HLB Safe System for citrus-tree production in nurseries

The need for HLB-free trees

Planting of HLB-free trees is one of the pillars of the three-pronged approach for effective HLB control. HLB-free trees can be produced in insect-secure nurseries, where trees are protected from insects vectoring the HLB bacterium. Most citrus trees in SA are not produced in insect-secure structures. To incentivise the expensive transition to insect-secure structures, and to promote industry readiness for HLB, the HLB Safe System for the production of citrus trees in nurseries was developed as part of the HLB/ACP Action Plan.

Qualifying nurseries must be certified by the Citrus Improvement Scheme (CIS), using CIS-approved propagation material exclusively. HLB Safe nurseries must preferably be located away from citrus orchards and must comply to specified infrastructural and operational requirements aimed at preventing HLB transmission to trees. Various levels of compliance are recognised, depending on the nursery’s distance from citrus trees, which influence the risk assessment under the various incursion scenarios.

The Action Plan makes provision that HLB Safe nurseries in an ACP and/or HLB quarantine zone might officially be permitted to move citrus trees to pest-free areas.

First HLB Safe nursery in SA

Komati Fruit Nurseries outside Malalane (Fig. 1) is a purpose-built citrus nursery that follows specific guidelines for HLB Safe compliance. The nursery has capacity to produce around 150 000 citrus trees, all inside insect-secure structures that are >1km away from the nearest citrus orchards. Since November 2021 Komati Fruit Nurseries has been approved by CRI as a level 1 HLB Safe nursery.

To distinguish the HLB Safe compliant nurseries, CRI developed an HLB Safe™ certification trademark. HLB Safe nurseries can use the trademark on communications, and it will also be incorporated on the CIS Tree Certificate to indicate that the certified trees were produced in an HLB Safe nursery.

The HLB/ACP Action Plan and HLB Safe System documents can be downloaded from the CRI website CRI website under the Biosecurity folder or can be requested directly from CRI Biosecurity Manager Paul Fourie at phf@cri.co.za.