Abstract
Base rot, caused by Ceratocystis paradoxa , can be a severe disease of pineapple planting material and can result in poor establishment of plants. Pre-plant dipping of pineapple crowns in potassium phosphonate is used to control Phytophthora cinnamomi root and heart rot and was tested for efficacy against base rot in this study. Dipping crowns in 0.5% potassium phosphonate for 2 min significantly reduced the severity of base rot on inoculated crowns in two trials with ‘MD2’ and ‘73–50’. Fresh crowns had a more marked response to potassium phosphonate than well-cured, dried crowns. In studies with amended media, the growth of C. paradoxa was not inhibited by phosphonate concentrations of up to 100 ppm. Growth was reduced at higher concentrations but phosphonate did not completely inhibit growth of C. paradoxa even at the highest rate of 6000 ppm. Potassium phosphonate failed to control incidental Penicillium funiculosum infection of basal crown tissue .