Abstract
Antifungal activity of water, ethanol, lanolin and cocoa butter plant extracts derived from seven Mexican Chihuahuan desert inhabiting plant species (Larrea tridentata, Flourensia cernua, Agave lechuguilla, Opuntia ficus-indica, Lippia graveolens, Carya illinoensis and Yucca filifera) were evaluated against Phytophthora cinnamomi. All plant extracts were active against Phytophthora cinnamomi. Two (L. tridentata and F. cernua) out of seven plant species tested had the optimal antifungal activity against this fungus specie, with minimum inhibitory concentration (MIC) values as low as 6.96 and 8.6 mg/L. Some of the plant extracts had moderate to low activity against P. cinnamomi, and the variations of active polyphenolic (condensed and hydrolysable tannins) compounds in the plant extracts estimated via colorimetric methods indicated that the inhibitory activity may not based on a general metabolic toxicity but perhaps the antifungal potency is conferred by group or groups of toxic metabolites. Based on the antifungal activity, crude plant extracts may be a cost effective way of protecting crops against P. cinnamomi. Because plant extracts contain several antifungal compounds, the development of resistant pathogens to these plant extracts may be delayed. Key words: Antifungal activity, plant extracts, polyphenols, MIC50 P. cinamomi.
Highlights
The stramenopile Phytophthora cinnamomi Rands causes root rot of avocado and is one of the main limiting factors of this crop (Ceja et al, 2000; Messenger et al, 2000)
Antifungal activity of water, ethanol, lanolin and cocoa butter plant extracts derived from seven Mexican Chihuahuan desert inhabiting plant species (Larrea tridentata, Flourensia cernua, Agave lechuguilla, Opuntia ficus-indica, Lippia graveolens, Carya illinoensis and Yucca filifera) were evaluated against Phytophthora cinnamomi
Some of the plant extracts had moderate to low activity against P. cinnamomi, and the variations of active polyphenolic compounds in the plant extracts estimated via colorimetric methods indicated that the inhibitory activity may not based on a general metabolic toxicity but perhaps the antifungal potency is conferred by group or groups of toxic metabolites
Summary
The stramenopile Phytophthora cinnamomi Rands causes root rot of avocado and is one of the main limiting factors of this crop (Ceja et al, 2000; Messenger et al, 2000). Castillo-Reyes et al 4555 to others species as Eucalyptus and Pinus species (Linde et al, 1997), and pineapple (Allen et al, 1980) Their virulence is associated with temperature between 21 to 30°C, poorly drained soils and excessive moisture. The application of chemicals among which are the fungicides metalaxyl and fosetyl-aluminum to the soil, leaves or trunk injection (Whiley et al, 1986) and biological control agents including bacteria and fungi in soil, as Pseudomonas spp., Streptomyces spp. and Trichoderma spp., Myrothecium roridum, Aspergillus spp., or Paecilomyces spp., are other techniques useful to inhibit P. cinnamomi (Reeves, 1975; Gees and Coffey, 1989; Mass and Kotzé, 1990; Casale, 1990; Stirling et al, 1992; Duvenhage and Kotzé, 1993)
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