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There are several forms of liquid fertilisers that most people are familiar with. The commonest are liquid fertilisers such as the commercial fish emulsions or soluble fertilisers. Alternatively, there are manure or compost ‘teas’ which are made from materials such as manure soaked in water. Herbal teas, such as those made from comfrey, are also useful for providing nutrients to plants. Most such liquids can be applied as a foliar spray or directly on the soil around plants.

Brewed compost tea, however, is completely different to these products. It is brewed aerobically, and this process grows millions of beneficial microorganisms to feed the soil and help combat disease. This type of compost tea is increasingly being used in permaculture and on organic farms as a way of improving soil fertility naturally to produce strong and vigorous disease-resistant plants. It is quite easy to make your own compost tea at home to try out its properties for yourself, and there are also commercial products available.

There are many articles and websites about making brewed compost tea. An article by Elaine R. Ingham, who is the president and director of research at Soil Foodweb, Inc. and a professor at Oregon State University in Corvallis claims that compost tea is more beneficial than simply applying compost to the soil in the traditional way. She states that compost tea “makes the benefits of compost go farther, helps suppress foliar diseases, increases the amount of nutrients available to the plant, and speeds the breakdown of toxins”.

There is sound science to support these claims. As Ingham points out, the soil is full of both ‘good’ and ‘bad’ microorganisms. The goal of gardeners is to enhance the beneficial microorganisms in this soil foodweb. The ‘bad’ bacterial decomposers and the plant-toxic products they make are enhanced by anaerobic, or reduced-oxygen, conditions. However, compost tea is made through an oxygenated and highly aerobic process, which grows the ‘good’ bacteria and other microorganisms. Good bacteria work against the detrimental ones in several ways: They consume the bad ones, compete for nutrients, and they compete for space.

The brewing process in compost tea production extracts microbes from compost and then multiplies them. Beneficial microorganisms include bacteria; fungi and protozoa. Ideally the compost tea will contain both a vast number, and a great diversity of types of organism.

Brewed compost tea can be used in two main ways. Used as a soil drench it provides food and energy for microbes in the soil. As a foliar spray it combat disease and acts as a natural fungicide – for example for controlling downy and powdery mildew on grapes. When sprayed on leaf surfaces, the beneficial organisms in the compost tea eat up the exudates from leaves that would otherwise feed harmful organisms.

Making your own compost tea

To make good compost tea, you need good quality compost which has been made aerobically. That means turning the compost heap and ensuring it heats adequately so weed seeds and pathogens are killed.

Ingham describes how compost can be dominated by either bacteria or by fungi. For compost tea to be used as a foliar spray, it must be bacteria-dominated, whatever the plant. Bacteria-dominated compost is also best for applying to the soil before growing vegetables and herbs. Research has shown that a foliar spray of bacteria-dominated compost tea is extremely useful to prevent the foliar diseases that plague most gardens. Therefore the bacteria-dominated compost tea is the most useful for home gardeners although fungi-dominated does have some applications.

Ingham’s main points for making good bacteria-dominated compost are summarised below:

• compost should be made from a preponderance of green materials – a mix of 25 percent high-nitrogen ingredients, 45 percent green ingredients, and 30 percent woody material. High-nitrogen materials include manure and legumes, such as alfalfa, pea, clover, or bean plant residues. Green material includes any green plant debris and kitchen scraps. Woody material includes wood chips, sawdust, paper plates and towels, and shredded newspaper
• mix a whole pile at a time
• make sure you have a mass that measures at least one cubic metre.
• Moisten the pile as you make it so that it is damp but not wet.
• The more you turn the pile, the more the compost tends to become bacterial.
• after six to eight weeks, the centre of the pile is cool or barely warm to the touch. The compost is now ready.

Brewing and using the tea

The requirements for making brewed compost tea are easily obtained. There are many different recipes for making the brew – Ingham’s simple method is summarised below, but you may want to research other possibilities on the Internet. You will need:

• some of your well-prepared compost
• clean water (rain water, bore water, or town water that has been left to stand in the sun for a day to lose its chlorine)
• a 25 litre plastic bucket
• an aquarium pump that can run three bubblers (air stones), three bubblers. and a three-way gang valve to distribute the air to the three bubblers
• a couple of metres of tubing
• unsulphured molasses (preferably organic)
• something to use to strain the tea (e.g. old nylon stocking)

Tea made with this method brews for two or three days and must then be used immediately. So plan your batch to suit your needs, such as making it on a Wednesday for use on the weekend.

Method

Fill the empty bucket loosely half full of compost. Set up your pump and tubing so that the pump delivers air to the three bubblers at the bottom of the bucket. Hang the gang valve on the lip of the bucket and bury the bubblers at the bottom under the compost. Fill the bucket to within 7cm of the rim with water, and start the pump. When it’s going, add 30g of molasses, then stir vigorously. After stirring, you’ll need to check the bubblers to make sure they are on the bottom and well spaced apart. Stir the tea at least a few times a day. A vigorous mixing with the stick shakes more organisms loose and into the tea. Every time you stir, be sure to reposition the bubblers.

After three days, turn off the pump and remove the equipment. If you leave the tea aerating longer than three days, you must add more molasses or the good organisms will start going to sleep because they don’t have enough food to stay active. Let the brew sit until the compost is pretty much settled out, 10 to 20 minutes, then strain it into the other bucket or directly into your sprayer. You’ll have about 12 litres of tea. Use the tea immediately, within the hour if possible.

The solids can be put back into the compost pile or the garden soil, as there will still be good bacterial and fungal foods left in them.

Anaerobic decomposition

The most important thing in making brewed compost tea is for it to have sufficient oxygen, otherwise the tea will start to smell and become anaerobic, which can harm your plants. Ingham points out that “bad smells mean bad business”. Properly oxygenated compost and compost tea smells sweet and earthy. Anaerobic compost tea should not be used on your plants, as a product of anaerobic decomposition is alcohol, and even a very small amount destroys the plant’s cell walls. Ingham recommends that if compost tea smells bad, you can add another pump with more bubblers, and stir it more often, to aerate it until the smell goes away.

Using the tea

In a healthy your garden, spraying plants once in spring may be adequate . The beneficial insects in the garden should spread the compost tea organisms around the garden, preventing pest problems for the rest of the season. If you don’t have good levels of beneficial insects in your garden, you can spray at least once a month, or as often as every two weeks.

To control damping-off, spray the soil with full-strength tea as soon as you plant. On trees and shrubs, spray two weeks before bud break, then every 10 to 14 days.

 References

‘Brewing Compost Tea: Tap your compost pile to make a potion that is both fertilizer and disease prevention’ by Elaine R. Ingham. From Kitchen Gardener issue 29, pp. 16-19

‘Notes on Compost Tea’ by Steve Diver, Appropriate Technology Transfer for Rural Areas, 2002. www.attra.ncat.org

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I am a little bit out of my depth tonight. Firstly I am not used to speaking to such a fantastic roll up of people so thank you all for coming out on a stormy night like this to talk mangoes.  I normally now work in the post harvest system for mangoes and why they go green and not ripen properly sometimes, but I did spend 17 years in Mareeba, the home of tropical mango production in Queensland.  I have spent 6 years in Bundaberg up until now, which is still home to some quite large mango plantations so I have a pretty big interest in mangoes.

Our contribution to being a member sometimes is to get up and speak about some topics that might be interesting to people.  So I looked at a few of our training packages and tried to pull out all the things that were interesting at this time of the year in mangoes. I find this the most interesting part of your newsletter. If there is enough discussion we will all learn something about mangoes.

I recognize that mango growing in this area is one of the greater challenges in life. It is all because of what happens during flowering and fruit set.  I think you will realize why it is so difficult to grow mangoes in SE Queensland after you hear some parts of my talk because the flowering is difficult, pollination and fruit set is quite difficult and maintaining disease and insect control at times in this environment is quite difficult – not impossible, so don’t give up!

