Dealing with black spot fungus in pawpaw / papaya

Last year we reluctantly pulled out the last of our pawpaw trees.  This was because we were not able to keep the black spot fungus under control sufficiently to be able to harvest fruit of a quality we were prepared to eat.  It was a very difficult decision because there is nothing more delicious than a tree-ripened pawpaw.

This tree and another which we dug out few years back were planted ten years ago and probably gave us about a tonne of fruit over that time.

The black spot fungus didn’t show up in the first 2-3 years, and during that time it was not unusual to have more than 20 fruit on each tree at one time, and to harvest a fruit every couple of days at the height of the season.

However, once the fungus became established for many years we were harvesting smaller than normal fruit which did not have the full “ripe pawpaw” flavour and was infected with white spots which we cut around.

We tried a range of approaches to controlling the fungus, including spraying with wettable sulphur and Seasol.  Unfortunately without any clear guidance as to how often to spray, and without any certainty that these were the correct measures to take, combined with long periods away from home, we didn’t persist with any particular regime.

However we did get the impression that both the sulphur and the Seasol had some beneficial effect, but only in the presence of good soil health and regular fertilizing.

Today I came across a post on Jerry Coleby-Williams’ website on how to fortify your pawpaw plants to better withstand the effects of this exotic fungal disease caused by the fungus Asperisporium caricae.

What he recommends is a combination of:

  • spraying with wettable sulphur  monthly from (February to October);
  • regularly removing severely infected leaves and fruit and all fallen foliage (all year round);
  • removing old mulch at the end of autumn and replacing it with fresh; and
  • maintaining the overall health of your pawpaw by a combination of good drainage and modest but regular feeding.

Jerry emphasises that well nourished pawpaws are more important for disease control than spraying. Go to his website to see what he prescribes in detail, particularly the advice on the  nutritional requirements for pawpaws.

Pruning Dragon Fruit

I have to admit that I have not found good information anywhere on how to prune Dragon Fruit.  What I am going to tell you here is a result of my own “trial and error” approach over several years.  It seems to work for me, but who knows whether there is a better approach that I don’t know about that might yield a whole lot more production.

Our plants are around 4 years old and last year they produced over 40 fruit (I stopped keeping records after 40, so the total could have been over 50).  Probably because of our cool and dry winters our Dragon Fruit go dormant in the winter, with very little new growth and no flowers.  Fruit is produced between January and June.

Three days after flowering

Three days after flowering

We had the first bud on our three plants on 6 December, and it flowered on 18 December this year, though I didn’t get around to photographing it until yesterday (21st).  This was three weeks earlier than the first flowering last year.

On the 20th I carefully counted all the buds that had appeared since the 6th – in two weeks we had gone from one bud to 29.

These plants were partially pruned in November, but then I got too busy to finish the job.  But this has given me the chance to think about the effect the pruning might have had on bud location, though this is all guess work and observation – no evidence-based theory here.

A range of buds, from just appeared to on the way to flowering

A range of buds, from just appeared to on the way to flowering.  Note the ants on the bud.

What I am seeing this year is similar to what I have observed in other years.  The most buds (by far) appear on downward growing branches.  In addition, there are far more buds on branches that have been pruned (whether the pruning was done by chopping off the branch through the green section or cutting it off at a node) than on un-pruned branches.

As you can see in the photo above, ants take a great deal of interest in the buds, but they do not seem to do them any harm.  I suspect that the buds exude something that is useful to the ants, and maybe in return the ants discourage insects that may be harmful to the bud.  Does anyone have any information on this?

The photos below show buds formed near the pruning point, however not all of the buds on a pruned branch are this close to the pruning point.  Nevertheless, as I said above, by far the most buds are on pruned branches.

It doesn’t seem to matter whether the pruned branch has grown some more branches at the pruning point.  Many of the branches I pruned in November have done this, but they still have buds on the pruned section – and not on the new, un-pruned branches.

Another factor to think about (maybe before you plan your Dragon Fruit planting) is whether you will grow them on poles with spreader frames on top or horizontal beams.  You can see a short discussion here.

If you are just starting out with Dragon Fruit, remember that they should not be pruned until they are at least one year old, and ideally not until they have had one good flowering and fruiting season.

