Acotanc: Coping with Mass Demand for Tree Seedlings

Coping with Mass Demand for Tree Seedlings

Author: Richard Hordacre
Organization: Hamel Nursery
PO Box 329
Waroona, WA 6215
Phone: +61 08-97331241
Fax: +61 08-97331417
ATCROS Reference:


The demand for the production of native tree and shrub seedlings has changed dramatically over the last twenty years. The methods of production have also evolved and developed.

There has been a major evolution in Western Australia, maybe even in Australia in the last 10 to 15 years regarding the amount of tree and shrub seedlings that have been planted. It is quite amazing how things have taken off in that field. Not just in the high rainfall areas where the Tasmanian Blue Gum industry is escalating, but also in dryland areas. If you had a chart of seedlings planted in the last ten years, it would be quite mind-blowing, although insignificant compared with the number that have been removed. But we are getting there.

This great number of seedlings planted has put a demand on tree nurseries around the state to supply those seedlings. We are often asked to provide huge numbers of quality seedlings at a very low price, fitting specifications of height, diameter, disease-freeness, plantability, user-friendliness. We are just expected to pull it out of the hat and provide the customer. This is great: it gives us a real challenge. I am here to speak on that subject and also I would like to demonstrate some of the historical changes that have happened in the last 10 to 15 years in reaching the point where we are at the moment.

I brought a bit of junk from the nursery to show you. This is a very low-tech presentation. We will go back to the beginning, talking about methods of propagation of twenty years ago. This was perhaps the only way of producing seedlings: peat pots and also paper pots. Not a bad system: being biodegradable was the big advantage of it. You could keep 80 seedlings in a small tray like that, so it was mass production. There were inherent problems with this system. There were no drainage holes, no air pruning. These little things acted a bit like buckets. If the roots from a bigger tree managed to penetrate through the base, they would spread all over the bottom of the tray, and the poor old tree planter would have to get out an axe to separate them. People still use that system, but it is almost redundant in WA.

Similar to the tubes, but a cumbersome way to grow trees, individual pots present problems with filling them. I don't know if there were machines designed to fill the pots. The planters were presented with trays of these things. They had very poor root pruning. Roots tended to bind around the base of the pots and you ended up with a weaker seedling. It was really more of a thing for the backyard market or tubestock seedlings that were going to stay only for a short time and then be transferred out again.

This is one of the first soft-celled systems, called J-7s. Main Roads wanted all of their seedlings to be grown in these. I still can't work out how they actually filled them. In theory, it was quite a good technique. There is a root-trainer system down the sides so the roots are pointing toward China. They developed a special racking system to contain the pots. Being quite a deep pot is an advantage as you get good root growth. However it was not really the best system for mass handling and production of seedlings. A lot of these soft-celled trays could be reused, but a lot of them ended up falling apart and being chucked on the tip.

You could say the same for this variety of soft cells. They have the root-training ribs on the side and the water slot in the bottom.

These didn't have the training system: the theory and practice was to paint the soft cell tray with a root-inhibiting paint, which contained a copper sulfate product. When the roots touched the sides of the tray, they were burned off by the copper in the paint. It was reasonably effective. If the paint was applied properly, the roots didn't penetrate the sides, but it was really a form of bonsai, because you were killing the active, growing roots, which was sort of defeating the purpose. I think this system is still in practice. I think CALM still uses it: painted quick pots, they call them. There were 40 cell and 64 cell trays. Not a bad system. Again it was going into mass production. It was cumbersome and expensive to paint, not totally effective with root pruning. The workers hate them because there were sharp edges that were always causing little nicks and cuts. And the rubbish tips fill up pretty quick. Down at Manjimup you are not allowed to dump these things at the local tip. A half million trees would fill two big skip bins with these cells. They were not really reusable.

The earlier models of the hard-cell, moulded tray systems were the old 70 ml pot. Individual again, a pain to fill and carry around. That is quite a lot of soil. You can only fit 20 in a standard size tray. Difficult to manage, but having that amount of soil has a few advantages with survival in the field. I think this system is pretty well redundant now.

Here are the forestry tubes. A good little tube, it has root trainers on the sides, little plastic moulded bits that guide the roots. Air pruning is an advantage. This old system didn't have air pruning in the base, so you get a lot of root balling and a weaker seedling. The main problem with these was the handling. They came out with different ways of containing the pots. This was good on a small-scale in the nursery but not so good for mass planting. You have someone on the back of a tree-planting machine, rolling along at 5 km per hour, trying to separate seedlings, you just couldn't do it. It is still used extensively in some nurseries.

That led on to the Gameto hard-cell trays. Quite a few companies are competing for this market because it is so huge. Some are West Australian-made. 72 or 64 cell seems to be the standard. We have stuck with this dimension of tray: 35 cm by 30 cm. Most of the trucks have racks set up for these carrying systems. You can pick up two trays in two hands without breaking your back.

There is a new product out this year, a bit deeper. The volume of the new trays is about 70 cc compared to the old volume of 50 cc. This should give a better survival rate, especially in the wheatbelt. Again, it has root trainers on the side, air pruning on the base. You do lose some soil out of the bottom, but once it is moist it holds fairly well. The open weave in the bottom allows another machine to loosen up the seedlings in the tray: a tray popper. The planters can then extract the seedlings with ease.

Here is an import job, 90 cc, also has root trainers and air pruning. That little angular bit at the bottom might cause root crowding, which is a real thing with some species. You get a kind of ball and socket down there, especially with some of the fast-growing Eucalypts, which presents problems later on. With Proteaceas like Banksias and Hakeas it is a good system because they don't have a huge tap root like Eucalypts.