We will go back to a little bit of science to explain that mangoes do follow that yearly pattern of vegetative growth after harvest, where we get 1 or 2 flushes. We also get a bit of a root flush. Then we move into some sort of vegetative dormancy and that might happen from about May onwards when we get set up for flowering.  It is the environmental conditions that happen in winter – June and July that really determines what sort of level of flowering you get. After flowering it is the environmental conditions that we get in August-September-October that determines what sort of crop we get.

I reckon there are 5 IFs in mangoes:

IF they flower; IF they set; IF we get them through to maturity; IF they ripen; IF there is any money around on the market.

If those 5 IFs fall into place, it is a pretty profitable crop.

That is the basic phenological cycle that mangoes go through. As I hear people talk about manipulating flowering, they are doing it by trying to manipulate that phenological cycle: when the rest phase is and when the growth phase is. Here are a couple of facts:  For mangoes to flower they have to have cold weather.
There is a way around it but it is quite difficult to manage but the traditional one is that you need cold weather to come in. 10 – 15°C to come in at the very early stage of flower development as long as those terminals are at least 7 weeks old. So we need dormant terminals that have built up carbohydrates, some cold and then action to happen, which is what induces flowering.

We can manipulate this in a couple of ways. We can manipulate dormancy like they do in the Philippines where they use Cultar® to actually put the tree into a false dormancy and then break dormancy with potassium or calcium nitrate sprays.

Sheryl:  Can you go back a bit and discuss about the terminals being 7 weeks old?
Terry:  That is the suggestion that the flush must be a hardened flush and building up carbohydrates otherwise it just doesn’t flower.  We know young red flushes can flower and I have occasionally seen this in Mareeba, but a much better flowering occurs on buds dormant since end of May. We then need the cold as a trigger but not too cold or we get a male flowering.

Of course during fruit set it can also be too cold and if you start getting night-time temperatures below 13° during flower set you get quite poor set in Kensington Pride.  13°C is the benchmark figure but we know it is a little lower for R2E2. Calypso is certainly lower but for Kensington Pride we have a figure of 13°C that has worked out in the growth chambers.  In Bundaberg up to 20th Sept we normally get overnight temperatures of 10, 11 or 12°C yet we can still set fruit, so when we get warm days, I think we get a bit of an offset from that.  So now you can see that to get mangoes to work in an environment can be a bit tricky.  You need cold weather to get initiation but not too cold. Then it has to warm up during flowering to actually get fruit set.

In some cultivars we can prune off early flowers to get re-flowering at a better time. In Nam Doc Mai which gets really bad powdery mildew, all the flowers can fall off but they will flower again.  Some varieties are very good at re-flowering.  Keitt mangoes are very good at re-flowering. Most of the Florida varieties are ok but Kensington Pride is pretty lousy. Ian Bally in Mareeba may have a list of cultivars which re-flower after flower pruning.

The other thing about flowering is the use of potassium nitrate to induce flowering. It only works on some varieties. It does not work at all on Kensington Pride. It works marginally on R2E2 but it works quite well on Carabao.  The Filipinos and Thais use it twice to induce flowering each year.  You have to have dormancy but calcium nitrate works just as well and is a little bit cheaper.

Watering 

There is a lot of conflicting information about how you water mangoes during flowering particularly about putting the water off until fruit set. The water usage is quite low through winter but they do need to be kept actively “alive”, and need to be watered to push flowering at the right time. Start early September to get those buds going.

Fertiliser

It is very essential to fertilize mangoes to get regular cropping. You need to get new flushes every year to get flowering to get fruit set.  Of course it is essential not to over-fertilize.  As a guide I like leaves to 1.2% nitrogen coming into flowering. 1.2% nitrogen is certainly not dark green – you would have to say light green and when you go to the sunny side of the tree you think you have under fertilized it. It looks a little bit on the pale side. That is about 1.2%.

We know boron is important because of fruit set, and to get pollen tube growth you have to bring them [the trees] it at 50ppm leaf boron. Boron you can overdo it. Mangoes are very intolerant of too much boron but you have to have it.  I am one of the people that advocates putting it on the ground because it is very important for sap flow and calcium nutrition in the tree. I notice your recommendations are giving boron sprays right through until October. Our recommendation is 0.9% soluble spray Solubor® at  stage B because that will give us enough boron for what we do, but we should actually have it on the ground.  Stage B is when the buds will be about 1-2cm long ie., early bud break. 1% is 10ml per litre.  Some varieties like R2E2 need a lot of boron and if you don’t have enough boron you get the bent flower tip and you end up with some internal issues.

Sheryl:  So you are saying spray the flowers with boron as well as putting a bit of boron on the ground.
Terry:  Yes, in very low doses on the soil. 1gm per square metre.  Mix with water and spray the ground. On our sandy soils we don’t exceed 10kg/hectacre treated area that is our top rate. Even at that rate in our R2E2 mangoes we get toxicity at times when the soil is not so deep. Boron deficiency symptoms are typically holes in the leaves and splits and trunk weeping.

Toxicity is indicated by a very irregular burn on the margin of older leaves.

Calcium  If you don’t have enough calcium in Keitt mangoes you end up with internal troubles – what’s called Keitt Disorder. To overcome the problem we try to improve fruit load, lower nitrogen and increase calcium supply.  You will see occasionally that 1 or 2 kg gypsum per tree is recommended and that is the ball-park, any more than that would saturate the soil with calcium. If your pH is below 5.5 use lime, and above use gypsum. 

Sheryl:  What size tree would that be in?
Terry:  Probably a 3 metre tree.
Sheryl:  You mentioned to stop jelly seed we need the calcium. Getting calcium into the tree is a bit difficult.
George:  With calcium nitrate spray, does that actually burn the leaves?
Terry:  We have to be very careful of the rates we use. I think 1% is fine but higher than that we start getting little bits of tip burn and if it is fruit that is getting a little bit of burn then that ruins the fruit.  Depends on the pH, we mainly suggest using gypsum.
Sheryl:  So how much per square metre?
Terry:  The golden rule has always been about 10 tonne per treated hectare.
Sheryl:  I think Peter says a closed handful.
Terry:  That sounds a lot more sensible.  I am saying that the commercial trees are using 2 kg on a 3m tree per year of gypsum.
Sheryl:  What periods would you put them on? What growth of the tree?
Terry: It is very important to go for those major growth phases, it has to be on prior to flowering, again in November and then for the flush, but we do try to avoid the wet season particularly in the very sandy soils that we grow mangoes on you just can’t control and it all just goes through the system and you can’t control it.

Potassium and Magnesium They do like magnesium. When everything is set and we know we have a crop we can spend some money on the trees then we top up with potassium and magnesium but in a ratio of 2 to 1 potassium to magnesium. We tend not to put Potassium and Magnesium on until the fruit is about egg size. If you don’t have it you end up with a lot of internal troubles.

Diseases 

The other thing that has to happen at flowering time is the control of diseases. This is to protect flowers and leaves. If anthracnose gets on older leaves it remains as inoculum for later on.  Anthracnose is a problem in this area because we get rain at flowering and we have some inoculum in the tree and we get it spreading down to our flowers and young fruit and we get no fruit set.
With the way the disease spores infect the fruit we have to use a protectant fungicide like Mancozeb or a curative like Octave ®.

