Dr. Francis Chaboussou wrote Healthy Crops, published in 1985. The book explains why crops get diseases and draws from hundreds of research papers from around the world.
Chaboussou was a French agronomist employed by the National Agricultural Research Institute (INR). Examples in the book draw heavily on vineyard experiences, but include other major crops such as rice, maize, cereals, pip fruit, summer fruit and vegetables. He does not mention kiwifruit, but that is not important. The principles required to grow any healthy crop rely on healthy soils. They are not crop-dependant.
Chaboussou noticed a recurring theme: pests and diseases have followed the increased use of herbicides, pesticides, fungicides and nitrogen and chemical fertilisers. Chaboussou looked at viruses, bacteria, fungi, insects, mites and nematodes. He used hundreds of examples, and found tremendous similarities in the factors that lead to any diseases which he called parasites.
The introduction to Healthy Crops sums it up.
"Pesticides and nitrogen fertilisers are responsible for the resurgence of pests and diseases, including psyllids, mites, new cereal fungal and viral diseases, and viruses afflicting fruit trees and vineyards. The physiological state of the plant is altered by the intrusion of the pesticides to the detriment of the plants health, setting it up for infection. The susceptibility of plants to diseases or insect attack being created by free nitrogen in cells, resulting from the break down of protein. However, the relationship between plant and pest or disease is, above all, nutritional in origin. If a plant contains free nitrogen including certain amino acids, then it has something the parasite wants and is attracted to. If the plant is truly healthy, then it will not be susceptible to attack."
The relationship between the plant and the disease is not static. It changes in response to certain other factors including: genetic factors (varietal resistance), the physiological cycle of the plant (such as the state of flowering and age), day length,climate, nature of the soil, fertilisation, nature of the rootstock, and, finally, the effect of pesticides on the plant’s physiology.’ Resistance and susceptibility depend on the level of soluble substances. A state where protein break-down predominates is linked to disease, while the state of protein building correlates with resistance.’
Chaboussou came up with three major conclusions:
(Chaboussou did not know the definition of a fully-fertile, well-balanced soil.)
We maintain you can make your vines healthy for about $1,000-$2,000/ha by using the right fertiliser substances. We do not believe regrafting vines and paying for PVR's at a cost of around $50,000 per hectare, is the true solution to the problem of Psa.
We’ve proved this by doing it on many orchards and reducing Psa on all of them. If it is there, it is not thriving. To get a properly balanced soil, you must have an accurate soil test. That’s where all the problems start; in the soil. We get tests from Perry Agricultural Laboratories, (PAL) in Missouri, USA, and our recommendations from Kinsey Agricultural Services, (KAS). We are also trained to calculate what is required to balance a soil, and to recommend according to the results. It can get complicated.
Once the vines are healthy, the number of chemical sprays needed will reduce to almost zero, at your choice. Most chemical sprays are chlorine and nitrogen based. They physiologically damage the leaf in particular by causing protein break-down, making it increasingly susceptible to disease infection and insect attack.
The most important thing is to balance your soil so the plants' immune system is fully functional. From there, the plant can self-protect and self-heal. To do that you must have an accurate soil test and recommendation. I am not suggesting we can bring vines back from the grave. Nor do I claim a monopoly on healthy plants. Others have been saying the same thing, but like us, they are ignored. Below is a questionnaire and guidelines. Get just a few answers wrong, and your crop could do better.
The system we use is proven all over the world. This system has produced the best yields of wheat in NZ; best quality and quantity of wheat in Germany; 37t+/ha maize silage in USA; best quality and quantity raspberries; best quality and quantity bananas in Guatemala and South Africa; 20t+/ha of lucerne all over the world, and growers being paid US$12.50/kg for their high yielding grapes by wineries in California, to name just a few successes. (Best quality and quantity relates to competitions held in various countries.)
Kiwifruit have the potential to produce 12 flowers and 12 fruit per cane. Currently, 4-5 are produced. Do you think you are doing well enough when crops are below 50% of potential? The difference is lack of carbohydrate brought about by poor nutrition and some current cultural practices.
Many kiwifruit growers will also be involved with other types of farming. So are we. It is not just about crops. It is more about the soil. It does not matter what plant, crop or animal you grow, or what disease you get, the best answer always comes back to getting the soil fertility right. The key is the soil test and recommendation.
Kiwifruit growers should be wary of doing the same things they’ve done in the past if they don’t want the same results.
Take for example, Psa-V says Kiwi Fertiliser’s Tim Jerram. Tim says growers need to look at their soil and work to fix the balance of nutrients and minerals, in order to grow more resistant, healthy vines – so they don’t keel over to Psa or any other pest or disease.
“They’re trying to kill Psa, but the soil is still deficient in nutrients. The disease will come back again if nothing else changes.”
In contrast to many orchards in the Bay of Plenty, the 20-plus kiwifruit orchards Tim and Brett Petersen are fertilising with a Kiwi Fertiliser regime for several years, are yet to suffer from Psa, including Tim’s own orchard in Katikati.
“My neighbours have Psa-V and one has cut out one of his blocks of Gold. I’m directly in the path of the wind and there is nothing on my orchard. I’ve got a little block of Gold, and the rest is Green.”
When his neighbours were hit by Psa, Tim was getting called two or three times a week to warn him about different sprays going on.
“I couldn't work out what the strategy was.
“Growers were just grabbing at straws and spraying things on and hoping things were going to improve.
“There are a lot of growers in that basket. There is nothing that they can hang their hat on that this is going to work.”
Tim is putting the resistance of his and other orchards down to having balanced soils, with excellent mineral levels, after having testing his soil during the years and administering the right fertiliser for his soil’s needs.
“You've got to put back in what you are taking out – what’s going out the farm gate. But you need to start doing that from a balanced state, not a deficient one.”
All growers or farmers who start with Kiwi Fertiliser should start with a Perry Agricultural Laboratory soil test. Tim says some kiwifruit orchards are lacking almost everything when it comes to trace elements.
Our goal is to lift the overall mineral level to ‘excellent levels’ says Tim, which can take between 24-36 months for some minerals and up to five years for others. Girdling is a questionable approach growers should be thinking about more closely too, says Tim and Brett.
Girdling goes against the natural order of things. In normal circumstances, about 60% of sugars manufactured in the leaf go to the roots and 50% of that goes into the soil to feed the microbes. In turn, the microbes make the minerals available to the plant.
“Girdling stops that from happening,” says Brett. But it’s pseudo-economic reasoning that is behind girdling, says Tim.
“Growers do it to spend the least amount of money to get results.
“Plant-wise it leaves a lot to be desired”, and through fixing the soil and growing more healthy, resistant plants, they will achieve those results and more, naturally anyway”.
Rob Martin is pretty new to growing kiwifruit. He has had his orchard at Te Teko for six years, growing half a hectare of Gold and 5ha of Green. Psa has made Rob stand back at look at the ‘whole picture’ and that has led him to using Kiwi Fertiliser on his orchard.
“From a global perspective, the only thing making sense to me is a well balanced biological approach,” says Rob. “The object is to build a plant that is going to have a strong immune system and resist any disease or pest.
“From a new grower’s perspective, it’s been difficult being challenged by Psa, and I can’t make any sense out of the direction coming out of the scientific side of things.
“There is no logical way forward there for me – what they’re working on – with the copper etcetera. That is how they try to kill it, rather than looking at why the disease is there in the first place. It is not logical that a disease can attack a truly healthy organism.”