Effect of rate and time of application of tetrapion on nassella tussock (Stipa trichotoma Nees) in South Africa

Abstract

Tetrapion was applied at rates of 0, 44; 0, 88; 1, 76 and 3, 52 kg a.i. ha^-1 at monthly intervals to nassella tussock (Stipa trichotoma Nees) plants of various ages. The efficacy of the three higher tetrapion rates was the same throughout the year, but 18-month-old plants took approximately 1 year longer to die than 6-month-old plants. Significant differences were only recorded between the lowest application rate of 0, 44 kg a.i. ha^-1 and the three higher rates. The application of tetrapion at 0, 88 kg a.i. ha^-1 is most cost-effective and appears a promising alternative to other herbicides currently used for nassella tussock control. Results, furthermore, showed that tetrapion proved reliable in killing nassella tussock under varying climatic conditions.