LONG-TERM RECOVERY OF BRACKEN (PTERIDIUM-AQUILINUM (L) KUHN) AFTER ASULAM SPRAYING

This paper investigates the effects of a single asulam application, sp rayed from the air, on the rhizome biomass, bud density, fronds and ca rbohydrate reserves of bracken (Pteridium aquilinum (L.) Kuhn) using a time sequence approach. Regression models were used to investigate ho w these characteristics varied with time after spraying, and were used , where appropriate, to calculate the time taken for full recovery aft er treatment. Frond density and biomass recovered in approximately eig ht years, bud numbers in seven, but rhizome biomass and total carbohyd rate reserves required 10 to 12 years to recover. The consequences of these results are compared with predictions from a computer model and discussed in relation to the best timing of re-treatment and the manag ement needed for long term control.