Plant Healthy – ‘putting biosecurity at the heart of the horticultural trade’

This article was submitted to the Small Woods Magazine in February 2020

The name Phytophthora, a genus of plant pathogenic fungi, derives from the Greek for ‘plant destroyer’. It includes the infamous potato blight, Phytophthora infestans, the plant disease responsible for the death of approximately one million people in Ireland in the mid-19th century. Potato blight is just one of nineteen species of Phytophthora listed on the UK Plant Health Risk Register. Other species of Phytophthora infect a wide range of horticultural, agricultural and forestry hosts, ranging from much loved garden favourites, e.g. Chrysanthemums, to woodland species such as the iconic oak tree.

There are many other fungal diseases of plants, there are also bacterial, viral and less well understood plant pathogens, e.g. phytoplasmas. The biological threat to plant life does not stop at pathogens, certain species of insects and nematodes also harm plants. Collectively these species are known as plant pests. Some pests exist in equilibrium with plants in their natural ranges. However, exotic plant pests are now a principal driver of biodiversity loss with many ecosystems, already altered by human actions and climate change, presenting new niches for harmful pests to thrive.

Unprecedented pest damage is now occurring in gardens, on farms and within forests throughout the world. In recent times a number of exotic pests have been introduced to the UK. In 2012 the Independent Panel on Forestry identified 20 such introductions in as many years on trees alone. There are still numerous pests that are currently not present in the UK. It is essential that we keep these pests at bay and protect the valuable ecosystem services that plants provide us with. It is for this reason that we welcome the UN designating 2020 as the International Year of Plant Health: www.yearofplanthealth.co.uk

Plant pests are rapidly changing our countryside. Recently introduced exotic insect pests include oak processionary moth, which cause damage to oak trees, disrupt woodland ecology and can cause severe rashes and respiratory problems to people. In recent decades Dutch elm disease has killed most of our mighty elms trees, a once revered feature of the British landscape. Currently, another disease, ash dieback, is resulting in the removal of mature ash trees across the UK. Elm and ash provide habitats for many obligate species – that is wildlife species that exist only on these trees. Our trees are now under an unprecedented ‘chronic’ threat from climate change and a variety of relatively ‘acute’ threats from plant pests. Unfortunately, it appears that together climate change and plant pests compound their destructive potential to cause increased harm to plant life.

Understanding how plant pests move from plant-to-plant, be it at the garden or global scale, is key to halting the spread and damage caused by plant pests. Central to defending plant life against pests is the concept of biosecurity. Biosecurity is a set of control measures or behaviours that governments, industry and the general public can adopt to help protect plants from plagues of pests.

It is with an urgent need to improve biosecurity that the Plant Health Alliance was formed as an outcome of a conference held at Highgrove in February 2018. The steering group members include Government, industry and NGOS representatives and actively look to combine and advance efforts to improve biosecurity in the UK and beyond.

The Alliance is now working to raise awareness and address the threats that plant pests present to the health of our plants. A key step in delivering this purpose is the publication of the Plant Health Management Standard.

The Standard is the technical document that sits are the heart of a the recently launched Plant Healthy Certification Scheme. The Scheme was soft launched in February 2020 and a ‘pioneer group’ of nursery businesses will be going through the certification process over the next six months. Feedback from these scheme applicants will help improve the auditing process and scheme function. Once the scheme is 'bedded in' and full funding has been secured, the intention is to promote the scheme publicly.

To find out more about the Plant Healthy initiative please visit: www.planthealthy.org.uk

Alistair Yeomans, MICFor CHort

Auditors discussing biosecurity measures in the despatch shed at Delamere Nurseries – February 2020 – note plant health information on the back wall.