has developed new varieties of Helleborus that make them easy to
care for in the garden. They are resistant to most
pests and diseases. (see Helleborus Gold Collection)
There are few remaining threats, and they are described below.
Aphids are probably the biggest pest. Primarily,
they attack the new leaves. Other uninvited guests
such as snails can sneak up in moist summers. There
are snail repellants in garden centers or one can use the ever-popular
“beer trap”.Furthermore a stinging
nettle-slurry can be used to prevent that aphids colonize the
In a cold winter mice can sometimes eat the new
buds of the plants. The neighbour´s cat can help to minimize
Root nematodes, which are not visible with the
naked eye, can be a problem. Should the plant exhibit stunted
growth while it is getting good food and nutrients, this
might be the cause. The nematodes suck on the roots of the plant,
preventing food and water to the leaves of the plant. It is very
difficult to attack these insects. Plants showing these
symptoms should probably be dug from the garden and disposed
of properly so that the nematodes do not increase.
Western flower thrips can attack the flowers.
This generally would occur in the autumn. If there is a gnarly,
deformed growing tip on new leaves this could also be the cause.
At the first frost, thrips will be eradicated.
Fungal diseases are more difficult
to the plant than pest damage because the appearance
of the plant can be influenced negatively and/or the entire plant
is the most famous fungus to attack Helleborus, it causes the Black-Spot
disease. As the name suggests, this fungus creates black
spots on the leaf edges. At the first signs of this disease you
should start a control program. All the affected leaves
should be cut off and thrown away so the fungus
will not spread. Spray control programs with fungicides
can be effective in controlling the disease. Watch closely for spread
of the fungus once observed for repeat treatments. Causes of the
disease can be a low pH and a location in the garden with too much
The symptoms of the Black Spot are similar to those of the Black
Death disease, which is recently reported from England.
It is probably a virus, which creates black spots
and black streaks on all parts of the attacked plant. These plants
must be destroyed because there is no cure for
the virus. One of the few preventative measures one can take is
to keep pest infestations to a minimum as they transmit the disease.
In the spring healthy leaf stalks can be attacked by a rhizome
and stalk decay. The stalks lie on the ground and have
brown or black areas at the base
of the stalk. Several fungi can be the cause of these symptoms:
e.g. Pythium, Phytophtora or Rhizoctonia. Treatment for these fungi
is difficult. It is important to plant in soil that is well drained
and does not hold moisture.
These were the pests and diseases which can occur at Helleborus
under bad conditions. If other “visitors”
or fungi lose their way on your Helleborus, you can get information
in a specific shop, or you can use our discussion