Your Backyard Fruit Bowl – Mountain pawpaw and babaco

Immature babaco fruit_Image by fernandozhiminaicela via Pixabay.com

In the depths of winter, it’s hard to not get stuck in the winter fruit rut – seemingly endless apples, pears, oranges and imported bananas. Sure, you can supplement with bottled and dried fruit from the pantry shelves, and frozen this and that from the icy depths of the nearest chest freezer, but after a while, the mind tends to wander back towards the juicy, subtropical delights of warmer climes.

Winter is a time when many Kiwis escape to a welcoming island in the Pacific, where these exotic fruits abound. While growing the true tropical papaya is beyond the grasp of most of the country, (apart from the seemingly winterless far north, and even then, it’s marginal), there are a couple of extended Caricaceae family members that can be grown in parts of the country with milder climates, some of which I’ve known to even fruit as far south as Christchurch, in the confines of a glasshouse.

Believe it or not, the babaco was actually touted to be one of the next big New Zealand fruit crops in the 1970s, when vast quantities were grown in the Auckland region. Unfortunately, due to a number of factors, they never took off like some of their stablemates (tamarillos and kiwifruit), and have somewhat faded into oblivion, much like the oddball kiwano (African horned melon).

Nevertheless, if you have a hankering for the tropics, a sheltered spot in a region immune to winter’s most savage blows, or a capacious conservatory or glasshouse, there are some papaya-relatives which are worth a whirl and might just give your backyard fruit bowl that final je ne sais quoi.

On that front, this article is the last one, rounding out this ‘Your Backyard Fruit Bowl’ series – thanks for tuning in!

Mountain pawpaw and babaco: a short family history

Mountain papaya_Vasconcellea pubescens growing 2100 m above sea level_Michael Hermann via Wikimedia Commons

The mountain pawpaw, Vasconcellea pubescens (formerly classified as Carica pubescens) is native to South America, and grows at altitude (above 1,000 m) from Panama to Bolivia and in Chile and Argentina. Given that it is adapted to the cool cloud forests of the Andes, it is significantly more cold-tolerant than the related tropical papaya, Carica papaya. Its growth form and foliage are highly ornamental, and even if your climate is not conducive of fruit production, mountain pawpaw is worth considering for its aesthetic value alone. The five-sided fruit are smaller than that of tropical papaya. The flesh of mountain pawpaw fruit is similar to that of its tropical cousin, less sweet but aromatic with a sharp taste, and is usually cooked prior to consumption, retaining its firm texture.

Babaco, Vasconcellea x heilbornii (syn. Carica pentagona) is likely a hybrid between a mountain pawpaw and Carica stipulata, more commonly known as toronche or toronchi, another natural hybrid. It is the most cold-tolerant member of the papaya family and has been grown in elevated areas of Ecuador (> 2,000 metres) since pre-European times. The plants are incredibly prolific, and well-suited to container culture under glass in cooler areas. Outside its native range, the babaco has been cultivated commercially in the Middle East, North America, the Channel Islands, Italy and here in New Zealand, thriving in warmer temperate and subtropical zones.

Not sure what to plant or where to start? Our backyard orchard guide has you covered.

Suitable climates and growing conditions

Vasconcellea pubescens foliage_Image by Melburnian CC BY 3.0 via Wikimedia Commons

Mountain pawpaw grows well in the warmer regions of the country; fruit production is best in low-or frost-free areas with average temperatures between 12 and 18°C. I have known them to produce satisfactorily on the West Coast of the South Island, where they thrive in the humidity. Plants will fruit in their second year, and the fruit ripens from October to January. They can crop for five to seven years, and produce up to 50-60 fruits per year, each 8-20 cm in length. The plants are relatively short-lived and often replaced around the five-year mark. They can survive temperatures of down to -3°C without permanent injury; while the plants may lose their leaves, they will regrow as long as the main stem is not irreparably damaged. The plants are reasonably wind-tolerant, but need protection while young.

In terms of pollination, mountain pawpaw follows the complicated regime of its tropical cousin, C. papaya. Some plants (the majority) are dioecious. These produce larger, short-stalked female flowers which generally don’t set fruit on their own, except for a few which will set pathenocarpically (without pollination), giving seedless fruit. Smaller male flowers are borne on the same plant on longer stems, which pollinise but do not set fruit themselves. There are also two sets of monoecious variants. The first produces solely bisexual flowers (all flowers being both male and female and therefore usually self-fertile). The second type of monoecious plant is partly bisexual, at certain times producing short-stalked male flowers and at others, bisexual flowers as mentioned above. It is thought that high temperatures in midsummer influence the type of flowers produced – supressing the development of the ovary, which signals production of solely male flowers and prevents fruit formation. If these trees have their tops cut out, they may also switch to just producing female flowers. (Phew, complicated alright!). The ratio of each type of flowering plant mentioned above produced in any population of seedling-grown mountain papayas varies greatly, so for a guaranteed crop, plant three to four seedlings in close proximity to ensure good fruit set. Pollination is by wind and insects, and if you find nature isn’t taking care of things, you can get out a paintbrush and hand-pollinate in your spare time.

