Extracts of Inula viscosa Control Downy Mildew of Grapes Caused by Plasmopara viticola

Abstract

The oily paste extracts of Inula viscosa leaves made with organic solvents were effective in controlling downy mildew caused by Plasmopara viticola in detached leaf tissues of grapes in growth chambers. Thin-layer chromatography of such extracts revealed the presence of 11 Rf regions of which four contained highly effective compounds against the disease. Two major inhibitory compounds, each comprising 10.6% of the total paste weight, were identified as tomentosin and costic acid. An emulsified concentrate formulation of the oily paste extracts provided excellent activity against the disease in the field. The effective dose (concentration) required for 90% control of the disease in treated shoots in the field was below 0.125% (paste in water). No seasonal fluctuations were observed in the control efficacy of six extracts made from I. viscosa leaves harvested during the period of May to July. In whole vines, treated and artificially inoculated, the paste concentration required for 90% control of the disease ranged between 0.30 to 0.37%, whereas in naturally infected vines it was 0.58%. It appears that I. viscosa is a valuable source for fungicidal preparations against downy mildew of grapes. This is the first report on the control of a disease with I. viscosa extracts under field conditions.

Fungal Assemblages Associated with Roots of Halophytic and Non-halophytic Plant Species Vary Differentially Along a Salinity Gradient

“…In the first place, the great differences observed between the root fungal colonizers and those dwelling few centimeters apart in the rhizospheric soil would indicate specific adaptations either by certain fungi to enter and extend within plant tissues or by the host plant to trim among the soilborne-to-endophyte candidates. The latter capacity has been already observed in some plant species [32], and roots of Inula species (including the ones studied here) are known to produce antimicrobial metabolites that may affect their colonization by fungal endophytes (e.g., [33,34]). Fungi also differ broadly in their ability to invade plant tissues, and probably, the final selection of root colonizers is the result of both plant barriers and fungal capabilities.…”

In Vitro and In Vivo Activity of Selected Plant Crude Extracts and Fractions Against Penicillium Italicum

“…Extensive studies were conducted to elucidate the nature and the biological activity of sticky fleabane extracts (Wang et al 2004). All types of sticky fleabane extracts proved to have significant antifungal activity where the oily leaf paste made with organic solvents exhibited the greatest in vitro antifungal efficacy against dermatophytes, Candida spp and downy mildew (Cafarchia et al 2002;Cohen et al 2006). Furthermore, a sesquiterpene lactone isolated from I. viscosa flowers possessed in vitro efficacy against Microsporum canis, M. gypseum and Trichophyton mentagrophytes (Abu Zarga et al 1998;Cafarchia et al 2002).…”

Essential oil of AlgerianInula viscosaleaves

“…The yield obtained is comparable to this reported in the literature 14 , for the same plant gathered in March 25 the yield increases to 0.453 %. Previous report 27 showed that spring and summer is the period of active growth of Inula viscosa. GC-MS analysis led to the identification of 23 components accounted for more than 80 % of the whole oil (Table 1).…”