What was it all about?

Citrus is one of Australia’s most important horticultural export crops so it is vital that disease-free, true-to-type propagation material is available to prevent incurable diseases from entering citrus nurseries and orchards. Use of healthy planting material will avoid potential yield loss and the costly exercise of replanting infected blocks.

Graft-transmissible diseases, spread by infected plant material, are of most concern as they can kill trees and there is no cure. While huanglongbing and citrus variegated chlorosis (CVC) remain exotic to Australia, there are a number of graft-transmissible viruses and viroids in Australia that can cause stunting, yield loss and even death in some scion and rootstock combinations.

This investment supported the work of the National Citrus Repository Program from 2015 to 2018. The program maintains and disease tests citrus foundation trees in the repository as well as disease testing any new Australian citrus selections entering the repository.

From foundation tree budwood, Auscitrus creates daughter trees and multiplies large numbers of buds for industry. New varieties can enter the program if no known diseases are detected after pathogen testing and elimination.

At the end of the project, 122 publicly owned citrus clones were housed in the repository, from Australian and overseas sources. A minimum of one tree of each variety is held in screen houses in two secure locations NSW.

In addition to ensuring the availability of healthy planting material to industry, the program boosts preparedness for an exotic disease incursion by providing a disease-free source of genetic material protected from insects, that could be needed to rebuild the industry.