Mountain pawpaw are commonly grown from seed, or can be propagated via cuttings, as for babaco (see below). To grow from seed, extract the seeds from the pulp that surrounds them by rinsing well with water (a kitchen sieve held under the running kitchen tap might help), then soak them in warm water for four hours. This helps break down the germination-inhibiting compound found on the outside of the seeds. Sow in a good-quality, free-draining seed raising mix (look for one with a reasonable percentage of pumice, I prefer the Tui brand for this). Germination takes approximately 30 days in a warm spot. Prick out into fairly tall pots to encourage tap root development.

Babaco do best in subtropical or warm temperate climates with minimal frosts, and are tolerant of cooler, humid conditions too. They will grow in sheltered coastal environments. They can be grown up against a brick wall or building for additional frost protection (unlike many other fruiting plants, their roots are non-invasive and easily controlled – hurrah!). Like the mountain pawpaw, they will tolerate frosts down to -2 or -3°C and may lose their leaves, but these will regrow. The babaco’s growth form is that of a small, herbaceous tree-like shrub, with a tropical appearance. They usually have a single trunk, but may form shoots at the base of this. The plants can reach three or four metres in height, with trunk thickness proportional to their overall vigour. Allow approximately three metres between plants. Like mountain pawpaw, babaco are relatively short-lived and will need replacing after 5-7 years.

Babaco are as simple in terms of pollination as mountain pawpaw are complicated. Plants will fruit within one to two years of planting. Plants only produce female flowers, which set parthenocarpically, without need for pollinisers or pollinators, and the resultant fruit are all seedless. This self-sufficient tendency also adds to their suitability as a crop to grow under glass. Babaco fruit are torpedo-shaped, five-sided and can be in the region of 6-12 cm long at the small end of the scale, and up to 30 cm long at the larger end, weighing up to 2 kg each! The size of the fruit is generally governed by its position on the stem – and the plant’s overall vigour. The lowest fruits ripen first, and are usually the largest. If picked when the fruit just starts to turn yellow, they will ripen fully off the plant, and store well for about a month at 6°C.

As babaco don’t produce viable seeds, they must be propagated clonally via cuttings. For this, soon after fruiting, you need to remove an entire stem about 30 cm above the ground, then cut it into 30 cm pieces. Dip one end in a rooting hormone, then leave to dry out for 1-2 days before placing vertically in holes dibbled in free-draining propagation mix (e.g., 50:50 sand/pumice mixture) to callus. Once rooted, with obvious top growth, either pot on or transplant into their intended final growing position.

Site selection and planting

Babaco plant showing foliage and ripening fruit_Image by josch13 via Pixabay.com

Mountain pawpaw - plant in spring or early summer, choosing a site in full sun or semi-shade. Allow three metres between individual plants. Free-draining, fertile soils are most appropriate, most other soil types except heavy, waterlogged conditions are tolerated. The plants are fairly drought-hardy once established, but prefer good moisture levels throughout the growing season.

Babaco prefer a sheltered spot and will fruit in shaded locations, but thrive in sunny positions. Partial shade is preferential if they are grown in climates with particularly hot summers. They will tolerate a range of soil types, including clay. For best results, a lighter, well-drained soil type with good fertility and a pH 6-6.5 is ideal. As for mountain pawpaw, spring or early summer planting is best. Babaco do very well in pots, especially in cooler areas where they can be taken into a conservatory or glasshouse for the winter, or grown under cover year-round. Their foliage lends a tropical vibe to any living area.

Culture and care

Both mountain pawpaw and babaco are fairly drought tolerant one established, but benefit from good levels of moisture, particularly during fruit set and flowering. They will not tolerate waterlogging, so take care not to over-water.

Both will benefit from applications of well-rotted manure and/or compost in spring and summer. Avoid fertilisers high in nitrogen, which encourage excessive vegetative growth and can contribute to a decline in fruit quality/texture and storage potential.

Pruning

Mountain pawpaws are very easy-care in this regard. They fruit on the current season’s growth. Each year, allow a low-growing side shoot to develop, this will be used to replace the current main stem. The previous growing season’s fruiting stem is removed at ground level once it has finished fruiting. This renewal process keeps the plant fruitful and prevents it from reaching an unmanageable height.

Babaco do best when kept to a single, or maximum of two stems. Plants that are allowed to grow and produce fruit on multiple stems usually produce lower-quality, smaller fruit. Remove extra stems at the base of the plant, making well-angled pruning cuts so the water drains freely off the cut surface. Remove stems after they have fruited (letting each produce for no more than a year, or two at most). This practice encourages new stems to develop in their place, any excess of which can be used to propagate new plants.

Pests, diseases and what to do about them

The most significant disease-causing organism affecting papaya overseas, papaya mosaic virus, is not know to be present in New Zealand. Both babaco and mountain papaya are reasonably hardy, but may suffer from root rots in cold, wet soils and fungal foliar diseases in cool, high humidity environments. Keeping an open canopy when pruning can enhance airflow and help prevent foliar disease taking hold.

