Experiments were conducted in laboratory and screenhouse to determine the
effects of light, temperature, salt and water stress, seed burial depth, and
amount of rice residue on seed germination and seedling emergence of wild
bushbean and to evaluate the response of that weed to commonly available
POST herbicides in the Philippines. Germination (81 to 85%) was not
influenced by light; however, it was higher at 30/20 C (88%) than at 25/15 C
(82%) and 35/25 C (80%) day/night temperatures. The sodium chloride and
osmotic potential required for 50% inhibition of maximum germination were
149 mM and −0.28 MPa, respectively. Seedling emergence (81%) was similar for
seeds placed on the soil surface and for seeds buried up to 4 cm deep. No
seedlings emerged from a burial depth of 8 cm. Rice residue applied on the
soil surface up to 8 t ha−1 did not affect seedling emergence (72
to 80%) of wild bushbean. The herbicide bentazon provided 100% control of
wild bushbean when applied at the three- to five-leaf stages. However, to
achieve 100% control by 2,4-D and metsulfuron-methyl + chlorimuron-ethyl,
herbicides had to be applied at the three-leaf stage. The information gained
from this study can help in developing components of integrated weed
management programs for wild bushbean. A deep-tillage operation to bury weed
seeds below their maximum depth of emergence and early application of an
effective POST herbicide can help in managing this weed in rice fields.