On a recent visit to South Australia I caught up with Ian Tolley who taught production horticulture to visiting Ag.Sc. students from the University of Adelaide, Waite Campus for more than 40 years. He travels extensively overseas as a consultant/trouble shooter advising governments and industry on Citrus within a framework of Horticulture. In 1965 he was awarded a Churchill Fellowship in Citriculture. He also has an ABC gardening session every 6 weeks. In 1995 he was awarded an Order of Australia Medal for services to the community, horticulture and the citrus industry and with Bruce Morphett has written for the SA Botanic Gardens an illustrated handbook called Citrus for Everyone.
Citrus in Pots
Ian: For terracotta pots there’s an excellent product out in a spray pack called Terra-Shield. You can clean the inside of the pot with stainless steel wool before you use it and spray it 2 or 3 times. It won’t allow the magnesia to seep out and make the pots look awful – it’ll make them waterproof and it’s permanent. It’s a methyl silicone compound so it really lasts.
Sheryl: I have some very large ceramic pots I was thinking of putting some citrus in, but don’t like the idea of having to repot every so often. I was thinking of painting on something to burn off the roots when they touch the sides.
Ian: You’re talking about Spinout but what will happen is that when the roots touch the sides they will just go round and round.
Sheryl: It will become root bound!
Ian: Undoubtedly, but it won’t cause the tree a moment’s worry in the pot. It has never been told that root bound is bad – it has never been told that shaping trees is good. It’s only when you get out into the orchard and you’ve got a pot bound tree grown in a small bag. If you plant it like that, it may never get established and when the first wind that comes along then there’s a problem.
If you want to use wine tubs then you should prepare them for long term use before planting. Use raw linseed oil and soak them with several applications because it tightens up the boards and makes them waterproof. If you’re really worried, then line the sides with 6mm black plastic. Make sure you’ve got several big auger holes in the bottom, one inch (25mm) in diameter. Use shade-cloth to cover the bottom. This will allow water to drain out of the auger holes but not the potting media. Sit the tub on two 3”x2” (7.5 x 5cm) hardwood timber bearers as level bases. Drainage will never be a problem and the barrel will last for decades. Now you can check that only a little water leaches out the drainage holes and not a drop more, saving fertiliser loss by leaching.
Sheryl: So I don’t have to repot every couple of years?
Ian: No – some of my citrus in tubs have been in the same substrate for 20 years but you must buy potting media that has the 5 ticks on the container. These are ASK Australian Standard requirements. Basically it should have a pH5.5 to 6.5 and an air filled porosity (AFP) of 25%. Some mixes have fertilisers added to the substrate and are then usually labelled as ‘citrus mix’.
Sheryl: What do you think are the best varieties to go into pots?
Ian: In principle all citrus species grow well in pots. The larger the fruit, the bigger the pot should be. All need to be shaped to maintain a compact shape producing many short but fruitful spurs. It is the way for even crop production and manipulation.
Propagation Mix
Use builder’s sand, washed and cleaned to cover seed for germination, using standard potting media as the substrate. Kevin Handreck in Adelaide is a fellow member of the International Plant Propagator’s Society (IPPS) – his book ‘Growing Media for Ornamental Plants and Turf’ is the plant grower’s bible and you must have it as a reference. He has revised and enlarged his 1984 original, now third edition published in 2002. (ISBN 0 86840 796 8.) The balance of the media is fertiliser and there are many forms. I tend to use organic types – Neutrog & Easy-Grow, both of which use compressed pelleted chicken manure bases. They are slow release and provide the bulk of the NPK segment, but both have micro-elements. I apply an annual dressing in spring over the garden for a very wide range of plants. For pots, unless they are very large, these fertilisers tend to overfill the space normally allowed for watering. An improved way for home gardeners with smaller containers is to try using Seasol on a regular fortnightly schedule as liquid feed. It contains growth stimulants and is not a fertiliser on its own. Include their Powerfeed to provide nutrients and the combination is easy to use.
Book Reference
Sheryl: Louis Glowinski in Melbourne says that the editors just won’t do any corrections when reprinting his book.
Ian: I edited the Citrus section of Louis’ book “The Complete Book of Fruit Growing in Australia” at his request. He told me also of the publisher’s reluctance to amend the text. I know he is unhappy about it but in general, it is an excellent reference book.
