Talk by Jenny Iriondo from Cedar Creek Nursery on Citrus

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Cedar Creek Nursery commenced in 1988 in a small backyard in Arana Hills, Brisbane. We planted 1000 seeds and the neighbour’s children and ours had great delight bagging the first seedlings. We grafted five varieties: Washington Navel, Valencias, Imperials, Ellendales and Page Mandarin and then another 10,000 seeds were planted. Retrenchment for Joe as an Engineer encouraged us to sell our trees at the North Pine Country Market. Hawkins Nursery came and bought from us and our family business has grown into what it is today.  Our two sons Michael and David are partners and we have growers from Cairns Emerald Gayndah and Mundubbera who regularly purchase for their orchards. Trees cannot move from Qld. to the other States because of the Citrus Canker. In Emerald more budwood was illegally bought in and the virus has destroyed thousands of trees in the hope of eradicating the disease. It’s still not known if it is controlled. The industry has been driven to improve the quality of fruit. The Imperial, Ellendale and Murcotts are competing with the large overseas market. Since 1986, varieties have been imported from overseas in the hope that a better eating variety of mandarin, orange and lemon would be found. Many varieties you may have heard of recently released are: Afourer, Daisy & Sunburst Mandarins; Navelina & Midnight Oranges and Verna & Limoneira Lemons. The low seeded Murcott has been the latest development as well as the low seeded Lemon. Everyone is very cautious and all are awaiting DPI inspections. The industry is at a standstill at the moment with the citrus canker outbreak. How did we learn it all? We go to International Conferences, we talk to people and we try everything.  The Encore, although we grow it, will never become a commercial variety and the reason is that it comes in late and it comes into the fruit fly season and hangs onto the tree and that’s the advantage of it. I was eating Encore in NZ in March at the Research Station. Daisy can also hang on the tree for six weeks. We also discovered that top-working Citrus trees are a waste of time for the professional grower.


The main rootstock for Imperial has been Troyer because it gives a heavy yield. The problem is that the rootstock grows over the graft and the fruit quality diminishes within 8 years and the trees need to be replaced. Commercial orchards now plant a new tree in-between and remove the older tree after twelve years. Cleopatra is another favoured rootstock for Imperials. It is susceptible to root disease and likes only sandy loam. Volkneriana has replaced the old Rough Lemon. Murcottts are less sweet and Eureka Lemons have smoother skin on the new rootstock. To overcome the cincture of Imperials on Troyer, we have been using an inter-stock of Valencia or Sweet Orange. Hopefully, this will produce better fruit and a longer lasting tree.

Planting out your tree 

Sheryl  The books say that citrus is shallow rooted but they’re not at our place! We tried to pull a couple out – not even with the car!

Jenny They’re not deep compared with say a macadamia and I’ve heard they’re no more than 1 metre and a lemon would have the most extensive root system but what they mean is that Citrus are surface bearers. People put on a lot of mulch. Keep the mulch away until the tree has been in the ground for 2-3 months and is firm in the ground and don’t put any mulch in with the soil when you cover it with dirt as it might not have broken down properly and it will burn the roots and that is why some trees go yellow!! You need to get air/sunlight/water to get those roots going. I wouldn’t mulch a citrus tree for at least 6 months if I could help it. Water in well so all the air pockets are gone. Our trees wouldn’t need fertiliser for six months and the leaf is the answer to when you need to do something. When we use to live in Brisbane, we only had to fertilise our trees when it started to fruit heavily and it only needs a lot when it gets to 3 years. (Jenny, others say they only fertilise after fruiting) If the leaf is falling off, something is burning the tree or it’s too dry. It’s only when it leaches out that you need to replace it. I’ve been up to Gayndah and I’ve had growers say to me that their trees aren’t growing so I’ve dug the tree up and the plastic’s still on! When you buy any tree and it doesn’t matter whether it’s a Mango/Lychee etc. my advice is to get the tree and cut it right across the bottom so if it’s been sitting on gravel etc. the roots may be twisted. Another problem we encounter is that people don’t get their soil tested before they start to plant out and one chap whose trees weren’t growing had really salty soil when we tested it. Never take things for granted. When we plant our seed, we plant them in polystyrene boxes which we paint inside with Copper mixed with white household paint so that when the roots get down to the bottom, the Copper burns the bottom of the roots so you end up with a fibrous root system. We might grow 500,000 seedlings for 100,000. We have a huge throw out. You don’t want anything inferior – you want everything straight and all those fibrous roots at the beginning. We guarantee that our trees will grow. When we put them in the bag a year later, you have your top roots at the top and they keep branching out so when you break all this mix away, they’re not tangled. We pay $66.00 a cubic metre for this mix and the reason is we know we will never have Phytophthora and we guarantee that you will have a good tree. We put our money into the root system – it doesn’t matter how small the top is. If you don’t have a proper root system, then you’ve wasted your money. You won’t get the problems if it’s growing in the ground properly.

Matt  If you do get a root bound tree, can you cut off all that root?