Would you like to share your pruning techniques here, along with your observations on the results?

If you are looking for more information on Dragon Fruit, have a look at the links at the end of the this post from the end of 2014.  And if you want to see the layout of our vege garden have a look at the two plans in this post. The first shows how the vege garden fits into the overall plan on our narrow ridge top.  Scroll down for a more detailed plan of the vege garden.  The Dragon Fruit are growing in Hugelkultur Shadehouse No.1.

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Branch pruned at the node

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Bud a few days old. The ants seem to take an interest in them right from the time they form

A bud right at the pruning point

A bud right at the pruning point – chopped through the green section

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Branch pruned by chopping through the green section

Growing Dragon Fruit from cuttings and looking after your growing plant

This post is a work-in-progress compilation of material on growing this delicious and low maintenance fruit.  I will edit it from time to time as I come across more/better material.

[Sunday night Oct 5: Have just revised the links at the bottom of this page – quite a few useful sites there now]

[October 6: added table of nutritional values of pitaya, added photos and associated text, added new links to source]

Our Dragon Fruit Experience

We started out with some cuttings of red dragon fruit in 2010 or early 2011.  They grew successfully in large pots, but we didn’t have anywhere where we could plant them out, so they stayed in the pots for ages, with some eventually extending roots through the bottoms of the pots and into the ground.  These plants are nothing if not hardy.

Three of them were planted out on a beam trellis in a shade tunnel in mid-2011 (the 30% shade cloth on these tunnels is extended only during the hotter parts of the summer).

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First dragon fruit bud – February 2012 – while the plant was still in the original pot

Two buds were produced in late summer 2012 – probably in late summer because the plants were not sufficiently established to flower earlier that summer.  Neither of these produced fruit.  In the 2012/13 summer we had two flowers and two fruit.

In October 2012 one-third of the floor or the shade tunnel was dug out to a depth of 200-300mm and filled with dead timber, including tree trunks, branches, twigs and leaves, and chip mulch from our annual firebreak clearing, then covered over with the soil taken out of the hole (or rather the two-thirds of the soil that remained after the rocks had been sieved out)  to make a modified heugelkultur/raised garden bed.  That’s the lush area in the background of the photo below, 10 months later.

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One of the dragon fruit on the trellis – late July 2013.  This shot gives you an idea of the post and beam trellis.  It actually recommended for red dragon fruit, but I fail to see why, and I know a commercial grower who has changed over from this to post and frame trellises.

In late July 2013, just before the photo above was taken, the remainder of the floor of the shade tunnel was turned into a modified heugelkultur bed.  The raised bed on top of the timber was a lasagne bed with layers of straw, poultry manure (including quite a few carcases), and compost.

By late December 2013, only five months later, the dragon fruit had responded dramatically.

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The same plant as above, but five months later (there is a second plant growing up the post in the background, but the branches here are from the one in the foreground).

We eventually had seven fruit from nine flowers on four plants from the 2013/2014 summer, harvesting the last of the fruit in May and June.  One fruit didn’t develop, and one was on a new plant growing out in “possum land” beyond the electric fence and was eaten by the possums before it was ripe.

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The same plant in mid-2014 prior to pruning

In hindsight it was really dumb to plant dragon fruit above a vegetable bed inside a rather narrow shade tunnel.  These things need to be able to grow as wide as they want, and they need to have a combination of old and new branches hanging down (fruit comes from both).  It just doesn’t work, and forgetting that the vines are there and standing up under one to get one of those small spines in the soft part of the ear is not fun.  As soon as we get an extension to the garden fenced we will be planting lots of dragon fruit there, from cuttings off these plants.

Propagating via Cuttings

While it is possible to propagate dragon fruit from seeds, it is along process and does not result in a vine with the same fruit producing properties as the parent.  With the cuttings you are getting a clone of the parent, and much more quickly.

You can make multiple stem cuttings from the one piece of stem, but focus on the lower and middle portions of the stem (away from the growing tip) to get the most robust material.  If you have an “intermediate” section of stem with narrow stem portions at each end, then it probably doesn’t matter where you take the cutting.

