Visiting Peter Sauer's Longan Farm

Welcome to Dragon Eye Farm – the dragon eye is brown like the shape of a Longan, so I get a lot of customers come here and just ask for Dragon Eyes! I started toying with the idea of growing Longans about 15 years ago and had a few seedling trees. At the time there wasn’t any grafting material in Australia and I grew them with Custard Apples, Lychees – I only had about 10 trees but they produced good crops so I went on a few safari trips up north to see what was available in Australia.

I brought back about 4 or 5 varieties of Longan that I didn’t have and planted them here in 1991 and grew them for around 4 years. I then ascertained what the best varieties were, and at the time the markets were accepting seedling type fruit but then they phased this out as better varieties came in.1994 was a very hot year and I had a severe fire through here and lost every tree, tractor sheds, irrigation, pumps - the whole lot - but what I found was that where the Longans were burnt out at ground level they shot out again and some of those trees are still here. Peaches etc. didn’t reshoot.

Longans are from the Sapindaceae family together with the Rambutan, Lychee & Akee. The trees don’t require heavy amounts of fertiliser – if you fertilise heavily, all you’ll get is growth without fruit. Longans seem to do well here – they like a sandy soil and don’t perform nearly as well on heavier soils. They have a few flushes through the year – some varieties have an orange flush and some have a red flush – there is another variety which has a yellow flush.

I have 8 varieties and start picking in February and go through to April. The early varieties are: KSweeney, which is a seedling of Kohala and came from the Hawaiian Islands – it’s a little bigger than Kohala fruit. Kohala has a softer sweeter flesh with a medium/large seed and doesn’t have a long shelf life compared to the Thai varieties and the window for picking them is only 3 weeks before the sugar levels start to drop off. Some years I can go in and take clusters of them or I have to individually pick because you don’t get them flowering all at once.

Sheryl: Longans are not supposed to ripen once they’re picked. Do you have a Brix Meter to test the sugar content in your fruit before you send them to market?

Peter: Yes, it’s called the mouth!! They are a good tool to have, though. If you squeeze the fruit and they’re very hard, the sugar levels will still be in the fruit but the water content in the fruit won’t be there so what happens then is they start to swell up and need a lot of calcium which is a major element. You need high calcium levels in your soil to grow good Longans because you need calcium for expansion of the fruit as they start to swell up. I have very high calcium levels: nobody has seen Calcium levels higher. You can tell the difference between the varieties with the colour of new growth, leaf structure and time of cropping. If you start picking from new moon to full moon, that’s the best time. Crisp varieties: Biew Kiew, Chompoo, Hauw Soft varieties: KSweeney, Kohala, Dang, Daw

Member: The higher the Potash the firmer the flesh.

Peter: The Thai varieties you can pick anytime and the sugar levels will still stay in them but they’ll get more flesh ratio as the moon comes on.

David: Mine tasted better when they were smaller so I think you’d be better to eat them early when they’re sweet and fragrant than when they’re bigger and tasteless.

Fertilisers: I use a lot of gluconates – you don’t need too much of it – use it as a foliar spray. You can’t get it in small quantities. I use calcium/magnesium fertilisers. I get my soil tested at the end of March after the heavy rains and the reason. I do it then is all the minerals have leached out of the ground. I use SAFE at Burleigh on Gold Coast and they test for soil, leaf and water analysis so as soon as you see the flowers start to open, you take a few leaves below the flower pinnacle from different trees over the whole orchard and collect 80 leaves and send it off. If you use hard chemical fertiliser you can do a lot of damage by burning the roots off and also to the worm population and fungi in your soil. These chemicals are salt laden and can build up your chlorine levels in your soil and you lose a lot of your microbe activity – the rhizomes on your roots will be attacked from the salts as well as your worm population, and there’s a lot of pathogenic fungi in your soil. If you can grow good weeds, then you can grow good trees!

Barb: How do you apply your calcium?

