Setaria lutescens (yellow foxtail) plants, grown from five seed
sources were compared in California. Seed sources were: Connecticut,
Iowa, Massachusetts, Pennsylvania and California. Morphological
and physiological differences between biotypes include: plant
size, growth habit, time required to mature and reproductive capa
city. Most significant is the prostrate habit of the California biotype.
Biotype seed studies also indicate differences in dormancy and
requirements for seed germination. After-ripening, stratification
and temperature are implicated.
Growth and reproductive capacity of Connecticut, Pennsylvania
and California Setaria lutescens biotypes are compared. Biotypes
were grown with and without alfalfa (Medicago sativa) under California
alfalfa forage production methods. The California biotype of Setaria lutescens yielded 85% more seed than Connecticut and 71%
more than Pennsylvania when clipped monthly to a height of 7.6 cm.
When grown with alfalfa (Medicago sativa) and harvested monthly, the
California biotype produced 98% more seed than Connecticut and 93%
more than the Pennsylvania biotype. First-year forage yield of
alfalfa was reduced 35% and the plant density of alfalfa reduced 48%
when grown with California Setaria lutescens. Growth and reproductive
capacity of Echinochloa crusgalli and Setaria lutescens were compared
when grown with and without alfalfa under California forage
production methods. When the two grass species were grown together
at densities of 2300 plants /m² Setaria lutescens produced mature
seed while Echinochloa crusgalli failed to reproduce. Echinochloa
crusgalli plant density and seed production was reduced by second-year
alfalfa. Setaria lutescens density was reduced but seed production
averaged 10,000 seeds/m². Dry matter yields of first-year
alfalfa and plant density of first- and second-year alfalfa were reduced
when grown with Setaria lutescens.
Field studies of Echinochloa crusgalli and Setaria lutescens
growing in commercially cultivated alfalfa were conducted. Transects
of alfalfa strip checks showed field densities of Echinochloa
crusgalli and Setaria lutescens to be largely dependent on the cultural
practice of curing alfalfa forage in windrows
