This is the second of four posts that focus on which plant species are my highest priority going forwards. This kind of periodic reassessment can be useful to reflect on the performance and potential of different crops, and to avoid the temptation to become a wide but shallow, “one of everything” plant collection which lacks the genetic diversity to achieve any meaningful local adaptation.
Tree crops are an essential component in any system which receives above average rainfall, and given my property was once covered in thick vine scrub rainforest which was cleared over a century ago it seems only natural that my land will predominantly return to a forested ecosystem in time. Arriving when I did means I can have a major role in steering the direction of that revegetation and insert a range of useful tree crop species into the mix. I also hope to maintain a patchwork of trees and open spaces to support a diversity of habitats and browsing resources for my goat herd. Depending on their management, goats have the potential to either prevent the regeneration of useful trees and shrubs, or to stimulate and restructure the forest as it emerges. Clearing understory is especially useful at lowering wildfire risk.
Now on to the top twelve tree crops which have emerged as the most promising candidates for creating a productive agroforestry system on my particular patch of land.
1. Bunya nut/parana pine (Araucaria bidwillii/angustifolia). This is by far the most important tree in my system. It has already proven to produce long lived, productive trees on neighbouring properties and early plantings of seedlings are growing rapidly. It is also the only tree species that I can access deep wild genetic diversity in the surrounding region. Add in the enormous potential for domestication through hybridisation with the parana pine, and this species has the most potential to transform agriculture across a wide swathe of the world. I am especially keen to begin a community project to plant diverse remnant bunya nut seedlings all around my little village. We could easily establish thousands of trees, such that in a few decades it could represent a significant resource for feeding the people living here. I have calculated that around 15 trees produce enough calories to feed one person for a year (on average, though output varies considerably year to year, so bunya will only ever be a component of a complete agricultural system).
2. Black bean tree (Castanospermum australe). Continuing with starchy staple trees, this one has a long list of advantages. It grows wild on my property, with one especially large mature tree producing many buckets of large, starchy seeds every winter (timed nicely to come on just as the stored bunya nuts are losing edibility). Black bean seeds store even better, lasting easily for six months without any special conditions. The main downside of this tree are the toxins which need to be processed out of the seeds, a technique I have yet to master. I am hopeful that fermentation with the right complement of microbes might make this process easier than the traditional aboriginal method of prolonged soaking in running water. The genetic diversity of this tree in my region is quite low, a legacy of the best strains being propagated by the aborigines. I am putting out feelers to access seed from the tropical northern end of our state where the original diverse populations are found. This tree has knocked chestnut off its perch. I have had too many problems storing and germinating its short-lived seeds, and have no hope of accessing any more genetic diversity.
3. Macadamia. Next I will focus on oilseed tree crops, a valuable complement to fat production from dairy goats. Macadamia nut is the premium species for this purpose. They grow like weeds under my conditions. Goats graze around them without damage. Seed from narrowly bred commercial strains are readily available, but diversity can be added to the population by including seed from remnant early hybrid trees which are relatively abundant on old farmsteads (we have one such tree in the cattle yards which is just as productive as modern strains). Pure species are also available and I should add a few to the mix soon. The seeds store well for a few months through autumn, which coincides nicely with the season when the goats stop milking before kidding.
4. This one is a toss-up between two options as a second major oilseed tree crop. The ideal option would be the oil palm (Elaeis species). I managed to get a small number of advanced seedlings of hybrid oil palm from a specialist nursery at a moderate price. These have been planted in the orchard and if they are growing well after a few years I plan to buy a whole lot more (there is a chance it will be too cold for them here, though I have seen mature specimens in our nearby capital city). This species produces large bunches of oil rich fruit, which can be boiled to separate the pulp oil, then the kernels can be crushed and boiled again for a different grade of oil. The oil is mostly monounsaturated/saturated fat, which means it can be easily stored. Oil palm has a very long history of use in central Africa, long before it became the villain of deforestation and industrial production. If this species fails to perform, then I will give more attention to candlenut (Aleurites moluccanus). This species is growing vigorously on my parents’ property, producing wheelbarrows of fruit every year. The oily seeds are dried and roasted then consumed in small amounts in Indonesian cuisine, because they contain phorbol esters which makes them mildly toxic. There is supposedly a low toxin strain of the tree in Vanuatu, so maybe one day I can track that form down. In the meantime, I am planting small numbers of this potentially useful tree. The oil can also be used in lamps and for various non-food purposes.
