Current trends in crop protectants

From discovery to development

New products typically go through three stages on their way to market: discovery, development, and registration. Discovery involves the identification of novel compounds by chemical synthesis or from natural sources. It includes screening for biological activity and preliminary toxicological and environmental testing.

Technological advances have streamlined discovery and enabled companies to generate many more options from which to select candidates for development. An earlier 2016 study by Phillips McDougall for CropLife International reports that in 1995, about 52 500 new molecules were synthesised and screened for each one that was developed further – compared with 159 574 synthesised and screened for each one developed in 2010 – 2014.

Development starts with small-scale production of sufficient material for trials. Researchers will also optimise manufacturing and formulation – the formulation of the final crop-protectant is as important to its efficacy and safety as the active ingredient itself.

Biological development involves field trials of product activity against targets such as weeds or pests in specific crops grown in different microclimates. In-depth toxicity and environmental studies form part of development. Toxicity relates to product safety in living organisms, while environmental chemistry relates to product breakdown and residues.

Data generated during development will eventually support the application for registration. Each country's regulatory body sets the requirements for registration, but in most countries, these have become more stringent.

The 2016 Phillips McDougall study shows that the total cost of discovering and developing a new crop-protection product increased from USD 152 million in 1995 to USD 286 million by 2010. Research to generate data in support of registration and direct registration costs accounted for about 53% of this cost in 1995 compared with 63% in 2010 – 2014.

Given higher development costs, it is not surprising that companies are more selective about which compounds to develop. Phillips McDougall reports that about one product was registered for every four developed in 1995, compared with one registered for every 1.5 developed in 2010 – 2014.

Problems in the product pipeline

According to Phillips McDougall, the number of new crop-protectant active ingredients introduced per decade peaked at more than 120 in the 1980s and 1990s and declined to fewer than 40 in the 2010s. During 1995 – 2010, the time from discovery to sales grew by more than a third, to over 11 years.
Increased regulatory requirements are one reason for the slower introduction of new products. For example, in SA, crop-protectant registration must be supported by proof of efficacy based on local field trials. Products are tested in at least three trials in three different Köppen climate zones for two years – and this is done on each crop type for each target. Further trials are required to determine withholding periods.

Field trials can be exasperating. The data must show consistent statistical differences between treatments, so trials may be useless because the target pest or disease failed to appear in that area in that season. And deviations from protocol – such as spraying at a different time – can invalidate a trial.

On top of this, the slow processing of registration applications sets the availability of products in SA back by an additional one to two years. This impacts not only new products but also amendments to existing registrations. Since Africa represents less than 4% of the global crop-protectant market, international companies have little incentive to engage in a frustrating registration process.

The trickle of new products is especially worrying because existing products are slowly drying up: growers fear that the product pool will soon be empty.

Resistance and regulation are the two main reasons for product losses. In some cases, the loss of crop protectants also increases the risk of resistance, because the few remaining products are over-applied. Market demands that growers spray fewer products pose the same danger.

The 2016 Phillips McDougal report asserts that six of the top 10 products (by volume) used in major US crops in 1968, have since been banned. In the EU, nearly 60% of commercially significant crop-protectant active ingredients were removed after the introduction of more stringent regulations in 1991.

Can biologicals step into the breach?

Biological control agents are crop pro-tectants extracted from or consisting of living organisms. Examples include natural pyrethrins extracted from Dalmatian and Persian chrysanthemums, entomopathogenic bacteria such as Bacillus thuringiensis, entomopathogenic fungi such as Beauveria bassiana, and sterilised false codling moths.

Consumers and regulators perceive biologicals as safer and more environmentally friendly than synthetic chemicals. Whereas many synthetic crop protectants are under pressure, regulators and markets are encouraging the adoption of biologicals as part of integrated pest-management systems. In some countries, companies can register biologicals more easily, and the efficacy bar may be lower for biologicals than synthetic crop protectants.

The 2018 Phillips McDougal study reports a surge in new biologicals. The rate of introductions has gone from an average of three per year from 1960 – 1990 to an average of 11 per year from 1990 – 2016. New biological introductions surpassed new synthetic introductions in most years since 2000.
Phillips McDougal also points out that 2017 was the first year more biological than conventional crop protectants were patented. A recent analysis by S&P Global states that biologicals had a market share in 2020 of more than 18% for pest and disease control in fruit and vegetables. Biological herbicides held no significant market share in 2020.

Although conventional crop protectants still make up around 90% of sales, significant investment by traditional crop-protection giants and a swarm of start-ups suggests a bright future for biologicals – provided they can overcome some drawbacks.

Existing biologicals are generally more expensive but less effective than conventional crop protectants. Biologicals target a narrow spectrum and can seldom provide adequate control under high pest or disease pressure. Because biologicals rarely exterminate the target, they are not stand-alone solutions for quarantine pests.

The narrow spectrum and rapid breakdown of most biologicals also present difficulties in postharvest applications, such as controlling the array of decay organisms that attack fruit.

Tremendous advances in biological crop protectants must occur before synthetics can be abandoned entirely. Meanwhile, growers would do well to steward the remaining synthetics, starting by implementing integrated pest-management systems, avoiding practices that promote resistance, and demonstrating responsible use.

Ultimately, we all consume agricultural products, and we all depend on ecosystem services, so safer crop protectants benefit us all. The challenge is finding optimal solutions based on science rather than sentiment.

Further Reading