Dennis W. Fulbright, Professor
Michigan State University
My wife Jane and I visited Australia from January 17 – February 1. The trip was part work and part vacation. I made a presentation to a chestnut nut rot meeting held by Chestnut Australia, Inc. at Tweenhills Chestnut Farm owned by John and Heather Kane. John and Heather were also our hosts and took us to other farms. Later, I also reported our laboratory findings to researchers at the University of Sydney. This is a report based on that quick visit. First, I want to say how well we were treated by all of the growers, how open and sincere they were when discussing various issues, and how impressed I was with the care they give their trees. Before I get started, I need to say how mournful we were to hear about their countrymen's' suffering due to the extreme drought conditions that brought on fires, both natural and set, that have wreaked such havoc on such a wonderful people in a great and bountiful land. The fires were just beginning as we traveled and we departed just as the fires became horrific.
Overall, the chestnut trees and orchards in Australia were beautiful with all the trees wearing long, dark green leaves. Most trees that I saw were 10-20-years old, but younger and older trees were also present. There is very little chlorosis and no obvious insect damage. The trees showed signs of rapid growth and pollen was produced in abundance by some cultivars. Other than root rot and nut rot, there are few diseases and insect pests. My overall impression of the chestnut orchards is that they show great response to the resources put into them and the future of the industry appears bright unless they begin to over produce nuts. While impressed with the growth of the trees, I cannot help but comment on the large number of trees beginning to grow into each other, shading flower buds. Severe pruning or tree removal will probably need to occur in many of the chestnut orchards I drove past and visited.
We arrived in Canberra and were picked up by Heather Kane and taken to Tweenhills Chestnut Farm for the chestnut rot meeting. We ate lunch and talked to about 40 chestnut growers from all over Australia including Tasmania. They had toured John's dry-land chestnut farm that morning while waiting for us. The meeting started with Stephen Morris speaking about CALM storage units.
The CALM is a modified atmosphere unit that keeps carbon dioxide (CO2) at higher than ambient concentrations, but not so high as to induce foul odors and flavors. The idea is that the chestnuts are placed in a sealed plastic bag and they respire releasing CO2 into the sealed environment. Normal atmosphere, that is, before the bag is sealed consists of oxygen at 21 percent and CO2 at less than 1 percent. Once the bag is sealed and the CO2 is produced from the respiration of the chestnut, the CO2 concentration rises to about 16-17 percent, which will stop fungal growth and insect development. When CO2 rises, the concentration of oxygen is reduced to less than 4 percent. The oxygen sensor will let in atmospheric gases (where oxygen is at 21 percent) if the CO2 concentration goes too high. The CALM unit is built to hold bins of chestnuts and they are sealed at the bottom with duct tape. This sealing has been problematic. The system works best when the nuts are slightly dry and the room is cooled. The proper CALM atmosphere is achieved in 2-3 days. The oxygen sensor and pumps, the only mechanical parts of the CALM unit are powered by a 5 volt (or 12 volt) DC power source. For more information go to www.postharvest.com.au/chestnutpostharvest.html. It is thought that the unit should be good for at least 2 seasons. A single CALM unit should be able to handle 2 to 4 bins on a pallet.
Another speaker was Lucas Shuttleworth. Lucas is a first year graduate student at the University of Sydney working for Prof. David Guest. He has found that up to 70 percent of the chestnuts on some farms have internal nut rot. They know that rainfall at flower time makes it worse. The disease of the kernel is caused by a fungus known by several names, but Phomopsis nut rot is the most commonly recognized name.
Between Sunday, January 18 and Tuesday, January 20th, John and Heather Kane took us to five chestnut farms including their own farm Tweenhills. Most of these farms were about halfway between Canberra and Melbourne. It is a really lovely area and a place frequented by Australian tourists. Four of these farms were more typical of an average grower in that they had somewhere between 1,000-3,000 trees with production values of 8-10 tons of chestnuts. The fifth farm was a very large apple farm and packinghouse that also grew and packed chestnuts. They had an extremely large apple business as they serviced the major cities of Australia. Their chestnut production was also the largest in the country with approximately 200 tons of chestnuts produced each year.
After touring these five farms and listening to the growers, I have been left with some impressions of the chestnut industry in Australia. Below are my interpretations, and my summary should be appreciated for what it is—a superficial picture of a new industry based on my short tour.
The chestnut industry in Australia appears to be loosely organized. There are issues and problems that relate to all growers and these are the types of issues with which the national group tries to find solutions. Phomopsis nut rot caused by the fungal pathogen is one of these problems and that was why I was at the meeting. Chestnuts Australia, Inc. helps develop grower communication and serves as a source of information that all growers can use. It does not market chestnuts, but it does promote chestnuts and their use. My impression is that Chestnuts Australia, Inc. is similar to Chestnut Growers of America. The volunteer board of directors of Chestnuts Australia, Inc. finds ways to work with the government to help find solutions to problems beleaguering the industry; however, the governmental jurisdiction changes every so often. What at one time could be a state supported issue may need to become a national supported issue as state support for that type of research dries up. It is volunteers of Chestnuts Australia, Inc. that makes this type of focus possible. They have at least one, half-time paid employee working for them.
