Toxicity and Preventive Activity of Chitosan, Equisetum arvense, Lecithin and Salix Cortex against Plasmopara viticola, the Causal Agent of Downy Mildew in Grapevine

Abstract

Grapevine, a crop of global economic importance, is annually affected by diseases that can compromise the quality and quantity of the harvest, producing large economic losses. Downy mildew caused by Plasmopara viticola (Berk. & M.A. Curtis) Berl. & de Toni is one of the most important diseases in the vineyard. To fight this pathogen, winegrowers often rely on conventional chemical fungicides or copper-based formulations, whose use is determined to be reduced by the European Commission due to their environmental consequences. Hence, alternative plant protection products (PPP) in grapevine must be considered and studied. In this context, we selected several alternative commercial products, based on basic substances (BS) or low-risk active substances (LRAS), to evaluate their suitability to deal with P. viticola. We measured the preventive activity of the products, both in vitro and in planta, as well as their toxicity against the sporangia and zoospores of the pathogen. Results showed that four commercial products were effective against the pathogen directly and preventively, being composed of approved basic substances, more concretely, chitosan, Equisetum arvense, lecithins, and Salix cortex. Among those, the products composed of lecithins and Salix cortex were the most toxic and active preventively. Therefore, these basic substances should be promoted in the vineyard as an alternative to conventional treatments in order to transition to a more sustainable viticulture.

Use of natural‐based commercial products as an alternative for providing bioprotection against verticillium wilt of olive

“…This compound has also been tested for its effect against VWO, showing a 22% reduction in disease severity, 27 as well as against grapevine downy mildew, showing less than a 30% reduction in disease severity. 56 However, in planta experiments revealed a moderate effectiveness of the two chitosan products against VWO because 70.9% and 66.4% of disease progress reduction was observed for chitosan 1 and chitosan 2, respectively (Table 4).…”

“…Andreu et al 55 observed a low effect of willow extract on the mycelial growth of postharvest fungi such as Botrytis allii, Botrytis cinerea, Penicillium expansum, Monilinia laxa and Monilinia fructigena, with inhibition not exceeding 26% for any of these fungi. In addition, Andreu et al 55 and Llamazares-Miguel et al 56 demonstrated that willow extract completely inhibited the germination of Plasmopara viticola spores. Llamazares-Miguel et al 56 also showed that the willow extract reduced downy mildew severity 4), copper phosphite (5), horsetail extract (6), mimosa and oak extract (7), Al ligno.…”

“…In addition, Andreu et al 55 and Llamazares-Miguel et al 56 demonstrated that willow extract completely inhibited the germination of Plasmopara viticola spores. Llamazares-Miguel et al 56 also showed that the willow extract reduced downy mildew severity 4), copper phosphite (5), horsetail extract (6), mimosa and oak extract (7), Al ligno. 1 + mimosa and oak extract (8), olive extract (9), seaweed extract (10) and willow extract (11).…”

Assessing Copper-Alternative Products for the Control of Pre- and Postharvest Citrus Anthracnose

“…It is known to have preventive effects on fungal diseases, attributable to the high percentage of silica [ 60 , 61 ] and antifungal effects linked to its high concentration of flavonoids and phenols [ 62 ]. To date, there are some reports documenting its efficacy in the control of plant pathogens such as Plamopara viticola [ 63 , 64 ], Alternaria solani [ 65 ], Phytophthora infestans , Puccinia triticina [ 66 ] and grapevine trunk pathogens [ 67 ]. In in vitro assays carried out in this work, both Biorend (chitosan) and Equibasic (equisetum) significantly inhibited the growth of C. gloeosporioides at all the tested concentrations, with best results observed at 1% of commercial product.…”

Are Basic Substances a Key to Sustainable Pest and Disease Management in Agriculture? An Open Field Perspective

“…Therefore, a careful evaluation of the outcomes of basic substances' employment in the open field is highly necessary. Fortunately, the literature regarding both the approved and potential basic substances is continuously growing, as evidenced from scientific studies and review papers [20][21][22][23][24][25][26][27] (Figure 1).…”