Diseases of Alfalfa and Clover 



-VJ 



DODDER 



The dodders, Cuscuta sp., are parasitic flowering plants which 

 attack a great niunber of hosts. In clover and alfalfa fields, 

 dodder may become very destructive, killing in ever-widening 

 circles. In the center of the infested areas the host plants will 

 be entirely killed, while about the margin of these dead areas will 

 be seen the dense mat of orange or yellowish stems. 



The parasite consists of slender, yellowish or orange-colored, 

 much-branched stems, on which are borne at rather frequent inter- 

 vals clusters of white flowers. There are no leaves nor roots pro- 

 duced. The parasite is entirely dependent upon its host for food. 

 It twines about and over the clover or alfalfa, producing a great 



Fig. 671. — The Leaf Spot ox Clover. Compare this with Figure 8. 



mat of stems. In order to get its food, the Cuscuta produces 

 lateral, root-like organs, called haustoria, which penetrate into the 

 stems and leaves of the host, thus diverting the flow of host sap 

 into itself. In this way the host is slowly killed, but in the mean- 

 time the dodder has grown out to new hosts. 



