THE FULL REPORT
This is a comprehensive summary of the unpublished full research report Field and Postharvest Control of Insects in Native Australian Cut flowers by Bill Woods and Kevin Seaton. A photocopy is available from RIRDC on phone (02) 6272 4029. The researchers can be contacted on phone (08) 9274 5355,  fax (08) 9368 3223.
 The move to an integrated quality management system to control insects has cleared the way for the Australian cut flower industry to secure greater sales in high-value markets, particularly Japan and the United States.
The move was instigated following research showing that the industry's earlier "blanket spraying" approach was unsuccessful and costly both in terms of labour and insecticides.

Geraldton waxflower growers were the first to adopt the recommended control measures and exporters of other flowers are moving to adopt similar protocols.
 

Background: realising the high-value potential

The Australian cut flower industry's earlier inability to meet strict international quarantine requirements had prevented it from fully realising its potential in high value markets such as Japan and the United States.

Both the United States and Japan's entry requirements state that flowers must be free of live insects before they can enter the country.

This was a major problem for the industry. In 1990 about 18 per cent of Australia's exports to Japan (or almost one in five stems) had to be fumigated because of insect infestations. The insects causing rejections were aphids, caterpillars, suckling bugs, spring beetles and thrips.

Having to fumigate in the country of import resulted in flowers being damaged, higher costs, and delayed deliveries. These factors resulted in a loss of consumer confidence.

To address these issues the Rural Industries Research and Development Corporation commissioned Mr Bill Woods and Dr Kevin Seaton from the Entomology and Horticultural Industries Branch of the Western Australian Department of Agriculture to examine Field and Post-Harvest Control of Insects in Native Australian Cut Flowers.

Their report says the industry's move to plantation production had led to a ten-fold increase in the value of exports of native   Australian cut flowers. Exports reached $24 million in 1993_94, according to Australian Bureau of Statistics' figures.

The move to plantation production, however, created "oases" which attracted insect infestations.
At that time, little or nothing was known about the types of insects involved, their biology and numbers, or about the movement of native insects to native flowers grown in plantations.

Earlier control practices had been found to be ineffective.
For example, while methyl bromide was effective against insects it damaged native flowers, as did the level of gamma irradiation required to kill insects.

To address this, the project investigated ways of developing an integrated system for eradicating insects based on:

  • defining insect population dynamics on flowers in field plantations and developing effective methods to control these insects in the field, and
  • developing a post-harvest insect disinfestation system capable of killing insects remaining on flowers after field treatment while preserving flower quality.
    •             

     Key findings

    The report's key findings were that:

    The Australian wildflower industry had to implement an integrated quality management system if was to produce quality flowers free of insects that did not require fumigation on arrival at export destinations.

    That irrigated wildflower crops were at risk from high infestation of insects particularly with the depletion of soil moisture reserves in surrounding pasture and bush during spring.

    For Geraldton wax, the number and type of insects appeared to be higher for later cultivars, particularly those which were white or had large pink flowers.

    To address these problems the report recommended:
     

     

    Methodology: monitoring and propagating

    Insects were monitored at two sites: a commercial flower farm (Coorow) and a research station (Badgingarra), not far from coastal Western Australia.

    Temperatures were more extreme at the commercial flower farm. The research station site had a higher annual average rainfall, 633 mm compared with 413 mm.   The Geraldton waxflowers cultivars grown at each site were Purple Pride, Alba and Mullering Brook. The cultivars were four years old.

    Early pink cultivars Newmarracarra and CWA Pink and a late white-to-pink flowered floriferum-uncinatum hybrid selection Lady Stephanie were also grown at Coorow.
     
    Plants were propagated from cuttings and were planted in rows 2 m apart and 2 m between plants with a 4 m workway between each double row.

    The plants were maintained with trickle irrigation and a top dressing of NPK blue or   superphosphate once a year plus supplementary applications of N plus K and trace elements. The bushes were pruned to a height of 450 mm following flowering.
     

    Making accurate assessments

    Sticky traps were found to be a good means for determining insect pressures on flowers. However, these traps need to be calibrated for particular varieties, seasons and flower farm situations. By collecting this information over a number of years it is possible to make accurate assessments of the insect risk and thereby determine the appropriate spray program.

    The report says that regular field spraying was found to be necessary from August onwards and that Mavrik was effective in controlling most insects, especially thrips, in Geraldton wax for two weeks. Dominex was found to be effective in dealing with beetles for periods of two weeks. However, in cases   where nititulid larvae and eggs were present, the report said weekly sprayings may be needed.

    For post-harvest control, the report states that dipping with Cislin10—a wetting agent, and Benlate, was found to be 100 per cent effective if insects numbers were below a threshold of 10 insects a bunch.

    Tests showed that dipping could be done in bulk using a crate to hold 25 bunches of flowers with the whole crate being immersed in a bath of insecticide solution. This approach could be adapted to suit a range of flowers, once their suitability was ascertained.