Rootstock influence
Let me dispel a myth about rootstocks in pots. Potted plants automatically develop root growth to fill the pot so even on this ‘blasted’ Swingle citrumelo (and don’t edit ‘blasted’ out!) you could put that in a pot and it would do fine. Any rootstock is suitable providing the potting media meets the criteria I’ve mentioned. There is a nursery in Northern California that says ‘we are using a special citron dwarfing rootstock and have done for many generations’. This is a load of codswallop because any rootstock will do in a pot because the pot ultimately restricts the root ball and limits the top growth! If you use slow growing rootstocks like the deciduous Poncirus trifoliata [it grows the best quality fruit as well as its dwarfing mutation P.trifoliata var. monstrosa (flying dragon.)] So if you wanted superb quality fruit – internal and external, these rootstocks impart a cold tolerance which is fantastic in the lower cooler areas of Australia. In the tropics they will slow rank growth. You will get prolific precocious cropping from both and they are resistant to nematodes and phytophthora.
Seedling or cutting grown Citrus
If you should want to try this then they should only be grown in pots as they may be affected by phytophthora parasitica in tropical/sub-tropical climates or phytophthora citrophthora in temperate climates if grown in soil.
Rootstocks
I’ve spent over 40 years studying and trialling citrus rootstocks and rootstock/scion interactions. Cleopatra mandarin rootstock produces good quality fruit – it’s great on alkaline (pH10) soils. It can be slow growing and a little bit of a light cropper to start with but once it settles in, it’s OK. For Broken Hill or other similar limestone areas this would be one of the few that would cope in such harsh conditions. For you in sub-tropical to tropical areas it grows well. It is mildly tolerant to phytophthora and nematodes, but as for many citrus rootstocks, mounding will avoid wet feet in heavy rainfall periods.
Cross-Pollination induces more seediness in Citrus
40 years ago I imported a tangelo group from California. All are Dancy mandarin x Duncan Grapefruit. Orlando,(early) Minneola,(mid-season) and Seminole.(late maturing.) We were told they won’t crop unless you cross pollinate them. We went to no end of trouble with Lemons and Valencias to get cross-pollination. I can tell you that Orlando can produce 50 seeds and outdo Murcott anytime! Minneola were somewhat the same with 30-40 seeds and that was unsettling. Seminole we could get up to 60-80 seeds, so I began to query this ‘fact’. The Californians still said that this was the way to go. We were able to produce good sized crops with much less seed when grown in areas more isolated from other pollinators. So this was an exercise in ‘don’t accept all you are told’ but do your own trials in your own environment if you are not certain. Some years later, we found more real facts from the work done by Dr. Anna Kultinow at Waite Institute Campus of CSIRO into developing seedless mandarins (refer to my book). Seedlessness affects fruit size so some varieties that are normally a good size if you do not pollinate them (e.g. cover them with bee proof netting) and not get any pollination, the fruit size drops to a stage where it is no longer commercially practical. Seedless Valencias seldom get to large size because they don’t have seeds so if you have 3-5 seeds you get reasonable size Valencias.
From a pollination point of view in mandarins, you have to determine if it has a propensity for over-pollination and therefore extreme seediness like the Murcott. Now we have a bind that Dr. Koultinow is in the middle of where she can’t go any further. By saying ‘if I give you a Murcott that is absolutely seedless, I can’t guarantee you large fruit size’. There is a trade-off in pollination of citrus cultivars right through that we would like to have the best of all possible worlds.
The summary of what I observe currently is this: that we need a little pollination for the varieties of which we speak in the mandarin and mandarin hybrids. Minneola, Orlando and Seminole are mandarin hybrids, all of those are Dancy Mandarin crossed. (note: I didn’t say Tangarine because that word is an American sales ploy.)
So we need to put up with some seed and enjoy some superb varieties particularly Minneola provided you leave until ripe on the tree. If you try and market it with a glossy skin – firm, tight, packable it’s as sour as any lemon you will ever grow. These are some of the trade-offs with some varieties.
There’s a new variety, Daisy, but if you have Black Spot in your area you could have a really good collection of spores if you’re a Pathologist! (Lovely fruit – lousy growing) In Morocco they grow seedless Clementines on large orchards over 500 acres where they don’t get cross-pollinated. All the new varieties are aiming for as little seed as possible, as resistant to fungal diseases as possible, easily peelable, good colour and preferably with regular cropping. If you do get alternate bearing, this can be solved by pruning and tree shaping following the off-crop year. All citrus fruit is born on terminals. Reducing terminals AFTER a light crop reduces the following crop from heavy to moderate but larger fruit. Kara is the latest maturing mandarin, easy to peel and excellent flavour. It does have a few bumps on the skin so it’s not saleable in the marketplace, but is an excellent fruit for the home garden.