Sheryl:  Octave is quite expensive isn’t it?
Terry:  It is very expensive, but during flowering it is a best choice. If you are relying on protectants you need to ensure good coverage. So how do we control mango pests particularly without relying on inorganic chemicals? The first thing is never let a plant come onto your property that has diseases such as bacterial black spot.  (Always known by the angular pattern that is slightly raised and slightly greasy appearance of the leaf spot on the leaf).  It is such a difficult disease to try and cure – almost incurable on some varieties like Keitt.  The next trick that we have in controlling diseases is controlling the inoculum level in the tree. We have been doing some work of actually going through and removing all dead material in mango trees. Now this can cost about $10 or $12 on a commercial orchard to get in, get material out and sweep it out from under the tree and get it broken down to mulch.  But in some orchards it is the only way we have been able to control the disease, as whenever we get some dead material in a tree we end up with some quite nasty diseases like dendritic spot coming in on our fruit, so controlling the inoculum is really important.  What does all this mean to those of you who have only a few trees?  Well it means that before flowering, I like to have my trees really clean ie., when I go in and do that end of May prune to take the odd branch out and remove the dead wood.

George:  Does the sunlight getting into the tree help?
Terry:  It dries the tree out and lets a bit of wind go through it.  If you actually target the dead branches, stuff that has been hit by scale that is good.  The other thing is to have a uniform flush come away after, particularly to stay ahead of stem end rot. Do this in Feb.

Pruning 

Give your Mangoes a light prune straight after harvest to get all of those dead sticks and any branches that have gone a bit vigorous. I try to get some shape back into the tree and get my flush coming away and then I come back about May-June to take out some more dead wood and some vertical branches that are giving me too much height. Leaves older than 2 years are actually parasitic on the tree which means they no longer contribute to the carbohydrates of the tree so all pruning should be designed to remove those leaves so leave new leaves on and strip all the old leaves off. Do this in May.

Pests 

The other issue during flowering is the Flowering Caterpillar – not normally a problem but something we check for. We have some new chemicals which we use like Success [Yates® Success® Naturalyte® Insect Control] – active ingredient is Spinosad which is derived from naturally occurring beneficial soil bacteria and this is put on during early fruiting.  If you are growing trees in mid-suburbia where everyone has lots of ornamental trees you would know about fruit spotting bug.

George:  Especially in a garden with mixed fruit. They move from tree to tree.
Terry:  They are very fast. There has been some work done in the Burdekin and Tablelands and we are finding the peak of the fruit spotting bug in September-October and it is causing fruit drop, but it is such a hard pest to control that we are hoping that we can wear this one.  We haven’t found a pheromone for it that seems to work nor can we find lures to trap them and the only chemicals we have are harsh.

Our last pest that happens around flowering time is mango scale. Commercially it is our most severe pest. I think it is a problem because it causes dead material in the trees and just the very efficient nature of this pest.  The females lay 200 eggs at a time and those little crawlers move out over the next 24 hours.  They don’t move very far – they are all males. The females walk a bit further but the males stay close to their mother and in summer the life cycle can be only 40 days so it is a very efficient pest.

Member:  Organic control?
Terry:  With very good pruning and getting rid of the old material out of the tree and with some of these new parasites you will get away from this particular insect. We have imported a parasitic wasp and are doing trials before release.
Member:  Possum control?
Terry:  I have seen tin used successfully around the base to stop them climbing on the trees.
Sheryl:  In a previous newsletter, in Mackay they had an old fishing net which they put at the base of the tree about 90cm high from the ground and about 4 layers.  A possum likes something taut that he can hang onto so the net is loose and the possum does not like being off balance.

Varieties 

Maybe it is more my taste but I actually prefer cultivars like Nam Doc Mai because I can get it to re-flower very nicely into warmer weather like October. As you will see in the latest newsletter it is explained that mangoes are one of those ones that are monoembryonic or polyembryonic.  The monoembryonic ones we definitely graft because they do not come true to type from seed. The polyembryonic ones they do come true to type from seed but we also graft them because we have some data from Nth Qld looking at long-term yields and the actual grafted trees have always out yielded the non grafted trees even for things like Kensington Pride which are polyembryonic.

Dwarf Trees

I have had a little experience with the use of Sabre. I don’t know if Sabre itself is a dwarfing root stock or because on Sabre the tree is productive that it has kept the tree smaller.  The only big root stock trial that has gone on in Australia is the one in Katherine and in that one Sabre came out pretty well.  It has now been replicated by a grower up there who claims to have some very nice dwarfing root stocks but I have not actually seem them. 

Sheryl:  Is it a secret?
Terry:  No, they are being commercialised.

Article compiled by Barbara O’Connor and edited by Sheryl Backhouse.

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What I want to tell you a little bit about is the Red Bayberry, whose scientific name is Myrica rubra (Myricaceae).  They are in a family of their own.  There are other Myrica, like Myrica nana.  They are a northern hemisphere family and occur in North America and Asia.  Myrica rubra or red bayberry is the only really edible one and that is largely because it has been selected over time.

The other ones are mostly shrubby types like the Myrica in North America.  You probably wouldn’t recognize them as being in the same group.  Red Bayberry sticks out ‘like a sore thumb’ as being different from everything else in the group.  It comes under a whole lot of different names and some of them are ‘botanically confused’.  Sometimes, if packaged in tins, they are called Arbutus, which is actually the Irish Strawberry Tree.  Other times they are called Yang Mei, which is the conventional Chinese name for the fruit.  It is also called Chinese Bayberry, Waxberry and a few other things.

It is a fruit of China and a very attractive fruit.  We are trying to bring it into Queensland in a way that we can select for superior cultivars and release them.  We do not want to release inferior genotypes which might damage the market and, in particular, consumer perceptions at the outset.

Growing Condition Regarding soils, they like slightly acid 4 – 5.5pH.  They are growing very well on the red earth soil type at Maroochy Research Station and are virtually leaping out of the ground.  I think that is slightly acid, very well drained and very fertile.

It comes from China particularly in Zheijiang Province, grows on low mountains and likes high humidity around fruiting and it is a very attractive tree.  It has been grown over there and selected in China for many centuries.  The wild types are almost inedible so one has to be very careful when trying to bring a product like that into the marketplace.

This is the sort of climate that it grows in: minimum temperature about -4°C, maximum around 40°C; so it is very tolerant to a wide range of temperatures, but the average is a fairly pleasant 18°C.  It likes fairly high rainfall, particularly around fruit development.  If this fruit is not matured at high humidity it has a prickly mouth feel, so picking the best areas to grow it in Australia is a little bit tricky.

We have done some climate mapping and have worked out that areas that it should grow are around Nambour, in northern NSW and further up in Queensland, but very near the coast to maintain high relative humidity.  The trees grow very quickly and start bearing at 4 years old.  There is a juvenile period that you have to get through of 3 – 5 years. It takes fairly nasty soils even virtually growing in rock. If you peeled away the top of the root ball you can see these little nodules.  There is a Nitrogen fixing association and so, like a legume, this plant can fix its own nitrogen but instead of having a microbe called Rhizobium, it has a microbe called Frankia.

We were lucky to find it in Australia because we brought seed in and did not expect to have it, but Frankia is also a nitrogen fixing organism associated with casuarina.  Thus, we suspect that it has been infected by Casuarina frankia, but we have yet to confirm that the strain(s) we have in Australia is actually fixing nitrogen.  We will do this as soon as we can.

It is very vigorous growing.  They do tip pruning to try to get a nice form to the tree encouraging branching.  It looks a lot like a lychee orchard, the trees are about the same size as the lychee trees.  They need to be pruned to keep them down, they are very vigorous and they also need to be thinned to keep fruit numbers down as they bear very heavily.

Pests & Diseases
I think that lorikeets will attack them.  We had them under bird netting the first year that they fruited here and didn’t have any losses to birds.  We will probably keep them under bird netting as I suspect they will be attacked by birds.

