Gall Wasp Preventative Treatment – ‘Overhaul’

Photo by NSW Department of Primary Industries

Finally we have a new preventative for the infuriating gall wasp that has been decimating our citrus, lemon trees in particular, across Victoria.

‘Overhaul’ is an organically* rated kaolin clay (used in papermaking and ceramics) and has been used in broad-acre agriculture to reduce heat stress and sunburn in tree and horticultural crops (e.g. tomatoes) for 18 years; in that time an unexpected secondary benefit has become apparent: the fine coating of clay resulted in less insect damage to crops. It is hypothesised that the clay works in a variety of way depending on the insect: repelling, reducing egg laying, impeding grasping, restricting movement, altering behaviour, inducing paralysis and mortality, and camouflaging the plant. Whichever way it works, trials by the NSW Dept. of Agriculture in the Riverland and Sunraysia have found it significantly reduces the incidence of galls (from Citrus Gall Wasp) in their citrus trees. Both number and size of galls are reduced (70-90%).

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Citrus Gall Wasp

Citrus Gall Wasp

(Photograph by Bulleen Art & Garden)

Citrus gall wasps (Bruchophagus fellis) are small (3mm) shiny black wasps native to northern Australia. There they have natural predators (two parasites) which keep the number of gall wasps under control. As the wasps have gradually moved south (thought to be via the movement of infected citrus trees), they have appeared in many areas without their natural predators, and consequently have exploded in numbers and caused considerable damage.
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Queensland Fruit Fly

Queensland Fruit Fly

(Queensland fruit fly. Photo © Agriculture Victoria)

Queensland fruit fly is a significant pest that has been found in areas of Victoria for a few years now. Recently there is evidence the fly is establishing itself in Melbourne and surrounds. It feeds on a wide range of fruits and vegetables, and is understandably causing a great deal of anxiety for both home gardeners and commercial growers. Queensland fruit fly from the start of spring and through summer and autumn. They are able to survive mild winters as well.
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Lots of Lemons?

Lots of Lemons?

Photo from Wiki Commons

If you have a Lisbon Lemon, you are probably looking at a glut of lemons right now. Even Eureka and Meyer lemon trees are full of fruit, but it is the Lisbons that are just groaning with huge loads of lemons. And these are the best of lemons, super lemony, tart, strong, wonderful skin for grating – the perfect lemon.

So, what to do with this superfluity of lemons? For years my brother has been banging on about his preserved lemons, I have been nodding gently and looking impressed, but secretly wondering what on earth you actually DO with preserved lemons. Then… my niece cooked me dinner one night and it was sensational. I was tactfully asking exactly what was in the dish to take it from good to superb, when she told me how the preserved lemons she had made took it to the next level – and this was in New York, in a kitchen the size of a postage stamp. I asked around, and it seems everyone is using preserved lemons, especially in Morrocan cooking (yet another culinary train that left without me).
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Citrus Root Stocks

Citrus Root Stocks

Photo from Wiki Commons

Citrus are grafted onto rootstocks in order to give the tree protection from pests and diseases, greater tolerance for specific soil conditions, a shorter time before full fruit production is reached, tolerance to cold (or heat), to drought or waterlogging. There are different rootstocks to serve different purposes. At BAAG we commonly see four different rootstocks:

Trifoliata – Poncirus trifoliata
Excellent tolerance to phytopthera, Tristeza and citrus nematode, poor resistance to Exocortis, poor tolerance to salinity and alkalinity. Excellent tolerance to poor drainage, good tolerance to sandy and loamy soils. Cold hardy. Shallow rooting, but dense fibrous roots. Generally highly fruitful with very good quality fruit. Poor drought tolerance. Incompatible with Eureka Lemon

Troyer root stock
Good phytopthera resistance, excellent Tristeza resistance, limited Exocortis tolerance, moderate nematode resistance. Good in sandy, loamy or poorly drained soils. Moderately tolerant of salinity, limited alkalinity tolerance. Very cold hardy. Gives trees high productivity and good quality fruit. Benefits from additional micronutrients, and calcareous soils leads to micronutrient deficiency. Medium rooting. Incompatible with Eureka lemon

Rough lemon
Rough lemon is a very good rootstock for producing large highly drought tolerant healthy trees with extensive lateral and vertical root development, however it tends to produce fruit rough in texture and lower in juice. These negative effects can be at least partly countered by adjusting nutrition programs but rough lemon also tends to produce larger fruit with thicker skins. Commonly used with Eureka lemons due to their incompatibility with other rootstocks.

Flying dragon rootstock – Poncirus trifoliata ‘Flying Dragon’
This citrus rootstock is used to dwarf the variety grafted onto it. It is a mutated Trifoliatia species which has hooked thorns and is much slower growing. Due to the difficulty and slowness in growing Flying Dragon, Citrus varieties grafted onto this variety are usually more expensive. It imparts the same characteristics to the scion, including cold hardiness, tolerance to root fungi and nematodes. The tree grown on this rootstock grows to about 1.5 – 2 meters in size which is about half the size of a normal citrus tree depending on the variety of tree. Dwarf Citrus trees grow well and are as strong as general types of citrus trees with the same quality and size of fruit.

