Final report

Objectives of the project

The key goals of this study were to improve the economic viability of organic kiwifruit production and provide the community members with some research capability. Any increase in fruit volume and fruit size that arises from this research proposal will improve the viability of the organic kiwifruit sector and give it a better foundation on which to move forward. In addition, the community members hoped to be able to use the skills gained in this project to achieve robust results from future studies, such as testing new products or management techniques.

Component parts and methodology

Manual of organic kiwifruit production practice

A manual describing production practices for organic kiwifruit has been put together by a collaboration of scientists from Zespri, Hort Research and the Argos project. Organic management practice has developed along many independent paths and there has long been a need for information to be collated and made available to all kiwifruit growers. Sources of existing information for the manual included a recent survey of organic growers (Zespri Innovation), a review of research in organic kiwifruit (HortResearch), and the outcomes of research carried out in this project.

Increasing bud break on Hayward kiwifruit

The project planned to test the effectiveness of using winter oil sprays to increase bud break and flowering of kiwifruit. The trial intended to build on a review of winter chilling carried out for ZESPRI (Austin et al. 2003).

Year 1 (2004-2005). The focus at this initial stage was on screening a large number of treatments employing HortResearch staff to carry out most of the experimental work. In subsequent years growers and packhouse staff would carry out work on commercial orchards and HortResearch staff would provide experimental designs, techniques, training and analysis. Initially, a large number of treatments were to be screened by painting oils on individual canes. The project planned to test at least:

  • Three types of oil: a narrow range mineral oil, a fish oil and a plant-based oil.
  • Two times of application: 10 and 60 days before bud break
  • Two oil concentrations.

During bud break all canes were checked for phytotoxic damage. The time of bud break, amount of bud break, proportion of flowering shoots, number flowers on each shoot, and number of flowers per winter bud were measured during spring. This trial was carried out in the organic block at the Te Puke HortResearch orchard.

Year 2 (2005-2006) In this year the project refined the various treatments, repeated the best ones, and carried out further testing by painting individual canes. We also tested the most promising treatments by spraying whole vines on commercial orchards. The trial was organized as a replicated, randomized block design. Growers and packhouse staff applied treatments and monitored bud break and flowering.

Year 3 (2006-07). We were able to extend this part of the project by an extra year after the seaweed project was terminated prematurely (due to disappointing results in the first stage). We were able to test a wider range of oils on single cane trials and also test the effect of adjuvants. We also carried out commercial field trials testing fish oil and mineral oil at four different sites.

Increasing fruit size on Hayward kiwifruit

Year 1 (2004-2005). The objective of this part of the project was to carry out a screening trial to assess whether seaweed extracts are able to increase fruit size of kiwifruit. We planned to test if spraying shoots is a suitable technique for screening seaweed extracts. This was to be achieved by comparing the effects of spraying whole vines, spraying shoots, or dipping only fruit in the extract. This part of the trial was to be carried out on Hort16A vines as fruit growth in this cultivar appears to be more responsive to applied products than Hayward. A range of extracts from various species of seaweed were to be assessed. Using at least 10 replicate shoots per treatment we tested:

  • Three products, all BioGro certified seaweed extracts available in New Zealand
  • Two application times
  • Three concentrations of seaweed extract

At harvest we measured the weight and dry matter of fruit. The trial was carried out on an organic block at Te Puke Research Orchard.

Year 2 (2005-2006). We planned to test the most promising treatments by spraying whole vines on three commercial orchards. Participating local packhouses were to have measured fruit size at harvest (individual weights for whole vine). However after the first year of testing seaweed products we were unable to identify any growth response from any of the products tested. The team decided to cancel the second year of the seaweed trial and to transfer the funding towards an extra year of work on the bud break oils.

Can compost tea increase productivity of kiwifruit?

This trial ran for a period of three years and was intended to determine if applications of compost tea could improve the microbial conditions in the root zone and hence improve root health, nutrient uptake, and finally fruit size. This type of 'whole plant' approach involved measuring any gradual changes over more than one season. Any worthwhile effect should have been detectable after three years. We used several different sources of commercial quality compost tea for the trial. The tea was applied regularly through the growing season to soil in five organic kiwifruit orchards. Unsprayed areas acted as controls for comparison and there were at least two replicates of the sprayed and unsprayed treatments at each site. Each plot contained at least three rows of kiwifruit. Both Green and Gold kiwifruit varieties were included. The effect of the compost tea was monitored annually at all sites by analysis of soil, leaves and fruit.

