The uptake of phosphorus acid sprays into kauri foliage

Abstract

Kauri dieback caused by Phytophthora agathidicida is a serious problem affecting forests throughout the upper North Island. A potential control tool is the use of phosphorus acid (phosphite) as a foliar spray. This study investigates various commercial formulations of phosphorus acid in combination with adjuvants, for their potential uptake into kauri foliage. Large differences were seen in the uptake between the upper (adaxial) and lower (abaxial) leaf surfaces. The upper kauri leaf surface gave negligible uptake (<5%) while the lower surface had >65% uptake across all formulations tested. From these results, the potential for spray operations is discussed.