We didn’t get any fruit fly in them that we know of.  There is a fruit fly exclusion netting type shade cloth that has been developed and is being tested at Maroochy.  Another good thing about that is it also maintains a high humidity within the structure than outside so this might initially give us a high value crop that can grow in that type of structure. Although they are pretty tough trees they do have a series of diseases and pests that attack them, a range of rots and a range of nematodes too, like Meloidogyne.

In Australia we do not know yet what will affect them.  The only problem we have had up at Maroochydore is a leaf curling caterpillar that folds the leaves around but they have been able to control that with a spray of insecticide.  We do not know if it gets fruit fly.  They have said fruit fly but they are talking about Drosophila which is just a vinegar fly so we do not know whether Queensland fruit fly will get stuck into them or not.  The fruit is a prohibited import because there is a published record in Indonesia of it being a carrier of fruit fly so we can’t bring the fruit into Australia.

Member:  Why don’t you irradiate it? Daryl:  It is too soft. Member:  They irradiate mangosteen. Daryl:  Yes, irradiation is a possibility, but the other thing is to get it in here you need to irradiate a fruit and demonstrate Probit 9 control, which is controlling 99.999+% of the fruit fly.  It is a massive undertaking.  It takes years to do it, so that work would have to be done in China.  It is not really practical at this stage.

We brought a small consignment of fruit into Brisbane airport in conjunction with AQIS (Australian Quarantine and Inspection Service).  Thus, it came in under the supervision of AQIS.  We set up a small testing group of Australian consumers, basically a group of people from AQIS and a group of people I grabbed ‘off the street’.  They did taste testing in the secure facilities.  Immediately after that, all of the fruit were destroyed; so there was no risk of anything coming into Australia from the fruit.

But what it did show was that the small group that we tested (only ~17 people), ~15 out of the 17 people really liked the fruit.  So we think that if we can get it growing here, then there is going to be good acceptance.  I am now working with DPI.  The plants up at Maroochy that were mentioned comprise our first minor planting of 12 plants.  They will fruit for the second time this year, and at Hamilton in Brisbane we are setting up a trained taste panel to do some tasting on those fruit.

We know they are not optimum but what we want to do is to get feed back from the panel as to what we should be selecting for.  Also up at Maroochy Research Station we have ~200 seedlings that we expected to fruit this year, but they didn’t and we hope they will fruit next year.  Then we will apply what we learnt from the taste panel this year to putting in selection criteria for that population of 200 next year, hopefully.

Flowers
The flowers are miniscule.  You can hardly see them on the inflorescences.  There are separate male and female flowers.  More often than not they are on different plants so it is a dioecious crop.  Occasionally you get a plant that has both male and female.

The 12 trees that we have up at Maroochy Research Station are ~50% male and 50% female.  In China you do not need many males as pollinators so they tell me.  I am no good at Chinese, so I can’t swear to it; but, you need about one pollinator per hectare, which is very low.  As the pollen is very tiny it is profusely shed and it is wind blown so it is possible.  We have had no problem with fruit set but our trees need to be thinned as they bear too heavily. 

Fruit
The fruit has a seed, like the seed inside a cherry stone, very hard to get at ie a very hard testa, like a cherry stone.  Arranged around are all these papillae, little ‘fingers’ of flesh.  They are a little bit like vesicles in an orange fruit, except they have knobbly tops and in two months you end up usually with a deep red fruit.  It is very high in anthocyanin; therefore, it is a very good antioxidant.  People are very interested in it for its functional food properties as well.  There has been a lot of analysis of the fruit done in China and Japan and we will also be conducting antioxidant analysis on the fruit here in Australia this coming season.

Member: When do you pick it? Daryl: You pick it fully ripe.  It fruits in mid summer.  This is a problem with it.  It is very soft when it is ripe, just like a mulberry, for example.  So to move it around, you have to be very careful.  If you pick it earlier it will not ripen fully.  It will not ripen to full flavour so that is where the logistics become an issue.

It is all hand picked, but what they do is they shake the tree and let them fall to the ground with a lot of mulch under the tree.  So a lot of it is hand picked, but also a lot of it is picked up off the ground when they shake the tree.  Similar to mulberry.

I guess what we are thinking of here is if we can get it going is that you would be looking at something like a Tatura trellis type production system.  That is, train the tree in a V shape and collect fruit underneath, so there is minimum damage upon fruit fall or shaking based harvest to the fruit.  It is actually a very attractive tree, just like a lychee when it is developing.  So green to red ripening fruit – just like a Christmas tree – and then the bright to deep red fruit at harvest time.  I should also say that there are a whole range of cultivars that vary in colour from pure white through to almost black, so red or a deeper red is not the only colour, there is a range of pinks, and even some yellowish coloured ones which might have a very low concentration of anthocyanins.

Harvesting To give you some idea, it does bear heavy and the trees tend to fall over so in China they prop them up with bamboo poles to stop them from collapsing and damaging the branches.  Harvesting in China is by bamboo ladders.  They collect them into bins and take them back to the factory for processing and they pick up the ones that have fallen off the tree.  Labour is very cheap there.  It may be only costing around about $1-2 per day for labour. 

June is when it ripens in China so in Australia it is supposed to fruit in December.  What we find is that it actually fruits at the end of November, but possibly if we can produce it in different climates we can use a natural phytotronic effect on the eastern coast to get a series of production times; just like we do with Bowen Mangoes, which starts off in Darwin around October and ends up in Coffs Harbour in March at the latest – so we are looking to do that.

Marketing/Transport
In China it is put into juice, it is frozen, carbonated drinks and spirits are made from it, however, it is mainly sold fresh.  In recent years production has been increasing exponentially, the reason being that now they have improved infrastructure for transport and can market this fruit more widely throughout China.

It is a very perishable fruit.  It is in the same bracket as strawberries, raspberries, loganberries or mulberries; very soft and so you need to handle it carefully, quickly and at low temperature.  They have selected superior cultivars, one is Biqi for example and they graft that superior cultivar onto seedling rootstocks in China.  They use more woody stock and scion materials than we typically use in Australia. They market them in plastic baskets, in gift wraps and in cartons – a whole range of things.  It comes in on the back of trucks which does a lot of damage.  We have done some studies as to where damage occurs and most of the damage occurring in China happens between the trees and when it gets back to the packing shed. Because they are using trucks without springs and using bamboo poles with baskets at the end – as they walk along it sort of wobbles and so the fruit gets jiggled around.  Back in the shed there is some pretty crude sorting (slide).  There are spaced bars and different sized fruit falls through at different positions, so they get some size grading done.

It is not a very good fruit to carry around because if you buy a basket it is about this deep (display) so the fruit down the bottom get crushed.  There are a bunch of shallow trays that they use and a colleague of mine from England is suggesting that in Australia we should try to pack them in an egg carton type arrangement.

At first when they come onto the market they will be hopefully be pretty high value because people have to put up a lot of money to establish an orchard and wait 2 or 3 years to reach bearing age.  So they are almost as big as lychees but unlike lychees you don’t have to peel them.  You just pop them in your mouth, suck off the flesh and spit out the seed – more like a cherry.

Trying to get the product into Australia is taking a great deal of time.  We are trying to do it properly so that everybody benefits – the industry benefits, the consumers benefit.  As you probably know, it is very hard to get a new crop adopted and get anyone to invest in bringing it over here.  I have been working on it for about 8 years now, probably longer, and I have worked over the years with a group of people in China (slide) and Australia.  Yueming Jiang, Li Jiangrong, (an Australian Chinese) Shiming Lui, Graham McGregor (who unfortunately passed away; but, he was the raspberry breeder in the Victorian Department of Agriculture), Garth Sanesky (who is up at the DPI at Nambour and is a plant breeder), Sherrie Wei (who is a marketing specialist based in Taiwan) and Stephanie Kirkhoff (will be doing the consumer taste testing. She is based at the DPI Hamilton Food Group).