An annual Soil Foodweb analysis was conducted to measure total and active fungi, bacteria, mychorrhiza and protozoa. Soil nutrients, organic matter content and pH were measured. An assessment of earthworm numbers and root health was carried out. Leaf samples were taken using a standard sampling method and nutrient concentrations measured. Fruit yield was measured and fruit maturity assessed by soluble sugars (brix) and dry matter measurements.

The participating growers were responsible for managing this trial under the guidance of HortResearch. Scientists held an initial training day for the participating growers to guide and train them in data collection e.g. taking soil samples, leaf samples, earthworm assessments etc.

Outcomes

Manual of organic kiwifruit production practice

The manual consists of the following components:

  • Soil Systems
  • Basic facts of plant physiology
  • Monitoring soil health
  • Compost and compost tea
  • Chilling and Flowering
  • Pollination in organic kiwifruit
  • Site selection
  • Organic pest and disease management
  • Economics of organic kiwifruit production

The texts are available to all registered kiwifruit growers on the Zespri Canopy website. Hard copies are available from COKA and from Zespri field representatives by request. A copy of the fact sheets that make up the manual is attached.

Increasing bud break on Hayward kiwifruit

A report titled “Increasing the productivity of organic kiwifruit” by Snelgar, Blattmann and Ramankutty dated April 2007 is attached. This report sums up all of the bud break work carried out over the three year period.

Increasing fruit size on Hayward kiwifruit

Attached is an article published in the Kiwifruit Journal of May/June 2006 Journal titled “Can Seaweed Sprays Increase Kiwifruit Size?” by Snelgar, Blattmann and Max.

Can compost tea increase productivity of kiwifruit?

Attached is a report titled “Evaluation of Compost Tea in Organic Kiwifruit (2004-07)” by Spiers and Hoyte dated September 2007.

Overview of results

Manual of Organic Kiwifruit Production – This series of nine fact sheets gathers together information from a wide group of scientists, extension staff and growers into one easily read resource. The manual will be of most use to new organic kiwifruit growers and existing growers considering conversion to organics. The manual provides factual advice on a range of issues that will give much reassurance and support to growers who are unfamiliar with organic growing methods. The advice is factual, based on good science and field experience. It is an acknowledgement that the application of scientific method and research to organic growing methods can improve the productivity and profitability of organic kiwifruit production.

Seaweed Trials - We were unable to identify any seaweed products that acted like a plant growth regulator in directly stimulating fruit growth when they are applied to the fruit, or the leaves near the fruit. This was disappointing, as it prevented us from continuing to the next stage where we had planned to test seaweed products on whole vines. With the limited amount of testing done on the seaweed extracts used, we cannot rule out the effectiveness of these products when applied in a different manner.

Organic oils - Our trials have shown that a number of oils are able to increase both bud break and flowering on vigorous wood that has widely spaced winter buds. Oils would be far more attractive as a bud break enhancer if they were effective on all wood types, including low vigour wood. Our results suggest that the addition of a spreader can increase the efficacy of oils on low vigour wood. Although painting mineral oils on canes does increase bud break, spray applications of oils have not been as successful. This reduction in efficacy may be due to lower rates of deposition and retention of oils when they are sprayed. These factors can sometimes be improved by using different droplet sizes and a formulation to optimise droplet adhesion to the buds. In future trials we will be working with specialists in spray technology to try to solve this issue.

Compost teas - In this study, compost tea applications had no effect on soil, leaf and fruit parameters measured.