Correct Pronunciation and Identity
Sheryl: What is the correct way to pronounce:
Persimmon
Pers-immon. (Per-simmon is the American pronunciation)
Tangelo
Tang-elo with the emphasis on the first syllable – not Tan-gelo (only one l also)
Poorman
Pomelo is pronounced Pomelo and that name is often used instead of its proper name of Poorman. It’s great for breakfast. The tree is easy to grow and a consistent cropper. The fruit hangs on the tree much longer than the common white fleshed Marsh grapefruit. Poorman (or Pomelo) has very few seeds, dark flesh, very juicy, when you eat it you think – I’m drowning in this! and when you finish you say – in my mouth I have a beautiful grapefruit aftertaste which you don’t get in the Pummelo family. Poorman is thought to be an Orange x Seville hybrid first recorded in Australia as early as 1820. New Zealand introduced it in 1855 because it has a low heat requirement. They renamed it New Zealand grapefruit, and latterly Goldfruit. They can’t grow true grapefruit in NZ because of their cold climate. (low heat units) We have a Smooth Red Seville (looks like a red grapefruit) that is an Australian mutation of the common rough (yellow) Seville. It is sour but good for marmalade. These two are NOT related to the Pummelo (citrus maxima) family
Pummelo
Pronounced Pum-melo, looks like a flattened Grapefruit – usually very large, somewhat seedy (like Wheeny grapefruit) To flourish, they need very high numbers of heat units so they only grow well in the real tropics. Thailand has six cultivars covering the full year of cropping at maturity.
Citrus grandis decumana (a Pummelo selection of unknown origin)
It has no common name – butter yellow, the fruit is very small here now because you can see the (very low) bud union physiological incompatibility. Whilst I have inarched to save the tree and there are more suckers, so I can then put more inarches to separate limbs. You can see that the suckers have come from the rootstock indicating a (bud union) restriction and reducing the fruit size from head size when we first got it and now it’s a miserable specimen with very thick skin. A high 35cm budding or better still, grafting, would have solved this problem by producing a smooth union.
Pummelos are used extensively in Thailand and neighbouring tropical countries but they have many better cultivars than this one. They cut the skin in 1” strips, scrape away the white pith, soak the skin in a saturated sugar solution for 48 hours, The dried slices are chopped into 1” squares put on racks to dry and that’s their sweetmeat – their lollies! It’s very nice. This cultivar has a very distinctive, highly ribbed leaf. The Pummelos in general have large, very smooth leaves and a round shape.
Sheryl: It tastes very mild and not at all tart.
Grapefruit
This is Star Ruby – I imported the first lot in as seed from the US Citrus and Date Station at Weslaco in Texas. This is one of the original red grapefruit, products from irradiation of Marsh Grapefruit. The yellow splotches on the leaves are the result of sunburn toxicity. In southern California on subsequent visits, I found they grow them under date trees and they don’t show this problem at all – they just don’t like direct sunlight and it’s a deficiency caused by genetic changes through the irradiation. Star Ruby is one of the best. Ray Ruby, Rio Red are other selections but they are all seedling selections from the original experiment.
Chironje (pronounced cheer–own-aa)
Sheryl: This is fantastic – just superb.
Ian: It’s a chance hybrid that’s been known in Puerto Rico for hundreds of years and was found in the forest by American botanical explorers in the 1800’s and sent to Washington and then to California. I’ve been growing it for 30 years and I still think it is one of the best of the non-mainline varieties. It holds its fruit on the tree, doesn’t granulate, keeps its juice and what you are eating is fruit from last year. It’s a cross between an Orange and a Grapefruit. The researchers in California have established that but their parents have been lost in antiquity. They haven’t been able to trace it in Puerto Rico other than to say that there are a whole lot of grapefruit and oranges around and there’s a mixture of everything but they can’t put it down to two in particular. The industry is now beginning to do DNA testing. If anyone is really interested then one could do something about identity in the future.
Limes
Palestine Sweet Lime
Taste is like Barley water, no acid. Used for generations as a rootstock in the Middle East until improved virus testing procedures put it out of contention. Grown on Troyer Citrange rootstock – A myth: some industry people keep on saying Troyer Citrange is different to Carrizo Citrange – they are both the same. Any differences are the result of seedling variation as they are not 100% genetically true-to-type. I have the US chart to confirm their true origin and I am happy to provide it.