Jenny  Yes, cut off the bottom, pull the bag up and leave it over the base of your tree which is the rootstock.  If you keep the black plastic there, you’re not getting all the suckers developing on your rootstock. When you disturb all these roots, the rootstock is going to start growing and this method stops you banging the mower against the tree and will stop any wildlife like hares from attacking the trunk of the tree. If you’re putting on the oil and the copper, you will have a healthy leaf because the Copper is going to treat the roots whether it’s in clay/sand/rock – you’re treating the whole tree.  If you’re putting the oil to cover the leaf  ¼ % mix the two together and coat the whole so the insects are fooled. If your leaf is not healthy, it’s because you’re not treating the roots because the roots are not absorbing the Copper because you haven’t kept the leaves healthy. So what I’m asking you to do which is very cost effective is get some Norshshield or other copper product which is very cheap – get some oil and mix them together and do this every 10 days especially when it’s wet from October to March. If you keep your tree healthy your leaf will be healthy and you won’t need to use any insecticides. You won’t have a zinc or magnesium problem. There’s a chap I know who goes out every night and sprays his trees with Molasses & water every night I’ve never seen a bug on his place ever. Check out the internet for the rate.

Sheryl The bugs don’t like the stickiness.

Jenny With gall wasp, the DPI say to spray the last week in November and the 1st week in December so if put oil on your trees at these times, that will get rid of your gall wasp.

George Fungus doesn’t like zinc so if you keep your levels up, your tree is healthy.

Jenny We haven’t had to put any zinc on the trees but it comes back to good drainage. If you have bad drainage, and you get over-watering, you’ll run into problems with your zinc. We get a lot of good bugs like the Assassin Bugs/Ladybirds.

Fertilise In winter when it’s cold the leaves can’t absorb anything so the root system have gone to sleep so usually in winter you’ll see the signs where they’re not absorbing magnesium and that’s when you start getting symptoms of yellow blotching.

Sheryl What do you think of foliar fertiliser?

Jenny We’ve tried foliar fertiliser but we don’t believe that’s it’s very effective. We’re looking to spend $10,000 on this Longlife Fertiliser but if you miss putting on fertiliser and the tree needs it, you’re holding the tree back so if you have a fertiliser in there that’s releasing  all the time, you’re a `step ahead. We also put fertiliser through the water. We might put Calcium through one day and Potassium the next.

George Do you get leaf analysis?

Jenny We use to have it all done but we do it ourselves now. If you get the experts out and they take a little bit of the potting mix and they go and test it and you’ve got 100,000 trees and your watering system that sprays inside to out, not all trees are getting the same amount of watering, it’s a nightmare. You have to judge looking at the leaf. The inside tree is going to look different to the tree on the outside. If you put a little fertiliser on every month from August to April, you’ll have continual growth. We use Nitrophoska Blue.  

Frost  Up the coast we grow everything out in the open so if we have a tree flushing in May and we get a cold winter, the frost can kill the trees. The frost will affect soft growth so if you have hard growth you won’t have a problem so we’ll stop fertilising in April

Pruning  Do you know you’re suppose to keep the centre of your tree aerated so keep it open. 

Jenny I’ve spoken to experts on Fruit Fly and they say the worst problem is tomatoes. We eradicated tomatoes on our place and perhaps that’s why we don’t have fruit fly problem this year.

George We grow Tomatoes but our citrus don’t get touched at all.

Sheryl  Jenny has invited us up again.  They want to get into breeding different varieties and they’ll show us how to cross-pollinate so we’ll plan on a visit when the trees are flowering in September.

Jenny   What we are looking for at the moment is a Mandarin that has a consistent colour. If you are growing your trees in Emerald for example, it’s very hard to get a deep red colour. They’re a pale yellow colour because of the heat. The market loves red so if you get a deep orangy colour, people go for it. We’re trying to reduce the number of seeds, the dryness and have a more consistent size in the Mandarin and we’re doing this by crossing flowers. If you want to go commercial, put in some Tahatitian Limes in a small way. You want them to be fruiting from July – Nov. 

Peter It’s too late. The Mango growers have bulldozed all their trees and have put in Limes.

Jenny It seems to be who you know but the cooking shows are all recommending Limes. You can bring on flowering in citrus by cutting watering. 

John Why are shop bought Mandarins terrible.

Sheryl I think it’s because they’ve had too much water pumped into them so the sugars are diluted.

Jenny  I know one grower who sprays his Murcotts to keep them green as he wants to pick them in November when the price is high. They use to spray Ellendales with a certain chemical to get the sweetness into the fruit because they were picked too green and the sugar to acid ratio is really difficult to work from season to season so that’s why it has become a difficult piece of fruit to market. The DPI did a lot of work on the low seeded Murcott. We took the budwood to Indooroopilly and they radiated the seeds. From radiating the budwood, they were grown on in 1998, and they’ve come up with this low seeded Murcott. They’re now down to around 5 seeds per fruit. There are tighter restrictions today but eventually there will be better fruit in the shop.

Murray I have a friend who has a fruit juice shop at Brookside and he buys Hickson because he gets more juice out of them than Oranges and he has no trouble selling them. We juice our Mandarins and it freezes well for at least 6 months.

George We find the best tasting juice is Tangelo. 

Jenny We juice then heat it to 70º and it bottles well – keeps for 3 months at least.  

Sheryl:  Jenny and her two sons, David and Michael, run Cedar Creek Nursery, 470 Cedar Creek Road, Belli Park Qld 4562. Located approx. 2 hours north of Brisbane. It is a specialist wholesale nursery – visiting by appointment only. Ph: 07 5447 0101. email:

Article compiled by Sheryl Backhouse