In the recent years we have had financial support from RIRDC (Rural Industries Research and Development Corporation) to keep the project going.  We are working with ANFIC (Australian Nursery Fruit Improvement Company) – Gavin Porter is an old colleague of mine and he has put some money into this project and their member nursery in this part of the world is Birdwood Nursery up on the Sunshine Coast.
Recently we have been working with UniQuest which is a commercialization arm of the University of Queensland, and they have just put up $16,000 into the project to help us continue it on.  We are very grateful for all of that support. We also have an ice cream company called Lick Ice Cream interested in trying to make us some ice cream so if they do make some ice cream we will bring it along and ask you to taste it.

Questions Member:  What does it taste like? Sophia:  It’s sweet and sour. Daryl:  Which isn’t exactly a taste that Australian consumers know.  When you say it’s sweet and sour, you know what you mean by it; but, Australian consumers don’t know what sweet and sour is.  It is hard.  It is acid, but at the same time it is sweet.  It has a berry like quality, like mulberry.  When we did the taste testing here most of the taste testers said that it is most like mulberry.  Have you tasted it?  Sophia:  Yes, I have tasted the fresh fruit. Daryl:  Do you think it tasted like mulberry? Sophia: More like strawberry.

Daryl:  Most Chinese tend to prefer a much sweeter fruit, with low acid.

We have never lost a plant.  We have grown lots at Gatton.  We have neglected them.  We have kept them pot-bound for 6 years and have never lost a plant to disease.  We have lost them to other things eg. it fell over and never got watered.  We brought in seed from China to propagate.

Sheryl: Did you select the trees that the seed came off? Daryl:  It came from marketed fruit.  We did not select the trees, but it was allegedly Biqi fruit.  We know it was an elite variety. Sheryl: I have been told that they won’t let out their best varieties from China. Daryl:  No they won’t, not officially. Sheryl: How true to type from seed? Daryl:  Biqi is one of the best varieties but is not very true to type.  So that is why with the original 12 plants that we have, about half have fruited.  The present fruit quality is not something we would like to let out yet because that could damage their reputation.  People won’t like them as much.  They are still quite edible.  I like them, but the really wild fruit in China is like eating turpentine. Member: So are they grafted in China?  Or are they a lot of seedlings? Daryl:  Nowadays, mostly grafted.  Traditionally they were mostly seed.  In the past a Chinese family would be affluent by having 10 of these trees.  They have been highly prized. Sheryl: So when does your project finish?  What is your timeframe? Daryl: The first RIRDC project finishes next year, but my project will not finish until I am dishing out bayberries.  It has taken this long to get this far and we want to see it right the way through. Sheryl: What plans do you have for marketing?  Are we going to be able to get access to it? Daryl:  Our intent is to have a line for home use. Member: Bisexual would be nice. Daryl:  Well, that too.  We said before we could always do double grafting as well. Member: You could do that. Daryl:  We have yet to do the fruit counts.  We don’t have money for staff on this, we just have money to rent the land from the DPI to grow them. Member:  Want some volunteers? Daryl:  Well, we might. I will ask Garth.  Because we would like to know about fruit set. Member:  If you really needed more people to look after them, propagate some of the seedlings, I am sure members here would be willing to do so. Daryl:  We don’t with Maroochy because it is government but with Birdwood Nursery we have asked them to sign a material transfer agreement.  We have no trouble growing them from cuttings in our nursery. Member:  Do you think that there is any chance that we could taste them at some stage or there won’t be enough?  What do you do with them all? Daryl:  We don’t know yet.  Stephanie from the DPI is corresponding with Garth to work out if she can get enough fruit for the taste panel.  She has 4 or 6 tastings and we don’t know how well they will bear.  Garth said it is a good flowering season.  It’s compact. The reason why we want to try ice cream is because some of the bush food people tried making ice cream with their lines. Member:  How long does it take to get to maximum production? Daryl:  Within 8 years, I am told in China.  You have to thin them.  About the same as lychee trees.  We have the devil’s job getting the seeds to germinate.  It took me 3 years to get a batch of 200 of them to germinate.  In the end I don’t know what happened. I tried stratification.  I tried acid treatments.  I tried cracking them.  Tried heat. Sheryl:  Smoke? Daryl:  No, but it won’t be smoke as they haven’t evolved in that kind of climate.  Someone said heat or dry.  In the ground I think it gets dry and wet, dry and wet and they slowly crack.  A bit like a macadamia, eventually they get to germinate. Member:  How big is the seed and stone? Daryl:  The seed is tiny – probably no bigger than an apple seed.  The stone is like a cherry.  So it is a really thick exocarp around it and every time I tried to crack it in a vice or with a hammer, I would end up fracturing the testa – that is, you fracture the seed inside as well.  In China they dry them. Member:  Can you buy those dried products here now? Member:  Yes, in Melbourne I have seen some and Chinese friends here got some in Sunnybank. Member: Pesticides? Daryl:  In China they grow them organically.  It is one of the few things that is grown totally organically and the government have actually got an organic certification scheme in place for them because they are very popular in Japan.  The Japanese are very discerning consumers.  They do not need to treat them with anything.  It is amazing.  So in spite of having pests and diseases on them they are not catastrophic or anything like that.  Very resilient which is another reason why we would like to put it out for home gardens because we think as a tree it will be pretty maintenance free.  If fruit fly gets into stuck into it, we might not get any fruit. Sheryl:  So besides the planting at Nambour have you any other plots around? Daryl:  I have a small planting at Gatton which is for stock plants.  We have two trial plots in Victoria where I started off.  One is in the Dandenongs and one is in Tatura.  Actually the trees are going well, but they have not fruited yet and they have been neglected since my colleague passed away.  I went down there last year and they were about this high.  One is on a strawberry grower’s property under a material transfer agreement and the other one is with the DPI Victoria station at Tatura. Sheryl: A woman sent some seeds up to George but they are not up yet. Daryl:  Just be patient.

Member:  I had those in pots several years before they went out, but they started to bear within the second year of planting out at Maroochy.  They are probably 5 or 6 years old.  Which made us think, these guys must be fixing nitrogen.  They were greener than the mangoes nearby, so then we went scrubbing around and found lots of mycorrhiza in the mulch as well intimately associated with the roots and then also these nodules.   We hit every second tree with Cultar.  That really slowed them down.  They did not get the shoot extension and none of those trees set fruit in the first year.  They had fruit buds, but their development was so arrested.

Compiled by Barbara O’Connor

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The Cherry of the Rio Grande, Eugenia aggregata, is a native of Brazil and grows quite well in South East Queensland, George has one in his backyard that is 5m high. It is a small evergreen tree, 4-5 meters in height, with dark green, glossy, waxy leaves very similar in appearance to other eugenia species such as brazilian cherry (E. uniflora) and grumichama (E. brasiliensis).

The flowering season starts in spring and extends over three months, like the grumichama it has a few crops per year. The flowers are white and quite showy. The one-inch oblong fruit is a beautiful dark red to purple, and is produced soon (~3weeks) after flowering. The fruit is thin skinned with one large seed in the centre. The fully ripe fruit is generally tarter than the grumichama and has a very juicy flesh. It is considered by our president to be superior in quality to the grumichama.

The fruiting season usually is September – December. The fruit is nice fresh and can be used in  jellies, jams or juices. The fruits also freeze well, so they can be picked when mature and frozen for later use.

Cherry of the Rio Grande is still usually propagated by seed, although seedlings may take up to 4 to 5 years to begin producing fruit. If superior varieties, for example, large-fruited forms or sweeter fruiting forms, are found by anyone growing a number of plants, they be propagated by grafting onto seedling rootstocks. Veneer grafting has been successful but other variations could also work. Considered a slow grower, cherry of the Rio Grande will grow at the rate of 2 to 3 feet per year and makes a very attractive large shrub or small tree, depending on how it’s trained.

