The Effect of Foliar Spraying of Acacia Hockii De Wild with Picloram and 2, 4-D/Picloram Mixtures and Additional Treatment With Picloram Granules

Abstract

Picloram was applied to Acacia hockii de Wild bushes (1,900 bushes per ha.) as a spray delivered both aerially to half ha. plots and to individual bushes. The spraying took place in February, August, September and October,1968, which were months previously found most effective. The arboricides used were Tordon 22K (24 per cent picloram a.e.), Tordon 01 (24% 2 4-D a.e. and 6% picloram a.e.) and Tordon 10K granules (10% picloram a.e.). Both solutions used were diluted to and 5% picloram a.e. The "aerial" spraying delivered 0.6 kg. and 3.0 kg. picloram a.e. per ha. and the ground spraying delivered 2.5 g. and 12.5g. picloram a.e. per bush using 1 and 5% solutions respectively. The "aerial" spraying was a failure and it is concluded that it is not possible to deliver sufficient picloram to kill A. hockii bushes economically by this means. The ground spraying only achieved 70% kill or more at the higher concentration of picloram solution. This was inferior to previous trials and it is concluded that moisture stress was inhibiting picloram translocation. The addition of 3g. a.e. per bush in granular form improved kill but not sufficiently to warrant the expense.Pre-burning of treated areas did not seem to affect the results and made the movement of spraying teams much easier. The use of a mixture of 2, 4-D and picloram depressed the amount of kill compared to that achieved with picloram alone, even when the solutions used contained the same amount of picloram.