There are several possible reasons for these results:

  • The sites chosen for this study were organically managed and, in most cases, had a reasonably long history of relatively high inputs of organic matter and relatively low inputs of pesticides. These sites may be biologically optimal and have soils that already contain high concentrations and wide diversity of microorganisms, such that the application of compost tea may have had no appreciable effect on the microbial population and thus no effect on the measured parameters. It is possible to speculate that if the study had been conducted on biologically deficient sites, a more positive outcome could have been achieved.
  • The crop used in the study is a perennial vine, with a large, deep permanent root system growing in fertile soils with high organic matter content. It is possible that this system is so well buffered that any changes may take longer than three seasons to become evident.
  • The compost teas used in this study were still being developed, and may not yet be optimised for kiwifruit. Compost tea is a biological product and is subject to a huge array of variables, so it is to be expected that quality improvement will be a slow process. Perhaps if the study is repeated in a few years, a more positive outcome could be achieved.
  • The results of this study reflect the true position, that compost tea has no effect on kiwifruit when used and tested for three seasons.
  • This project has produced results that will be of use to both organic kiwifruit production and conventional kiwifruit production. While it was disappointing that we could not demonstrate any positive response from the limited work on seaweed extracts or the three years work on the compost tea, these results will assist growers when they make decisions on where best to spend their budgets for fertiliser, plant protection and foliar sprays. The bud break oil results are very promising, with some organic oils producing results equivalent to non organic methods in some situations. The challenge is to extend the range of conditions in which the organic oils work so that we can eventually look forward to an agent that will work consistently in organic orchards. We are not there yet, but have made significant progress towards the goal.

Extension of results

Our findings have been presented to growers at:

COKA meetings:

  • May 2005. A summary of the bud break oil and the seaweed trials was presented by Bill Snelgar.
  • August 2005. All interested parties attended a presentation of results to date, by Mike Spiers.
  • March 2006. Mike Spiers presented a summary of results to date to all interested growers and participants.
  • July 2006. A summary of the results from the oils trials was presented to organic growers by Bill Snelgar at the COKA AGM.
  • May 2007. A summary of the oils results to date presented by Bill Snelgar.
  • November 2007. A report on the overall progress of the project was presented to COKA by Ian Schultz.

Articles in COKA newsletters:

  • April 2006. An article on the project to date by Nolene Almond.
  • August 2006. An article on the oil work was published in the August edition of the COKA newsletter.
  • February 2007. A report on the compost tea trial progress to date.
  • June 2007. An update on the project, prepared by Nolene Almond, was printed in the June issue of the COKA newsletter.
  • August 2007. An update on the bud break oil trial by Snelgar, Blattmann and Ramankutty.

Articles in the Kiwifruit Journal:

  • May/June 2006 Can Seaweed Sprays Increase Kiwifruit Size? An article on the seaweed trials and bud break oil trials by Snelgar, Blattmann and Max.
  • An article on the compost tea trial to be published in early 2008.
  • An article on bud break oils to be published in winter 2008.

There are no further research projects planned by COKA. Zespri is undertaking several projects on bud break enhancement as part of the industry’s search for a replacement to HiCane. The findings of this project will be incorporated into future research on this topic. Our research has assisted the search for agents that improve bud break on all orchards, organic ones included.

Acknowledgements

This project would not have been possible without the Sustainable Farming Fund support. We recognise the importance of this fund for assisting research which enhances the ecological integrity of New Zealand’s primary industries.

Considerable support was provided by Zespri International Ltd, both directly as cash, through its large input into the fact sheets and assistance given to the research team.

This project relied heavily on the contributions of growers, packhouses and suppliers of some of the products used. COKA would like to acknowledge and thank the following growers who donated their orchards and time to allow the field work to be conducted:

Dianne and Leo Whittle, Nolene Almond, Tim Oliver, Peter Sievwright, Peter Melton, David Watson, Hamish Payne and James Trevelyan.

Some of the products used were supplied either at no cost or at reduced rates. Thanks to: Fred Harvey, Dave Whittaker, Grant Paton, Graeme Reid and SeaLord Ltd.

Cheryl Prew from Soil Foodweb Laboratories provided valuable advice and did the analysis for the compost tea trials at reduced rates.

Packhouse operators carried out field trials on our behalf. They provided the staff, facilities and analysis of results at no cost. Thanks go to Trevelyan’s Pack and Cool, Seeka Kiwifruit Industries Ltd, Apata Ltd and Satara packhouse.