Product: BoroniaBotanical name: Boronia heterophylla and hybridsCultivar: B. crassipes × B. heterophylla ‘Lipstick’

BORO

NIA

Quality specifications for Australian wildflowers

Product: BoroniaBotanical nam

e: Boronia heterophylla and hybridsCultivar: B. crassipes ×

B. heterophylla ‘Lipstick’

Boronia is a filler product grown for its dainty, small, 4-petalled flowers densely clustered along the stems. Boronia heterophylla is the main species grown commercially for cut flowers.

It is a small woody shrub endemic to WA. Several cultivars and hybrids are available with superior flower features and an extended colour range, from white and lemon, pale to hot pink, to deep blackish purple (‘Purple Jared’). Both flowers and foliage are aromatic. Indeed, Boronia megastigma (brown boronia), grown for its unusual brown flowers, is an important source of essential oils.

‘Lipstick’ has slightly scented, vibrant pink, bell-shaped flowers 8–10 mm long, held on short pendulous stalks.

Boronia has a long history in cultivation as an ornamental plant: B. megastigma was introduced into Britain in the 1840s; and bush-picked boronia has sold since the 1800s. Other boronias have to date been limited in their floriculture potential owing to difficulties in propagation.

Plants will produce marketable harvests within 12–15 months of planting but have a relatively short economic life (typically 5–6 years).

In Australia, the main growing areas are the south-west of WA, the south coast of NSW, central Victoria and the east coast of Tasmania. Overseas, boronia is grown in several countries, including New Zealand, the USA (California) and Israel.

Low winter night temperatures (6–15 °C) are needed to initiate flowering (low temperatures optimise the speed of flower development and the number of buds initiated, while warmer temperatures may lead to flower abortion).

Boronia needs deep, well drained, moist soils to grow well. Plants have shallow root systems and need to be protected from hot and dry conditions by windbreaks and well irrigated during the warmer months when actively growing. Growers need to ensure that plants are well irrigated and fertilised from flowering through to autumn to maximise stem length at harvest. Grow-through at the stem tips can be a problem. Careful management of crop nutrition in the lead-up to flowering may help to minimise this. Stems are pruned back to 35 cm at flowering to maximise the following year’s crop (cutting stems back too far will kill the plant).

Plants are susceptible to nematodes and a range of root diseases caused by the fungi Phytophthora, Pythium and Rhizoctonia. Foliage can be affected by rust, and flowers are susceptible to botrytis.

Some markets, such as the USA, currently do not accept flowers or plants belonging to the Rutaceae family, which includes Boronia and Crowea.

Water stress during or after harvest reduces quality. Boronia needs to be moved quickly from the field to a cool packing shed. Stressed stems wilt quickly and flowers shrivel.

Overmature flowers tend to close up again, making it difficult to distinguish between immature and overmature stems. When overmature, ‘Lipstick’ flowers tend to turn white.

Boronia is very sensitive to drying out. Pick straight into water in the early morning, maintain hydration and quickly cool the flowers. Handle carefully to minimise flower drop.

Flowering season: September–October, depending on locality. The flowering season in any given locality is short, typically 2–3 weeks.

Typical vase life: 7–11 days (poorly handled Boronia may last for only 3–4 days).Export can reduce the vase life, especially if the transport conditions are not cold, the product has dried out, or transport takes too long.

Other products to which this specification can be generally applied: Other Boronia species, cultivars (e.g. ‘Moon Glow’ and ‘Cameo’) and hybrids such as ‘Purple Jared’ , and superior selections, including ‘Stella’ , Cascade’ and ‘Purple Rain’

Left: Boronia is available in a range of colours, e.g. ‘Purple Jared’

Right: Typical bunches look like this

Common defeCts

Stage 1 Immature stage, unacceptable

to markets: flower buds immature and closed (will not

open after harvest)

Stage 2 Early stage, preferred by only a few markets, e.g. for export:

most flower buds still closed

Flowers bleached owing to overmaturity – discard

Grow-through Wilting flowers – avoid by harvesting at correct maturity

and by avoiding water stress after picking

The stages shown apply to the product at market entry. Pay attention to the weather, time of year, and mode and duration of transport, because the flowers will continue to open during transport. You must consult with your target market to ensure that the flowers arrive at the desired stage.

Common defects to avoid at market entry:

n Leaf and flower drop

n Sparse flowering or missing flowers

n Overmature (faded to white) flowers

n Wilting stems

n Dried-out flowers

n Damaged, yellow or discoloured leaves

n Presence of diseases (e.g. rust), insects or feeding damage

n Missing sections of foliage

n Grow-through

Stage 3 Prime stage for export and

domestic markets: 50%–70% of flowers open

stAGes of oPenInG

Broken stem ends – trim evenly before marketing

Flower drop – do not market; avoid by treating bunches with

anti-ethylene silver solution

Poor-quality foliage

Sparse flowering at stem tip – discard

Product: Boronia

Stage 4 Late stage, suitable for only some domestic markets: all

flowers open but some starting to turn white with age

Rust disease on leaves – discard; avoid by applying

appropriate fungicide treatments before harvest

Close-up of rust-infected shootBuds at stem tip have not developed – discard

Bleached and browning flowers – discard

Insect-damaged flower – discard stem if a large number of flowers are

damaged

Stage 5 Mature stage, unaccepted by

many markets: flowers closing again and turning white as

they age

Flower development from immature bud to overmature where flower closes up

again as it ages

For comparison: just right and slightly immature stem at left

Rust-infected shoot (left) compared with

healthy shoot

FLOWERS

Appearance (‘Lipstick’)

Flower colour clear and uniformly deep pink.