Try to use a stem that is a few inches in diameter (> 2 inches), but smaller stems will work – the danger is that the stem may dry up too much when being “cured” or before it produces roots in the pot. Thicker cuttings suffer less stress.

When you make a fresh cutting, it’s best to place it in a shady location for a week or more to allow the cut end to dry and “heal” to avoid fungal infections, before placing it into soil.  You may see roots starting to develop during this period, but it is not necessary to wait for roots before potting the cured cutting.

Thereafter, a good, well-drained potting mix will serve to encourage roots to grow.

Water once every one to two weeks and let the soil dry up, too wet can cause fungus attack.  Keep mulch away from the base of the plant to avoid introducing fungi and rot.

With filtered sunlight and warm temperature, the vine will grow a root first, then, once the root is established, new branches will sprout from the nodes.

When new growth appears (this may take as long as four months, depending on the weather and season) they are ready to plant in the ground in a sunny location.

 

Growing the Mature Plant

Dragon fruit need to grow up a trellis, but they need to be able to “hang” their side branches out from the main stem (or from a beam or frame on top of the trellis) in an arc.

Remove lateral growth until the stems reach at least a few feet up their support. Then you can prune the tips of the stems to induce multiple branching, and eventually, fruiting.

This cactus develops some pretty thick and heavy stems, so your support will need to ultimately hold quite a bit of weight. Use twine or bands of fabric to help attach it to the support, avoiding wires that can cut into the weighty stems.  Eventually the stems will grow aerial roots to grip onto the support.

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A man inspects dragon fruit trees on a plantation in rural Cambodia. Photograph: Heng Chivoan/Phnom Penh Post: 30/7/12

This plant is very efficient because it can grow roots on any surface. It can also absorb water and nutrient through any surface. It can also utilize low light or partial shade but it grows better in full sun. BUT be careful when the plant is moved from low light to full sun – on very hot days the vine can sunburn easily.  Growth and fruiting are better in full sun (and the plant needs at least half a day of sun), but in the hotter part of summer I use 30% shade cloth.

Flowering, Pollination and Fruit Development

The main flowering is in summer and then fruit develop into autumn and winter, however the time taken to reach maturity depends on the size of the fruit, so from flowering to ripe can be as short as six weeks or, more usual, several months.

[Need to add more information here]

Feeding Your Dragon Fruit

Dragon fruit needs low nitrogen and high phosphorus in the soil, particularly as it approaches, and during, the growing and fruiting season.  They “hibernate” in winter in our climate.

Pruning

When your plant is at least one year old, strong and vigorous, and ideally having proven its ability to bloom and fruit abundantly (this may take 18 months to two years in our climate), you can begin to take stem cuttings.  Because the plant needs to be pruned once it is mature and has fruited (in order to produce many new side stems and therefore many fruit) you will have an opportunity every year to make cuttings from the pruned material.

It is on the new branches sprawling over the top of the support structure where most of the new flowers are produced, although flowers can pop-up anywhere on the plant.

The Nutritional Value of Dragon Fruit

Nutritional Value of Pitaya

Click on the table to go to the source at: Dragon Fruit: Nutritional Value, Health Benefits and Calorie Count for more information

 Some useful links

NT Government AgNote D42: The Pitaya or Dragon Fruit A four-page technical note on key aspects of cultivation.

NT Government Growing Note: Pitaya (Dragon Fruit) One-page note with some material not covered in above AgNote

Dragon Fruit Production Guide (Pinoy Bisnes Ideas) A lot of good information, some of it in more detail than the above publications.

Pitaya Growing in the Florida Home Landscape  One of the most complete sources I have found on growing dragon fruit.

Dragon Fruit (Pitaya) – How-to Guide for Growing   Includes a video on hand pollination.  A very good source of information on growing dragon fruit, with some information that I hadn’t seen elsewhere.  This is actually an Australian self-sufficiency website, and the author is based in South East Queensland.

Pruning Pitaya (Dragon Fruit) (Sub-tropical Fruit Club of Queensland Instruction with photos for pruning. Use the search box on this page “pitaya” for a huge amount of useful/interesting information on Dragon Fruit

Dragonfruit Cactus (Botanical Growers Network publication) Some of the information fills gaps in the above sources, or gives a different slant on some topics.