Kusaie
The yellow fruited form (mutation) of Rangpur, and of Indian origin. It leaves Tahitian Lime for dead. Kusaie produces much smaller fruit year round (the fruit stays on the tree) whereas in temperate climates, the tropical Tahitian produces only one crop and then sheds it.
Rangpur
A dark orange colour – larger fruit than Kusaie. It has a nipple on the bottom to identify the clone, and also crops year round. The reason I like them both is because they are hybrids and believed to have mandarin in their background. This gives them cold tolerance and the ability to react to changing conditions including shaping so that they can flower and fruit all year round. I think they make some of the best patio specimens and useful too.
Citrus hystrix
A prized fruit (very bumpy skin) in Thailand. The women have the most gorgeous black flowing hair. When their children go to school they can get lice in their hair. If you grate the fruit, it makes instant shampoo in water. It foams up, has a beautiful smell, kills the lice and keeps their hair in beautiful condition, as it is a natural insecticide. The leaves are used in infusions for tea etc. It depends where it is grown as to whether the leaves retain that strong characteristic. The tropics are the best climate. Some people kid themselves when they grow it in cool climates, do their infusions and think it is nice, but the reality is different.
Sheryl: This is what we call Kaffir Lime?
Ian: Wrong name! There is no mention in any respected citrus journal of Kaffir. It is widely known in Asia as Makrut lime. I was repeatedly told that name over the four years I consulted in Thailand.
Blood Lime
It’s a CSIRO hybrid developed at Merbein, Victoria and patented. It has been made available to contracted growers only.
West Indian Lime
It’s a little seedy but it’s the most acid lime that you can grow. It is propagated by seed, but it tends to suffer from Tristeza virus – my particular cultivar was selected for its resistance. If you don’t have a high aphid population, you can get away with growing it from seed.
Wild Tangerine? or Wild Lime?
Sheryl: aaaaah!!!! very sour
Ian: I think it came from Indonesia many hundreds of years ago. It has a sharp lime flavour and is a good cropper. NT aborigines know about it – tends to be a little thorny but after a while you’ll notice in a few years, up at the top, some branches that are not too thorny. You can breed much of the thorniness out of citrus by using that observation. The further you are away from the original cell subdivision, the less thorns or juvenile vigour. Just take thornless buds or a small thornless graft from the tip of the plant and grow it on for several years more and you’ll finish up with very few thorns.
Rootstock Issues
Ian: These trees are on Flying Dragon rootstock and they’re all budded or grafted to Marumi Cumquat. We also use Flying Dragon as a rootstock for dwarfing trees in the field. It will tolerate a wide range of soil conditions even up to pH9 so long as there is very good drainage. In containers there is a need to stay in the range of pH5.5 – 6.5 to obtain the best nutrient availability. We have a Flying Dragon seed production planting in macropots. We use Flying Dragon rootstock for almost everything for home gardeners, providing we know the proposed budline is free of Exocortis viroid.
Sheryl: It looks like Flying Dragon would be excellent as a bonsai. When wouldn’t you use Flying Dragon as a rootstock?
Ian: Lemons – that’s the only one – the only compatible exception that is OK is Prior nucellar (means virus free) Lisbon. It’s an American cultivar and we had two – Prior and Monroe. When I did the field testing on Monroe, after 10 years I found it had exocortus viroid and had to scrub it. There were no reliable heat treatment facilities at that time. I don’t like Swingle Citrumelo – it’s a terrible rootstock. From a home gardener’s point of view, if I said to you: Do you want something very vigorous, grows to 10 metres, produces coarse fruit and doesn’t like limey areas? No thanks! They use it in Florida because they have a decline problem called Citrus Blight. This rootstock is resistant and it’s the only way they can keep growing citrus in the affected areas. There is an area in the Burnett Valley in Qld. that’s in quarantine due to it being (illegally!) introduced to Australia on infected budwood so hopefully it will stay there. It is not yet possible to destroy the organism.
Pest management
We use the systemic Confidor, mainly for Mealybug, once every 2-3 years. Ampol DC tron+ (sold in garden centres as PESTOIL) is by far the best and softest on beneficial insects and the operator as a regular maintenance for general insect pest control. Check out the label for more details.
Cumquats or Kumquats (either name is OK)
Marumi are much less vigorous than Nagami growing on the same rootstock. Nagami has a sharp sweet flavour and Marumi has a soft sweet flavour – there are oil cells in the outer skin of Nagami, but not on Marumi.