Most Cherry of the Rio Grande grow on a wide variety of well drained soil types; however, they prefer a slightly acid soil, and on alkaline soils may develop some micronutrient deficiencies.

Most of the time there is little problem in SEQ from cold, since cherry of the Rio Grande can tolerate temperatures down to –3 to -4° C without being killed. Trees should be fertilised with a fruit-tree-type fertiliser at least three times a year for good growth and fruiting. During periods of dry weather they will benefit from weekly irrigation.

Birds find the fruit tempting and the upper parts of trees are often picked clean before the fruit is even fully mature, it is also susceptible to fruit fly damage.

Cherries of the Rio Grande are easy to grow, requiring relatively little maintenance for the growth of healthy, productive plants. Fruit size and quality depends to a large extent on proper nourishment and an adequate water supply at the time of fruit development. When first planted, they need a complete fertiliser in a 1-1-1 ratio, that also contains magnesium. Start with no more than 100g at monthly or bi-monthly intervals, increasing the rates commensurate with growth.

If iron deficiency in calcareous soils is a problem, this should be applied in a chelated form by drenching into the soil when needed. Nutritional sprays to supply other minor elements should also be applied as needed. They should always be supplied with adequate water  especially during bloom and fruit development. Cherry of the Rio Grande has fairly good drought tolerance. It requires little pruning to make an attractive tree and is sometimes pruned to make a hedge.

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The Australian National Mango Genebank is the largest collection of mango cultivars and mango related species in Australia. The genebank is maintained as a collection of mature growing trees on the Department of Primary Industries and fisheries, Ayr Research Station. The collection consists of approximately 300 mango cultivars and related species, originating in many parts of the world.

The collection was started in the 1960’s in the Brisbane region with an introduction program targeting promising varieties from around the world. This program was later expanded to the Bowen/Ayr (dry tropics) and Kamerunga/Walkamin (wet tropics) regions of Queensland. In the early 1980’s the collection was moved to the Ayr Research Station where it is situated today. Within the genebank there are several smaller collections such as, Australian cultivars, foreign cultivars, green eating cultivars and Mangifera species. Although mango is not native to Australia, many selections of trees were made in the 1960’s. These trees were generally found in the vicinity of Queensland ports. Many of the trading ships in the 1800’s left mango seeds behind that found their way on to farms and stations. A number of these cultivars are represented in the genebank.

The collection also contains many of the more popular commercial varieties from around the world. The collection holds mango varieties from Malaysia, India, Sri Lanka, Indonesia, Mexico, Hawaii, Thailand, Vietnam, Philippines, Taihei, Jamaica, South Africa, Israel, USA, Australia, Kenya and Brazil. In recent times an effort has been made to collect the best green eating varieties from around South East Asia to supply the growing demand for green-eating mangoes in Australia. The collection now holds green-eating varieties such as Keow Savoey, Rad, Nang Klang Wan, and Falan, from Thailand, Xoai Tuong from Viet Nam, and Golek from Indonesia. The collection also holds a number of related Mangifera species that may, in the future prove useful in breeding programs or as sources of rootstocks. Some of these include M. odorarta, M. cesia, M. foteida, M. panjang, M. aplanata, M. zelynica.

The genebank has been used as a centralised source of mango genetic material for industry diversification over the past 40 years. Throughout its life the genebank has played a major role in all industry genetic improvement programs, supplying growers with new varieties and as a source of parental material for seedling selection and breeding programs. The successful Australian cultivar “R2E2” was developed using seed material from the Australian National Genebank. More recently the genebank has been a major source of parental cultivars used in the Australian National Mango Breeding Program, which has been very successful generating large numbers of high quality hybrids is using controlled crossing techniques between Kensington Pride and a number of varieties from the genebank. The Australian National Genebank is a collection that is continually having new accessions added and information on the accessions upgraded.  The collection is a vital part of Australia’s mango industry and an essential tool in the improvement of mango germplasm. Because they only have a single tree of each variety, they can only supply small amounts of budwood of any one variety.

If you are interested in any particular variety please contact the Farm Manager at Ayr:

John Brown 07 4783 0401 or Ian Bally, Senior Horticulturist, Horticulture and Forestry Sciences, Department of Primary Industries and Fisheries, 28 Peters St (P.O. Box 1054), Mareeba QLD 4880  Telephone  07  4048 4644   Facsimile  07  4092 3593  Call Centre 13 25 23

email  ian.bally@dpi.qld.gov.au   Mobile  0419 679 463

                                                                      Australian National Mango Genebank

                                                                                   Ayr Research Station

13-1	Carabao Mindinao	Hybrid 10	Mapulevu	Rosa
Amarto Seedless	Carabao Super Manila	Hybrid 17	Mar	Ruoyal Special
Golden Delight	Carabao Timited	Indian (Foran)	Millaroo 1	Rupee
Gudang	Carabao T’ville	Indian 1	Millaroo 6	S.B. Chowsa
Kasturi	Carrie	Indian 2	Momi K	S113
Kyal	Casino gold	Indian T’ville	Mulgoa Ramasamy	Sabre
Summerlee ii	Cathamia	Indochinese Late	Mullimby Gold	Saigon
Tom	Cedar Bay	Ingham Late	Mundappa	Santa Alexandrina
‘A’	Chandrakaran	Irwin	Mylepania	Sapa
A67	Chenkie	Isis	Nam Doc Mai 4	Sensation
Akbar	Chockanan	Jakarta	Nam Doc Mai T/A Select	Siphon
Alphonso	Cobera tongue	Jehangir	Nam Dok Mai	Smith
Ampalam	Coconut	Jewel	Navaneelum	Spirit of 76
Anderson	Common	Julie	Neelum	Spooner
Andreoli	Creeper	Kalapady	Nelson	Springfels
Ann	Crimson Blush	Kamerunga White	New Guinea Long	Sri Jaya
Anopan	Dashehari	Karutha Columban	Nimrod	Sufaida
Apple	Davis Haden	Keaw	Nixons Special	Summerlee i
Asam Rumuk	Dcheruku  rasam	Keitt	Nong Sang	Sungi Siput
‘B’	Dorothy	Kensington (M)	OK Rong	Tanjang pinang pink
B%	Dray	Kensington Grossman	Ok rong	Tekin
B.O.T.	Duncan	Kensington KRS	Olour	Telok Anson
Bacany	Early Gold	Kent	Ono	Temira
Bali Apple	Edward	Keow Savoey	Orange	Thai Wild
Bambaroo (K)	Elephants Tusk	Kimba	Padiri	Thar
Banana	Excell	Kishenbhog	Pahiri	Thomas
Banana Long	Fairchild	Kopu Reva	Pairi	Tiwi
Bangalora	Fajari	Kuini	Pajo	Tommy Atkins
Bangampalli	Falan	Kuru	Palmer	Tong Dum
Batawi	Fascell	Langra	Paris	Totapuri
Batu Ferrungi	Fifi	Larman	Parri	Trusso
Betti Amba	Florigon	Lemon	Parvin	Tuong dum
Beverly	Fred Roos	Lipens	Peach G.C.	Van Dyke
Black Jamacian	Fyhn	M. odourata	Phoenix	Vella Colomban
Black Java	G. Allan	M. panjang	Pico	Whiley 42
Blue	Gail	M.altisima	Pineapple	Willard
Bombay	Gedong	M.aplanata	Pirie	Willard (H)
Bombay Green	Glenn	M.foetida	Pope	Xoai Boui
Boribo	Golden Tropic	M.laurina	Predojevich	Xoai Bu
Bowen Early	Goldsworthy	M.quadrifida	Pulella Late	Xoai cat
Brady (K)	Golek	Macay	R2E2	Xoai Cat chu
Brindabin	Gouviea	Mag B	Rad	Xoai Cat Hoa Loc
Brindbin	Graham	Magovar	Rajah	Xoai Cat Thom
Brooks	Gratidge	Maha 165	Rapa	Xoai Nho
Browns Seedling	Gullivers Triumph	Maha Janka	Raspuri	Xoai Thanh Ca
Bullocks Heart	Haden	Mallika	Red Mulgoba	Xoai Tuong
Bundaberg Late	Harumanis	Manalagi	Repozo	Yorkys Knob
Carabao 1	Harumanis Red	Manggadol	Robers 1	Yusof
Carabao Flav	Hatcher	Manjeera	Roberts 3	Zardalu
Carabao Harbon	Himat pasand	Manoranjan	Roberts Special	Zill
Carabao Lamao	Hong-Sa	Manzanillo-nunez	Rockdale Saigon	Zillate
Carabao Losbanos	Hood	Manzano	Rockhampton Large

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I am often asked about whether grafted lychee trees are better than air-layered trees.