For general information on growing citrus trees, click here.

Tangelos

Most people have a favourite citrus, and the Tangelo is mine! I love the sweet/tart flavour, and combine that with its easy peel nature and super juiciness, it is my ideal citrus. Very hard to find regularly in the supermarket, it pops up on the shelves occasionally between July and October, but rarely. Better to grow your own.

A Tangelo is a hybrid cross between a Mandarin and a Grapefruit, which give it the easy peel skin and sweet/tart flavour. They are all self-fertile and rapid growers that can reach around 4-8 metres tall by 4 metres wide. They are evergreen very attractive trees attractive. They make a great specimen tree, hedge or screen and are very hardy and cold tolerant. They prefer full sun.

Varieties

Minneola

A mid-season variety with large bright red to orange fruit and a glossy, thin skin. This one has a really tasty grapefruit flavour. The tree tends to bear fruit every second year (biennial bearing).

Seminole

This tangelo was bred in the USA and has similar fruit to a Minneola except that the tree itself tends to over bear, making fruit smaller. It is wise for the home gardener growing this one to practise thinning the fruit. Fruit is late, ripening around July or August.

For general information on growing citrus trees, click here

Mandarins

Mandarins are attractive, evergreen, compact trees. They have small glossy green leaves which contrast beautifully with the intense orange fruit. They are self-fertile and fruit easily when given full sun, fertiliser and a well drained soil that is kept moist over the fruiting period. Thinning of flowers encourages larger fruit to form.

Mandarins are commonly used for screening, hedging, espalier or specimen plantings.

Dwarf varieties are also available for growing in large pots. Eat fresh or use in desserts.

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Grapefruit

Grapefruit grow on a vigorous evergreen tree that can easily reach a height of 4 metres or more, with a similar width. Pruning will keep them to a manageable size. All varieties like well-drained soil and full sun. You will be rewarded to with kilos of fruit if you choose the most suitable variety for your climate.

All grapefruits are self-fertile and are great eaten fresh when used in preserves or marmalades. Grapefruit trees are excellent for screening or hedging, they make fantastic shade trees and are easily espaliered. Not recommended for pots.
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Cumquats

All cumquats are self-fertile, evergreen and will grow happily in either full sun or part-shade. They are also very cold tolerant. Soon after the fragrant, white flowers appear they produce ornamental fruit which stay on the tree for a long period. The fruit can be used for liqueurs, preserves, marmalades, drinks and bottling. All cumquat varieties are excellent for containers, screening, espalier and standards.

Varieties

Marumi (or Meiwa)
This cumquat grows into a small tree (around 3m x 3m). A very persistant fruiting variety that peaks in autumn and winter. The round fruit has a tart flavour and sweet rind.

Calamondin or Australian
A popular variety that is highly ornamental due to its columnar, upright habit and glossy, compact leaves. It is a vigorous grower and can reach 8m x 4m when mature. Will remain much smaller in pots. An abundant fruiter that peaks in autumn and winter. The fruit is juicy and sour with loose skin.

Nagami

A small, elegant plant that can grow to around 3m x 3m. Remains slightly smaller in pots. A variegated form is also available. The fruit is small and oval shaped with a thin skin and it is very juicy and only slightly acidic. The only cumquat variety suitable for eating fresh off the tree. The skin is also edible.

Chinotto
Chinotto is an ornamental citrus that makes a stunning pot specimen. It produces small, bright orange fruit every year that ripen in winter. The fruit isn’t edible fresh as it is very bitter. It can be preserved, but generally this tree is grown as an ornamental. The leaves are attractively arranged in a spiral around the long and upright stems. Possibly the source of the popular Italian drink with the same name.

For general information on growing citrus trees, click here.

Australian Finger Lime

Photo © Daley's Nursery - Used with permission

Citrus australasica

Finger limes (Citrus australasica & Citrus australasica var. sanguinea) are native to the rainforests of SE Queensland and northern NSW.  A naturally thorny 6m tall understory tree producing the highly desirable 6-12cm long finger shaped fruit; they are highly adaptable and commercially are grown in poor soils.  Finger limes are genetically very diverse and it is this diversity that has resulted in the wide range of named cultivars displaying many and varied colours.  Grafted trees (root stock is Citrus trifoliata) will give you true to name fruit and will begin fruiting in year three, and will be fully productive at year six – producing up to 20kg fruit.

Position

Find a spot that has some protection from hot afternoon sun which can burn the fruit

Fruiting

The development period from flowering to harvest is around 5 months. Make sure trees have sufficient water at flowering and fruit set, and over the fruit growth time.  As with most citrus, fruit drop can occur naturally early in the season if more fruit is set then the tree can carry. Fruit may also be shed during very hot dry and or windy conditions.

