An In vitro Study on the Postinfection Activities of Hydrated Lime and Lime Sulphur against Apple Scab (Venturia inaequalis)

Abstract

The activities of hydrated lime and lime sulphur to stop infections of apple scab (Venturia inaequalis) were evaluated at 20°C using an in vitro test system based on isolated cuticles and scab conidia. Treatments were applied 24 or 48 h after inoculation that is 16 or 40 h after a predicted infection period, respectively. Efficacy of the postinfection treatments was assessed 72 h after inoculation by counting living primary stromata, which fluoresced brightly green when stained with fluorescein diacetate (FDA). A suspension of hydrated lime (5 g/l) as well as lime sulphur (1.5%) applied 16 h after infection killed early infection structures and stopped further development. Lime sulphur reduced the percentage of penetration to below 10% even with treatments 40 h after infection. The activity of hydrated lime is due to its alkaline pH of 12.45. Suspensions of calcium carbonate (6.75 g/l) showed no effect on percentage of penetration. Up to pH 12.0 effects of potassium hydroxide solutions on vitality of germinated conidia and percentage of penetration were weak. Values of pH 12.4 or higher were necessary to kill germinated conidia of V. inaequalis and their primary penetration structures. At pH 12.4 activity of KOH was comparable with the effect of hydrated lime. It is argued that the high pH disrupts the spore membranes. This is supported by the fact that dead spores and germ tubes did not fluoresce with FDA, which requires integrity of the membranes. For an individual spore the disruption of the spore membrane is an all-or-nothing event.www.blackwell-synergy.com J. Phytopathology 153, 485-491 (2005) Ó 2005 Blackwell Verlag, Berlin

Alternative control of Tetranychus evansi Baker & Pritchard (Acari: Tetranychidae) on tomato plants grown in greenhouses

“…Another strategy that has been used where conventional pesticides are not allowed, such as in ecological and organic production systems, is the use of non synthetic products for pest control (Campanhola & Bettiol 2003, Venzon et al 2008a. Lime sulphur is among these products allowed in organic systems, primarily used as a fungicide (Smilanick & Sorenson 2001, Montag et al 2005, but is also employed as insecticide and acaricide (Guerra 1985, Penteado 2000, Afonso et al 2007. The toxic effect of lime sulphur on insects and mites is given by the reaction of its compounds when applied to the plant with water and carbon dioxide, resulting in hydrogen sulfi de (Abbot 1945 Neem (Azadirachta indica) is another product that has been used as an alternative to control insect and mite pests.…”

Efecto de preparados minerales sobre el crecimiento y desarrollo in vitro de Moniliophthora roreri (Cif. & Par.) Evans

“…A nivel in vitro y en campo se han documentado estos mismos efectos sobre diferentes fitopatógenos para varios de los elementos y compuestos que componen los seis preparados minerales: bicarbonato de sodio (Yildirim et al, 2002), azufre (Khan y Kulshrestha, 1991;Williams et al, 2002;Williams y Cooper, 2004), polisulfuro de calcio (Montag et al, 2005;Holb y Schnabel, 2008;Ramírez et al, 2011a) y sulfato de cobre (Mills et al, 2004;Montag et al, 2006), entre otros. Por otra parte, es conocido que algunos de estos minerales inducen resistencia en las plantas, lo cual puede reducir la incidencia y severidad del daño en campo.…”

“…In vitro and field level have been documented the same effects on different phytopathogenic for various elements and compounds that compose the six mineral preparations: Sodium bicarbonate (Yildirim et al, 2002), sulfur (Khan and Kulshrestha, 1991;Williams et al, 2002;Williams and Cooper, 2004), calcium polysulfide (Montag et al, 2005;Holb and Schnabel, 2008;Ramirez et al, 2011a) and copper sulfate (Mills et al, 2004;Montag et al, 2006), among others. Moreover, it is known that some of these minerals induce resistance in plants, which can reduce the incidence and severity of damage in the field.…”

Erfolgreiche Bekämpfung des Apfelschorfs mit Kalziumhydroxid

“…In-vitro-Versuche ergaben, dass Kalziumhydroxid [Ca(OH) 2 ] Schorfsporen, Keimhyphen und Appressorien, aber auch das Stroma unter der Kutikula abtöten kann (Schulze u. Schönherr 2003;Montag et al 2005). Die Wirkung beruht auf dem sehr hohen pH-Wert von 12,4 (Montag et al 2005) Auch Blattschorf konnte auf den Blattoberseiten zuverlässig und ausreichend bekämpft werden, da bei den Behandlungen nur bei 'Jonagold' und 'Elstar' zum Zeitpunkt der Ernte einige wenige Läsionen zu finden waren (Abb.…”

“…Die Wirkung beruht auf dem sehr hohen pH-Wert von 12,4 (Montag et al 2005) Auch Blattschorf konnte auf den Blattoberseiten zuverlässig und ausreichend bekämpft werden, da bei den Behandlungen nur bei 'Jonagold' und 'Elstar' zum Zeitpunkt der Ernte einige wenige Läsionen zu finden waren (Abb. 3).…”