Improving mandarin production in Bhutan and Australia through the implementation of on-farm best management practices

The project was officially launched in Bhutan in June 2007. At this inception meeting the project objectives and main activities for the 2007 season were outlined. A draft survey of grower practices was circulated and feedback incorporated. The main activities for 2007/08 were the selection of demonstration orchards, collection of leaf & soil samples from the demonstration orchards for nutrient analysis, a comprehensive survey of citrus grower practices from all regions of Bhutan, to start monitoring the citrus phenological stages in different growing regions of Bhutan and to begin to implement best management practices on the demonstration orchards.

Four demonstration orchards have been established. Basic improvements such as basin formation to allow for application of water and inorganic fertilisers and the clearing of vegetation under trees were the first activities undertaken. Soil & leaf samples were collected and analysed and a basic fertiliser program started in February 2008. Selected trees at each of the sites have been pruned to varying degrees to assess the timing of operations and tree response in Bhutan (February & April 2008). Tensiometers were installed at one site at Rimchu in April 2008 to help in assessing soil moisture levels and water application timing. Meteorological and other general site information from the Punakha and Phuntsholing regions have been sourced. Citrus phenological data is also being recorded at these sites. More extensive soil sampling was undertaken in early 2008 and the results have just been received. More leaf samples will be taken in August-September 2008. A nutrient survey of citrus orchards in Bhutan will be undertaken in 2008 through the collection of about 100 leaf samples from the different growing regions. In late 2008 an application of gibberellic acid (GA) will be made to selected trees (when fruit are almost fully coloured) to delay fruit maturity (harvest) and improve rind firmness. The work on GA will be linked to researchers from the National Post Harvest Centre for assessment and measurement of fruit quality & firmness.

The first two week training visit to Australia by three Bhutanese personnel was made in October-November 2007. During the visit a wide range of both formal and informal training activities were undertaken. Formal training workshops were provided on soil and irrigation management (accredited course), citrus nutrition & citrus canopy management -including topworking. Practical sessions were undertaken on pruning, budding, grafting & topworking of citrus. Visits to two commercial citrus nurseries provided an insight into nursery production practices in Australia. Visits were made to a commercial citrus packing company and juicing plant to look at post harvest operations and facilities. Visits to the Auscitrus (supplier of citrus rootstock seed and budwood to the Australian industry) facilities at EMAI, Camden and the new established facility at Dareton were undertaken to provide an insight into the facilities and operations used to maintain the Australian repository of clean citrus germplasm. A visit to a commercial citrus orchard demonstrated Australian production practices.

The citrus grower survey was distributed to extension officers throughout Bhutan who collected information from citrus growers in the main production districts throughout July-December 2007. The survey focussed on collecting data on tree plantings, replanting plans, pest and disease problems (with an emphasis on Chinese citrus fruit fly & the pysllid vector of Huanglongbing), current control strategies, fertiliser and water application programs. A total of 401 surveys were completed which far exceeded expectations. All the survey data was entered into a master record sheet by project officer Phuntsho and sent to Australia in February 2008. Preliminary analysis of the survey data was undertaken at Gosford by Biometrician Anne Harris with additional input provided by the Australian project officer Julian Connellan. The data is currently being compiled into a comprehensive report outlining results on both a country and district basis. More detailed analysis may be warranted for some survey questions. Assumptions about the data collected will also need to be checked by the local DoA (Department of Agriculture) staff in the various growing regions before the final report is released. The survey data will provide an invaluable source of baseline data for this project and will be useful for any other projects undertaken on citrus in Bhutan.

Several training workshops have been undertaken in Bhutan by both the Bhutanese and Australian project team for extension and research personnel and these are outlined in Section 4.

NSW DPI has produced a training video for citrus growers in Australia & Bhutan on "Topworking Citrus" demonstrating the main budding and grafting techniques used in propagating citrus trees.

All promising genetic rootstock material from previous NSW DPI rootstock breeding programs undertaken at the NSW DPI Gosford site has been collected and transferred to the citrus arboretum at NSW DPI Dareton Agricultural Research and Advisory station.