Growing passionfruit: common questions

Simon Newett, Department of Primary Industries and Fisheries.

On this page are questions and answers about:

• Varieties and rootstocks
• Miscellaneous problems  (e.g. Why are fruit dropping off my vine?)
• Pests
• Fertilising and irrigation
• Preparation for planting
• Planning
• Marketing

Varieties and rootstocks

What variety should I plant?

In areas with subtropical climates, such as south-east Queensland and northern New South Wales, hybrids of the purple passionfruit (Passiflora edulis) and the golden passionfruit (Passiflora edulis f. flavicarpa ) are preferred for commercial production. These hybrids are tolerant of cool winters and retain the better flavour of the golden passionfruit. For many years, the predominant hybrids cultivated were E-23, Lacey, Purple Gold and Barlow's Special. Since the late 1990's varieties such as Supersweet 7 and Supersweet 9 have become dominant. New varieties, arisng from the Australian Passionfruit Industry Association's ongoing breeding program, are released from time to time to the industry. Performance of hybrids can be very vairable depending on subtle variances in environment, management etc. and specific recommendations on variety suitability for different growing regions are difficult to make. Always try small numbers of new varieties when they are released to see how they perform on your farm. Evaluate these for two years before committing to larger plantings.

For sites with a tropical climate such as North Queensland, P. edulis f. flavicarpa selections such as Panama and Marsh perform well. The newer Supersweet hybrids are also worth trying.

What can you tell me about the variety called Panama?

Panama is actually a tropical passionfruit from the same species as the golden passionfruit (Passiflora edulis f. flavicarpa). It produces purple fruit and is called a purple flavicarpa. Passionfruit varieties such as the Supersweet series are hybrids between Passiflora edulis and Passiflora edulis f. flavicarpa. Panama has larger fruit than the hybrid varieties but a lower pulp to weight ratio. Panama and other golden passionfruit selections are best suited to a true tropical climate. In subtropical regions, its growth slows considerably and pulp content of fruit diminishes significantly during the cooler months.

What is the best rootstock to use?

Hybrid passionfruit varieties have a varying degree of resistance to Fusarium wilt, so it is essential that a special wilt-resistant strain of P edulis f. flavicarpa is used as a rootstock when propagating these varieties.

Panama is generally grown from seed because it is a flavicarpa selection. Most plants established in this way have some resistance to Fusarium wilt. On the downside, however, there will be more variation in plant vigour, yield and quality compared to plants propagated by grafting onto a selected wilt-resistant strain.

Problems

Why do my vines flower but don't set fruit?

There are several reasons for vines flowering but not setting fruit.

• Poor pollination. This is the main cause and can be due to bees not working the flowers (for example during heavy rain); temperatures being too low or too high for pollination (optimum temperatures for pollen germination are between 20°C and 35°C); or rain directly reducing the viability of the pollen (moisture causes the pollen grains to split).
• Boron deficiency.
• Extended periods of overcast weather. This may cause flower drop regardless of pollination problems.

Why are fruit dropping off my vine?

There are three possible reasons for fruit dropping off vines:

• irregular watering in which the vines at times get insufficient water
• fungal diseases
• fruit fly and severe mite damage, particularly with young fruit.

Why are my leaves going yellow?

The most common cause of leaves going yellow is passionfruit woodiness virus. Other possible causes are:

• magnesium deficiency
• nitrogen deficiency on sandy soils
• 'winter yellows'. This is brought on by cold weather, windy conditions, low humidity or a combination of these.

What are these spots on my fruit and leaves?

Spots on fruit and leaves are usually caused by fungal diseases. The most likely causes are:

• Alternata spot
• Brown spot
• Septoria spot.

Why are my fruit bumpy or malformed?

There are several causes of bumpy or malformed fruit. Here are the main ones.

