Effectiveness of Three Phenylamide Fungicides Against Phytophthora cryptogea Isolated From Kiwi and Their Mobility in Soil. T. Zaviezo, Facultad de Agronomía, Pontificia Universidad Católica, Casilla 306-22, Santiago, Chile. B. A. Latorre, and R. Torres. Facultad de Agronomía, Pontificia Universidad Católica, Casilla 306-22, Santiago, Chile. Plant Dis. 77:1239-1243. Accepted for publication 27 August 1993. Copyright 1993 The American Phytopathological Society. DOI: 10.1094/PD-77-1239.

The mobility of phenylamide fungicides in sand and clay loam soil columns was demonstrated using Phytophthora cryptogea from kiwi to assess for the fungicides. Mobility appears to be a function of the chemical nature of the fungicide and soil texture. Regardless of the soil type, metalaxyl was highest, ofurace was intermediate, and oxadixyl was lowest in the degree of mobility observed. There was a tendency toward less mobility in clay loam soil than in sandy soil. Similarly, water that percolated through soil columns treated with metalaxyl inhibited P. cryptogea more than did water that percolated through soil columns treated with ofurace or oxadixyl. There was significant variation in the response to ofurace, oxadixyl, and metalaxyl among the species of Phytophthora. The ED₅₀ values obtained for P. cryptogea were 1.77, 1.1, and 0.22 mg/L for ofurace, oxadixyl, and metalaxyl. A single application of each phenylamide fungicide to 2-yr-old kiwi plants inoculated with P. cryptogea provided significant (P < 0.05) control of root rot. Protection persisted for 120 days after treatment with metalaxyl, the most active fungicide tested.