Meiwa – I was part of a working party in California in the 80’s to try and resolve the debate about the similarity of Meiwa and Marumi. Both were in the UCR station at Lindcove Field Station in northern California. It is a famous citrus repository from a worldwide point of view and this is documented and authenticated. A comprehensive range of experts in this field made a detailed assessment. It was decided, for all intents and purposes, Meiwa and Marumi were identical, so we adopted the name Marumi. Any reading you see that quotes Meiwa is pre the1980’s. We have gone to the one name to save confusion. I have not seen any difference and I’ve worked in Thailand, South Africa, Malaysia and Indonesia where I’ve studied the cultivar as well. I’m quite convinced there is no difference.
Sunburn control
Sheryl: When do you suggest painting the trunk?
Ian: Use white (reflects the heat) water-based paint EARLY and apply it on all citrus. With Mangoes, don’t dilute. It will last around 5 years. Many trees show sunburn, characteristically a bronze colour on the western side of the trunk followed by excessive dead bark. Check the eastern (protected) side to observe the difference.
Israel
Ian: Yes, I’ve been to Israel many times. I did learn a lot, as do most when travelling. eg In an irrigation experiment on 10 year old Plum trees, they got sheet piling (from the wharves) and divided the root systems on several acres for a random trial. They put the sheet piling down on each side of the trees – some of the roots were half roots, some quarter some three-quarter and some untouched. A drip irrigation system was fitted to the relevant sections of the new root systems. The results were startling for the time, but there was no loss of production on the restricted root systems and that meant adequate water could be applied using drippers on a very small area and the tree would develop a root system to cope with those changes. We now know that drippers are effective water savers in applying water by avoiding evaporation losses and because of accuracy of application. If crop potential is pushed to the ultimate limit then there is no water saving there. We should adopt the Israeli term of “tonnes (of crop) per cubic metre of water” to better relate our overall use of our most precious resource. As far as growing in pots though, the Israeli’s grow a lot using nutrient film techniques – you put the plant in the tube – like hydroponics – but the proper term is nutrient film technique (NFT.) They do a lot of this as they are short of water and they developed some superb nutrients for specific use with NFT. ie. Liquid NPK in the 1960’s cost an arm and a leg – you could apply Urea but you couldn’t inject phosphorus or potassium. They developed chemical combinations for drippers that became soluble fertilisers for the industry worldwide. Now they are in common usage and cost effective.
Publications
Sheryl: Have you written many papers that we could access?
Ian: I’ve written more than 60 papers about Horticulture. I’m currently trying to condense these onto a CD and in a book format. It will probably take around two years to complete as I need to revise and update every paper. I’ve written on rootstocks, the role of fertilisers and chemicals, how trees grow to name a few.
Marcotting
Sheryl: What plants wouldn’t you marcot?
Ian: You have to decide first if they are going to go into a pot (OK) or in the ground. e.g. If you marcot Camellias there could be one in the Phytophthora range – pithium, rhizoctonia, sclerotinia, ready to attack the sensitive bottom of the cutting. eg. In germinating citrus seeds, I am not interested in citrophthora or parasitica at that moment, I’m interested in pithium. The one that kills the Jarrah in WA is phytophthora cinnamomi, and Citrus are immune but there is a huge range of pathogenic fungi, I think I saw 600 species on one list.
Sheryl: So you’re saying that the majority of marcots in a sub-tropical climate are only suitable for pots?
Ian: Yes, for citrus in SE Qld (sub-tropical) you have problems with Phytophthora parasitica right into the tropics. From Sydney down we don’t have parasitica as it’s too cold. Parasitica works year round in warm climates. If you get a cold snap, it will go dormant but it doesn’t happen very often. In the case of Citrophthora it will stay dormant in summer and then activate when soils cool down.
Avocado
Ian: We grow Bacon (early) Hass (mid-season) & Reed (late-season) in Renmark and can achieve eight months of harvesting.
pH & climate
Sheryl: What’s your pH here – everything looks so healthy.
Ian: pH8.5 – all of the upper areas of SA are alkaline almost without exception. I recently visited a nursery on the Blanchetown Plains (on Goyder’s Line halfway to Adelaide from here) that had a pH11 – we are in a hot, dry desert environment. Last year we got 125mm of rain, previous year was 110 and we’re supposed to get 250. We have not achieved our annual average for so long we don’t know what it’s like.
Bay Tree
Can be used as a hedge plant or an indoor plant as it is easy to shape.