Fertilising

Finger limes require a lot less fertiliser than other citrus, possibly due to smaller leaves and reduced canopy. Commercial growers apply only 25-30% of the normal amount of fertiliser.  The majority of feeder roots tend to be in the top 30-60cm of soil and a low phosphorus fertiliser is recommended, applied in small amounts 2-3 times in the growing season.  Over fertilising can cause dieback.  Do NOT apply fertiliser from flowering up until the fruit is a minimum of 1cm long or fruit can abort.

Photo © Bulleen Art & Garden

Pruning

Avoid pruning in hot weather as the exposure to the sun may burn the fruit. The trees like regular light pruning – heavy pruning can kill a fingerlime.  Cut back any vigorous water shoots and suckers from rootstocks, and try to establish an open tree with 4-6 main branches. Once mature, an annual prune after harvest to renew fruiting wood and to keep trees to a manageable size (hard to get the fruit when they are 5m off the ground…).  Removing crossing branches and excessive growth helps protect the fruit from damage by nearby thorny branches.

Cultivars

More new ones come onto the market every year, as well as new hybrids, crossed with mandarins and cumquats.  Generally bred for colour and degree of seediness, new cultivars range from pale green to dark red.

New Cultivars

‘Autralian Blood’ (syn ‘Australian Red Centre’) is a hybrid with blood red rind, flesh and juice. This hybrid was produced by CSIRO by open pollination, from a cross between an Ellendale Mandarin (a mandarin and orange hybrid) and a seedling form of the Australian Finger lime (Citrus australasica var. sanguinea).

‘Australian Sunrise’ another hybrid producing pear shaped orange fruit which makes a stunning marmalade. This is a complex hybrid also developed by CSIRO: Citrus australasica x (Fortunella sp. x Citrus reticulata).

‘Australian outback’ (syn ‘Australian Desert’) (Citrus galuca) Not a finger lime but a native lime producing small round green juicy fruits ripening late December.  Wonderful in fruit sauces and as a garnish. Trees are tough, withstanding both extreme heat and frosts. Interesting fact: Trees are thorny to protect themselves from grazing by native animals, but above kangaroo grazing height they do not produce thorns. Commercial propagators take the non thorny material and graft onto commercial root stock (commonly the trifoliate rootstock).

‘Pink Ice’: Slightly bitter – think of grapefruit – wonderful as a garnish in drinks or seafood

‘Pink Champagne’: Plump fruit, crisp clean flavour. Grapefruit.

‘Rainforest Pearl’: A peppery number with bite. Piquant. Tash’s favourite

‘Red Champagne’:Red skin and flesh, amazing bouquet of flavours: Spiced apple, berry, apricot

‘Alstonville’: One of the easiest fingerlimes – fewer seeds and smooth easy eating flavours.

‘Chartreuse’: Gently acidic and lime flavoured, excellent lime/lemon replacer for seafood, garnishes, in your G&T.

‘Crystal’:  Green skin, green ‘caviar’ – very fresh, very juicy

‘Crimson Tide’:  Amazing deep red caviar, almost black skin

‘Yellow’: Grafted variety. Yellow skin and yellow flesh with lemong tang and grapefruit tones. Very pretty. Paul’s personal favourite.

And loads more coming onto the market all the time…

Uses in the kitchen

The juice of this lime is similar to exotic limes, but the juice is held in compressed juice vesicles which look a little like caviar. When the thin skin of the lime is cut, these vesicles can be removed and added to drinks, canapés (oysters for example), desserts, fruit salads, and used as a garnish or decoration. The vesicles will bounce up and down if added to carbonated drinks, which is sure to be a conversation starter at your next party. Juiced, the Australian finger lime can be used as a Tahitian lime substitute. For example, in south-east Asian cuisine. Finger limes can also be pickled or made into marmalade.

For general information on growing citrus trees, click here.

Recipe

SUMMER CURED ATLANTIC SALMON WITH AUSTRALIAN NATIVE FINGERLIMES.

Ingredients :
400 g Atlantic Salmon (skinned and boned)
2 Lemons, juiced
4 Australian Native Finger limes
40 ml Mirin
25 ml Rice Wine Vinegar
1 stick of Lemongrass (bashed with a mallet)
Pinch of Sea Salt
Pinch of White Pepper
½ bunch of Coriander
4 Bamboo skewers (soaked in water first)
Bunch of Rocket
Splash of Soy Sauce

Method :
Cut the salmon into finger-size lengths . Skewer the salmon length ways so you end up with long salmon kebabs .
Mix lemon and Australian Native Finger limes juice and pulp, mirin, rice wine vinegar , sea salt , pepper and lemongrass in a bowl .
Place salmon skewers in a shallow dish and pour liquid over the kebabs . Refrigerate for 5 minutes .

Serve on a bed of rocket with a little soy sauce drizzled over the top , and finish with picked coriander (This method of cookery is French and requires the acid in the citrus to slowly cook the fish) .