Improved Production Technology for Pitaya (Philippines Bureau of Agricultural Research) Check info on when to prune, time to first production and time from flowering to harvest.

http://dragonfruit.foodlywise.com/ An annoying site because of its strange links but there’s some good information if you can figure out how to follow them.

http://dragonfruit.foodlywise.com/how_to_grow_dragonfruit/growing_dragonfruit_commercially/growing_dragonfruit_from_cuttings/dragonfruit_stem_cuttings/  Covers several aspects of growing dragon fruit from cuttings.

http://www.vivapitaya.com/dragon-2.htm A selection of photos of dragon fruit growing in different circumstances – some ideas for supports, and indications of what healthy plants look like in the tropics.

Lee Reich: unusual fruits, soil organisms, compost tea, moon planting and a lot more

Just a quick one to alert you to a very interesting new podcast on the Northwest Edible Life blog featuring an interview with Lee Reich.

Lee Reich: soil scientist, horticultural scientist, author [link to leereich.com]

Reich has graduate degrees in soil science and horticulture and has worked in plant and soil research with the USDA and Cornell University, before turning to writing, lecturing, and consulting.  He has written at least nine books as well as running an interesting blog.   Because of his educational, research and practical experience in two fields which are an important part of the basis of permaculture, a lot of what he says in this interview will be of interest.  Erica, the host of the Northwest Edible Life blog, has a lively and easy to listen to interviewing style that keeps the flow of ideas coming throughout the interview.

You can also download the podcast – which leads me to the topic of mp3 player programs.  I’ve found a lot of the programs available for Macs to be a bit of a pain in the neck – and I totally refuse to use iTunes because like a lot of Apple’s market oriented software it is just too focussed on data collection.  Then I just stumbled on the fact that if I stored an mp3 file in Evernote I could also keep comments about the content of the podcast in the same in the same Note, as well as using Evenote’s very functional mp3 player straight from the note.  In fact what I do is to store the file in my General Library folder, along with pdfs etc, then link an Evernote Note to that file.

Screen shot 2014-08-11 at 3.03.12 PMEvernote is available for Mac Windows phones and tablets.  I recommend it as a great place to dump information that will be useful one day, or to keep copies of receipts (e.g. for equipment with a warranty), warranties, manuals, etc.  My only problem with it is that it can be difficult to extract files from Evernote once they are saved into a Note, but I get around that by “attaching” files to Notes (and by keeping most of my technical notes in Devonthink Pro Office).

 

Pruning fruit trees demystified

I love pruning fruit trees – when it works.  I think I understand the theory and mechanics of it, but I have one lemon tree that totally defies my pruning objectives.  Now Erica over at Northwest Edible Life has put out a blog post that explains pruning, from the essentials on up.  I didn’t know as much as I thought I did.

Here’s how she approaches it:

What The Backyard Orchard Culture Grower Wants

  • Healthy, long-lived, productive trees.
  • A long harvesting period of family-appropriate quantities of fruit.
  • Great quality fruit.
  • Backyard-appropriate size (small – think fruit bushes, not fruit trees!).
  • To never have to get out a ladder for any tree maintenance.

What A Fruit Tree – Any Fruit Tree! – Wants

  • To reproduce by making seeds.
  • To maximize captured sunlight and grow.
  • To balance its root mass with its leaf canopy (this is so important I’m going to talk about it in depth below).

After reading through the rest of her post I now understand that my lemon tree is trying to meet these three objectives, but a the same time is trying to deal with restrictions imposed by being hard up against the end of a shadehouse.  I have been pruning it without recognising the struggle it is going through.  To find an image that would illustrate this problem, I just went through my collection of photos of the development of the garden – pretty huge and extending back over about ten years – there’s not a single one that includes the recalcitrant lemon tree.  Sort of suggests how frustrated I am with my lack of pruning success with it .

Have a look at Erica’s post, it’s well worth not only reading but maybe making notes in your garden book, or dropping the post into your favourites list or database.  I’ve just clipped it into DevonThink Pro so I can refer to it whenever I need to.  Happy and successful pruning.