• Passionfruit woodiness virus. This is the most likely cause, particularly if your vines are not growing well and there are mottled yellow leaves present.
• Boron deficiency.
• Insect damage, particularly fruit fly.

Why are my fruit shrivelled?

There are several possible causes of shrivelled, poorly developed fruit. The main ones are:

• fruit fly damage
• sucking bug damage
• poor pollination
• boron deficiency
• insufficient irrigation when a heavy crop is set.

Why are my vines dying?

There are three possible causes of vines dying.

• Phytophthora blight, which shows first on the new growth, particularly after prolonged wet weather.
• Fusarium wilt. This is most likely if resistant rootstocks were not used. It normally causes rapid (within one or two days) wilting of the entire plant, especially in very hot weather.
• Base rot - a dry corky collar rot at ground level.

Why are my vines growing poorly?

The most likely cause of vines growing poorly is passionfruit woodiness virus. The disease is generally present at some level in most vines. When vines are growing vigorously, symptoms are not normally evident, but when vines are under any sort of stress (for example, cold weather, lack of water, lack of nutrients), the disease becomes evident and slows growth. Affected leaves are yellow and mottled and affected fruit bumpy and malformed.

Pests

How do I control fruit fly?

The best way to control fruit fly is to apply a bait spray of an approved insecticide plus yeast autolysate at weekly intervals. Apply twice weekly during wet weather, periods of high fly activity or where flies are seen stinging fruit. Fruit fly traps (one in the centre of each block) are useful in monitoring fly activity.

If bait sprays are applied correctly at the right interval, no other sprays should be necessary. Cover sprays of other insecticides are not recommended because they disrupt insect parasites and predators. They should only be used in an emergency if fruit fly populations get out of hand.

How do I control mealybug?

The first thing to do to control mealybugs is to spray the butt of the plants and the bases of the posts with chlorpyrifos to prevent ants farming the mealybugs for their honeydew. The preferred treatment is to introduce commercially available predators of the mealybug. If your pesticide spray program doesn't allow you to use this technique, the next best treatment is to spray with a mixture of methidathion and wetter or petroleum oil in December and January. However, remember that when temperatures are greater than 30°C, oil sprays can cause leaf burn.

Fertilising and irrigation

How should I fertilise my vines?

Fertilise passionfruit all year round. Base the amount and type of fertiliser used on leaf and soil analysis. Take leaf samples in July or August when the vines have slowed in growth. Passionfruit need year-round fertilising, so fertigation (applying fertiliser in the irrigation water) has some appeal because of its convenience. Because it is a more efficient way of applying nutrients, fertiliser rates can be reduced by up to 25%.

Do I need to irrigate my vines?

Yes, otherwise in periods of dry weather, you risk getting fruit drop and lower yields as the vines slow down in growth. Passionfruit yields are very much related to good strong growth throughout the year and irrigation is a way to ensure this. Adequate supplies of water during the normally dry spring period are crucial to promoting vigorous post-winter growth of vines and subsequent high yields. A reserve of up to 3 megalitres per hectare may be needed for this period alone.

Preparation for planting

Where can I get plants?

For most of the main commercial varieties, you need grafted plants and these are best obtained from specialist fruit tree nurseries. Remember to check that nurseries are growing their rootstocks from strains of P. edulis f. flavicarpa resistant to Fusarium wilt, and that they are using accredited scion wood.

Where can I get seed for passionfruit rootstocks?

DPI&F at Nambour produces and sells rootstock seed containing a high degree of resistance to Fusarium wilt. Some nurseries and growers produce their own seed for rootstock production.

Do I need a pollinator in my vineyard?

The current hybrid passionfruit varieties have self-compatible flowers so no pollinator is required. The situation with P. edulis f. flavicarpa varieties such as Panama is unclear, with some incompatibility evident. Therefore when planting clonal selections of these varieties, we recommend you interplant with alternate rows of seedling plants to ensure good fruit set.

Planning

Is my farm suitable for passionfruit?