5. Avocado. These are also an oil crop, though also a fruit, so a bit of an oddity. This means they cannot be stored for long, but a seed grown stand of trees usually fruit over a fairly long period in winter (which also nicely coincides with a period of lower milk production as the new kids drink most of it). Genetic diversity is fairly limited, with only a small number of clones grown commercially to provide large amounts of seed for direct sowing. The trees are also mildly toxic to goats (who seem to enjoy eating them unfortunately) and the trees seem pretty picky about where they like to grow on my weird clay soil, so the total number of trees I can grow will probably be limited. I keep my eyes out for unusual varieties for sale as fruit, but whenever I direct sow small numbers of seeds the chance of getting a mature tree is fairly low.
6. Next onto the true fruit. I regard these as relatively low importance, despite the fact I love eating large amounts of fruit throughout the year. For most of European agricultural history fruit was not domesticated and relatively small amounts of wild fruit was foraged seasonally. Many Europeans are genetically predisposed to have difficulty absorbing fructose for this reason, and I suspect my fruit consumption may be higher than optimal. One fruit that really stands out under my conditions is the persimmon (Diospyros kaki). Wild trees are occasionally spotted in the area, covered in astringent fruit that dodge the birds and bats until they are fully ripe (which makes picking and ripening indoors an option for humans). I have gathered local wild forms, plus two local seed grown forms with better fruit quality, and started growing seed from a half dozen grafted astringent forms, so I have a pretty decent diversity to work with. I also have seedlings of the American persimmon (D. virginiana) and grafts of black sapote (D. digyna) coming on that could be hybridised with the kaki population. Diospyros is a large and diverse genus so I will keep adding other species to the mix as they cross my radar to add to a hybridisation program. The fruit of D. kaki can be dried due to their very high sugar content, and done right the drying can break down tannins at the same time. Dried fruit is probably the best end use for this tree crop, but I need to set up equipment to handle larger quantities of fruit, most likely tied to a wood fired heat source to drive the dehydration process during our typically damp autumns.
7. Jackfruit (Artocarpus heterophyllus). This species has proven itself to be productive when grown in just the right location. The plant produces large fruit with sweet pulp, coupled with edible starchy seeds as a bonus (though they don’t store readily). A few other species in the genus like kwai-muk (A. parvus) should be able to grow here and could be hybridised with jackfruit. Many more useful species in the genus are true tropicals, so I am hopeful people in those regions can be inspired to do more wide crossing to produce new staple tree crops like breadfruit and breadnut. I have planted a few kwai-muk seedlings near my jackfruits but so far the wallabies seem to have taken them out (a common issue for imported seedlings pumped full of artificial fertilisers). I might need to find seed and grow my own unappetising seedlings to get this side of the genus established. Luckily rare fruit growers in my area are making kwai-muk more common every year, so seed should be available to purchase soon.
8. Mandarin (Citrus reticulatus). Citrus also grow like weeds here, which isn’t surprising since we have a few native species which grew in this area. Grafted mandarins were an early bounty for producing winter fruit, but these trees tend to burn out pretty quickly. I was lucky to stumble upon ponkan mandarins, an old strain which grows reliably from seed and produces excellent quality fruit (you just have to cope with the huge basal spines and upright columnar growth habit). I have an orchard with a couple dozen ponkan trees that are nearing maturity. As a more minor pursuit I am interested in tracking down seed grown strains of valencia orange (which hang on the tree right through spring) as well as true lemons and limes. Citrus seed cannot be dried and stored, so tracking these varieties down is a fairly hit and miss process, but I will succeed sooner or later.
