Page 14 - INTRA MUROS December 2020

GARDENING

PARASITIC PLANTS IN OUR GARDENS

By Elize Malan

n South African gardens Dodder and with long string-like tendrils. It has to find
IMistletoe are key culprits. a host within five days of germination or
it will die. After attachment, the Dodder
Mistletoe (Viscum capense) plant’s roots die off.
This is a hemi-parasite indigenous to
South Africa. The parasite has root-like structures called
haustoria that penetrate the host plant’s
Seventeen different species are recognised vascular system for nutrients and water.
and they form prominent clumps of The host plant deteriorates and can die.
vegetation attached to the branches of
various tree species. Although the parasite The thin tendrils are not easy to spot
has green stems and produces green when the infection starts, but it spreads
leaves, it can only manufacture a limited rapidly and covers grasses, flowers and
amount of food and is dependent on its herbaceous plants with a yellow blanket.
host for survival.
It is an annual parasite and produces
The plants flower in winter and the fruit copious amounts of very fine seeds. The
ripens around the peak of the dry season seeds can be dormant for up to ten years
in summer rainfall areas. It is a good food in the soil before germination.
supply for birds during this time when
food is scarce. Birds spread the sticky Please note:
seeds to branches of other trees when Small pieces of tendril that are dropped
cleaning their beaks. Germination occurs when removing this parasite from your
immediately but penetration of the host’s plants are capable of re-attaching and
tissue, and establishing contact with the will continue growing and regenerating, if
conducting tissue, can take up to one year. haustoria are embedded in the host plant.

Heavy infestation causes certain parts How to get rid of Dodder in your garden
of the host plant to die. Removing the
Mistletoe plant from the host will cause Cut off its supply of nutrients:
more damage to the host tree. Preferably Cut the contaminated plant below the
trim off the branches of the parasite and point at which the Dodder is attached to
paint the cut ends to limit regrowth. the plant. This may not always be possible.

Dodder (Cuscuta) Pulling up the plant: Mistletoe - (Viscum sp)
Consists of about 145 species and is a The plant will die, but so will the parasite.
holoparasite, introduced to South Africa Check for small Dodder seedlings In situations where Dodder is pervasive,
with host plants that were imported germinating and remove as they appear. the infested plants can be removed and
as animal fodder. It is a leafless twining the soil treated with a pre-emergence
parasitic plant. Dodder is widely Prevent seed formation at all cost: herbicide to prevent seeds from
distributed throughout the temperate and Be vigilant and eliminate infection areas germinating.
tropical regions of the world. before seed formation.
References:
Unlike hemi-parasites, Dodder does not Chemical control: Clive Bromilow: ‘Problem Plants of South
have chlorophyll and is totally dependent Once Dodder has infested an ornamental, Africa’
on a host. selective herbicides cannot be applied
without harming the ornamental host. Kaley Mierek, Chris Marble, Nathan
After independent germination, Dodder Contact herbicides will damage and/or kill Boyd, and Shawn Steed: ‘Biology and
seedlings entwine around a host plant the host plant. Management of Dodder (Cuscuta spp.)
in Ornamental Crop Production and
Landscapes’

Tel: 012 804 1807
Fax: 012 804 0278
Web: www.garden-group.co.za
E-mail: admin@garden-group.co.za

Photos supplied by: Carol Knoll
Common Dodder - (Cuscuta campestris)

12 INTRA MUROS DECEMBER 2020