Benchmarking South African plant improvement

Certification of pome- and stone-fruit plant material is at an all-time low. What are the problems, and how do we solve them? A summary of the task-team report.

The percentage of certified pome- and stone-fruit trees sold has dropped to an average of 33% — a figure that would be even lower if not for the 78% certification of plum trees triggered by increased awareness of plum marbling.

In contrast, 97% of wine-grape vines are certified, and the percentage of certified table- and raisin-grape vines is growing. This suggests that grape growers consider certification an indispensable guarantee of vine quality. So why do pome- and stone-fruit growers take a different view?

A recent project aimed to answer this question by benchmarking the South African Deciduous Fruit Plant Certification Scheme against successful local and international plant certification schemes.

The project was overseen by a reference group comprising representatives of the shareholders of SAPO Trust (Hortgro Pome, Hortgro Stone, the South African Table Grape Industry, Raisins South Africa, and the Canning Fruit Producers’ Association), PlantSA, the plant improvement organisations (SAPO Trust, TopFruit, and Stargrow), and the Deciduous Fruit Nurserymen’s Association.

The reference group appointed a task team led by Hugh Campbell (Hortgro) and including Nolan Africander (DALRRD) and Rachel Kriel (PlantSA).

Ten plant certification schemes and institutions — listed in table 1 — were evaluated on paper. The task team also visited several institutions and nurseries in Europe. In South Africa, the team conferred with growers, industry organisations, nurseries, technical advisers, plant improvement organisations, DALRRD, and PlantSA.

The project outputs are redefined goals for plant improvement and best-practice guidelines for its implementation in South Africa. The focus is on pome and stone fruit, and table and raisin grapes.

Table 1: Plant improvement schemes and institutions benchmarked

Entity	Country
Naktuinbouw and Vermeerderingstuinen	The Netherlands
Centre Technique Interprofessionnel des Fruits et Légumes [Interprofessional Technical Centre for Fruits and Vegetables]	France
Centro Attività Vivaistiche [Centre for Nursery Activities]	Italy
National Clean Plant Network United States Department of Agriculture	United States
Clean Plant Center Northwest Washington State University	United States
Foundation Plant Services University of California, Davis	United States
Citrus Improvement Scheme	South Africa
The South African Seed Potato Certification Scheme	South Africa
The South African Seed Certification Scheme	South Africa
Vine Improvement Association South African Plant Certification Scheme for Vitis	South Africa

What is plant improvement?

Plant improvement is the ongoing process that produces better fruit trees — for example, selections that are higher yielding or have better quality fruit. New varieties or selections can be imported, locally bred, or locally selected from mutations discovered in orchards.

Plant improvement includes selecting and multiplying propagation material that is free of economically important pests and diseases. If a new selection is virus-infected, thermotherapy, re-testing and re-evaluation of the material also form part of plant improvement.

What is plant certification?

Certification means different things to different people. In the context of plant improvement, certification is the process of providing growers with evidence that plant material of official varieties has been tested and certified for trueness-to-type, health status, and physical quality.

Varietal authenticity refers to whether a cultivar is distinct, unique, and stable. New cultivars are evaluated for at least three years under local conditions to ensure that they are genuinely different from already established cultivars and will not revert to their parent type.

Trueness-to-type refers to whether all offspring of a particular cultivar or clone consistently show the unique characteristics of that cultivar or clone. Certified plant material issued for propagation is traceable to sources that have been checked for trueness-to-type.

Nursery trees are inspected in summer to confirm trueness-to-type. The scion and the rootstock are marked to ensure that growers receive the correct material.

Health status is determined by testing and visual examination. Testing is the only way to assess freedom from viruses and viroids, while a visual examination is sufficient to detect certain pests and diseases.

Plant certification schemes also set standards for the physical quality of nursery trees. For example, trees should be a specific size and not show drying out or damage.

Although certification is not an essential component of plant improvement, it assures growers that the plant material’s trueness-to-type, disease status, and physical quality have been independently confirmed.

What is plant quarantine?

Plant quarantine is the process of isolating plant material for observation and testing to ensure that it can be safely introduced.

Importation of new cultivars or clones is one of the ways in which South African fruit growers can remain competitive. But importation also carries the risk of pest and disease transfer. Plant quarantine exists to mitigate this risk.

In South Africa, quarantine has historically been compulsory and carried out by the government, whereas certification of plant material has been voluntary and carried out by non-governmental entities authorised by the government.

The plant improvement top 10

The benchmarking exercise conducted by the task team highlighted ten aspects of the best local and international plant improvement systems.

1. Plant improvement organisations and other service providers are independent — they have no financial interest in cultivars or clones.

2. Plant improvement facilities in the European Union are self-funded through service provision and bud- and graft-wood sales.

3. Different specialised entities perform different plant improvement functions.

4. Laboratories provide diagnostic and testing services to support plant improvement and quarantine, and continually improve and update their technology.

5. Thermotherapy is performed to remove unwanted viruses that are detected in plant material.

6. Plant improvement organisations in the European Union are authorised by their agricultural ministries to provide quarantine services.

7. Nucleus material — which is free of specified pests and diseases — is the only source for tissue culture and is used for the regular renewal of conventional sources of propagation material.

8. Budwood collected in commercial orchards cannot be certified. Bud and graft wood, and rootstocks, are produced in biosecure mother blocks or budwood parks.

9. All plant material in the European Union must meet a set of minimum requirements enforced by inspection services.

10. Independent inspection services responsible for certification are also authorised to enforce regulations.

How does South African plant improvement work?

