Chitosan in the control of rose powdery mildew and downy mildew

Abstract

Microcrystalline chitosan at concentrations from 0.025% to 0.2% was evaluated in the control of Sphaerotheca pannosa var. rosae and Peronospora sparsa. Shrubs were sprayed with chitosan 4 times at weekly intervals. Depending on the concentration used, chitosan reduced development of powdery mildew from 43.5% to 77% and its effectiveness was similar to triforine at concentration 0.03% (standard). Observations of rose leaves under light microscopic, which had been done 24 h after spraying showed, that chitosan caused strong hyphae deformation which almost completely collapse. Cell walls of the pathogen were sunken, corrugated and longitudinally cracked. When applied against P. sparsa effectiveness of the compound at concentration 0.0625% was similar like oxadixil at dose 0.016% (standard) and ranged from 55% to 74%. Efficacy of chitosan decreased with increasing of its concentration.

Effect of Sodium Bicarbonate and Oils on Powdery Mildew of Matricaria chamomilla.

“…Yohalem (1997) stated that management of grey mould (Botrytis cinerea) and powdery mildews in tomatoes, cucumbers and potted roses can be achieved when applied rapeseed oil amended with either sodium bicarbonate or an emulsifier. Wojdyla (2002) reported that Paraffin oil was better in the control of rose powdery mildew than the vegetable oils.…”

Impact of Mineral Oils on Dynamics in the Aphids Presence and Virus Infection of Tulips 'Leen Van Der Mark' Cv. in the Field Cultivation

“…They were not, however, apparent effect on plant growth and development. Opinion that mineral oils can cause slight symptoms of phytotoxic reaction was also confirmed [McKenna 1999, Nikolov 2000, Wojdyła 2002, Iovieno et al 2005, Urbanowicz and Wróbel 2005, Wróbel and Urbanowicz 2007. It is also possible that the brighter green color seen on the leaves of tulips after applying the mineral oils is related to the distribution of chlorophyll.…”

“…Available literature indicates that besides fungicides [Wojdyła and Łyś 2000, Rongai et al 2009, Wojdyła 2009, bio-preparations [Wojdyła and Orlikowski 2008], and fertilizers [Wojdyła 2004], also mineral oils can be useful for competing the fungal-origin plant diseases. It has been demonstrated the high effectiveness of the oils used for a direct control of fungi which cause powdery mildew [Wojdyła 2002, Jee et al 2009]. In the case of other pathogens that cause leaf spot Schneider 1993, Wojdyła 2010], rust [Wojdyła and Janiewicz 2004], and gray mold [Wojdyła 2003], the efficacy data are relatively scarce, and the resulting effect of combat fluctuates around a dozen to several dozen percent.…”

“…These preparations are nowadays highly refined, less toxic and are an important complement to traditional methods for combating pests and pathogens of horticultural crops [Furness 1981, Northover and Homeyer 1999, Wilcox and Riegel 1999, Wojdyła 2005, 2015, Moyer and Peres 2008. They are widely used mainly in integrated pest management programs in the USA [Kallianpur et al 2002], New Zealand [Beresford et al 1996], and Australia [Nicetic et al 2001, 2002, Northover and Timmer 2002. Already in the 80s of the twentieth century, in France, the use of mineral oil for the protection of potato seed plantations during the growing season was regarded as a standard treatment [Kerlan et al 1987].…”