Effects of wiping herbicides on serrated tussock (Nassella trichotoma (Nees) Arech.) and African lovegrass (Eragrostis curvula (Shrad.) Nees)
M.H. Campbell and H.I. Nicol, NSW Agriculture, Orange Agricultural Institute, Forest Road, Orange, New South Wales 2800, Australia.
Flupropanate (Frenock®) and glyphosate were applied to serrated tussock (Nassella trichotoma (Nees) Arech.) by wiping at Tuena and Dalgety, New South Wales and flupropanate was applied to African lovegrass (Eragrostis curvula (Shrad.) Nees) by wiping at Dalgety in September 1995. Flupropanate was also applied to serrated tussock at Tuena by spraying. The rates applied by wiping were 1:10, 1:20 and 1:40 (herbicide:water) and were applied in one or two passes. The rates used for spraying flupropanate were 0.75 to 1.5 kg a.i. ha-1. Flupropanate applied by wiping killed from 99 to 100% of mature serrated tussocks in Experiment 3, near Dalgety, from the lowest rate (1:40, wiped once) to the highest (1:10, wiped twice). In Experiment 4, near Dalgety, the variation in percentage kill from lowest rate to highest was 70-99%. At Tuena the effects were inferior to those at Dalgety with variation from 40 to 92% kill for the lowest and highest rate respectively.
The main reasons for the inferior result at Tuena were smaller plots, smaller tussocks and a faster speed of application. Flupropanate killed or damaged small unwiped serrated tussock, African lovegrass, cocksfoot, phalaris, and native grass plants near the base of mature tussocks. It appeared that flupropanate wiped onto leaves was washed to the soil by rain where it spread and affected grasses in close proximity to tussock bases. At Tuena, flupropanate applied as a spray on the same day as wiping gave 88-100% kills of serrated tussock from 0.75 to 1.5 kg a.i. ha-1. As the highest rate of glyphosate, 1:10, wiped twice, resulted in only 33% kill of serrated tussock at Tuena, higher rates will be necessary to obtain commercially acceptable results using this herbicide. Wiping as a method of herbicide application needs testing over large areas in the field to develop a reliable practical technique as free as possible from the variables inherent in the process.
Plant Protection Quarterly (1998) 13 (1) 36-38.