Page 24 - ALG Issue 2 2025

BIO-DIVERSITY
National
Plant Health
Week-Calling all
allotmenteers!
Our plants
need you!
The fifth National Plant Health Week
takes place from 5-12 May 2025. It is
a designated week of activity to raise
public awareness and engagement on
how to keep our plants healthy. For more
information about the week please see the
website Plant Health Action.
The week is a collaborative effort by
over 30 organisations across the UK who
are committed to protect the health of
our nation’s plants and trees. The week
is a partnership between Defra and
several organisations including the RHS,
The National Allotment Association,
Kew Gardens, Woodland Trust, and the
Horticulture trade working together to
communicate to their audiences about the
importance of plant health.
Over recent decades the threat to
UK plant health has increased, due to
several factors, including climate change
and globalisation in trade, travel and an
increased volume and diversity of plant
products entering the UK.
Plants are a crucially important part
of our economy, from agricultural and
horticultural production to timber,
medicines and wider co-benefits including
public wellbeing. They provide an annual
value to the UK at £15.7bn per year. The
health of our plants and plant products is
therefore of vital importance.
The economic benefit of our plants and
trees includes the value of our agricultural
crops, horticulture, flowers and fruits and
vegetables, and is estimated to contribute
£4.1bn per year to the UK’s economy.
We all have a role to play in protecting
our nation from plant pests and diseases,
and as allotmenteers you are our eyes
and ears on the ground and have a vital
role in protecting our plant health.
One example of a quarantine disease
that had an impact on allotment growers
and gardeners was the discovery of Potato
Yellowing Virus (PYV) in Yacon (Smallanthus
sonchifolius) in 2020.
PLANT
HEALTH
Yacon had started to take off in
popularity in the UK, and it was easy to see
why, this easy growing, hardy and attractive
perennial with tasty edible tubers from
South America seemed like a great fit for
the UK’s climate and soils. But unfortunately,
it also had a darker side.
Unbeknown to growers at the time
Yacon was able to host the notifiable
PYV. Now let us do a bit of jargon busting
here, a “notifiable” pest or disease MUST
be reported by anyone to the relevant
authorities.
To the Animal and Plant Health
Agency (APHA) for edible, horticultural
or ornamental plants and to Forestry
Commission for trees.
Notifiable plant pests and diseases are
the ones that have the potential to cause
the greatest damage to our agriculture,
horticulture or wider environment. Suspect
plant pests and diseases can be tricky to
detect, pests a little less so as they are
often visible and present even if they may
at times be minuscule and hard to spot.
Diseases and other pathology on the other
hand have the benefit of being invisible
to the naked eye, with occasionally just
the symptoms giving away their presence.
Sometimes we don’t even get the luxury
of symptoms especially for plants that can
carry diseases and express no symptoms.
Yacon is one such case.
Notifiable pests and disease can be
reported via the plant health portal at
DEFRA
www.planthealthportal-defra.gov.uk/
pests-and-diseases
In 2020 testing of imported and grown
yacon samples discovered the presence
of PYV. This virus while symptomless in
yacon has the potential to infect a wide
range of crops in the nightshade family
including potatoes and peppers, as well as
wild solanum species (nightshades). PYV
was also highly transmissible and could be
transmitted through sap, pollen, seed as well
as by the widespread peach-potato aphid
(Myzus persicae). In potato crops PYV
can cause mild yellowing symptoms in the
leaves or may even remain symptomless; in
infected pepper plants it can cause spotting
on leaves and stems as well as the death of
the buds and fruit.
Currently PYV is absent from GB.
24 | Issue 2 2025 | Allotment and Leisure Gardener