To grow passionfruit successfully, you need 70 cm of well drained soil and a frost-free site. Podzolic soils where the topsoil is less than 20 cm deep are suitable provided the lower levels are freely draining. Rows are sometimes mounded to provide better drainage. Good wind protection from the south, south-east and west is also required, though this may be achieved with planted windbreaks.

What area of passionfruit do I need to make a living?

Gross margins per hectare per year can range from a negative amount (loss) to around $10,000. True profit is what is left after deduction of fixed acosts and a proportion of the capital costs for the year from the gross margin. A two person team can typically look after around 3 hectares of passionfruit with some extra help during peak harvest periods. Areas larger than 3 hectares require the regular employment of a significant amount of extra labour. 

What prices can I expect to get for my passionfruit?

Prices received by the grower can be very variable, depending on fruit quality, the amount of other fruit in the market and how you are selling your fruit (main capital city central markets or direct sales to fruit shops or the public through Farmer's Markets etc.). Fresh market prices can range from $4 to $100 per 7kg carton and an average price over a whole year of $18 per 7kg carton is considered good.

Current and historical capital city central market prices and throughput volumes are available from the Ausmarket Consultants group at: www.ausmarket.net.au

About 30% of a normal crop is generally unsuitable for the fresh market. This is normally sold to a processing outlet. The current price for processing fruit is around 50c/kg.

Can I grow passionfruit in North Queensland?

Yes, but it is not without its problems. Some of the hybrid varieties are not suited to the warmer climate and produce low yields and poorly coloured fruit. This is because prolonged temperatures above 30°C cause vines to grow vegetatively at the expense of fruit production and quality. Heavy rainfall also affects pollen germination, reducing fruit set. It is therefore advisable to try hybrid varieties on a small scale initially to identify varieties that do best in your environment. The P. edulis f. flavicarpa or golden passionfruit selections such as Panama are better suited to the tropical conditions of North Queensland. Their dense foliage, however, favours pest and disease problems with the result that vineyards generally have a shorter life.

Another problem is that North Queensland is a long way from the main processing outlets in south Queensland and northern New South Wales. This effectively removes the opportunity to dispose of fruit which is not up to fresh fruit market standard.

How long will my vines stay productive?

The normal life of a passionfruit vine is about three years. After this, disease and insect pest problems often reach a level which makes it difficult to produce good quality fruit. In North Queensland, P. edulis f. flavicarpa selections such as Panama grow extremely vigorously and make effective pest and disease control difficult. These vineyards may need replanting every year or second year.

Is it easy to grow passionfruit organically?

For several reasons, it is difficult to grow passionfruit organically. The large number of potentially serious pest and disease problems makes effective control by non-chemical methods difficult. The intensive cropping pattern also makes it difficult to achieve profitable yields and quality from organic fertilisers alone.

Marketing

Where do I market my fruit?

There are two main markets - fresh fruit and processing. Good quality fruit is usually sent to wholesale markets in the major capital cities. Remember that interstate quarantine requirements have to be met for some of these markets. Fruit that is blemished is generally sold to processors for conversion into various food products. This requires a contract with the processor.

Further information

See the DPI&F Note: Is passionfruit growing for you? , written to help prospective growers decide whether or not the crop is a suitable commercial option. 

For commercial enquiries on passionfruit, contact:

DPI&F Business Information Centre on 13 25 23 - local call 8 am to 6 pm Monday to Friday (non-Queensland residents phone 07 3404 6999). E-mail: callweb@dpi.qld.gov.au

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Information contained in this publication is provided as general advice only. For application to specific circumstances, professional advice should be sought. The Department of Primary Industries and Fisheries, Queensland has taken all reasonable steps to ensure the information in this publication is accurate at the time of publication. Readers should ensure that they make appropriate inquiries to determine whether new information is available on the particular subject matter.

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Last reviewed 6 April 2005