Fargro technical officer Joshua Burnstone said the availability of conventional chemical solutions for pests and diseases has been steadily reducing in recent years and there is no reason why the trend will not continue.
Chemicals that do remain are increasingly burdened by tightening restrictions on their use to protect the environment, ensure workers' and consumers' health and safety and safeguard the efficacy of the products, which are often at risk of resistance that would render them useless, said Burnstone.
He explained that $4bn a year goes into developing synthetic pesticides. "It's a very slow process," said Burnstone, speaking at an International Plant Propagators Society (IPPS) conference. "The last new mode of action in herbicides was more than 20 years ago".
He added: "Also, horticulture is quite small and most large chemical companies won't see a profit and focus on broad acre agriculture, meaning that there is very little for horticulture."
Bio-pesticides buck the trend of conventional chemicals, reintroducing flexibility into growers' armouries and freeing them from many restrictions, he argued.
"Growers can be confident that bio-pesticides will work efficiently and effectively," he said. "They have to prove their efficacy in a number of trials for approval."