Studies on a Herbicide, 2-(α-naphtoxy)-N, N-diethylpropionamide (R-7465)

(1) Herbicidal Characteristics of R-7465

Abstract

These studies were conducted to obtain some information on the properties of a selective herbicide, 2-(α-naphtoxy)-N, N-diethylpropionamide (R-7465) for rice plants. Results obtained were as follows:
(1) R-7465 inhibited more strongly root growth than stem and leaf growth for both of graminaceous plants (such as Echinochloa Crus-galli Beauv.) and broadleaf plants. The degree of inhibiting activity for root growth was as follows: R-7465>>PCP-na>benthiocarb>>simetryne.
(2) The activity of R-7465 applied to root was investigated under condition water cultivation. The 50% inhibition of growth was obtained at 5.8ppm of R-7465 to rice, 0.54ppm to sweet corn, 0.25ppm to barnyardgrass and 0.0092ppm to oat.
(3) The most adequate time of R-7465 treatment was the emerging stage or the needle-leaf stage of barnyardgrass.
(4) The movement in soil of R-7465 was small, and the downward movement of water of 6cm for two days (3cm per day) gave movement of R-7465 to 1.5cm from soil surface.
(5) The persistence in soil of R-7465 was confirmed by 50% growth inhibiting effect, the activity persisted for 50-80 days on the treatment of 5g per are and for more than 100 days on the treatment 20g per are.
(6) The selectivity of R-7465 for rice plant and barnyardgrass was shown apparently in trans-planting paddy field. The treatment of 10-20g per are of R-7465 showed no injury for rice plant and satisfactory control for barnyardgrass.