terclim by ICS banner
IVES 9 IVES Conference Series 9 GiESCO 9 GiESCO 2023 9 Chitosan treatment to manage grapevine downy mildew

Chitosan treatment to manage grapevine downy mildew


Context and purpose of the study

Downy mildew is one of the most important grapevine diseases, caused by the Oomycete Plasmopara viticola. The management of the disease in organic agriculture can require up to 15 copper applications per year. However, copper accumulates in the soil, is phytotoxic and is toxic for organisms living in the soil, its use has been restricted in European Union to maximum 28 kg in 7 years. Therefore, testing of alternatives with equal effectiveness is desirable. Among those, the natural biopolymer chitosan, obtained from crab shells, proved to be effective toward downy mildew in plot experiments. The aim of our trials was to extend chitosan applications in large scale experiments in different years, cultivars and environmental conditions. 

Material and methods

Trials were carried out in 3 commercial organic vineyards of Marche Region, Central-Eastern Italy, along 3 seasons (since 2019 to 2021). Treatments were applied on cv Verdicchio of wineries Moncaro (in Castelplanio, AN) and Belisario (in Matelica, MC), and on ‘Montepulciano’ of winery Moncaro, in Angeli di Varano (AN). Chitosan was applied at 0.5% along the season, in the second half of the season following copper, and combined at half rate (0.25%) with half copper rate. Untreated and copper treated plots were used as a control. Downy mildew infections were recorded along the season, and disease incidence, severity and McKinney index were calculated.


The weather conditions were variables among the years and the vineyards. Chitosan treatments reduced McKinney Index of downy mildew, compared to untreated control, on bunches of cv. Verdicchio by 41.7%, 85.5%, and 43.9%, and on cv. Montepulciano by 17.1%, 68.9%, 45.2%, respectively, in 2019, 2020 and 2021. Similar results were obtained on leaves. In 2021, combination of chitosan with reduced copper rates protected leaves and bunches from downy mildew at the same level of copper. This investigation demonstrates that chitosan can be introduced in downy mildew management strategies and can integrate or even replace copper with similar degree of protection and with lower amounts of residues on the grapes.


Publication date: June 22, 2023

Issue: GiESCO 2023

Type: Article


Gianfranco ROMANAZZI1*, Simone PIANCATELLI1, Roberto POTENTINI2, Giuliano D’IGNAZI3, Marwa MOUMNI1

1Marche Polytecnic University, Via Brecce Bianche, I-60131 Ancona, Italy
2Winery Belisario, Via Merloni 12, I-62024 Matelica (MC), Italy
3Winery Cooperativa Terre Cortesi Moncaro, Via Piandole 7A, I-60036 Montecarotto (AN), Italy   

Contact the author*


chitosan, copper, downy mildew, grapevine, plasmopara viticola, Vitis vinifera


GiESCO | GIESCO 2023 | IVES Conference Series


Related articles…

Physiological and growth reaction of Shiraz/101-14 Mgt to row orientation and soil water status

Advanced knowledge on grapevine row orientation is required to improve establishment, management and outcomes of vineyards on terroirs with different environmental conditions (climate, soil, topography) and in view of a future change to more extreme climatic conditions. The purpose of this study was to determine the combined effect of row orientation, plant water status and ripeness level on the physiological and viticultural reaction of Shiraz/101-14 Mgt.

Effects of mechanical leafing and deficit irrigation on Cabernet Sauvignon grown in warm climate of California

San Joaquin Valley accounts for 40% of wine grape acreage and produces 70% of wine grape in California. Fruit quality is one of most important factors which impact the economical sustainability of farming wine grapes in this region. Due to the recent drought and expected labor cost increase, the wine industry is thrilled to understand how to improve fruit quality while maintaining the yield with less water and labor input. The present study aims to study the interactive effects of mechanical leafing and deficit irrigation on yield and berry compositions of Cabernet Sauvignon grown in warm climate of California.

The effects of cane girdling on berry texture properties and the concentration of some aroma compounds in three table grape cultivars

The marketability of the table grapes is highly influenced by the consumer demand; therefore the market value of the table grapes is mainly characterized by its berry size, colour, taste and texture. Girdling could cause accumulation of several components in plants above the ringing of the phloem including clusters and resulting improved maturity. The aim of the experiments was to examine the effect of girdling on berry texture characteristics and aroma concentration.

Application of a fluorescence-based method to evaluate the ripening process and quality of Pinot Blanc grape

The chemical composition of grape berries at harvest is one of the most important factors that should be considered to produce high quality wines. Among the different chemical classes which characterize the grape juice, the polyphenolic compound, such as flavonoids, contribute to the final taste and color of wines. Recently, an innovative non-destructive method, based on chlorophyll fluorescence, was developed to estimate the phenolic maturity of red grape varieties through the evaluation of anthocyanins accumulated in the berry skin. To date, only few data are available about the application of this method on white grape varieties.

Different yield regulation strategies in semi-minimal-pruned hedge (SMPH) and impact on bunch architecture

Yields in the novel viticulture training system Semi-Minimal-Pruned Hedge (SMPH) are generally higher compared to the traditional Vertical Shoot Positioning (VSP). Excessive yields have a negative impact on the vine and wine quality, which can result in substantial losses in yield in subsequent vintages (alternate bearing) or penalties in fruit quality. Therefore yield regulation is essential. The bunch architecture in SMPH differs from VSP. Generally there is a higher amount but smaller bunches with lower single berry weights in SMPH compared to VSP.