Grapes
There used to be a collection of 6,000 different vine species at the Viticultural Research Station, Nuriootpa in the Barossa Valley. A new director came in and bulldozed most of them so they’re now back to 1500 – he was sacked after 2 years but the damage and loss was done. At Irymple near Mildura Boulevarde Nurseries have installed a $500,000 glasshouse where they propagate grape vines year round using a French method. Kathy Mullins is the Tissue Culture specialist. Peter Smith owner of Sunraysia Nurseries at Buronga, NSW (across the river from Mildura) is the specialist in the commercial side of Vine Improvement
Figs
Produce two crops. The spring crop comes from completed spurs at the end of the previous year’s growth. By pruning a proportion of long shoots back to, say, 10-20cm spurs in winter, new growth from the spur will produce an autumn crop. Smyrna is the main commercial variety in the world. For it to be productive it needs to be fertilised with a Capri wasp. The Capri wasp is half the size of a tiny black ant that you can hardly see and lives in the Capri fig. Its cycle starts in there until the point where it emerges from a hole in the Capri fig base about a quarter of the size of a pin head. You place a wire basket on the windward side of each Smyrna tree and put one fig with emerging wasps in the basket– they’re very poor flyers. It’s only when the Smyrna fig base opens that the Capri wasp can go in and lay its eggs. So, every day, you pick another fig and put it in the basket over a period of some four weeks. Smyrna figs have one major crop unlike some of the other types – they are green almost translucent so that when you dry them you can almost see through the fig.
Take cuttings and put in sand to callous and place another pot on top to cut out the light. Most figs appreciate a hot dry summer so you may have problems. For a single tree pruned to contain it to a small size, try a plastic cover over summer harvest. The added heat will not be a problem. eg Marsa Matruh (Egypt’s major fig production area on the Libyan border,) regularly gets temperatures in the range of 40-50C in the summer harvest period! They would be great in pots espaliered where climate moderation is practical. Tony Stevens of Rare Fruit Society in Adelaide (ph: 08.8524 2192) is the Fig guru here and has a collection of some 60-90 cultivars. He could recommend a variety to suit.
Secateurs and budding/grafting knives.
We stock Italian Manaresi secateaurs and a range of left and right handed grafting and budding knives. I have used my own personal snips for 20years and they are still in good condition. They are OK for both left and right handed people also. They have two cutting edges, take much less muscle to operate and produce clean unbruised cuts. We use a standard (fine) Diamond hone to sharpen.
Budding Knife
It’s a myth that Grandpa’s old cowhide strop was a good sharpening tool. It bends and also applies extra pressure on the knife edge. I make Strops by request. Cowhide on a rigid board – smooth one side and nap on the other. If you drop your blade you can straighten the blade on the shiny side of the leather. After you’ve budded say 200 or so buds you can strop the blade on the nap side keeping the blade really sharp without the need for major sharpening and consequent wear. I threw out all my oilstones decades ago as they were seldom straight and they take off too much metal, so shortening the tool’s life. My left handed budding knife is 25 years old and still has the original curve at the tip – most people tell me they get 5 years of commercial use out of theirs. (using oilstones!) Never use a budding knife for cutting plastic because plastic is severe on a blade – just buy a cheap Stanley knife and keep breaking off the segments when they become blunt. I use the plastic end of that cutter to control the depth of cut when removing plastic budding ties and this avoids cutting the plant.
Citrus seed production
We have supplied high quality citrus seed to commercial nurserymen for more than thirty years. The seed is graded, heat treated for pathogen elimination, dried and dusted in Thiragranz (TMTD) prior to heat sealing in one litre HD plastic bags. To do the job we built a stainless steel unit that shreds the fruit separating the seed from the skins. A reciprocating stainless steel screen separates the seed from the pulp. The seed and mucilage is treated with hydrated lime and washed clean. We don’t dry the seed off completely – it’s a bit like giving birth – every ‘variety’ is so different. With Cleopatra mandarin (small seed) you could easily over dry it and then next year the time could be different! This year could be humid – I dry through a controlled Harvest Maid but the humidity I cannot control, so then I could have a problem. This process still requires a professional touch. The label will give date of extraction, what tree the seeds came from, date, variety, what we treated it with, complete with perishable storage and planting instructions.
Ian propagates trees for the Rare Fruit Society of SA and has some 100 varieties of citrus trees for sale as well as propagation tools so if you want the rare, then write to him at PO Box 2 Renmark SA 5341 or fax: 08.8595 1780 email: ist@riverland.net.au.
Article compiled by Sheryl Backhouse