Differential activities of BOA, DIBOA, and crude water extract of Secale ce
reale 'Elbon' were studied in culture dish bioassays using several vegetabl
e and weed species. On average, DIBOA was about seven times more inhibitory
to root growth and four times more inhibitory to shoot growth than BOA. Al
lelochemicals from S. cereale inhibited shoot more than root elongation of
cucurbits Cucumis melo, Cucumis sativus, and Cucurbita pepo. Small-seeded c
rops Lycopersicon esculentum and Lactuca sativa were sensitive to S. cereal
e. Large-seeded crops, including the cucurbits and Zea mays var. rogusa, we
re tolerant. Among the small-seeded weeds Amaranthus palmeri, Digitaria san
guinalis, Echinochloa crus-galli, and Eleusine indica, E. crus-galli was le
ast susceptible. Inhibition of germination by BOA or DIBOA occurred only in
small- to medium-seeded species, including A. palmeri, D. sanguinalis, E.
indica, L. sativa, L. esculentum, and Sida spinosa. Large-seeded species C.
melo, C. sativus, C. melopepo, Z. mays var. rogusa, Ipomoea hederacea var.
integriuscula, Ipomoea lacunosa, and Senna obtusifolia were tolerant to al
lelochemicals from S. cereale. This bioassay indicated a promising potentia
l for controlling small-seeded weeds in large-seeded crops.