What to do with your crop

Mountain papaya_Vasconcellea pubescens fruit_Rik Schuiling TropCrop - Tropical Crops Services_CC BY-SA 3.0 via Wikimedia Commons

Firstly, a word of caution when harvesting and handling all papaya fruit – the plants’ stems, and unripe fruit exude milky latex, as figs do, and this can cause unpleasant rashes and dermatitis-like skin symptoms. Unripe papaya fruit can induce abortion, so consumption of green fruits should be avoided. Papaya fruit contain an enzyme, papain, which breaks down proteins and as such, is well known as a meat tenderiser, but can cause allergic reactions in some individuals.

Mountain pawpaw fruits have a good flavour but are less sweet than the true tropical papaya. The flesh around the seeds is the sweetest, and the seeds can be eaten too – they have a spicy, peppery flavour. Mountain pawpaw fruit is more commonly eaten cooked than raw and the flesh retains its firm texture after cooking. It can be used in desserts, jams or savoury dishes or be bottled in light syrup. The enzyme papain, contained in the fruit’s flesh, means it can be rubbed on tough cuts of meat to tenderise them.

Babaco fruits are aromatic and have refreshing, melon-like, cream to white flesh, which is said to be reminiscent of strawberry, pineapple and actual papaya in terms of flavour. Some people find the flesh slightly effervescent (fizzy), hence this quality, combined with its tropical fruit flavours means babaco is sometimes known as ‘champagne fruit’ They can be eaten fresh when fully ripe, and the whole fruit, including its thin skin, is edible. The cut fruit does not brown over time, and as such is an excellent addition to fruit salads. Babaco also have an affinity with seafood and make a refreshing, distinctive addition to seafood salads in their raw form. They can also be stewed, with the addition of a little sugar and used in various baked goods, including pies, shortcake and strudel, much as you would use stewed apples. They can also be preserved in syrup, turned into juice and added to ice cream bases and smoothies. For the latter, I have successfully frozen cubes of peeled babaco/papaya in a Ziploc bag. The fruit also makes good jam, on its own with a touch of lemon, or in combination with other fruits such as berries, babaco and boysenberry being a notable Kiwi combo.

In terms of health benefits, pawpaw and babaco fruits have useful levels of vitamins A and C plus fibre.

Babaco fruit salad

1 medium babaco
Caster sugar
4 kiwifruit – a mixture of colours, if available
Chilled dry white wine

Wash the babaco but don’t peel. Cube the flesh, place in a serving bowl and sprinkle with caster sugar to taste. Peel and slice the kiwifruit into rings and add to the babaco. Spoon portions of the papaya and kiwifruit mixture into individual dishes, half-filling them with the white wine just prior to serving, ideally with crisp dessert biscuits, e.g., lemon tuiles alongside.

Babaco gingerbread

From the New Zealand Tree Crops Association’s publication ‘Beyond Apple Pie – Savouring your seasonal fruit’.

100 g butter, melted
½ cup treacle
2 eggs
550 g plain flour
1 tsp ground cinnamon
1 tsp ground ginger
1 tsp mixed spice
½ tsp baking powder
½ tsp baking soda
½ cup milk
1 cup diced raw babaco pieces.

Preheat oven to 175°C, and grease and line a 1 kg loaf tin.

Sift all the dry ingredients except the baking soda together in a large bowl. Melt the butter and treacle together in a saucepan over low heat. Stir the baking soda into the milk in a small cup. Gently mix the butter/treacle mix, milk/baking soda mix into the dry ingredients. Fold in the babaco pieces and beaten eggs, then turn into the prepared tins. Bake for 25-30 minutes, until a skewer comes out clean. Cool in the tin for 10-15 minutes before turning out onto a rack. Slice and serve plain or buttered.

Disclaimer: the information supplied above is of a general nature and provided as reference material only. In regards to pest and disease control, please consult your agrichemical consultant for suitable products, application rates and further region-specific information.

Anna-Marie Barnes is an active member of the New Zealand Tree Crops Association who endeavours to grow and preserve as much of her own fresh produce as possible. When the weather’s no good for gardening, she can usually be found inside working on a batch of homemade cheese or soap.

The New Zealand Tree Crops Association is a voluntary organisation promoting interest in useful trees, such as those producing fruit, nuts, timber, fuel, wood, stock fodder, bee forage and other productive crops. Find out more about the NZTCA here: https://treecrops.org.nz/

Image credits

Immature babaco fruit_Image by fernandozhiminaicela via Pixabay.com
Mountain papaya_Vasconcellea pubescens growing 2100 m above sea level_Michael Hermann via Wikimedia Commons
Babaco plant showing foliage and ripening fruit_Image by josch13 via Pixabay.com
Mountain papaya_Vasconcellea pubescens fruit_Rik Schuiling TropCrop - Tropical Crops Services_CC BY-SA 3.0 via Wikimedia Commons
Vasconcellea pubescens foliage_Image by Melburnian CC BY 3.0 via Wikimedia Commons