True-to-type of the cultivar ‘Lipstick’.

Flowers clustered densely and massed evenly along and around the entire marketed stem.

Minimum leaf visible.

When to harvest

50%–70% of individual flowers open at the base of the stem, and those at the tip showing colour (immature flower buds will not open after harvest).

Avoid harvesting when flowers are wet.

Damage Not faded.

No wilting. No flower drop.

Minimum number of flowers deformed or damaged (including mechanical damage).

Contamination Product free of grit and soil, weeds or weed seeds, living or dead insects, and signs of insects or spiders, such as webbing.

Pests and diseases

No insects, insect damage or disease.

LEAVES

Appearance Fresh, mid green and crisp.

Damage Not dull or wilted. No leaf drop.

No yellowing. Minimum leaf damage or blemish.

Minimum evidence of pests, such as webbing, and disease. No evidence of rust.

Free of visible chemical residues.

STEMS

Appearance Well branched and balanced. No irregularly branched stems.

Rigid and strong enough to support blooms, without being too woody and bulky.

Bend <15°.

No obvious grow-through, where the shoots at the stem tip grow through the flowers: maximum 3 cm tip growth beyond flowers (but soft tips will wilt after harvest).

Leaves are usually stripped from the lower 8 cm – check customer requirements.

Neatly cut end.

Length According to market demand.

RECOMMENDED HANDLING AT HARVEST

During harvest, it is critical to minimise drying out and exposure to heat. It is better to harvest early in the day, as long as the stems are not wet (which can encourage botrytis).

Preferably pick into clean potable water, ideally with added registered biocide or a reputable commercial postharvest solution, and transport promptly to a cool, shaded packing shed (within 30 minutes after picking).

Handle stems carefully, as flowers fall off easily.

GRADING AND BUNCHING

Grading Reject any contaminated stems.

Sort stems according to flower maturity, length and thickness.

Stem length According to market demand.

Bunching The number of stems per bunch varies, and is determined by their length and by market and buyer requirements.

Presentation is important. Stay consistent for the grade and make all bunches the same.

Use 1 tie near the base (3 cm from bottom).

Especially for export, stems should be approximately the same diameter within a bunch, with the ends aligned.

Stems per bunch

Different markets require different bunches – broadly:

Stem length (cm) Av. no. of stems per bunch (typical bunch

weight, g)

80 10 (400)

70 10 (400)

60 10 (350)

50 10 (250–300)

40 10 (250–300)

Sleeves Avoid sleeves, which increase humidity and favour botrytis.

HOLDING AND STORAGE

Cooling Effective cooling soon after harvest is important to retaining quality and maximising vase life. The preferred option is:

• Cool, process, cool – for example, remove field heat by cooling flowers immediately by placing in a cool room at 2–4 °C in buckets of postharvest solution, process flowers (bunch, grade), and then cool to 2–4 °C by either forced-air cooling (if boxed) or holding overnight in a cool room.

Forced-air cooling of packed flowers is ideal for large volumes of product.

Temperature and humidity

Hold in a high-humidity cool room (95%) at 2–4 °C for up to 2 days, but preferably much less.

Disinfestation (see ‘Common postharvest problems’ below)

Do this before a long (overnight) anti-ethylene pulse orafter a short pulse (room temperature).

Product: Boronia

HOLDING AND STORAGE cont’d

Anti-ethylene treatment

‘Lipstick’ and other B. heterophylla selections are ethylene sensitive. There are two alternative anti-ethylene treatments:

1. Use a commercial anti-ethylene silver solution, e.g. Chrysal AVB, as these have been shown to increase vase life (for more details, refer to Postharvest Manual*). Treat bunches according to the product label (concentration, temperature and duration of treatment). Uptake may be less effective if flowers are poorly hydrated before pulsing. Do your own trials to optimise the procedure: over-pulsing can have adverse effects (e.g. rapid closing and shrivelling of flowers).

2. Alternatively, you can add EthylBloc sachets to cartons when the flowers are packed (see ‘Packaging’ below).

Postharvest solutions

Postharvest solution: After a short anti-ethylene treatment, transfer flowers to clean water, preferably with added registered biocide or a reputable commercial postharvest solution, and cool to 2–4 °C. Hold in solution for 8–16 hours before marketing.

Holding solution: Same as the postharvest solution.

Longer-term storage

Boronia does not tolerate long-term storage. Sell quickly.

PACKAGING

Pack bunches of the same size (stem number, weight or thickness) together.

