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Effect of Phosphite on Tomato and Pepper Plants and on Susceptibility of Pepper to Phytophthora Root and Crown Rot in Hydroponic Culture

October 1998 , Volume 82 , Number  10
Pages  1,165 - 1,170

H. Förster , J. E. Adaskaveg , D. H. Kim , and M. E. Stanghellini , Department of Plant Pathology, University of California, Riverside 92521

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Accepted for publication 16 July 1998.

Tomato and pepper plants were grown hydroponically in a greenhouse using phosphate or technical and commercial formulations of phosphite as sources of phosphorus nutrition to determine the effects on plant development and susceptibility to Phytophthora root and crown rot. Phosphite-treated tomato and pepper plants were deficient of phosphate and developed phosphorus-deficiency symptoms. Growth of plants (leaf area and leaf, stem, and root dry weights) that were fertilized with phosphite was significantly (P < 0.05) reduced compared with phosphate-fertilized plants. In Phytophthora capsici--inoculated pepper plants, incidence of Phytophthora crown rot was significantly reduced in phosphite-treated plants compared with no phosphorus or phosphate-treated plants. Incidence of crown rot in pepper plants treated with 1 mM phosphate plus 0.3 mM phosphite was intermediate between plants treated with only phosphite (1 mM or 0.1 mM) and plants treated with phosphate (1 mM).

Additional keywords: phosphonate fungicides, phosphorous acid

© 1998 The American Phytopathological Society