An award-winning scientist’s pioneering work in horticulture will be remembered long after his passing.

Dr David Steven, who died in Auckland recently, developed integrated pest management (IPM) systems for both the kiwifruit and avocado industries.

Armed with a BSc (Hons) and a PhD, David began his career at the Ministry of Agriculture and Fisheries Research Centre in Levin before moving to the entomology division of the DSIR at the Mount Albert Research Centre in 1975.

Breakthrough

His development of the KiwiGreen IPM in 1991 came at a crucial time in the history of New Zealand kiwifruit, with exports under threat – particularly in Europe – as traditional “calendar spraying” was leaving a relatively high load of pesticide on the fruit.

New Zealand kiwifruit growers had relied on cheap, persistent pesticides applied on a regular schedule, regardless of whether they were needed or not.

Before the European export situation came to a head, Dr Steven and his team at the DSIR had already been working for several years on developing pest monitoring techniques for kiwifruit and learning how to control pests using softer pesticides.

He had to devise monitoring techniques for key kiwifruit pests and then determine a critical level for each of these pests that, if exceeded, would justify the need for a spray.

His greatest challenge would prove to be convincing growers who had spent years using the same spray programme that they actually did not need to spray if the pest numbers were below a critical threshold, and then getting them to switch to using softer chemicals that left fewer residues.

Dr Steven and his team succeeded in pulling together the key elements of an IPM system – KiwiGreen - within two years.

Field trials

Such was the faith of the industry in his approach, Dr Steven was allowed to run field trials on an unheard-of scale, using entire orchards that accounted for a large percentage of kiwifruit industry production.

The success of his approach and the urgency of the problem was such that within four years of those initial trials, the entire kiwifruit industry was required to implement KiwiGreen pest monitoring.

Dr Steven left government employment in 1995 to set up his own research company IPM with his wife Jill.

He continued his work with the kiwifruit industry, refining KiwiGreen, as an independent researcher.

In 1997, he was awarded the Royal Society of New Zealand Science and Technology Medal by the Governor-General in recognition of his work in developing the KiwiGreen programme.

He was made a Fellow of the New Zealand Institute of Horticultural Science in 2000, recognising his contributions to both the society and the field.

He turned his attention to the avocado industry in 2002, helping to design and oversee the implementation of the IPM system AvoGreen.

Dr Steven worked closely with the industry, providing mentoring and technical support until AvoGreen was eventually made mandatory for export avocado production in 2010.

New Zealand Avocado CEO Brad Siebert said: “David’s expertise was invaluable as the avocado industry developed its IPM programme, AvoGreen, and we remain indebted to the skills he brought to the sector.”

Dr Steven also collated research material for an IPM manual for the persimmon industry, where he was employed for several years as research manager.

Advice sought

When Psa – a bacterium that can kill kiwifruit vines – hit the industry in 2010, Dr Steven’s advice was sought on how IPM principles could be applied to the management of this devastating disease.

In 2017, the kiwifruit Industry Advisory Council awarded Dr Steven its prestigious Hayward Medal for his enormous impact in a lifetime of service to the kiwifruit industry.

When presenting the medal, IAC chairman and Zespri director Paul Jones said it recognised Dr Steven’s work to fundamentally shift how the industry manages pests and diseases, improving environmental outcomes and underscoring confidence in Zespri kiwifruit.

“KiwiGreen fundamentally shifted how the kiwifruit industry manages diseases and pests and changed the philosophy of agrichemical use forever.”

New Zealand Kiwifruit Growers Incorporated chief executive Colin Bond told Coast & Country News that Dr David Steven made an enormous contribution to the New Zealand kiwifruit industry by introducing a complete shift in dealing with pests and diseases.

“David’s pest-management programme KiwiGreen revolutionised the industry by targeting specific pests and diseases with environmentally friendly chemicals.

“This not only saved money but importantly, protected the environment as well,” Colin said.

“New Zealand’s kiwifruit growers mourn the loss of this great pioneer.”

Dr David Steven was also on the end of the kiwifruit grower helpline for many years, advising growers on what and when to spray to help ensure they could deliver the highest-quality fruit to market.