THE right nutrients in the right place on a crop plant can be as effective as a fungicide, a New Zealand plant pathologist told a Riverlands conference this week.
The chief researcher for Omnia Primaxa, an Australian-owned group that is commercialising New Zealand research, Dr Adrian Spiers, has cast an electron microscope over the decades-old organics industry claim that healthier plants are less susceptible to pests and diseases—and found it true.
Although Dr Spiers distances himself from the organic sector and unscientific “snake oil” solutions, he says that after studying plant pathology for 35 years, and going inside the plant to see how disease attacks, he’s learned that a plant’s best defences are often its own.
“We’ve discovered the most cost effective way to increase production is to allow the plant to use its own defences,” Dr Spiers said.
“It’s been proven now that distressed plants emit chemical signals that open them up to pests.”
“Slugs tend to attack the distressed lettuces. Healthy plants give vibrant signal that makes the insects leave it alone.”
“More robust plants mean greater productivity.”
Dr Spiers has a background in fungicide research with major New Zealand research agencies, but said the more he learned the more he realised that nutrients alone can also stimulate some plant immunity to disease.
“The best of both worlds often seems to be certain formulations of nutrients accompanied by a small amount of fungicide,” he said. “If it’s with the right nutrients, you often only need a very small amount of fungicide to make a difference.”
Depending on the situation, different nutrients can elicit different immune responses from the plant.
For instance, Dr Spiers said, very low amounts of urea can alter the properties of water, so that its molecular structure changes and it moves differently through cell membranes.
But while it’s understood that certain responses occur, it’s often not understood why. “You could have an army of PhD students looking at this,” Dr Spiers said.
His own research is focused on identifying commercially viable “elicitors” that stimulate a response in the plant, effectively bridging the gap between nutrition and fungal control.
The trick is building formulations that not only stimulate the plant, but keep it productive while it fights disease.
“When you stimulate the plant, that costs energy, so you need to supply nutrients to make up that energy deficit while the plant is fighting disease,” Dr Spiers said.
“If you put an elicitor on but it’s costing the plant something to fight disease, and it can’t replace that energy, it’s not going to produce as much fruit or vegetation.”
The bottom line, he says, is a more “holistic” range of products, some of which rely on nutrients alone, some which combine nutrient and chemical, but all of which rely on activating the plant’s own defences and minimise the use of chemicals.
Dr Spiers develops products for Omnia Primaxa, and wouldn’t discuss the details of its formulations, but Rob Clarke of Omnia Specialities, the Australian owner of the group, said the principle had been established across about 1000 trials in a NZ$500,000 research project funded by NZ government agency HortResearch.
Dr Spiers was in Australia this week to address the annual Omnia Primaxa conference in South Australia’s Riverlands.
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