Care should be exercised to secure seed free from
impurities. If one is not a competent judge, he should send a sample to
his state experiment station for examination. The practice of
adulteration is decreasing, but the seed may have been taken from land
infested with pernicious weeds.
The impurity most to be feared is dodder. There are several varieties,
the seeds varying in size and color. The same pest may be found in
clover fields, but the injury is less because the clover stands only
two years. The dodder seed germinates in the soil, and the plant
attaches itself to the alfalfa, losing its connection with the soil and
forming a mass of very fine vines that reach out to other alfalfa
plants. In this way it spreads, feeding on the sap of the host plants
and killing them.
When the infestation is in only a few spots in the field, the remedy is
to cover with straw, soak with kerosene oil, and burn. All the
infestation at the edges of these spots must be destroyed.
When the dodder is too widely distributed throughout the field to
permit of this treatment, the only course is to plow the field at once,
and to grow cultivated crops for two or three years. It is believed
that no variety of dodder produces seed freely in the eastern states,
and that the hay made from the first crop of alfalfa or red clover will
not contain any seed of this pernicious plant.
Next: The Seeding