Phytoparasitica (2002) 30 (3) - Systemic fungicides enhance ...

A. Levin and Y. Cohen (2002)
Systemic fungicides enhance oospore formation of Phytophthora infestans in host tissues
Phytoparasitica 30 (3)
The 23rd Congress of the Israeli Phytopathological Society - February 11-12, 2002
Abstract: The effect of systemic fungicides and SAR (systemic acquired resistance) plant activators on sexual sporulation of Phytophthora infestans, the causal agent of potato and tomato late blight, was studied in the field, greenhouse and under laboratory conditions. Field and greenhouse studies demonstrated that preventive administration of systemic fungicides and SAR plant activators (metalaxyl, Canon, cymoxamyl, dimethomorph and ß-aminobutyric acid [BABA]) to potato plants enhanced the ability of leaf or tuber tissues to support sexual reproduction of P. infestans. The enhancing effect in potato tuber tissue was restricted to fungicides possessing the ability of phloem translocation. Laboratory studies demonstrated that post-infectional administration of fungicides (metalaxyl, Canon, cymoxamyl, dimethomorph) or SAR plant activators (BABA, Bion, salicylic acid) to petri dishes containing potato tuber or tomato leaf discs, inoculated with A1+A2 sporangial mixture, enhanced oospore production. The enhancing effect was dependent on the concentration of the chemical and its time of application. No enhancement of sexual sporulation was observed when protective fungicides, herbicides or systemic fungicides, which possess no activity against P. infestans, were used. Metalaxyl enhanced oospore formation only when one or both isolates, comprising the A1+A2 sporangial mixture, were sensitive to metalaxyl, but not when both isolates were resistant. The data suggest that systemic fungicides or plant SAR activators which possess activity against late blight may enhance sexual sporulation of P. infestans. The epidemiological significance of this finding was discussed.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Database assignments for author(s): Yigal R. Cohen

Research topic(s) for pests/diseases/weeds:
control - general
population dynamics/ epidemiology

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Phytophthora infestans	Potato (Solanum tuberosum)
	Phytophthora infestans	Tomato (Solanum lycopersicum)