52 | New Scientist | 6 November 2021The back pages
CULTURA
CREA
TIVE^ L
TD/ALAMYThese articles are
posted each week at
newscientist.com/makerWhat you need
Tomato seeds or plug plants
A warm place to grow themTOMATOES can be one of the
easiest and most rewarding
home crops. Besides thriving in
the ground, they also love pots,
hanging baskets and grow bags,
producing loads of tasty fruits for
salads, cooking and pizza sauce.
It is now the end of the tomato
season in the UK and time to
review the performance of this
year’s crop. Sadly, my plants
suffered badly from blight caused
by a fungus-like organism called
Phytophthora infestans. Many
other people experienced the
same issue – the first signs are
sinister brown spots on leaves
and fruit, which spread within
days to destroy whole plants.
The pathogen drifts through
the air as spores and germinates
best on plants in the conditions
of a rainy British summer, like the
one we just had. Most tomatoes
grown outdoors succumb to
blight by the end of the season,
in autumn, but this year my plants
were showing signs of infection
by early August, so I got only a
few fruits before the rot set in.
Once blight reaches a plant, it
can’t be saved, but you can take
steps to reduce the chances of
infection. To lessen humidity
around the leaves, space out your
young plants well, hold foliage up
off the soil by tying it to supports
and remove lower leaves as they
age. Avoid splashing the leaves
when you water, too.
Don’t allow plants to grow
from last year’s fruit that fell on
the ground, because they may
harbour spores. (The same goes
for potato plants, because thisHome-grown tomato plants can get ravaged by blight, but there
are easy steps you can take to prevent it, says Clare WilsonScience of gardening
Banish the blight
pathogen causes potato blight
too.) And you can keep an eye
on the “blight forecast” from
blightwatch.co.uk, which tells
you if the disease is on its way
based on local temperature and
humidity, so you can pick any
ripe fruits in the nick of time.
Most helpful of all is to choose
tomato varieties that have some
natural resistance to blight. I have
previously been sceptical of this
strategy after hearing of plants
sold as blight-resistant that
didn’t live up to their name.
But a newer variety called
Crimson Crush seems to have
exceptional disease resistance.
It is the first tomato to have two
different resistance genes instead
of one, according to the UK’s
Royal Horticultural Society.
There are now related Crimsonvarieties, available from several
seed suppliers.
Another good strategy is to
grow several tomato varieties, if
you have room, because different
ones can be resistant to different
versions of the pathogen, says
Katherine Steele at Bangor
University, UK, who helped to
develop Crimson Crush. “There
is a constant arms race between
the pathogens and the plants.”
I plan to try a few different
Crimson plants next year as well
as some old favourites. I would
love to hear about readers’
experiences with these new
varieties at @clarewilsonmed
Science of gardening on Twitter or Facebook. ❚
appears every four weeksNext week
Citizen scienceClare Wilson is a reporter
at New Scientist and
writes about everything
life-science related.
Her favourite place is her
allotment. @ClareWilsonMedFeedback
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