Amateur Gardening – 29 June 2019

29 JUNE 2019AMATEUR GARDENING 5

Colourful character: In next week’s AG (in the shops July

2) I show you how to keep your dahlias, hollyhocks and

clematis healthy and flowering all summer.

Six common summer diseases to tackle

Careful husbandry and good garden hygiene will help keep your plants healthy

AG readers are asked to help stop deadly disease

1

Grey mould, or botrytis, affects many
ornamentals and edibles. There
is no chemical control, but improving
ventilation around plants and removing
dead plant material can help deter it.

2

Hollyhock rust shows as orange

leaf spots with pustules underneath.

Dispose of affected material and treat

with a fungicide. Avoid dense planting

and monitor new plants for the disease.

3

Broad bean chocolate spot is a

fungal disease that can affect the

stem, causing plant collapse. Give plants

good ventilation and destroy infected

material. There is no chemical control.

4

Powdery mildew is another
common fungal problem that
causes white patches on leaves. Treat
with a chemical and destroy affected
material. Watering reduces plant stress
and the likelihood of the disease.

5

Blight affects outdoor tomatoes

when the weather conditions are

right (check  ahdb.org.uk for ‘fight-

against-blight’ updates). Leaves and

fruits brown and rot. Burn affected

material. There is no chemical help.

6

Clematis wilt affects many varieties,

especially large-flowered ones,

causing rapid wilting and death. Cut

back affected plants to ground level and

new healthy shoots may return. Deep

planting and regular mulching also help.

AG readers are being asked to help

prevent a deadly bug-carried disease

from entering the UK.

Xylella fastidiosa is a bacterium that

results in the death of many plants. So

far it is only found on mainland Europe

and the Royal Horticultural Society

hopes gardeners will help prevent it

reaching our shores.

To this end, volunteers are needed

to create a map showing the

distribution of spittlebugs,

one of the chief carriers of

Xylella, that are found in

gardens and woods

from April to late June.

Also known as

‘froghoppers’, they can

transmit the disease as

they move between plants

feasting on the sap. There are

ten froghopper species in the UK

and the young, called nymphs, produce

whitish, frothy blobs (often called cuckoo

spit) on leaves and branches.

Xylella is established in Italy, France

and Spain and has resulted in the death

of millions of olive trees in southern Italy.

It affects more than 500 different plant

species, including garden favourites

such as lavender, oleander, rosemary

and flowering cherry.

The disease stops water moving

from the roots to the leaves, and plants

often show symptoms such as leaf

scorch that can be confused with other

problems such as drought or

frost damage.

Gerard Clover, head of

plant heath at the RHS,

says: “Xylella remains

our number-one

concern, but is not an

issue bound by the

garden fence.

Understanding how and

where the disease’s primary

vectors move is fundamental to

understanding how we can stop the

devastation of our gardens and

environment should it arrive.”

If you spot cuckoo spit in your

garden, report it at  brc.ac.uk/

irecord/xylem-feeding-insects.

Further information is available at

 xylemfeedinginsects.co.uk.

to create a map showing the

feasting on the sap. There are

ten froghopper species in the UK

problems such as drought or

frost damage.

Gerard Clover, head of

plant heath at the RHS,

says: “

our number-one

concern, but is not an

issue bound by the

garden fence.

Understanding how and

where the disease’s primary

vectors move is fundamental to

Frothy cuckoo

spit is created by

the larvae of

froghoppers that

may potentially

carry the disease

Xylella fastidiosa

A mature froghopper

A froghopper larva in

its frothy cocoon