202 REPORT OF THE DEPARTMENT OF BOTANY OF THE 
which might interfere with the growth of dodder. Yet no dodder 
appeared on either of the spots although they were kept under ob- 
servation for two years. Nothing is known as to the viability of 
the dodder seed used, but it is scarcely possible that all of the seeds 
were incapable of germination. 
Mr. F. E. Dawley, Fayetteville, N. Y., informs us that in a simi- 
lar experiment made by him strikingly different results were ob- 
tained. Mr. Dawley sowed 27 dodder seeds in an old alfalfa 
field where there had been no dodder previously and 27 spots of 
dodder resulted. 
It is probable that under favorable conditions dodder may be 
spread by the mower even when no seeds are formed. Sometimes 
during a spell of rainy weather the newly-mown hay keeps fresh 
for several days and the dodder on it not only remains alive but 
continues its growth and is capable of attaching itself to living al- 
falfa stems with which it may come in contact. Owing to their 
tangled condition bunches of dodder-infested hay are often draggea 
short distances by the mower. Should it happen that such bunches 
are dropped upon plants which, in some manner, have been missed 
_ by the mower, the dodder finds its opportunity. It is also possible 
that the dodder may be kept alive until new growth starts. Ina 
wet time alfalfa starts up very quickly after mowing. 
That it is possible for dodder-infested hay to bring about in- 
fection in the open field is shown by the following experiment: On 
July 10, 1906, two handfuls of dodder-infested hay each contain- 
ing about a dozen stalks were placed among alfalfa plants 12 to 
14 inches high. The dodder had not commenced to bloom and 
there were certainly no seeds. The plants and ground were wet 
at the beginning of the experiment, but subsequent weather condi- 
tions were not recorded. The first observations on the experiment 
were made July 26, three days after the field had been mown. Al- 
though the hay had been removed the stubble showed, unmistakably, 
that infection had occurred in both spots. In one of the spots three 
plant were so much affected that the dodder was visible at a dis- 
tance of 20 feet. In the other spot, dodder was firmly es- 
tablished on two plants. Subsequently, two other experiments of 
this kind were made. In one of these the dodder-infested hay was 
placed on the bare stubble of a newly-mown field; in the other, 
among a new growth of alfalfa two to four inches high. The 
weather being dry the dodder failed to establish itself in both 
cases. 
