Studies on the potential of the basic substance chitosan in managing Podosphaera pannosa on cutting roses and Erysiphe polygoni on French hydrangea

Abstract

Horticultural production systems have to move forwards to an environment-friendly and sustainable plant production. Basic substances can be added to reduce the use of synthetic plant protectant in conventional plant protection strategies. Regarding the protection of ornamental plants, less is known about the usage and behaviour of these alternative strategies and components. In our study, an infection of Podosphaera pannosa and Erysiphe polygoni in two different cultivars of cutting roses and one cultivar of French hydrangea was investigated. We studied the effect of a weekly foliar treatment of the basic substance chitosan (0.05 g/m2) compared to a water control and potassium hydrogen carbonate (VitiSan, Biofa GmbH, Münsing, Germany) in both production systems. As a result, in cutting roses as well as in French hydrangea, we found a significantly decreased infected leaf area following the use of chitosan and VitiSan compared to the water control. In both treatments, we found a stronger effect in French hydrangea, compared to roses. Results also indicate that the basic substance chitosan has to be used at a low pathogen level. We present a promising approach to reduce conventional plant protectants in ornamental plant production.

Epidemiology and control of strawberry powdery mildew: a review

“…Similarly, a weekly foliar treatment of 0.5% chitosan on cutting roses decreased infections by Podosphaera pannosa (Wallr.) de Bary (Wulf et al, 2023). However, field studies with chitosan suggest it should be applied when pathogen levels are low (Wulf et al, 2023).…”

“…de Bary (Wulf et al, 2023). However, field studies with chitosan suggest it should be applied when pathogen levels are low (Wulf et al, 2023). Although chitosan has been authorised in the EU as a basic substance and in at least one European Union member state for SPM control, there are no reports of efficacy in scientific literature.…”

The use of stinging nettle tea (Urtica sp.) to control Aulacorthum solani and Macrosiphum euphorbiae on Ranunculus asiaticus

“…For the authorisation process, no data for efficacy are demanded (Feldmann and Carstensen, 2018). Different basic substances, for example Equisetum arvense, lecithine, hydrogen peroxide or chitosan, are already shown to be promising for implementation in plant protection strategies (Copes, 2009;El Hadrami et al, 2010;Jolly et al, 2018;Trebbi et al, 2021;Wulf et al, 2022Wulf et al, , 2023. For other basic substances such as Urtica sp., only a meagre amount of data are available.…”