It depends on the following list of criteria:

• The variety of lychee you wish to grow.
• The location you wish to grow that particular variety.
• The habit of growth you wish to achieve.

The standard commercial process for propagating lychee trees is via the method known as air-layering or marcotting. This involves girdling a strip of bark and interrupting the cambium on a nicely shaped branch. High volume air-layer production is usually applied to branches ½ – 1 inch in diameter. The cambium is the vascular plant tissue that supplies the roots of the tree with nutrition that has been photo-synthesied in the leaf canopy of the tree. A bolus of moist rooting material contained in a sheet of foil or plastic is applied around the bare strip. Over a period of 7 – 10 weeks roots form in this foil container. When the foil ball is fully filled with roots the branch is cut off below the strip and planted either in a container or directly into the ground.

An air layered tree, unlike a grafted tree, does not possess a tap root. Instead, an air-layer will form a relatively large spreading root system. This larger root system will lead to accelerated growth. In a grafted tree, a cutting of a particular variety (the scion) is attached to an already established root stock. The graft union involves getting the cambium of the scion to align with the cambium of the rootstock and then sealing this union from exposure to bacteria and pests. Different methods of grafting can be used, such as veneer grafting and chip budding, but the most common graft type is known as a cleft graft. If all goes well the union of the scion and rootstock heals and you end up with one variety of tree growing on another variety. The root stock may be an air layer of a common variety or it may be a seedling. Generally speaking, plant varieties are grafted onto a seedling rootstock that is best suited for a specific soil growing condition. In the case of fruit trees such as apples, peaches or citrus the rootstock is selected to be resistant to soil pathogens specific to a geographical region. Usually, rootstocks are selected for their resistance to soil nematodes and fungi.

Unfortunately, lychee trees are difficult to graft. This means that unless great care and excellent grafting technique are applied the graft will not take. So, for a lot of grafts you may end up with no results. The end result of this is increased expense and from the large scale growers perspective this is not so desirable. On the other hand if you want a tree that is dwarfed (you have a very small yard or a container) grafting may be a desirable alternative.

There are certain varieties of lychees that do not tolerate soils with a high pH. This is typical of limestone soils such as those found in southern Dade County, Florida (the county where Miami is located).

One variety that will not grow well in lime rock is the Emperor. The Emperor is a unique lychee that produces an enormous, juicy fruit with a tiny seed. To grow an Emperor in limestone soils you must graft the tree and the end result is a dwarfed slow growing specimen. If you grow an Emperor in Western Broward County where the soils are old Everglades muck then you can plant an air layered emperor directly into the ground and it will grow magnificently. This is because muck soils have a very high organic content and the levels of humic acids give the soil a lower and closer to neutral pH. Lychees thrive in more acidic soils with a high organic content. This is one of the reasons that mulching around lychees greatly improves their growth rate and overall health.

So in answering original questions if you had asked what is the best way to propagate Brewsters and Mauritiur trees for planting in Western Broward I would say air-layering. If you want to grow an Emperor tree in south Miami it needs to be grafted.

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Recently, a number of new fungicides that have phosphorous acid as the active ingredient have come on the market. Other names that you might hear for this are “phosphonates” or “phosphates.” Examples are ProPhyt, Phostrol and Agri-Fos. Aliette (fosetyl-A1), an older fungicide, is the prototype for this group of fungicides. However, the long standing patent on Aliette had prevented similar fungicides from being developed up to recently. In Australia, where the patent did not apply growers have been using these types of fungicides for over a decade. 

The term “phosphorous acid” should not be confused with phosphoric acid or phosphorous (P) which is a fertilizer component. In fertilizers, P is normally found in the form of phosphoric acid (H3PO4), which readily disassociates to release hydrogen phosphate (HPO42) and dihydrogen phosphate (H2PO4-). Both of these ions may be taken up by the plant and are mobile once inside the plant. Phosphorous acid is H3PO3. A single letter difference in the name of a chemical compound can make a major difference in its properties. Phosphorous acid releases the phosphonate ion (HPO32-; also called phosphite) upon disassociation. Phosphonate is easily taken up and translocated inside the plant. Phosphorous acid does not get converted into phosphate, which is the primary source of P for plants.  Because phosphorous acid and its derivatives do not get metabolized in plants, they are fairly stable and probably contribute little or nothing to P nutritional needs of the plants. Some researchers have investigated the ability of phosphorous acid to act as a nutrient source for plant growth and found that P-deficiency symptoms developed with phosphorous acid as a sole source of P. This means that although phosphorous acid can control diseases it is not a substitute for P fertilization. The inverse is also true: phosphate is an excellent source of P for plant growth, but is unable to control diseases other than improving the general health of the crop. So applying high amounts of P fertilizer will not work as a disease control measurer. Researchers have found that phosphorous acid fungicides are especially effective against Oomycete pathogens, such as Phytophthora, Phythium, and Downy Mildews in a number of crops. Phosphorous acid has both a direct and indirect effect on these pathogens. It inhibits a particular process (oxidative phosphorylation). In addition, some evidence suggests that phosphorous acid has an indirect effect by stimulating the plants natural defence response against pathogen attack. This probably explains the much broader spectrum of activity observed in fungicide efficacy trials in small fruit crops in Michigan. We found, for instance, that ProPhyt had efficacy against Downy mildew, Phomopsis, and Black rot (but not much against Powdery mildew) in grapes. We also have evidence of activity of these compounds against Anthracnose in blueberries. 

The phosphonate ion is highly systemic and fairly stable in plants. The systemic activity allows them to be applied as foliar fungicides for prevention of Phytophthora and Phythium root rots. They also display curative activity but follow label directions. These fungicides are sold as solutions of potassium and/or sodium salts of phosphorous acid. To compare them, one should look at the “phosphorous acid equivalent,” which should be listed on the label. Since these fungicides are actually in salt form, care must be taken not to exceed a certain concentration as crop injury may result, follow label directions.

