Phytopathology (1996) 86, p. S62 (Sedegui et al.)

M. Sedegui, R.B. Carroll, A.L. Morehart, D.P. Whittington, A. Arifi, R. Lakhdar and A. El Ismaili (1996)
Detection of metalaxyl resistant isolates of Phytophthora infestans in Morocco and Delaware
Phytopathology 86 (11 suppl.), S62-S62
Abstract: Phytophthora infestans was isolated from foliage and tubers of potatoes obtained from commercial fields in Morocco and Delaware. Late blight had not been reported from Delaware in 50 years. Potato and tomato plants were inoculated with each isolate to establish pathogenicity. Isolates were then analyzed to determine mating type, genotype at two allozyme loci Gpi and Pep, and sensitivity to metalaxyl. Measurements were made every 5 days and EC50 values calculated on radial mycelial growth, on leaflets in metalaxyl solutions and on potato tuber disks deposed on filter paper saturated with metalaxyl. Moroccan isolates were mating type A1, Gpi 100/100, Pep 92/100 (US 6). Delaware isolates were A2 mating type, Gpi 100/111/122, Pep 100/100 (US 8). All isolates displayed resistance to metalaxyl up to 250 ppm.

Research topic(s) for pests/diseases/weeds:
pesticide resistance of pest

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Phytophthora infestans	Potato (Solanum tuberosum)	Morocco
	Phytophthora infestans	Potato (Solanum tuberosum)	U.S.A. (NE)