Citrus Leafminer

Phyllocnistis citrella

This is a small nocturnal moth which lays its eggs on the underside of soft fresh leaves of citrus. The eggs hatch and the larvae rapidly burrow under the surface of the leaf, and it is these larvae that cause all the damage. The larvae feed on the epidermal cells of the leaf, creating the typical silvery snake-like ‘mined’ damage to the leaf.

Controlling Citrus-leafminer

Pheromone Traps
Finally something that works! One of our wholesalers in Victoria used these last year with great success. Called the eco-CLM Trap, it is a sticky trap combined with a very strong pheromone lure which attracts the male citrus leafminer. The result is fewer females able to lay eggs and much greater protection for your trees. The lure remains effective for around 2-3 months, and you need 1 for a small tree, 2 for a large tree. As soon as the weather warms up, the leaf miners become active, so install sometime in spring – temperature depending. Keep an eye out after 12 weeks and if damage is occurring – you may need to install another one. The pheromone is specific to the male Citrus Leafminer, so does not attract any beneficial insects that may be around.

Chemical control

While very difficult to control with insecticides because they are protected by their leaf ‘mines’, they can be managed by both cultural means and predatory insects. If choosing to spray, the best spray to use for the home gardener is white oil. The moths avoid leaf surfaces sprayed with oil. Spray every 5-7 days in warm weather and spray both upper and lower sides of new growth (don’t wait for leaf to fully open, start spraying when still tiny). Spray to the point of run off: i.e. have a fine mist over the leaves, but if the spray starts dripping off the leaves you have sprayed too much and the effort is wasted. Because this is an oil water mix, continually shake or agitate the mixture to prevent it from separating. Do not spray when the soil is dry, as trees should not be suffering moisture stress when you spray, and avoid spraying when over 32ºC.

Spinosad (marketed as Success) is reputed to be effective against leaf-miners, particularly Tomato leaf-miner. Whether or not it is effective against Citrus Leafminer is not known yet.

Natural Enemies

Brown and Green Lacewings predate on Citrus Leafminer. Green Lacewings are available as a biological control. They are highly susceptible to pesticides, so do not release them for 4 weeks after residual pesticide use.

Cultural control

Citrus Leafminer is most active over summer and autumn and is restricted to soft new growth, so you need to adjust pruning and feeding regimes to get the soft new growth when the Citrus Leafminer is not active. Keep watering and fertilizing to the minimum required for the health of the tree for the rest of the year. Prune leaf flushes at other times of the year.

Citrus Trees General Information

Citrus trees offer glossy green foliage year round, with sweetly scented flowers and beautiful and edible fruit. There are few trees that are as ornamental and practical as a citrus tree. Citrus are a must for every back yard. Varieties include: Cumquats, Grapefruit, Lemons, Limes, Mandarins, Oranges, Tangelos, Pumelos and various others.

Growing Conditions

Citrus trees prefer a full sun position. They will grow well with up to half a day of sun, but will produce more foliage and less flowers and fruit with less direct sunlight. They need to be protected from frost, which damages the foliage and fruit, and from wind. Good drainage is necessary for all citrus. Soils must therefore be well drained. Planting citrus in raised beds or pots is the best option if the drainage is poor. The addition of compost to the soil may help improve the drainage. Soils should be neutral to acid in pH to successfully grow citrus. Citrus are shallow-rooted trees and thus require regular watering especially during the hot summer months. Avoid digging or planting around the base of the tree. Keep the area under the tree free of grass and mulch well. Smaller varieties of citrus are ideal grown in large pots or tubs. Try Cumquats, Myer Lemons, Tahitian and Kaffir/Makrut Limes.

Mulching

Mulch Citrus in spring to conserve moisture during the hot summer months. Be careful not to build the mulch up around the trunk of the trees, as this may cause collar rot. Remove the previous years mulch before putting a new layer down.


Feeding

At a minimum citrus should be fertilised with Fruit & Citrus Food in early September and again in early March. In addition to this, under the mulch layer, a layer of manure and compost may be spread. Some older leaves may yellow as flowering is initiated. If the trees are well fertilised, mulched and watered during summer then an autumn application of fertiliser should be all that is required to keep the leaves green in winter. Alternatively, a liquid fertiliser may be used in winter as a quick green up.

Pruning

Pruning is really only necessary to remove dead wood and to cut out branches that are rubbing against each other; or to shape the tree as desired. Citrus Gall Wasp is prevalent in this area, so prune out all galls. Remove all shoots that come from below the graft.

Watering

Citrus are not deep rooted trees and thus require regular watering. Care must be taken to ensure they have
adequate water during the hot summer months. Do not over water citrus trees.

Pests

Aphids: usually found on new growth, particularly in spring and autumn. Squash by hand or use Garlic and Chilli sprays, Pyrethrum.

Scale insects: various types of scale affect citrus trees. These will be different colours, and are usually found near the mid vein and on the stems. Again, spring and autumn are the usual seasons when these are more
prevalent. Squash by hand or spray with White Oil or Eco Oil making sure to cover the insects.

