Comparisons of phosphite concentrations in Corymbia (Eucalyptus) calophylla tissues after spray, mist or soil drench applications with the fungicide phosphite

The fungicide phosphite was applied to 4- and 8-month-old Corymbia (Eucalyptus) calophyllla (marri) seedlings, by spraying to run-off with 0.25, 0.5 and 1% phosphite (2.5, 5 and 10 g/L a.i., respectively), misting with 10, 20, and 40% phosphite (100, 200 and 400 g/L a.i., respectively) or applying a 1% phosphite (10 g/L a.i.) soil drench. The phosphite concentrations in plant tissues were determined by High Performance Ion Chromatography analysis, 7 days after treatment. Phosphite concentrations found in the plant tissues were higher than previous published results. Phosphite concentrations were generally higher in the root tips than in mature roots, and in shoot tips compared to stems and leaves. Highest concentrations were recorded in root tips of soil drenched plants. When phosphite concentrations in shoot apices were compared, spray to run-off at 0.5% gave a comparable concentration to a 10% mist treatment and the soil drench, while a 1% spray was comparable to the 20% and 40% mist treatment. When phosphite concentrations in root apices were compared, spray to run-off at 0.5% and 1% gave comparable concentrations to a 10 or 20% mist treatment. All treatments except 0.25%, 0.5% spray and soil drench caused some phytotoxicity on the foliage.