The New Zealand kiwifruit industry is in serious trouble as growers battle the rapid spread of PSA, a bacterial canker disease that has seriously impacted most of the kiwifruit growing regions in the world. 52% of the NZ industry has now been affected and all efforts to halt the virulent disease have proved unsuccessful at this point. Graeme Sait, CEO of leading biological company, Nutri-Tech Solutions (NTS), recently returned from New Zealand where he has been consulting with growers and the key industry body, Zespri, to expand the resistance effort. NTS specialises in integrated disease management strategies and this kind of holistic approach has proven productive in similar situations.
The disease is similar to the canker linked to the upheaval of the citrus industry in Central Queensland several years ago. In that instance, the DPI ordered the removal and burning of all trees in the region and sterilised the soils and they successfully halted the spread of the disease. The New Zealand authorities may be ruing the fact that they did not act more decisively, as the disease decimates the 2 billion dollar industry. Antibiotics and copper sprays are the only tools that have looked vaguely effective to date. Some distressed growers have committed suicide when faced with the prospect of repaying debt upon highly leveraged, multi-million dollar investments that are suddenly reduced to the value of a lifestyle block.
Biological agriculture involves a ‘best of both worlds’ approach where an understanding of natural laws and principles can often offer insights where conventional, symptom-treating, agricultural science has failed. Graeme Sait explains:
“There is always a reason why a plant succumbs to a disease and it is not about a deficiency of a fungicide! Resilience involves a whole series of interrelated players including mineral and biological balance, cell strength and immune activation”.
NTS works with their team of agronomists in over forty countries. They have trained thousands of farmers on four continents with their widely acclaimed four-day NTS Certificate in Sustainable Agriculture course, and they are currently working with large organisations and Governments around the globe as the interest in the biological approach expands.
The suggested strategies for the NZ kiwifruit industry include reduced use of nitrate nitrogen and an emphasis upon trace minerals like molybdenum, cobalt and sulfur, which are linked to the conversion of nitrates to protein. Sait clarifies:
“Excess nitrates are a calling card for disease and you often need to change fertilising practices while ensuring that key minerals like molybdenum are present for protein production. This particular trace mineral was not previously measured in the kiwifruit industry”.
There were also suggestions relating to the cell-strengthening importance of silica and calcium. Sait explains:
“A strong cell wall is the barrier that reduces the spread of disease. Soluble silica is lacking in most conventionally farmed soils and it can also be a challenge to get good uptake of calcium in most crops. Silica can be foliar applied, as potassium silicate, to great effect, and chelated calcium can also be regularly delivered as a foliar spray”.
There are several key organisms that need to be present in a disease resistant soil and they include Mycorrhizal fungi, Trichoderma, Pseudomonas fluorescens, Bacillus subtilis and Azotobacter. Sait claims that:
“Several of these creatures have succumbed to the ravages of chemical farming but they can be reintroduced with inexpensive inoculums. These creatures buffer disease organisms and several of them are also immune supporters”.
There is a growing understanding that plants have active immune mechanisms that can be boosted, to increase resilience. Several substances have proven effective in this context, including salicylic acid and a substance derived from prawn shells called chitinase. Sait explains:
“Aspirin was originally copied from naturally occurring, plant-based salicylic acid and it appears that this substance is linked to immunity. Commercial preparations are available but it is even possible to trigger a substantial immune response with 100 aspirins in 400 litres of water per hectare”.
Graeme Sait recently submitted a 6000-word document entitled “Integrated Disease Management in Kiwifruit” for the consideration of the industry and he is hopeful that NTS can prove of assistance to our New Zealand neighbours.