Citrus Leaf Miner: These leave silvery trails in the leaf and the leaf edges curl inwards. Control using White Oil.

Citrus Gall Wasp

Citrus gall wasps (Bruchophagus fellis) are small (3mm) shiny black wasps native to northern Australia. Adult wasps emerge in spring, often timing emergence with the onset of a flush of new growth. The wasps have a limited flying range, so, unless they are moved by the wind, they tend to re-infest the trees they emerged from. After mating, the female immediately lays her eggs into the soft new season flush.
Best practice includes:

  • Reduce the amount of soft spring flush growth by pruning (and gall removal) and fertilising in late summer or autumn instead of late winter and spring .Use a balanced fertiliser rather than a highly nitrogenous one.
  • Spraying with Overhaul – a Kaolin clay product in spring and summer
  • Placing sticky traps (see below) into the trees around spring to catch emerging wasps and prevent them mating and laying eggs into the new growth. Adult wasps don’t fly far. They can be moved good distances by wind, but will tend to re-infect the tree they emerged from. Hence traps are useful to prevent re-infection.
  • Remove galls before spring, wrap and place in your rubbish bin (NOT your greenwaste bin).
  • Where possible, get neighbours involved and protecting their trees as well.

Sooty Mold and Ants: these are secondary problems arising from another pest problem. The presence of Sooty Mold and / or Ants is usually an indication that there is a Scale or Aphid problem. The Ants and Sooty Mold feed from the sticky exudate of the Scale and Aphids. Control the Scale or Aphids and these other problems will disappear.

Mineral Deficiencies And Other Problems

Iron Deficiency
Yellowing, mainly of the newer growth, with the veins standing out in green. Apply Chelated Iron at recommended rate. The pH of the soil may be too alkaline, making the iron is inaccessible to the plant. A trace element mixture may be added to the soil, to cover various other deficiencies.


Lack of Fruit
Trees purchased with fruit on may not fruit for several years after planting. It is best to remove the developing fruit early on young trees, so that more energy is used up in root and foliage growth to establish a strong tree. Heavy crops of fruit may result in smaller sized fruit. To avoid these problems it is best to thin out heavy crops, by thinning the newly set fruit on each branch by half to two thirds. Wheeny Grapefruit tend to fruit every second year and Mandarins may produce such dense growth they fail to fruit. Other causes usually result from uneven growing conditions, over fertilising and drought or waterlogging.

Click the following links for further information on each type of citrus…

Cumquats
Grapefruit
Lemons
Mandarins
Oranges
Tangelos

Citrus Names – Citrus taxonomy – Citrus Classification – The Bittersweet Debate

Photo © Bulleen Art & Garden

Botanical names: It is generally accepted that there are 3 (possibly up to 5) original citrus species and all the rest are hybrids of these (excluding the wild species still being discovered – at least 6 in Australia). Citrus have been hybridised frequently over a long time and over wide geographic boundaries, consequently, there is a great deal of confusion around correct botanical names of commonly known citrus. As genetic testing progresses, some of the more disputed classifications will be resolved, but in the meantime we are choosing to use the classifications of Prof David Mabberley, an eminent botanist and taxonomist.

POMELO
Citrus maxima (Sometimes incorrectly referred to as Citrus grandis)
Described by Johannes Burman in 1755 as Aurantium maximum and then in 1842 as Citrus grandis by Justus Hasskarl. In 1915 the confusion was cleared up by Elmer Merril who renamed it Citrus maxima (acknowledging the earlier description by Burman).
Believed to originate in the Malay archipelago. One of the original citrus species, and by hybridising with the mandarin is involved in the parentage of several of our current citrus:
Citrus × aurantium (pomelo x mandarin) which includes the following pomelo hybrids
1. Sour Orange (e.g. Seville orange). The sour orange has inherited more features from the pomelo than from the mandarin
2. Sweet Orange (e.g. Navel Orange, Valencia Orange). The sweet orange has inherited more features from the mandarin than the pomelo. This group also includes all the crosses of orange, mandarin and grapefruit such as tangors, ortaniques, tangelos and clementines.
3. Grapefruit: These are the pomelo backcrossed with the orange.

CITRON
Citrus medica
Referred to as Citron. Used as a Jewish symbol and called Etrog in Hebrew.
Citrus medica var. sarcodactylis, or the fingered citron is referred to as Buddha’s hand in China, Japan and Korea. Used there mainly in perfumery, but also as a temple gift.
Citrus medica is one of the original species and with hybridisation is involved in many well-known current citrus (hybrid parents in brackets).
Citrus x limon, (citron × sour orange) gives us our lemons and similar hybrids such as the sweet limes (sometimes called Palestinian/Indian/common sweet Lime)
Citrus × jambhiri, (citron × mandarin) produces the rough lemon (commonly used as a good rootstock) and similar hybrids like Rangpur lime and Mandarin lime
Citrus × aurantiifolia, (citron × lemon × Ichang papeda) gives us the well-loved lime (Lime/Key Lime/West Indian Lime/Mexican Lime).
Citrus × bergamia, (citron × sour/bitter orange) gives the wonderfully scented Bergamot orange.