These trays were manufactured overseas, Finland, I think. They are distributed locally. A pretty wild-looking tray, but over east a lot of nurseries have adopted this style. The same basic principles apply: the root-trainers, air pruning, bigger volume. Very good for pines, a bit cumbersome for farm trees. A little bit heavy. The main disadvantage is the expense, at least in WA. You are looking at about double the dollars for that compared to a locally-made job. It is a huge factor for a larger-scale nursery.

The big advantage of the hard-cell trays is that they are reusable. There are lots of different tecniques for cleaning them up: steam sterilisation, chemical baths such as chlorine. Washing trays like that is a pain. Usually they are dipped in a chlorine bath and kept there for about a half an hour, to get rid of any pathogens or pests. We charge a tray deposit, to help in getting trays back. It has been terribly complicated because of the GST. We are thinking of disbanding that system just because of the paperwork involved. We can't get a straight answer out of the tax department.

The other one I should mention is the plug tray. It is a soft-celled tray, but there is a new hard-celled one. There are 512 little pots in there. It is used mainly for early propagation of seedlings which are then transferred into the normal nursery tray. Some people use that as an insurance policy in their nursery. If you have a difficult-to-propagate species and you are not sure of the germination rate, or if you have an expensive sort of seed, you plant one seed in each cell. Some of the seed is becoming quite prohibitive in price. Most of the seedling buyers accept that. They will pay for it. Newer seeding machines have been developed to seed them automatically. Not a bad system, but you have to be very particular about time of transfer, because, as you would imagine, root binding can occur very rapidly if left in there a few weeks too long. Some people paint them with a root-inhibiting paint to stop root balling. I think CALM nurseries at Narrogin sell planted plug trays to growers. If you are a nurseryman, you can buy these already planted and germinated. They are available. It is not a bad system if you have bad water or soil. A lot of nurseries have started to propagate for farmers using the farmers' seed. You don't get a reduced price because sometimes the seed requires a lot of cleaning.

The increase in demand for seedlings has also meant a bit of a revolution in seeding systems, actually seeding the seed into the trays. Native seed comes in a huge range of different sizes. We catered for that by drilling three different size holes in the top. In our first year we seeded a half million trees. Some nurseries still do it like that: I feel for them. You just can't control the number of seeds accurately, you get lots of misses, lots of multiples, which creates a lot of work later on.

We went from that system to this revolutionary system. This is connected to an industrial type vacuum cleaner, aluminium frame, perspex, irrigation nozzles of various sizes for different size seeds. Amazingly, it actually worked. It works well with uniform, graded seed. You can regulate the vacuum from the machine. The seed is spread onto a plate, the vacuum suck up the seed with a seed for each jet, placed over the top of a tray, the vacuum is cut and they all drop in. We seeded 1.5 million Blue Gum trees in the first year.

Most nurseries with over a half million seedling capacity have gone to a high tech, automated and precise vacuum seeders, or drum seeders. You can turn our 5 or 6 thousand trays a day. That equates to 3 or 4 hundred seedlings a day. The change in seedling production to tray-filling machines, seed cappers, watering tunnels, fungicide applicators: there is a whole gamut of high tech equipment nowadays. The only disadvantage is that it costs a fair bit of money. All the parts are quite expensive. There is only a handful of seedling line equipment producers in Australia. They have the market by the throat.

In the mid-80s to mid-90s a lot of seedlings were raised on the ground on small pallets, ankle height, quick and easy and cheap to produce. Very user unfriendly. That is largely redundant. Most benches are waist height now, with a range of tops, weldmesh, angle iron frames, channel steel frames. Basically the tray hangs in mid-air suspension. You get terrific air pruning qualities and good air flow reduces disease problems. A lot of nurseries have gone to rolling benches, where the tray comes off the end of the seeding line and goes straight onto the bench. Once the bench is filled, it is pushed out into the nursery. This is tremendous for worker efficiency.

There are cheaper versions of benches. Quite a few big nurseries suspend their trays on one plain wire on either side, hanging in mid-air. Rows and rows of benches, huge struts at the ends. They work well, but are user unfriendly. The people who actually work with these benches don't have many good things to say about them. The trays have to be moved back and forth to be worked on.

There have been huge changes in the amount of different types of chemicals and fertilisers available to nurseries. Most of the large-scale nurseries have gone for liquid feed systems, fertigation, either applied with a boom spray or through the irrigation system. Most of them have gone away from slow release fertiliser, because you lose control over the growth of the seedlings. The little granules can dump all their contents in one week and cause burning problems. it's not a problem in the bigger pots, but can be a disaster in the small cells.

Not long ago, you didn't have much choice about the seed you bought. You bought it from a seed merchant who hadn't cleaned it. You got it as it came out of the picker's van. Nowadays you have access to seed orchard, plantation grown pure seed, coated seed; there are all sorts of new advances. Transport systems are improved. Quite a few trucks have a capacity of 200 thousand seedlings, shipped across the Nullabor for 2 cents a seedling. One or two people can load and unload a truck in a couple of hours using a conveyor system.

There is quite an exchange of seedlings between WA and the eastern states. They go both ways. Mainly to cater for shortfalls. Last year was a particularly big year for the Blue Gum industry in the east, and there was a big shortfall; you could just about name your own price for Blue Gum seedlings.

The final point I would like to make is about the support for us nursery people who have undergone all this mass demand, and all the pressures that are put upon us. We have a bit of support out there. There are a few grower organisations, the Nursery Industry Association, which is really helpful and information sharing. They help us politically as well as in the nursery. The local WA Farm Tree Nursery Association, we meet once a year and air all our problems and do a lot of information-sharing. It is comforting to know there are other people out there doing the same thing and who will help us out. The advantage of these organisations is that we have a political voice. If something is going terribly wrong and affecting our production, we have a bit of clout as far as numbers go.