Abstract:
Three experiments whose objectives were to investigate cover
crop kill by winter freeze, weed suppression by 'Micah' barley and
other spring cereals, and allelopathic potential of cereal covers
were conducted at the Vegetable Research Farm and in the greenhouse
and growth chamber facilities at OSU in 1989/90. Kill by winter
freeze failed under the warm winter of Corvallis in 1989/90.
Complementary usage of herbicides and residues for weed control is
suggested.
Residues of herbicide killed 'Micah' barley suppressed (79-88%)
weed emergence and growth for up to six weeks in tomatoes, lettuce
and cucumber. Allelopathy, besides physical effects of the mulch,
contributed to weed control in the system. Greenhouse and growth
chamber bioassay studies confirmed the presence of seed germination
inhibitors in residues of 'Micah' barley and other covers.
No differences in yield among treatments were observed for
each crop when weeds were controlled six weeks after planting.