MANDARINS
Citrus reticulata
Mandarins are still to be thoroughly genetically tested and there are two main groups of thought on their classification. One keeps all the species together under Citrus reticulata and the other gives tangerines and satsumas their own species. For the purposes of this fact sheet we will keep them all grouped together and wait for genetic testing to definitively sort it out later.
One of the original species, varieties of this species includes the mandarins, tangerines, and satsumas.
• Mandarins
• Tangerines – closely related to, or a type of mandarin. Referred to as Citrus tangerine by those who believe it belongs in a separate species. Similar to an orange, but smaller, sweeter and stronger. Very thin peel and easily peeled like a mandarin.
• Satsumas – closely related to, or a type of mandarin. Referred to as Citrus unshiu by those who believe it belongs in a separate species. Seedless with a sweet delicate flesh. Loose, thin slightly leathery easily removed peel. Similar in size and shape to mandarins.
Extensively hybridised with citron hybrids, pomelos and pomelo hybrids to form a wide range of oranges, grapefruits and specialty citrus. It is the mandarin that adds the sweetness to these hybrids.

CUMQUAT OR KUMQUAT
Citrus japonica – formerly known as a separate genus Fortunella japonica
Within this species are several separate groups:
• Marumi/Morganni/Meiwa
These are the round cumquats, with sweet skin but sour flesh. Used in marmalades and brandied cumquats, as well as other forms of preserves.
• Nagami
These are the oval cumquats with very sweet soft skin, allowing the fruit to be eaten whole; the sweet skin contrasting with the sour flesh giving a pleasant sweet/tart flavour. Smaller growing than their round cousins, they are ideal in pots. Like all cumquats they are prolific fruiting.
Also produces a variegated form, sometimes called centennial cumquat.
Cumquats have been used in hybridisation to create new edible citrus, two of which are readily available in Australia:
• Calamondin (x citrofortunella microcarpa): A hybrid of a mandarin orange and a cumquat
• Limequat: A hybrid between a Key Lime and a cumquat.

AUSTRALIAN LIMES
There are debatably 7 species of Australian limes. The Finger limes are the most readily known and have been recently used in hybridising to produce various new hybrids. Native limes currently available in the nursery industry include:
FINGER LIMES
(Citrus australasica). Sometimes referred to as Microcitrus australasica
These come in an array of colours from almost clear, to yellow, green, pink, and reds. Desirable for culinary use due to their citrus tang and their caviar like vesicles.
ROUND LIME (DOOJA)
(Citrus australis)
A round lime similar to the Key lime. A distinct and pleasant flavour.
DESERT LIME
(Citrus glauca) formerly Eremocitrus glauca
Heat, drought, salt and cold tolerant characteristics have made this lime useful for breeding and hybridising. The fruit is small with a distinct lime flavour.

CITRUS HYBRIDS

CLEMENTINE
(Citrus x clementina). Arguably a hybrid between a mandarin and a sweet orange, but some consider it to belong to the Citrus reticulata species. Very similar to satsumas and tangerines.

TANGELO
A hybrid of a tangerine (Citrus reticulata) and either a pomelo or a grapefruit.
• Honeybell Tangelo is a hybrid cross between a Thompson Tangerine and a pomelo
• Minneola Tangelo is a cross between a Duncan Grapefruit and a Dancy Tangerine
• Seminole Tangelo is a cross between a Bowen grapefruit and Dancy Tangerine

YUZU
(Citrus x junos).
Bred from crossing Citrus x ichangensis and Citrus reticulata.¬ The C. ichangensis (also called Ichang papeda and regarded by some as a subgenus of the citrus genus) parent gives the Yuzu its cold tolerance. The Yuzu has a tart grapefruit like flavour with mandarin overtones. Very aromatic peel.

TAHITIAN LIME (also called Persian Lime)
Citrus x latifolia
A highly regarded hybrid lime, regarded as a new species and as such has an ‘x’ before the species name. The correct botanical name is Citrus × latifolia. Generally believed to be a cross between the key lime (Citrus × aurantiifolia) and a lemon (Citrus × limon).
A heavy bearing tree producing juicy seedless fruit with a fine rind and little pith. They are conventionally eaten green, before they turn yellow at full maturity and lose flavour.

LIME OR KEY LIME (also called West Indian or Mexican Lime)
Citrus x aurantiifolia
Smaller, seedier and more acidic than the Tahitian Lime, with a thinner rind and a more aromatic flavour. Used in the classic Key Lime Pie (from the Florida Keys – hence sometimes know as Key Lime).
The tree is thorny and shrubby to 5m. Not frost tolerant, needs a warm protected position in Melbourne.

