Phytotoxicity of phosphorus acid in <i>Leucodendron</i> Safari Goldstrike

Abstract

The efficacy of phosphorous acid (FoliRFos) was tested for the control of Phytophthora cinnamomi in the cut flower Leucodendron Safari Goldstrike The fungicide was applied monthly in accordance with the prescribed label rate commencing in December 2005 During the winter months of 2006 phytotoxicity was observed in the treated plants The treatment was suspended for 2 months to avoid further damage after which time the foliar applications began again No plant deaths caused by P cinnamomi occurred in the treatments with the phosphorous acid whereas there was a 20 death rate in the untreated plots Growers should be aware of potential phytotoxicity from phosphorus acid on Leucodendron Safari Goldstrike as it can cause stunting of the plants and affect the quality of the blooms Application on Leucodendron Safari Goldstrike should be made with caution during winter months when plants are not actively growing Further work should be undertaken to determine whether using lower rates of the chemical during the winter months when the plants are apparently more susceptible to infection would result in less phytotoxicity