While I was told that there are a few growers with seedling trees (by seedling I mean non-grafted trees), almost all chestnut growers plant and maintain grafted trees. The grafted trees are purchased from chestnut farms that produce grafted trees for this purpose, and I was not made aware of any nurseries that catered to this need. It was apparently no trouble getting young grafted trees for new plantings. Something I found amazing is the number of chestnut trees that have been re-grafted to new cultivars. Some trees (and I don't mean ten or 20; I mean hundreds), have been grafted twice or three times. That is, they were top worked to new cultivars. Reasons for this would be: since the industry was new, they did not know the best cultivars at the time the industry was started; they needed more pollen and had heard that another cultivar produced more pollen; nuts were better tasting or peeled easier. In other words, they had reasons to change the cultivars. What this left were orchards with rows representing various cultivars, much like we commonly do with apple cultivars. It was obvious that the grafting technique had changed in time as some top working was performed on smaller branches high up in the tree. Currently most grafting appears to be done by cutting the top of the tree off on the main trunk and placing 5 or 6 scion sticks between the bark and the cambium.
It should be noted that there are few, if any Chinese chestnut trees planted in Australia. The growers who had tried Chinese chestnut hadfound them to be woefully inadequate for the industry. It is said that they did not grow well on their farms and took too long to get into production while producing small nuts. Some motivated growers are trying them again, but do not hold out much hope. Now that they are in production with their trees, they feel they have more time to test new ideas or re-visit old ones.
Since most of the trees are grafted, what species are they grafted to? Most are grafted to European or EuropeanX Japanese cultivars. I found the cultivar 'Colossal' and 'Bouche de Betizac' neither one that has a strong following. 'Colossal' apparently takes too long to drop all its nuts (more than 2 weeks), and 'Bouche de Betizac' drops its nuts free from the burs, leaving the burs attached to the branches of the trees. This is a problem because Phomopsis nut rot is managed by sanitation techniques and removing old burs from the orchard is part of that management program. Cultivars with nutless-burs attached to branches complicate that management scheme.
So as I mentioned earlier, cultivars are placed in the orchard for various reasons, not just because they are available. To emphasize this point even further, the only chestnut grower cooperative available to the approximately 300 growers in Australia is based on proprietary cultivar use. If you are a member of the cooperative, you have the right to grow cultivars that non-members are not legally allowed to grow in their orchards. These cultivars apparently provide a marketing advantage that translates into higher returns since it costs over $10,000 to join the cooperative. There are currently about 16 growers in the cooperative.
On the farms, I was shown various cultural practices. I saw grafted trees being pruned so they would take on a vase or wine glass shape, but with a central leader allowed to grow up the middle of the tree. This was done to allow more sunlight to penetrate the tree and increase yields. I heard that they applied lime in order to raise the pH preventing the naturally acidic soils to drop below pH 6.0. I saw growers who put fertilizer in the irrigation water (fertigation). They keep track of micronutrients and add them as needed. When I asked how they know what is needed, they indicated that was up to the lab doing the testing. Later, I was told that the numbers are based on some "other" type of fruit tree, not necessarily based on what is known to be best for chestnut (since that is not necessarily known). But they do not treat it like it is an unknown; they respond to the numbers and apply the materials as "needed."
Every grower must harvest, clean, store and market their own chestnuts; therefore, ever grower must have their own equipment. In the five-farm visit, I saw the same types of equipment in the barns and packing sheds—some newer–some older, some larger–some smaller—regardless of the size of the farm. The grower dealing with a few tons had the same type of machinery as the farm with 200 tons. I saw three different types of harvesters and someone also stated that there is still nothing better than hand harvesting (they use migrant labor primarily from Malaysia). I saw the FACMA Italian-built vacuum harvesters and various versions of finger harvesters attached to front loaders. These were unique and the concept was being applied for smaller growers where the equipment would not be dedicated and could be attached to most front loaders.
Once harvested, the chestnuts enter the farm's packing shed and the chestnuts were placed into a de-husker (de-burring) unit, air cleaning (blower) unit, floating and washing unit, inspection belt and size grader. All of these actions have been nicely interconnected by the manufacture. The inspection belt was the most amazing. As the chestnuts went down a short belt, each chestnut was turned over for the inspector several times. The cooperative members have their own equipment on their own farms—not much is shared and equipment redundancy reigns supreme. Each farm has one, two or three walk-in coolers.
Most of the marketing takes place between brokers and the individual growers. Each grower is competing against all other growers for the highest price. There are no chestnuts being imported from other countries in April and May when the chestnuts go to market. This reduces the competition that those in the northern hemisphere experience in November and December when European, Chinese and Korean chestnut hit the market at the same time as the North American chestnuts.
I did speak with one grower who had invested in a meal (flour) processing business. He sent chestnuts to China to have them peeled. They were sent back and processed to a meal. He admitted the business has not been as lucrative as he had hoped and he blamed it on having the wrong type of grinder.
Some Australian growers are interested in developing other avenues of marketing chestnuts as they see prices dropping as chestnuts become even more available in April. At this point in time, most are still satisfied with the prices and are unwilling to change their direction even though others are adamant that chestnuts will go unsold once over-production occurs.
Overall, it was a great trip full of many lessons and learning points. I came away thinking that there really is a parallel universe.