Bhutan

Achievements

Key indicators and performance for 2009-2010

Indicator: Control measures for fruit fly and psyllid insect vector of citrus greening disease tested under commercial orchard conditions in Bhutan

Performance: In 2009 preliminary phytotoxicity trials to control fruit flies and citrus psyllids were conducted on mandarins using horticultural mineral oils under Bhutanese commercial growing conditions. The trials demonstrated that there were no apparent negative effects on the mandarin trees. Trial protocols, to be undertaken later in 2010, for the use of horticultural mineral oils against the major citrus pest (Chinese citrus fruit fly) should lead to the development of alternatives to the current control measures, which rely on the use of the synthetic pyrethroid, cypermethrin, and the organophosphate, dimethoate. Trials are currently underway in Bhutan to assess both the phytotoxicity and efficacy of sulfur against powdery mildew at a number of topographically different locations, to give growers an ability to manage this disease and introduce a regular pruning program for citrus orchards.

Achievements from the 2009-10 Annual Report

The Bhutanese Government wishes to substantially increase the country’s production of citrus (mainly mandarin)—from the current annual total production of 36,000 t to, hopefully, export 100,000 t annually. A project seeks to lift overall productivity of Bhutan’s citrus on a sustainable basis and improve the quality and yield of its present mandarin cultivar.

During 2009–10 the project continued to implement improved management practices on project demonstration orchards. Trials to assess the effects of the plant hormone gibberellic acid on mandarin rind quality and fruit maturity were undertaken in 2009 and continued in the 2010 season. One positive but unexpected result was that treated fruit did not develop postharvest moulds, compared with untreated fruit.

Improved management practices continue to be implemented at all four project demonstration sites, with the continued application of chemical fertilisers and the use of pest control measures and canopy management practices. Soil moisture monitoring equipment (tensiometers) installed at the Rimchu demonstration site has continued to provide valuable soil moisture data throughout the growing season.

In April 2010 two project personnel from Australia travelled to Bhutan to establish a permanent drip irrigation system at the Rimchu demonstration orchard in the Punakha district. In Bhutan the majority of orchards, being located on the mountain slopes, do not have a permanent water supply on farm. Providing irrigation to tree crops throughout the growing season is uncommon and any watering is usually done by hand. A novel pump that uses stream flow to pump water was sent to Bhutan from Australia and successfully installed.