9. Atherton raspberry (Rubus probus). This crop has been such a joy to grow. It is a self-supporting, moderately spiny, clumping raspberry that produces large tasty pest proof fruit all through winter and early spring. All it needs is a spot in the landscape where it gets a little ground water to support fruiting through what is normally a dry part of the year. I could potentially hybridise it with other species in the genus (including more temperate/cultivated strains which perform terribly here) but to be honest this plant already does pretty much everything I could ask for. The only possible improvement would be a more intense flavour since it is a bit on the mild side to my palate. So I will put that idea on the bottom of the list, something to tinker with in my seventies if I am still around by then.
10. Pitaya de Queretaro (Stenocereus queretaroensis). This is the only truly speculative species on the list. It is an upright cactus that produces large tasty fruit in several colours which has been cultivated in Mexico on a considerable scale. It is pretty much unknown in Australia, but that was true for dragon fruit cactus (Hylocereus) just a couple of decades ago. Dragon fruit grows and fruits really well for me, but I cannot justify the work involved in building support structures for it (especially since they tend to rot and collapse around the time a plant matures and begins to fruit). I really want to find a self-supporting alternative. Fruiting plants should require nothing more than being planted and harvested, such is the low value of their output (just a little sugar, water and flavour). I germinated a large number of seedlings of this promising cactus years ago, that are still languishing in pots. I could easily germinate a lot more in the future. I became hesitant when I observed that prickly pears (Opuntia), a normally weedy species, failed to grow in my weird low calcium soil. I started assuming that Pitaya de Queretaro would suffer from the same issues. But I decided the potential of this species in other places is too great to stick to my usual zero input mantra. So I will be growing out a limited number of these cacti and supplementing their minerals to get them moving, all with a view of sharing them more widely in the future. This is as simple as dumping a few pieces of concrete in the rooting zone for the plant to suck on. The genus Stenocereus contains other less domesticated species, and there are other decent fruiting upright cacti that should hybridise, so I will see how many of them I can add to the mix for some possible crossing in the future.
11. Jaboticaba, Grumichama and Brazil Cherry. I see these as a complementary set of small fruited species in the Myrtaceae family. Jaboticabas produce huge crops of sugary fruit, several times through the warm months if rain is sufficient. Their high sugar content means they can be crushed and fermented into wine or vinegar. Grumichama produce several crops of soft mushy fruit, a little susceptible to fruit fly, but we have usually eaten our fill by that time. Their best trait is that they grow and fruit reliably in the competition zone from bamboo, so they get to fill an unusual empty niche on the farm. Brazil cherry are the weediest of the group, but they fruit at odd times and the fruit hold on the tree quite a while. They can be crushed and turned into a very refreshing drink all through the summer. All of these species are hardy and pest free for the most part. There is also a growing amount of diversity in the genetics of all species slowly becoming more available through the efforts of rare fruit growers.
12. Mango. I almost didn’t include this species in the list, but I have to acknowledge its productivity even if it is somewhat sporadic. Mangoes only set crops every few years in my region, when spring is consistently dry enough for the fruit to escape being attacked by a fungus. This means the trees build up huge reserves of stored energy, so when a good year comes the resulting avalanche of fruit can be overwhelming (which makes it easy to take them for granted). If I have persimmon drying methods set up I could easily extend them to summer crops of mango. I have been slowly gathering seed grown mangoes in my orchard, focusing on varieties like Nam Doc Mai which are somewhat resistant to the fruit ruining fungus so they tend to give smaller but more consistent crops. Rare fruit growers are importing even more diversity of traditional forms from SE Asia, so I am hopeful I can broaden my small collection of this luxurious fruit crop in the future. The trees also seem to enjoy growing in parts of the orchard with the worst soil that nothing else likes, so that is worth appreciating as well.