INDONESIAN LIME
Unknown botanical name
This lime is only a recent introduction to Australia and currently grown by Engalls in NSW. It produces a small flat fruit, turning from green to yellow / orange when fully ripe, mainly in winter. They are incredibly juicy and the tree is only small, but very dense and bushy. Fruit has conventionally been used in cooking, especially as a marinade for meat.

RANGPUR LIME
Citrus x jambhiri
A hybrid between a mandarin and a citron hybrid

ORANGES
Citrus x aurantium
The oranges are hybrids of the pomelo and the mandarin, deriving their sweetness from their mandarin parent. Both sweet and bitter oranges are included in this grouping. The sweet oranges include many subgroupings such as Navel Oranges and Blood (or pigmented) Oranges. The sour oranges include Chinotto (Citrus x aurantium var. myrtifolia) and Seville.
Oranges are also involved in backcrossing and further hybridisation to give more edible citrus such as the grapefruits (Pomelo crossed with orange), bergamot oranges (Pomelo cross bitter orange) and lemons (Citron x bitter orange)

LEMONS
Citrus x limon
A hybrid between a bitter orange and Citron
There are many different cultivars, the two most common in Australia being the Lisbon and Eureka.
The other commonly grown lemon is the Meyer lemon (Citrus x meyeri) and it is believed to be a hybrid of a true lemon and either a mandarin or orange.

GRAPEFRUIT
Citrus x aurantium (Often referred to as Citrus x paradisi)
A hybrid derived from backcrossing a sweet orange with a pomelo. Can be highly acidic to sweet, and yellow, pink or red.
Used in further hybridisation to create tangelo varieties.

Oranges

All oranges are self-fertile, small to medium evergreen trees. They have large, dark green, glossy and aromatic foliage. The pure white flowers also fill their surroundings with their characteristic scent in spring.

The trees themselves grow large, but are easily kept pruned to a height and width of approx. 4 metres. All oranges prefer a sunny aspect with protection from frost.

As we know, they produce juicy fruit packed with Vitamin C and are generally eaten fresh or juiced. Blood Oranges are excellent for garnishing too.

Orange trees are perfect for hedging, screening, espalier, shade and as a specimen tree in any garden. Dwarf varieties can be used in pots to lend a Mediterranean feel to your courtyard garden.

Varieties

Blood Oranges

To successfully get the colouring in a blood orange the tree needs hot dry summers, cold wet winters and autumns with cold nippy nights and warm sunny days. Just the tiniest bit fussy…

Maltese

Maltese is an older variety of blood orange that develops a more regular and distinct red pigmentation in hot, dry areas with cold nights. It has a sharp, sweet flavour and the small fruit has a blood red splash on the skin. The flesh is very juicy and seedy.

Arnold

Discovered by Mike Arnold in South Australia, this is a newer variety that produces a red pigmentation in coastal climates. Better colour is produced in cooler climates. The smallish fruit ripens mid-winter and has a distinctive tang. The tree is also small and bushy, making it suitable for pots or a small garden.

Cara Cara

Not a true blood orange but a naval orange producing large seedless fruit that are very sweet and low in acid. Unlike other blood oranges that produce the red pigmentation along the veins in the flesh of the fruit, the Cara flesh is all the same colour, similar to a ruby grapefruit and they get their colouration from Lycopene rather than Anthocyanin which colours a true blood orange. Temperature can alter the colour.

Tarocco

Generally regarded as the sweetest of all blood oranges. Has the highest Vitamin C of all the oranges. Skin is orange rather than red and the red pigmentation of the flesh is often contained in the lower half of the fruit. Absolutely wonderful eating orange.

Navel Oranges

Lane’s Navel (syn. Lane’s Late Navel)

Originating from Curlwwaa, NSW property of L.C. Lane.  Very similar to a Washington Navel except that it colours later and is an excellent late holding navel. The tasty fruit begins to ripen in early spring and lasts until December. It has large fruit with a deep orange colour. It is easy to peel with very few seeds, much like other navels. One of the best oranges for fresh eating.

Leng Navel

This early ripening variety originated in Victoria and produces a fruit which is smaller and paler than a Washington navel. It has few seeds and a thin skin, making it a great choice for juicing.

Washington Navel

The richest and sweetest of all the oranges, the Washington navel has a low heat requirement and is the earliest to ripen (usually from May to June). It is the most popular backyard orange in Australia and is best eaten fresh. It is excellent for juicing, but must be drunk immediately as it will become bitter on standing. Oranges are medium to large, depending on the quantity of fruit set, and very sweet and juicy. Skin is relatively easy to peel and, being a navel, the fruit is seedless.

Navalina

An excellent cultivar imported from Spain in the 1980’s. Navelina has fruit which ripens around the end of April into May, making it a fantastic early season naval orange. It is sweet, seedless and juicy. Fruit can be slightly oblong in shape and naturally develops an attractive dark orange skin. The tree is compact and bushy.

Newhall Navel

The fruit is an unusual oval shape and is said to be the sweetest navel, making this variety a winner!