(There has been some minor changes to the above article, original at www.oardc.ohio-state.edu/grapeweb/OGEN/06032005 /Phosphorous AcidFungicide _Ellis.pdf )            

The following information collected by George Allen:

It is widely known that phytophthora in avocados can be controlled by the injection or spraying of phosphorous acid products. It is also useful on a wide range of plants that suffer from phytophthora invasion & other plant fungi type diseases to varying degrees. Plants that are affected include Mangoes, Blueberry, Apple, Loquat, Plum, Avocado, Coconut, Citrus, Cucurbits, Asparagus, Grape, Lettuce, Onions, Pineapple, Potatoes, Stonefruit, Strawberry, Raspberries, Blackberries, Tomato, Chilli, Egg plants, Potatoes, Oak trees, Beech trees, Durian, Cocoa, Pepper, Taro, Rubber, Rambutan, Longan, Papaya (Pawpaw), Santol, Guava, Rosella, Vanilla; the list is enormous. It looks like most fruit trees are affected to some extent by fungus-like diseases that can be controlled by these products. In our garden partial dieback indicates that Rollinia, Custard Apples, Soursop, Mango, Pawpaw, Jackfruit and a lot of the Myrtaceae are affected.  In Australia major parts of native flora are under attack and one of the main defences being used is phosphorous acid products/salts. This is a strange substance; it appears to be very safe, extremely stable in the plants (3 to 5 years) and to have no negative effects except for leaf burn when applied too heavily. Only recently has it been found existing naturally in plants. Yates do have a product on the home gardening market, but it is very low key. Use it and watch your trees respond. Do some research on the internet: you will be surprised and wonder why it has remained so obscured.      Highly Recommended for use on your trees

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South African plant pathologists were the first to show that root rot in avocado could be controlled by trunk injection with both phosphorous acid and the patented material Aliette®.  Aliette was briefly registered in California in the late 1980’s, but the registrant soon lost interest in pursuing a full pesticide registration when it became apparent that other researchers believed phosphorous acid could be registered as a fertilizer – a process much less costly and simpler than a pesticide registration. The company continued to hold on to the patents for the product and the breakdown products that were useful in root rot control.  By holding onto the patent, this effectively stopped other companies from pursuing a pesticide registration for phosphorous acid.    In 1990, a publication reported that phosphite could be used as a source of phosphorus fertilizer and this became the basis for the registration of phosphite as a fertilizer.  Subsequently, when the original patent expired, at least two materials have been registered as fungicides containing phosphite – Fosphite® and Agri-fos®.  There are, however, numerous phosphite materials that have been registered as fertilizers (for some brands see Brunings et. al., 2005, http://edis.ifas.ufl.edu/HS254), and every day seems to bring more brands onto the scene each making claims of having the best efficacy.

We wanted to see if we could detect an efficacy difference between Aliette, another registered phosphite fungicide and four different materials registered as fertilizers, for a total of six materials.  In a greenhouse, three-month old ‘Topa Topa’ seedling avocados with cotyledons removed were planted into a Phytophthora cinnamomi -inoculated organic potting mix.  A control was also planted without the inoculum, as well as an inoculated control.  One of six different materials was then applied as a soil drench until draining from the bottom of the liner.  The materials were applied at the equivalent phosphorous acid concentration.  There were 20 replicates for each of the controls and treatments.  The experiment was repeated twice.

At harvest, root fresh and dry weights were highest for the non-inoculated trees and lowest for the untreated, inoculated controls, in both trials.  All treatments’ associated weights intermediate between these two were statistically the same.  Even a repeat application of one of the treatment materials in trial II didn’t result in greater root weights than single application treatments.  Shoot weight, both dry and fresh, was much less affected by root rot and treatments.  There were no differences in fresh shoot weight in the second trial, not even between the inoculated and noninoculated controls.  The root and shoot weights of all the treatments in the second trial were higher than in the first trial, indicating that either the inoculum was not as effective or that the trial was not continued long enough to produce as much damage. 

Root rot studies often have dramatic effects on root weights while shoot weights may remain little affected.   It is clear from our data that phosphites reduced the severity of root rot in this study, but that there was no benefit of a single source of phosphite relative to any other source. 

Below:  Healthy and decaying avocado roots.

Copyright (c) [2013] Regents of the University of California

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In Venezuela, while they have many large, mature mango trees, no fruit is borne. There are heavy crops at other stations within a hundred miles or less. What is needed in order to produce fruit?”  Dr. Carl Campbell, was familiar with the problem. The most common cause is a location where the trees bloom during periods of high humidity and temperature. This leads to anthracnose infection of the flowers and no fruit set. It can be controlled by spraying with fungicides, such as those containing copper, carbamate (e.g. Maneb), or Benylate. It is so humid in southern Florida that Florida growers are wiped out most years unless they spray. There are varieties from Southeast Asia that will do better under such conditions. He mentioned varieties Saigon, Florigon, Pico and Carabao. The good news is that all of these varieties are polyembryonic and consequently most trees will be just like their parents. The bad news is that mango seeds are viable for only a couple of weeks after removed from the seed and dried. I asked whether you could extend the life of the seed by wrapping it in wet paper towels. Carl explained that mould is a terrible problem with seeds stored this way. The best approach is to surface sterilize the seed by dipping it in 10% chlorox, then pack it in barely moist (no free moisture should be visible) activated charcoal and ship in a plastic bag.

There are locations where the trees do not even bloom. (Carl said you need to be alert because sometimes people have insisted their trees do not bloom, but more careful observers contradict them.) Fungicides will be no help there. For example, he has seen large areas in the Philippines where mangoes do not bloom. This appears to be due to the uniformity of high rainfall and temperature which does not permit the trees to have their normal dormancy. In 1972 scientists in the Philippines found that if they spray the leaves with as little as 10 g/litre of potassium nitrate (no longer available because of the security issue) the buds will start elongating within 2-3 weeks and will bloom within a month. Spraying is done only once, but the trees are drenched completely. They time the spray to have bloom and fruit growth during the least stressful season possible. Apparently it is effective only when the tree has attained a “ripeness to flower.” Signs of this stage include: leaves become dull green or greenish brown and brittle when crushed with the hand and the tree has an appearance of suspended growth. Another use of this technique is to induce earlier flowering to beat the market and get higher prices for the mangoes. The fruiting season can be advanced several months in the Philippines.

Pestnet website says:  The answer may be fungus, insects or both. In Australia, Johnson and Muirhead (1988) recommended a spray of Mancozeb (800g/kg) at the rate of 2 g/ltr weekly during blossoming and then monthly until harvest. In countries with high rainfall, flowers are commonly infected by the anthracnose fungus, Colletotrichum gloeosporioides (sexual stage, Glomerella cingulata). It causes a blossom blight. Symptoms begin as small black spots on flower buds, peduncles, pedicels and the rachis of the inflorescence. Necrotic flowers abscise leaving the persistent peduncles. Lesions may enlarge and coalesce to form large patches of necrotic, brown tissue.

As for non-chemical methods: prune out diseased twigs and clean up fallen infected trash. Also, make sure there are no mangoes sitting in the trees as they are likely to be a source of inoculum. Sounds good, but almost impossible to do on large trees! Therefore, prune trees to no more than 4 m tall, starting from an early age. The other cause of the problem is blossom moth, the larvae of which eat the flowers. The easiest way to recognise blossom moth damage is to look for clumps of flower debris held together by webbing. If the remains of the flowers are pulled apart, it is possible to find the small caterpillars hiding inside. Other insects are a possibility: beetles, large grasshoppers or chafer beetles, which would only be obvious at night time. Put a sheet or umbrella beneath the trees to catch any insects that may be present when the flowers are gently tapped.   

Powdery Mildew in Mangoes  Signs to look for are when they completely lose their first flowering but put out a second flowering. You’ll usually see a white residue and the panicle flowers are brown and brittle. Some people spray neutral copper and a wetting agent when the panicles are almost ready to open and others swear by wettable sulphur and a wetting agent. Sulphur will give a good set.

Sheryl:  Here are Bob’s notes on how to extract the embryo before planting:

The husk must be taken off to expose the embryo. Watch out for the mango weevil borer which must be removed then plant the seed on its edge concave edge down and the top just above ground level.

Required tools:  Dry rag to hold the slippery husk and tin snips that have a mechanical advantage.  Hold the husk at one end with the rag and snip off about 5mm on the other end. The gap between the two sides of the husk is wide enough to let the blade of the tin snips in. Cut along between the two halves on the bottom concave section being careful not to cut the embryo. Lever the husk halves apart with your thumbs and gently pull the embryo out.  Plant out as soon as possible.