The Deciduous Fruit Plant Improvement Association is the authority delegated with coordinating pome- and stone-fruit plant improvement in terms of the Plant Improvement Act 53 of 1976. Among other things, the Act provides for the registration of deciduous fruit- and vine-certification schemes, plant improvement organisations, nurseries, and related laboratories.

The Deciduous Fruit Plant Improvement Association also has certain responsibilities for control of agricultural pests and diseases under the Agricultural Pests Act 36 of 1983, protection of plant breeder’s rights under the Plant Breeder’s Rights Act 15 of 1976, and management of genetically modified organisms under the Genetically Modified Organisms Act 15 of 1997.

PlantSA — Plant Improvement South Africa — is a non-profit company that manages voluntary plant certification schemes for deciduous fruit and grapevines.

Under the certification schemes, only registered plant improvement organisations may import, breed, or select new or improved cultivars or clones. Breeding programmes can operate outside the scheme if they choose not to register their cultivars or clones. Currently, only participating plant improvement organisations can apply for certification of propagation material, and only registered nurseries can produce certified trees.

The original material of new imports or newly discovered or developed cultivars or clones is held in a biosecure nucleus facility and is inspected and tested regularly. Nucleus material is used to establish foundation units belonging to plant improvement organisations. Plants in foundation units are individually inspected and regularly tested.

Foundation units provide material for mother units — primarily commercial orchards — from where the material is harvested to make nursery trees. Mother units are inspected regularly, but testing is less comprehensive and frequent than in foundation units.

Commercial propagation occurs in nursery units. Nursery trees are inspected but not tested. The assumption is that testing and safeguarding the health status of the parent stock will guarantee the health status of propagation material obtained from that stock.

The certification schemes prescribe the standards for certification, but as certification is voluntary, the Plant Improvement Act also sets minimum requirements for uncertified propagation material. Inspection of uncertified material is a DALRRD function. Although the Deciduous Fruit Plant Improvement Association can refuse to certify trees, only DALRRD can prohibit the sale of non-compliant trees.

The gaps in the current system

Plant quarantine and plant certification in South Africa are separate systems run by different entities. Plant improvement organisations and intellectual-property owners are eager to import and market new cultivars and clones. Combining the quarantine and certification processes offers the opportunity to optimise resource use and deliver new cultivars faster.

Currently, a low value is placed on buying certified pome- and stone-fruit trees. As certification is voluntary, about 10%–15% of trees originate from breeding programmes outside the certification scheme. Plant improvement organisations provide propagation material for the rest, but more than half of this is nonetheless uncertified.

Plant improvement organisations have multiple interests — they own or manage intellectual property, inspect their own plant material, provide certified propagation material, and sometimes manage laboratories. Some of these functions should instead be performed by independent service providers.

DALRRD should inspect uncertified plant material, but under current arrangements, most nurseries request the inspection of their uncertified trees from a contracted inspection service. DALRRD is notified when follow-up action is required — neither PlantSA nor the contracted inspection services have the authority to prevent the sale of non-compliant trees. Unfortunately, DALRRD lacks the capacity to follow up, so there is no functional mechanism to mitigate the risks of planting uncertified trees.

The current plant improvement system has existed for more than 40 years. Although it was built on solid principles, changes in some areas and lack of adaptation in others have reduced its efficacy — hence this review to identify ways in which the system can be re-aligned with best practices.

Task-team recommendations

The mandate of the task team was to draft best practices for plant improvement. Their investigation of successful local and international schemes led them to identify fundamental principles common to all, even though each followed different implementation strategies. Subsequently, the task team drafted a set of seven broad recommendations, summarised below.

1. Address the current and future importation and quarantine requirements by supporting the accreditation of international facilities to mitigate risk and streamline processes. Explore the opportunity of combining testing services for quarantine and certification to expand and expedite certification.

2. Establish an independent nucleus plant facility with a laboratory that can meet all quarantine and certification requirements, develop new and update existing test methods, and remove viruses from plant material by thermotherapy.

3. Do not limit registration of cultivars or clones for certification to plant improvement organisations but allow participation by individual intellectual-property owners.

4. Enable the utilisation of independent service providers for the pomological evaluation of new varieties in support of varietal listing and protection of plant breeder’s rights.

5. Establish independent services to conduct inspections at all levels of the certification process. There must be sufficient capacity to ensure accountability and traceability throughout the system.

6. Combine inspection services with effective auditing to ensure reliable certification.

7. Ensure that the sources of propagation material are biosecure — they must produce the best quality with the least risk.

Based on the above, the task team developed an implementation plan to improve the quality and health of plant material available to South African growers; to streamline the quarantine and evaluation of new cultivars and clones; and to increase the percentage of certified trees planted.

Bonus: What does clean mean?

Plant material that is free of pests and diseases is often referred to as clean. This term can be misleading because it may be understood to mean that the material is free of all pests and diseases — but no certification guarantees complete freedom from pests and diseases.

Most tests return a positive or negative result for a specific disease-causing agent. Plant certification schemes do not include blanket testing for all potential causes of disease. They instead focus on the economically important diseases of relevance to a specific industry.

Therefore, rather than talk about clean material, it is more accurate to refer to plant material as tested free of viruses specified by a particular plant certification scheme.

When new or mutated disease-causing agents emerge, new or updated testing for certification is required. There is an inevitable lag between recognising a new problem and developing testing and certification to control it.

Image: The task team visit Vermeerderingstuinen in the Netherlands.

Supplied by Rachel Kriel | PlantSA.