Species- and site-specific efficacy of commercial biocides and application solvents against lichens

Abstract

Control of lichens on stone cultural heritage is mostly achieved by a combination of mechanical removal with biocide applications. However, there is a lack of scientific evidence on the efficacy of different biocides on different species, and on the consistency of biocide effects on heritage sites in different environmental conditions. This results in some uncertainty when conservation interventions to control lichens are routinely defined on the basis of restoration tradition or empirical evaluation, without experimental measures of how lichens respond. In this work, we quantitatively evaluated (a) the efficacy of five commercially-available biocides, applied using a brush or with a cellulose poultice, against two species (Protoparmeliopsis muralis, Verrucaria nigrescens), and (b) whether the effects on the two species were consistent, per treatment, across three Italian heritage sites. Lichen vitality was quantified through analyses of chlorophyll a fluorescence (ChlaF) and ergosterol content. The results indicated that all the tested biocides, and their organic solvents, affected the vitality of both the species. However, most of treatments displayed different efficacy on each species, across the different sites and between brush and poultice applications. Accordingly, when a conservation intervention to control lichen growth is planned, biocide treatments need both species- and site-specific calibrations and lichen vitality should be properly ascertained in situ by monitoring ChlaF parameters (FV/FM and F0) twenty days after trial biocide applications

Phytochemical Compounds as Cleaning Agents on Granite Colonized by Phototrophic Subaerial Biofilms

“…The concentration employed in the treatment emulsions containing the essential oils, alone (T1-T3) and combined (T7), and those containing Preventol RI-80 ® (T10 and T11), was 2% (w/w) and 2% (v/v) for T10 [25][26][27][28]. As already mentioned, the essential oils used in the study have as principal active component various phenolic compounds at certain concentrations.…”

Selected Aspects Regarding the Restoration/Conservation of Traditional Wood and Masonry Building Materials: A Short Overview of the Last Decade Findings

“…As there are no substances particularly developed for cultural heritage, the biocidal substances used were typically those developed for other applications (such as commercially available pesticides, based on active ingredients as glyphosate, benzalkonium chloride, N-octyl-isothiazolinone, usnic acid, etc.) [61] or natural materials, such as natural extracts and essential oils [62,63] or lipopeptides [64].…”

Assessment of Paint Layers Quality 2. Identification of biological species grown on a railway bridge

“…In these conditions, the prevention of biofouling growth can be achieved either by the selection and application of high resistance coating materials to natural thermooxidative processes (thermal stress and UV action [6,13,14,16] and the molds action [8,10,15]), or through the use of appropriate antifungal biocides [35][36][37][38][39][40][41] (obviously with the necessary precautions -taking into account that the investigated bridge is in the Natura 2000 protected area [24]).…”