P&PDL Picture of the Week for
August 2, 2004


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). Click here to read the full story.

For more information on Dodder, click here

Click image to enlarge

Dodder appearing like a little
yellow string. 
Picture source: Virginia Tech
Weed Identification Guide

Accessed July 23, 2004.

Purdue Plant & Pest Diagnostic Lab Purdue Cooperative Extension Service