Cuscuta (dodder) is a genus of more than 200 species of obligate aerial parasitic plants in the morning glory family, Convolvulaceae. The genus is found throughout the temperate to tropical regions of the world, with the greatest species diversity in subtropical and tropical regions. Cuscuta species have a very distinct appearance, consisting mainly of leafless, yellow or orange, hairless twining stems and tendrils, bearing minute scales in the place of leaves. It has very low levels of chlorophyll; some species such as Cuscuta reflexa
can photosynthesize slightly, while others such as C. campestris
are almost totally dependent on the host plants for nutrition. If a dodder plant is allowed to grow unchecked, it will form dense mats in and over the host plant. Dodder plants branch and re-branch, spreading from plant to plant until large areas may be infested. Stem growth of 7.5 cm per day has been recorded. A single dodder plant may spread to a diameter
of 3 m or more.
Important dodder species in Africa include C. approximate (alfalfa dodder), C. epithymum (clover dodder), C. campestris (field dodder), C.reflexa (common dodder), C. kilimanjari, C. planiflora, and C. somaliensis.
Dodder derives nutrients by penetrating the stem tissues of the host plant with its haustoria (specially modified root-like growths) and absorbing water, carbohydrates and minerals at the expense of the host plant. As well as "starving" the host plant, dodder is also implicated in the transmission of certain bacterial and virus diseases. It is most troublesome where it is sown as a seed contaminant (e.g. lucerne, clovers, niger seed); where broad-leaved crops are grown as perennials or biennial
s (e.g. lucerne, clovers, citrus, sugar beet); and in horticulture where most crops in the rotation are broad-leaved (e.g. vegetables, ornamentals). Owing to its powerful metabolic sink effect, the damage to infested hosts can be severe, to the extent of total crop loss. Crop losses have rarely been measured, but there are estimates of 57% reduction in lucerne forage production over a 2-year period, and reductions of up to 40% in root weight and 3.5 to 4 tons of sugar per hectare in infested sugar beet. There is also further economic loss when crop produce, intended for export, is rejected or has to be cleaned expensively.
"Dodder is a true vegetal vampire. With its fine stems it sticks to its victims, then literally sucks the sap until killing the host." (Pamplona-Roger, 2000).
Dodder as a medicinal herb
It is recommended for people suffering from biliary disorder or gall bladder emptying-dysfunction. It can also be used as a poultice for slow healing wounds. Preparation and use of dodder as a medicine are given by Pamplona-Roger (2000).
Medicago sativa (lucerne), Guizotia abyssinica (niger), Beta vulgaris var. saccharifera (sugar beet), Daucus carota (carrot), Trifolium pratense (purple clover), Solanum melongena (aubergine), Solanum tuberosum (potato), Lycopersicon esculentum(tomato), Citrus spp. (citrus), Vigna radiate (mungbean)
Convolvulus arvensis (bindweed), Rumex abyssinica (wild dock), Rumex usambarensis (Kikuyu: mugagatio), Bougainvillea spp. (paper flower)
The presence of Cuscuta is always obvious from the twining stems and tendrils on a host plant. Infested plants show reduced vigour and, in particular, poor seed and fruit development. Leaves of infested plants are yellowed and eventually die. Severely infested plants wilt and die.
Affected plant stages
Seedling stage, vegetative growing stage, flowering stage, and fruiting stage.
Affected plant parts
Whole plant, leaves, and fruits/pods.