Peter: Once your soil test comes back, you refer to the chart put out by the Lychee Association because there’s nothing for Longans - you refer to the Lychee schedule and you want a pH of 5.8. With all fruit trees, you never go over pH6 whether it’s citrus, stone fruit or whatever. The reason for that is most of your microbial activity in the soil thrives under those conditions so when you get the test back and if you need calcium, then don’t look at dolomite. I’d go for gypsum as it contains sulphur which is important to the soil and it also contains calcium. You won’t raise your pH so if your pH is 6 then use 100g/m2 of gypsum. That’ll give you a fair bit of sulphur and calcium and put it on after fruiting finishes. I also spray with gluconate microbe nutrients.

I put Magnesium Oxide on the ground. There’s no magnesium in gypsum: dolomite’s got the magnesium. With magnesium oxide it’s a slow release and it lasts a long time but magnesium sulphate is quite good to use if you want a quick release of magnesium (Epsom Salts). When you’re applying foliar fertilisers, the water you mix them in must be acid so you want it about 5.5, do a litmus test.

Surbuff is a combination of a wetting agent and an organic acidifier and is an acid neutralising liquid which is added to your spray tank first (if required) and you can then add your minerals to it. What happens then is when its acid based, once it’s sprayed onto that tree, every bit of that fertiliser is into that tree with 20 minutes. Before you get the leaf analysis done you have to wash the leaves and you can’t spray anything on for about a month before. The first lot I sent off were old leaves and they showed high readings of all minerals and I was a bit sceptical so in the meantime the trees have flushed and I then sent off the new leaves and they showed higher readings than the old leaves because they were picking up more energy into the leaf for new growth and production so I had very good minerals in all the trees. The fertilising regime I use is all organic and high tech from Europe.

You can use Charlie Carp and seaweed fertilisers either through the irrigation or as a foliar spray. We do have Fruit Spotting Bug but they only seem to go for the split fruit as the fruit is hard to penetrate. I’ve never seen fruit fly. Fruit Spotting Bug like dense, dark places so it’s most essential to open up your trees to let air and light in. If you lie on the ground and you don’t see 30% light, the tree is too thick and needs to be pruned. Every year you should take out two major limbs out of your tree. Don’t muck around by just pruning a little bit here and there.

The sugar levels start to increase toward the end of the full moon. With foliar fertilising the best time is at the start of the new moon. A lot of people don’t believe this theory but it does work. If you want to test this theory, then try the sugar levels in your fruit on a moon that’s waning and you’ll find the sugar levels very low, but if you pick the fruit on a rising moon you’ll notice the difference.

Joe: If you use a refractometer and you pick the leaves on a tree about a week after a full moon and again a fortnight later after the new moon and you take another reading, your levels will be way up.

Peter I’m a great believer in carbon fertilisers and some of the better products are folic acids and humic acids and a good layer of organic material under the trees for mulch eg. forest mulch. We get carbon out of mulches and the one I have has a lot of humus in it, mineral fertilisers and the colour is very rich. I use it in my potting mix as well. Carbon is a detoxifying agent for the soil. I try everything on vegetables first.

Member: You put carbon with Biovern – Mac Industries in Victoria put it out in 20kg bags and use 200kg of Calcium to 1000kg of Biovern – I put mine through the Viacon fertiliser spreader.

Peter: Use 100g/m2. I use another product called carbonic acid and it releases carbon in the form of carbonate radicle into the soil for the microbes to feed on and with the folic acid and the humic acid what you’re creating is a feeder for all the hair roots – you eliminate phytophthora out of the soil.

Member: Biovern are talking about setting up a blending plant so you’ll be able to get different blends.

 Peter: I’ve been using my current system for the past 2 years – the only trouble I’ve had is this year I lost about 80% of my crop – reason being is Longans require high humidity and we had low humidity just before Christmas when the fruit were about ¼ size. Humidity was down to 10 – 15% and fruit just dropped off.

 Member: Would overhead sprinklers have helped?

 Peter: Definitely that would have worked.

Authored by: 
Peter Sauer
Sourced from: 
Sub-Tropical Fruit Club of Qld newsletter Aug Sept 2003
Date sourced: 
Aug 2003