Where to from here?
- Encourage careful monitoring of soil moisture management and recommend growers trial strategic timing of nitrogen application.
- The value of cross-pollinisers needs to be further investigated in the South-West of Western Australia. This should include investigation of flowering timing for pollination potential and visitation habits of pollinators to different flower stages and different trees with different flower intensity.
- Investigations into the use of GA3, to determine capacity to modify flowering intensity, timing of flowering and shoot flush. This will require better knowledge of the timing of the various stages of floral development.
- Investigate further the timing of spring vegetative flush, what may cause seasonal variations in this timing and the impact of this on flowering and fruit set. Further investigate potential options to modify the timing of the vegetative flush if shown as useful.
- Investigate the setting of fruit, what climatic conditions coincide with fruit set and determine if late setting fruit is subject to increased immature fruit drop.
Further reviews on the issue of alternate and irregular bearing have been commissioned by Avocados Australia. The reports are available via the Avocados Australia website (member services login required).
Presentations have been delivered on pollination and fruit set and alternate and irregular bearing as part of Avocado Study Groups and Qualicado workshops. Copies presentations are available via Avocados Australia's Best Practice Resource (password login required).
Special mention must be made of Dr Cengiz Erol who greatly assisted in the collation and review of the research literature on this subject.
This publication was previously published as Appendix G in ‘Improving technology uptake in the WA avocado industry’, a final report for Horticulture Australia Limited project AV06002. This was funded by the Agricultural Produce Commission — Avocado Growers Committee, Horticulture Australia Limited and the Department of Agriculture and Food, Western Australia. The complete final report is available electronically via Avocados Australia website (member services login) or Horticulture Innovation Australia.
Most of the following references and many more are available electronically via avocadosource.com, an extensive internet database of avocado information from around the world — hosted by the Hofshi Foundation.
Buttrose, MS and Alexander, DMcE 1978, ‘Promotion of floral initiation in ‘Fuerte’ avocado by low temperature and short daylength’, Scientia Horticulturae, vol. 8 pp. 213–217.
Cutting, JGM 2003, ‘Research note: Impact of spring and summer flush type on flowering intensity in ‘Hass’ avocado’, New Zealand Avocado Growers’ Association Annual Research Report, vol. 3 pp. 42–47.
Davenport, TL 1989, ‘Pollen deposition on avocado stigmas in Southern Florida’, HortScience, vol. 24 pp. 844–845.
Davenport, TL 2003, ‘Evidence for wind-mediated, self and cross pollination of ‘Hass’ avocado trees growing in Mediterranean environments’, Proceedings V World Avocado Congress (Actas V Congreso Mundial del Aguacate) 2003, pp. 221–226.
Davenport, TL 2007, 2007 Final Report, BARD Project No. US-3345-02R.
Dixon, J, Elmsly, TA and Smith, DB.2005, ‘Hass avocado tree phenology in 2004 for the Western Bay of Plenty’, New Zealand Avocado Growers’ Association Annual Research Report, vol. 5, pp. 13–26.
Dixon, J, Elmsly, TA, Dixon, EM, Mandemaker, A and Pak, HA 2007, ‘Factors influencing fruit set of Hass avocados in New Zealand’, Proceedings VI World Avocado Congress 2007, 3d-116.
Dixon, J, Elmsly, TA and Greenwood, AC 2008, ‘Differences in initial fruit set on determinate and indeterminate flowering shoots’, New Zealand Avocado Growers’ Association Annual Research Report, vol. 7, pp. 31–40.
Dixon, J, Elmsly, TA, Dixon, EM and Mandemaker, AJ 2008, ‘Hass avocado tree phenology 2004-2008 in the western Bay of Plenty’, New Zealand Avocado Growers’ Association Annual Research Report, vol. 7, pp. 21–29.
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Garner, LC and Lovatt, CJ 2008, ‘The relationship between flower and fruit abscission and alternate bearing of ‘Hass’ avocado’, Journal of American Horticultural Science, vol. 133(1), pp. 3–10.
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Ish Am, G and Eisikowitch, D 1993, ‘The behaviour of honey bees (Apis mellifera) visiting avocado (Persea americana) flowers and their contribution to its pollination’, Journal of Apicultural Research, vol. 32, pp. 175–186.
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Lovatt, CJ 2001, ‘Properly timed soil-applied nitrogen fertilizer increases yield and fruit size of ‘Hass’ avocado’, Journal of American Horticultural Science, vol. 126(5), pp. 555–559.
Nevin, J and Lovatt, CJ 1990, ‘Changes in starch and ammonia metabolism during low temperature stress-induced flowering in ‘Hass’ avocado’, 1990 Summary of avocado research. Avocado Research Advisory Committee University of California.
Salazar-Garcia, S. and Lovatt, C.J. 1996, ‘Effect of gibberellic acid on inflorescence phenology of the ‘Hass’ avocado (Persea americana Mill.)’, 1996 Avocado Research Symposium, pp. 45–49.
Salazar-Garcia, S. and Lovatt, C.J. 1998, ‘GA3 application alters flowering phenology of ‘Hass’ avocado’, Journal of American Horticultural Science, vol. 123(5), pp. 791–797.
Salazar-Garcia, S, Lord, EM and Lovatt, CJ 1998, ‘Inflorescence and flower development of the ‘Hass’ avocado (Persea americana mill.) during “on” and “off” years’, Journal of American Horticultural Science, vol. 123(4), pp. 537–544.
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