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Picarbutrazox sensitivity of different Pythium species.

Gilberto Olaya: Syngenta Crop Protection

<div>Picarbutrazox is the active ingredient of a novel seed treatment fungicide developed by Syngenta. Picarbutrazox belongs to the tetrazolyloximes chemical group of fungicides and its mode of action is still unknown (FRAC code U17). It has no known cross resistance to other oomycete compounds. Picarbutrazox targets oomycete plant pathogens and control diseases caused by <em>Pythium</em>, <em>Phytophthora</em> and downy mildews. Under lab, greenhouse and field conditions Picarbutrazox has shown to have broad spectrum of <em>Pythium</em> species control. The sensitivity to Picarbutrazox of 199 isolates belonging to more than 20 species of <em>Pythium</em> was determined. <em>Pythium</em> isolates were recovered from symptomatic plants including corn, soybean and other crops. Isolates were identified to species level using morphological and molecular tools. Another group of <em>Pythium</em> isolates were obtained from collections kept at Universities. Mycelial growth inhibition <em>in vitro</em> was quantified using the following Picarbutrazox concentrations: 0, 0.00001, 0.0001, 0.001, 0.01 and 0.1 All species of <em>Pythium</em> tested were sensitive to Picarbutrazox. The sensitivity distribution (EC50 values) across all <em>Pythium</em> species tested ranged from 0.000031 to 0.004236 with a mean of 0.000434 The Picarbutrazox sensitivity of more than 20 species of <em>Pythium</em> have been documented and the high <em>in vitro</em> intrinsic activity of this fungicide against <em>Pythium</em> species has been demonstrated. In addition, the efficacy of Picarbutrazox as a seed treatment against <em>Pythium</em> diseases of corn, soybeans and other crops has been demonstrated under field conditions.</div>