Glenn Nice, Weed Diagnostician , Botany & Plant
Pathology, Purdue University
Dodder is a unique plant in the fact that it
is parasitic. The relationship with dodder and its particular
host is absolute parasitic, meaning that there is no benefit
afforded the host whatsoever, and dodder must have its host to
survive. Dodder does not have any leaves or, for that matter,
any chlorophyll to produce its own food. It lives by attaching
to a host plant and extracting the host plant’s carbohydrates. It does this by penetrating
the host plant with small appendages called “haustoria.” Through
the haustoria, dodder will extract the carbohydrates.
Although not toxic or even unpalatable to some livestock, it can weaken the
host plant to reduce yield, quality, and stand. It is not to the advantage
for a parasite to kill its host, thus dodder generally will not kill its host,
but if the infestation is severe enough, it may result in the death of the
host plant. Work done in southern California reported that yield dropped from
2235 lb/A to 1576 lb/A when untreated for dodder (Cudney et al. 1992). In the
same study alfalfa plant number was reduced from 5 to 2 plants/ft2.
Once thought to belong to the morning glory family, it is now being placed
in a family of its own, called Cuscutacease. Dodders belong to the genus Cuscuta.
The USDA plant data base lists approximately 47 species (http://plants.usda.gov).
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