The lowdown on threats to biosecurity, biodiversity and food security.
The National Science and Technology Forum (NSTF) hosted a NSTF Discussion Forum on ‘Plant Health in South Africa – threats to biosecurity, biodiversity and food security’. It was an event two years in the planning and an extension of 2020 being declared the ‘International Year of Plant Health’ by the United Nations. It ran online from 10-11 June 2021. Below is a summary of their findings.
Plants are the food we eat and the material we build with, like timber. Plants create shade and beautify. Plants mean jobs. The South African citrus industry was valued at R19.3 billion in the 2017/2018 production period. That’s just part of horticulture which was valued at R77.9 billion. (Source: ‘A profile of the South African Citrus Market Value Chain 2019, Department of Agriculture, Forestry and Fisheries’.)
Plants are part of ecosystems – both causing an effect and being affected. Think of plants and the increasing demand for food, with the decrease of fertile land, and the interplay with climate change. Plant health is intrinsically linked to the survival of our planet and all that live on it. If we care about the eradication of poverty, the critical nature of food security and the importance of nutrition, then we care about plant health.
Insects and Pathogens
For the NSTF Discussion Forum, Prof Michael Wingfield honed in on pests and diseases. Wingfield is a 2020 NSTFSouth32 Award Winner in Plant Health. He is currently Advisor to the University of Pretoria Executive and was the Founder Director of the Forestry and Agricultural Biotechnology Institute (FABI) at the university. Wingfield is one of South Africa’s plant health stars, internationally recognised for his extensive research on insect pests and diseases of forest trees.
Pathogens and pests have a very negative impact on trees and will continue to do so, says Wingfield. Take Dutch Elm Disease where pathogens are carried by insects. It was introduced accidentally into Europe and North America and then caused devastation in the natural environment.
In South Africa, a recent example is the Polyphagous Shot Hole Borer (PSHB) and its fungus. Together these organisms can be aggressive tree killers, explains Prof Wilhelm de Beer, Associate Professor in Biochemistry, Genetics and Microbiology Department, FABI. It’s of major concern to farmers, foresters, landscapers, homeowners and ecologists. (De Beer provided further details in his presentation.)
Impact of Trade
The movement of people and our products – travel and shipping – has resulted in pests and pathogens moving around the world. Wingfield says that, since 1980, 70% of new pathogens were likely introduced via the live plant trade. (Source: ‘Biogeographical patterns and determinants of invasion by forest pathogens in Europe’, New Phytologist)
The solution isn’t going to be shutting this trade down. Wingfield’s data shows that, as of 2016, global floral crops (such as cut flowers and flower bulbs) were valued at US$55 billion. The tree nursery crops (trees, shrubs and other hardy plants) were valued at US$35 billion. There needs to be a balance between controlling plants (that may carry pests and pathogens) and the needs of the plant industry.
Some Solutions
Wingfield says solutions cover a wide range of options, for example:
- Selecting plants with resistance to the pathogens
- Innovative biological controls
- Chemical controls which can be used safely at times
- Quarantine
- Applying national and international policies which fall under biosecurity (ie the policy and regulatory frameworks for analysing and managing relevant risks to human, animal and plant life and health)
- Using DNA sequencing and the tools associated with it
Click here to find out more or read the full release on the outcomes of the recent conference.
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