of Phytophthora palmivora and can be used to control Morrenia odorata after soil treatment in citrus orchards, with the control effect of 96%, and the control duration up to two years.
Development Limits and Prospects of Bio-herbicides
Single host, narrow weeding spectrum
Ultimately, microbial herbicides are actually the pathogens of weeds. And because of this, the targets of biological herbicides are more specific. However, the agricultural ecosystem is complicated, and there are many kinds of weeds. A microbial herbicide that can only control one kind of weed cannot be time-saving and labor-saving. Therefore, biological herbicides have limitations in terms of practical promotion and large-scale use.
Weed control susceptible to environmental conditions and unstable
Like other biological pesticides, the active ingredients of bio-herbicides are mainly living microorganisms that are sensitive to climate conditions such as temperature and humidity. Among them, humidity and dew period are the main limiting factors, which can directly affect the germination, invasion, conidiation and re-infection of fungal spores and propagules, and thus affect the control effect of fungal herbicides. In addition, in general, microbial herbicides cannot be applied in combination with chemical pesticides at the same time, which greatly limits its promotion. If their interaction is beneficial to one or both parties, it will help the large-scale promotion of microbial herbicides.
Difficulty in fermentation and dosage form processing
At present, large-scale production of herbicide cells is mainly carried out by fermentation in the industry. However, some fungi are not easy to reproduce, or have decreased conidiation, poor conidial viability, reduced virulence after multi-generation reproduction, or poor stability after formulating, which affect its mass production and commercialization. The active ingredients of microbial herbicides are living organisms, which are water insoluble particulate matter. The granularity and hydrophobicity will directly affect the physical properties of the formulation such as wetting, dispersing and suspending properties, making it more difficult in formulation processing than chemical herbicides.
In the 21st century, countries around the world are speeding up the development of organic agriculture. According to the "World Organic Agriculture Overview and Trend Forecast 2018" released by FiBL-IFOAM (Research Institute of Organic Agriculture and International Federation of Organic Agriculture Movements), the agricultural land area managed organically was 57.8 million hectares in 2016. According to the data from Ecovia Intelligence, the total sales of organic foods (including drinks) in the past two decades have grown from less than US $ 15 billion to US $ 90 billion in 2016. The organic agriculture marked by ecology, sustainability, high efficiency and high added value inevitably requires safe, efficient and environmentally friendly biological pesticides. It is foreseeable that the rapid development of organic agriculture will drive the rapid development of biological pesticides, including bio-herbicides.
This article was initially published in AgroPages 'Annual Review 2019' magazine. Download the PDF version of the magazine to read more articles.