So there it is- the short list of tree crop species which are most worthy of my breeding efforts. I feel bad leaving banana off the list since it is by far the most productive species, but it is a genetically sterile crop incapable of responding to breeding work, so it doesn’t qualify for the list. I am steadily converting my plantings to the strains which produce best for me. In case you are interested, the dwarf Ducasse was an early stand out, but I have since found it suckers so intensively that clumps quickly end up crowded without constant maintenance. The fruit is kind of bland and thin skinned as well. Bluggoe is now steadily taking over as the main variety. It is short enough to manage fruit harvest, but is very slow to sucker which means clumps stay uncongested for many years without maintenance. The fruit is large, thick skinned and very flavourful. Mulberry could have made the list if the birds didn’t strip all the half ripe fruit. Shahtoot mulberries (M. macroura) seem to avoid this issue but can only be propagated by grafting. I tried growing this species from seed to restore fertility to the highly productive grafted clones but have had no luck producing viable seed so far.
Kei apples are also marginal so far. Only one tree from a distinct genetic source has produced consistently well so far, but it is closer to the driveway where it gets more run off and soil minerals. The remaining thirty odd trees might just need a few more years to mature and start fruiting properly. There is also some potential for hybridisation with another species in the genus. Wild sandpaper figs also deserve a mention, though they seem happy to self seed around the farm and all I have to do is harvest. An Eleagnus hybrid is also growing well, but time will tell if it ever fruits. If it does I will try to add other species to the mix and try breeding them. Monstera deliciosa also is likely to be planted in naturally shady spots now the canopy is starting to close in places. I might even gather a few different non-edible species in the genus to see if I ever get the chance to manually hybridise them.
Hopefully you can see that this modest selection of tree crops has the potential to produce meaningful yields of starch and fat at useful times of the year, plus a range of different sweet fruits spread over the entire calendar. Coupled with a single fruit for mass drying (persimmon) and alternate sugar sources (to be discussed in a future post) this assembly has the potential to supply a significant portion of my household needs, in return for nothing more than planting the seeds or seedlings then returning at the right time of year to harvest.
Apologies for the two posts in a row on a similar topic. My health is still a bit fragile, though my sleep schedule has shrunk from 12 to 8 hours a day and my strength are steadily returning. I’ll be sure to mix it up in following weeks, with a comparison of different methods for preparing my recent maize crop and a review of a few books on the history of the iron industry in the pipeline.
Kia ora Shane,
Thanks for a page full of raisins again. Just did what you are doing planting dozens of parana pines all around the village for future sustenance or grave danger of falling food.
What needs to go on your list however is pouteria in all its form. For us it is p.lucuma. what a food. Starchy and sweet like chestnut with maple syrup. Can be dried and stored. What I wanted to ask you is graft compatibility. We have a native pouteria costata with 2n=28 chromosomes. It is a super hardy shrub growing on clay from dry cliff edges to the bottom of headlands right to the high tide mark. It produces oily fruit with a thin pulp that taste like some resinous wild avocado. Maori used to grind the whole fruit and seed to extract oil. It produces most of the year and fattens wood pigeons. It seems to grow as slow as the exotic pouterias but it is everywhere in the warmer parts of coastal NZ and could provide a tougher rootstock as lucuma is a bit fickle with phytophtora and native armillaria. I can't find chromosome data on other pouterias and don't understand it anyway but I figured that canistel has the same numbers as p. Costata and can be grafted on p.viridis and lucuma. We are planning to start a project with a native nursery nearby on the coast run by the uncle of a friend who is learning syntropy stuff with us. Our friend wants to start a food forest on that stunning family farm at the headland but his uncle is ultra native conservationist. Funny enough the nursery is called Tawapou, the name of said tree! So we are scheming how to cloak the system in native garb. Being able to graft lucuma onto their Costata would be awesome but I would like some more affirmation of some potential success. Nobody seems to have thought about it so far.
Hope you get your full strength back soon. And then get some lucumas in the ground. Greetings to the goats (they love lucuma branches)!
Klaus
Couple of questions. How is the yield of wild vs cultivar macadamia?
Do you do any protections for wallabies? I understand the desire for breeding resistance, but with rare genes you could make an argument for protection.
Do you any of your tree crops provide a significant amount of protein? I realize that is what the goats are for. On a related note, have you looked into leaf protein concentrate? I have experimented with making it at home and I think the process itself is not so bad, though the flavor was not good. But, it could be a way to utilize other tree species (such as your mulberry that can’t hold onto its fruit) as a protein fallback.