New YorRK AGRICULTURAL EXPERIMENT STATION. 203 
The ability of dodder to continue growth as long as the alfalfa 
remains fresh is easily demonstrated by cutting off infested alfalfa 
stems and placing them in a moist chamber. In an experiment of 
this kind made by the writers dodder retained its color and tur- 
gidity on cut stems six days during which time the length of the 
threads increased about one inch. The writers have frequently in- 
fected alfalfa plants by placing dodder-infested alfalfa crowns and 
stems in contact with them in a moist chamber. 
Dodder may be propogated also by cuttings; that is, short pieces 
of the dodder threads placed in contact with alfalfa plants will at- 
tach themselves after the manner of seedlings. This was demon- 
strated in 1880 by Koch* and more recently by Pierce* and 
others; also, by the writers who made the following experiment: 
Five tip-end pieces of dodder threads, four inches in length, were 
placed among the branches of a ten-inch high alfalfa plant in a 
moist chamber. In 17 days the plant was thoroughly infested with 
dodder several threads of which were a foot long. 
Although the spread of dodder is not rapid it is by no means con- 
fined to the enlargement of the original spots. New spots are 
formed from time to time. Usually, the new spots appear in the 
near vicinity of the old ones. In a dodder-infested alfalfa field 
near Syracuse, examined by the writers in the spring of 1906, 
some of the large spots were surrounded by smaller ones which 
were plainly the result of secondary infection. One large spot 
about 15 feet in diameter was surrounded by 11 small spots two 
or three feet in diameter. The most distant of these was 20 feet 
away while four were so near that they almost touched the margin 
of the parent spot. Whether the small spots originated from seed 
or from infested hay carried by the mower could not be determined. 
The method by which dodder survives the winter is so important 
a matter that it will be discussed under a separate heading. 
PERPETUATION OF DODDER FROM ONE YEAR TO THE NEXT. 
In almost all botanical writings the numerous species of Cus- 
cuta are all classed as annuals. It seems to be the prevailing opin- 
ion that none of the dodders survive the winter in the thread form 
and that, in order to perpetuate themselves, they must start anew 
every year from seeds. Yet, so long ago as 1868, Dr. Julius Kuhn* 
~ Koch (55). 
= Peirce. (77). 
“Kithn (57). 
