210 REPORT OF THE DEPARTMENT OF BOTANY OF THE 
boundaries more sharply defined than at any other time. The 
alfalfa will then stand four to eight inches high while the weeds on 
the interior of the spot have scarcely started. Moreover, at this 
time, the live dodder is closely confined to a few plants and there are 
no long threads so that the danger of leaving some of the dodder 
undestroyed is not as great as it is later in the season. Of course 
some unnecessary work may be done on spots already extinct since 
it is difficult to distinguish active from extinct spots so early in the 
season; but this is probably offset by the increased size of the spots 
later in the season. Dodder spots escaping the first treatment 
should be destroyed whenever discovered. At each mowing a care- 
ful lookout should be kept for new spots. If any are discovered 
they should be marked so that they may be found again and de- 
stroyed after the hay is removed. To the inexperienced it may ap- 
pear that the ideal time to treat dodder in just after haying. How- 
ever, such is not the case. ‘The infested spots are then very difficult 
to locate. 
Both in burning out and in digging out dodder it is necessary to 
sacrifice a strip of alfalfa two to three feet wide all around the mar- 
gin of the spot in order to make sure that none of the dodder es- 
capes. If the spot is sharply outlined a strip two feet wide is likely 
to he sufficient; but where the margin of the spot is indefinite it is 
advisable to include a wider strip. 
lf it is desired to reseed the infested spots the digging out method 
is preferable to any other, provided the soil is not stony, since the 
spots must be dug up anyway before they can be reseeded. How- 
ever, we doubt the advisability of reseeding. In experiments made 
by the writers the reseeding of infested spots has been only partially 
successful. The principal difficulty is with weeds. The soil of in- 
fested spots is sure to be full of weed seeds, particularly those of 
green and yellow fox-tail grasses. Besides, if the dodder ripened 
seed there is danger that the alfalfa seedlings may become affected 
and thus foil the attempt at eradication. 
RESEEDING INFESTED FIELDS. 
When it becomes necessary to plow up dodder-infested alfalfa 
fields there frequently arises the question as to how soon the field 
may be safely reseeded with alfalfa. Before this question can be 
answered satisfactorily it must be known whether the dodder pro- 
duced seed. If the dodder ripened seeds there may be danger of 
the appearance of dodder in the new seeding. Exactly how long 