Put bunches of similar length together, and ensure all bunches meet this specification.

Pack boxes according to customer requirements.

Pack bunches firmly but ‘springy’ so the product will not move and be damaged. Packing too tightly can damage flowers during transit.

Pack bunches head to tail.

Use boxes with holes to allow forced-air cooling. Leave ventilation holes open to reduce humidity, ethylene build-up, botrytis growth and flower drop.

Do not line boxes with plastic, as this will increase humidity and the risk of botrytis. Use paper if desired.

Add EthylBloc anti-ethylene sachets to the cartons if required, according to the manufacturer’s instructions, when the flowers are packed (efficacy may vary depending on packing situation).

Cool flowers to 2–4 °C before transport.

LABELLING AND DOCUMENTATION

Label boxes and buckets as recommended in Postharvest Manual* or as required by customer.

Ensure box contents are exactly the same as specified in the documentation and on the end of the box.

TRANSPORT

Refrigerated vehicle at 2–4 °C. Preferably don’t transport with ripening fruit.

COMMON POSTHARVEST PROBLEMS Refer to Postharvest Manual* for general advice.

Fungal decay in storage due to botrytis (grey mould)

Insects (for export)

Effective preharvest management of botrytis with fungicides is essential, especially from bud initiation until harvest.

Effective management of insect pests before harvest is essential, especially within the 4 weeks before harvest. Use preharvest insecticide sprays to reduce the pest population at harvest.

Postharvest disinfestation dips are not recommended. If necessary (e.g. for export), treat flowers with a registered insecticide fumigant with stems in water.

Ethylene sensitivity and anti-ethylene treatment

‘Lipstick’ is sensitive to ethylene, and anti-ethylene treatment is recommended. Signs of ethylene damage include flower wilting and drop and leaf drop. See ‘Anti-ethylene treatment’ opposite. Other boronias may also be sensitive to ethylene, and trials of anti-ethylene treatment are recommended. However, B. muelleri ‘Sunset Serenade’ and B. clavata are not ethylene sensitive.

Drying out Wilted bunches can be revived by putting the whole stem under water for 2–3 hours. Bunches can also be misted to keep them from drying out. However, these treatments will increase the risk of botrytis.

JN: 9884 • Layout by W

ild Poppy Design • Edited by M

atthew Stevens, ScienceScape Editing, Sydney

Messages for importers and wholesalersn Recut stems and place into fresh water containing a reputable commercial

postharvest solution, registered biocide or flower food.n Cool product before marketing or sending on and keep it cool and dry.n Maintain good hygiene and keep containers clean.Messages for retailersn Recut stems and place into fresh water containing cut-flower food or a

registered biocide. Flowers can be misted to prevent drying out, but this will increase the risk of botrytis.

n Use clean buckets and containers for displays.n Do not display flowers in areas that are exposed to full sun, draughts, high

temperatures or vehicle exhausts, and preferably do not display near fruit and vegetables. Use refrigerated displays if possible.

n Tell the customer how to care for the flowers and emphasise the need for cut-flower food in solutions. Give the customer a sachet of cut-flower food to take home. Suggest that the customer re-cut the stem ends every couple of days.

Messages for consumersn Keep vase filled with the correct solution of cut-flower food. Check daily,

as flowers can use a lot of water. If cut-flower food is not used, change the water at least every second day. Always use clean vases and clean water. Ideally, cut 1–2 cm from stem ends every couple of days.

n Do not display in areas that are exposed to full sun, draughts or high temperatures. Keep as cool as possible without freezing.

Authors: Bettina Gollnow and Dr Ross Worrall. Photographs by: Dr Ross Worrall and Lowan Turton.This publication is one of a series of Quality Specifications for Australian Wildflowers. ISSN 1440-6845. ISBN 978-1-74254-010-8. RIRDC Publication No. 10/037. www.rirdc.gov.au*The Postharvest Manual is the manual ‘Postharvest Handling of Australian Flowers from Australian Native Plants and Related Species’, 2nd edition, 2010. ISBN 978-1-74254-000-9. RIRDC Publication No.10/027.Both publications were developed by RIRDC Project No. PRJ-000331.

SUPPORTING INDUSTRY PARTNER:The information contained in this publication is intended for general use to assist public knowledge and discussion and to help improve the development of sustainable regions. You must not rely on any information contained in this publication without taking specialist advice relevant to your particular circumstances. The Commonwealth of Australia, the Rural Industries Research and Development Corporation (RIRDC), the authors or contributors expressly disclaim, to the maximum extent permitted by law, all responsibility and liability to any person, arising directly or indirectly from any act or omission, or for any consequences of any such act or omission, made in reliance on the contents of this publication, whether or not caused by any negligence on the part of the Commonwealth of Australia, RIRDC, the authors or contributors.

© Rural Industries Research and Development Corporation. This publication is copyright. Apart from any use as permitted under the Copyright Act 1968, all other rights are reserved. Requests concerning reproduction and rights should be addressed to the RIRDC Publications Manager on phone 02 6271 4165.