Toc Summer Navel

Fruit is large and very juicy with an excellent flavour. Toc Summer navel is a late holding navel and crops well into summer. For those gardeners with space, planting a Navelina, Washington and Lanes Late will find themselves harvesting Navels for up to six months of the year.

Valencia Oranges

Valencia

Valencia has a high heat requirement, but works well in Melbourne if you leave the fruit on the tree for a long time. This makes it the last of all oranges to ripen. Leaving fruit on the tree helps to develop full flavour and sweetness. The fruit generally starts to ripen in October and can be left on the tree until the following April. Valencias require that perfect ‘hot spot’ in the garden. The fruit is large, juicy and relatively seedless, and sometimes a challenge to peel. Keeps well and produces excellent juice, second only to Navals when eaten fresh. Ripe fruit holds on the tree for months. Use tasting as your harvest guide.

Seedless Valencia

Very similar to the Valencia. The fruit ripens a little earlier but will still hang on the tree for up to 6 months. Although named seedless, this variety will produce a few seeds if pollinated by other varieties.

Sweet Oranges

Joppa

This is one of the original varieties brought here by the first fleet. Not widely grown these days, but it is an underrated backyard orange. The tree is a strong grower and produces fruit mid-winter. Oranges are medium sized, thin skinned with a good flavour and are exceptionally juicy. They have a few seeds and well worth a try. It crops consistently every year.

Mediterranean a.k.a Parramatta

This sweet orange grows on a vigorous tree and produces a medium sized fruit that contains only a few seeds. The flesh is pale and has a mild flavour. The easy to peel fruit has a pale orange skin at maturity and has the tendency to re-green.

Sour Oranges

Seville

Seville is also called the sour or bitter orange, and once tasted you will understand why. Only really used for making jam and marmalade. It has large flattish fruit. They have a sharp bitter tang and many seeds. The fruit ripens in mid-winter. It is a strong growing tree and makes a very attractive specimen tree.

Bergamot

This tree has been grown in the Mediterranean area since the seventeenth century. The oils from the fruit peel are what make this orange famous. Oil of Bergamot is used mainly in perfume and produced throughout southern France, Italy and Paraguay. The fruit are small and smooth with a bright yellow skin when fully ripe. Similar to a Tahitian lime. You can make delicious marmalade from the skins and flesh or use the juice in place of a lemon.

For general information on growing citrus trees, click here

Lemons

Lemons are that tree everyone wants in their backyard. They are useful for hedging, screening, espalier, producing some shade or as a specimen tree. Dwarf varieties are also popular choices for growing in a pot.

All varieties prefer full sun to part-shade and a well drained soil. They benefit from loads of organic matter at planting, they love a feed at least twice a year and dislike any competition around their roots.

They are all evergreen and self fertile. Lemons are used in cooking, drinks, desserts… and on your fish and chips!

Varieties

Lisbon
A vigorous and thorny tree which reaches around 3-5m x 3-4m. Lisbon can be more cold tolerant than Eureka. Fruit is produced mainly in winter, with a smaller summer crop. The lemons are smooth skinned, large and juicy with a few seeds. The rind is thinner than Eureka.

Eureka
A vigorous tree which grows to around 3m x 3m. The biggest benefit is that the Eureka fruits all year round (with the heaviest crop in winter), so you are nearly always guaranteed to have lemons on the tree. The fruit is medium to large and highly juicy. It has a thick, pitted, rough rind and only a few seeds. They tend to hang on the almost thorn-less tree for a long period of time.

Thornless
This lemon originated in South Australia and is very similar to the Eureka, commonly referred to as the Thornless Eureka.  The skin is smoother and finer than the Eureka.

Meyer
A smaller, more compact tree than Eureka or Lisbon, Meyer only grows to around 2.5m x 2.5m. Fairly frost hardy and consequently popular where frosts occur. It produces numerous crops of medium sized lemons throughout the year. Meyer is a hybrid between a lemon and an orange, which makes the fruit smoother, rounder and sweeter (less acidic) than a classic lemon. It has a thin, orange rind without the lemon zest flavour and amber flesh.

Lemonade
A vigorous and attractive tree  with a reliable and heavy crop in winter.   It is possible to produce a second smaller summer crop. The Lemonade looks like a lemon but can be eaten straight from the tree, just like a mandarin or orange. The fruit is a lot sweeter than a lemon, with a refreshing tang.  It makes a refreshing drink when juiced.

Other interesting Citron

Buddha’s Hand
Originating in India, this has to be the most unusual citron. It has a fruit which resembles a hand with finger like segments. The fruit contains no flesh and is entirely made up of white pith. Although not commonly used in a culinary sense, it is traditionally used for perfuming clothes and rooms in China and Japan. The tree is vigorous, but still small. Perfect for those wanting something a little different.

Etrog
This unusual citron is best described as a lemon on steroids. It can grow to double the size of a standard lemon and is long and is elongated in shape with a thickish skin. The fruit is used in Jewish religious ceremonies.

For general information on growing citrus trees, click here