Decoy disease and wood diseases: modern solutions to an ancient problem
Grapevine esca disease is a complex of diseases causing significant damage in all wine-growing regions of the world, the etiology and epidemiology of which have not yet been fully elucidated. Direct control of wood diseases remains difficult due to the absence of effective fungicides and the difficulty of penetration of active ingredients into the wood. Prevention is currently the only approach to limit their impact, paying particular attention to pruning wounds.
A marginal role is often attributed to the contribution of the genotype of the vine and/or rootstock to the development of the disease, a variable that instead seems to play a decisive role on the incidence and severity of symptoms; although no varieties resistant to esca disease are known to date, under the same soil and climatic conditions, genotype plays a crucial role, regardless of the type of graft and clone adopted.
Research is looking for innovative solutions to combat esca disease: CREA-VE in Conegliano (TV), in collaboration with Rauscedo Cooperative Nurseries, is experimenting with the application of RNA interference technology to induce a defense response in the plant. A further line of research considers the use of new jasmonic acid-based molecules for their ability to slow down the colonization of woody tissues by fungi involved in esca syndrome.
The reports reproduced in these films were presented at the 2021 edition of Enoforum Italia (May 18-20, 2021) as part of the module organized in collaboration with Vivai Cooperativi Rauscedo.
Understanding and managing bait disease and wood diseases
Olivier Viret, Changins-Wädenswil Agroscope Institute
Wood diseases cause major damage in all wine-growing regions of the world. The fungal species isolated from healthy plants and from plants with symptoms of Esca Mal are almost the same, but they differ from the fungal communities of the rooted cuttings. In the Swiss territory, the pathogenic fungi described in Decoy Disease, Black dead arm, Eutipiosis, and Escoriosis are present both in vines with leaf symptoms and in healthy plants sampled in the same vineyards.
In affected plants, lymphatic flow is greatly altered, as a result of fungi colonizing the conducting vessels, but also due to injury or stress related to climate or soil type.
Direct control of wood diseases remains difficult due to the absence of effective fungicides and the difficulty of penetration of active ingredients into the wood. Prevention is currently the only approach to limit the impact of wood diseases; in particular, attention should be paid to the size of pruning wounds as it directly correlates with the portion of dry wood that is formed in the underlying tissue. Experiments with rooted cuttings inoculated with mycorrhizae and/or antagonistic fungi of the genus Trichoderma have yet to demonstrate their long-term effects.
Studies on wood diseases must integrate many parameters such as varietal sensitivity to climatic stresses, rootstock type, soil and water management, vigor, and finally pruning. It appears that certain forms of planting, such as the Trentino pergola or the “bellussera,” show a lower incidence of wood diseases, perhaps because they are more respectful of the plant’s natural liana habit. Similar observations have been made in France, in the Champagne region, with the “chablis” type pruning system, in which up to four trunks per vine are regularly rejuvenated.
The 'bait disease from a vine perspective: the word from the varieties!
Elisa De Luca, Rauscedo Cooperative Nurseries
Grapevine esca disease is a disease complex whose etiology and epidemiology have not yet been fully elucidated. In the scientific bibliography, great attention is devoted to the study of the fungal communities potentially involved in the manifestation of symptoms affecting perennial and canopy organs, often attributing a marginal role to the contribution made by the genotype of the vine and/or rootstock to the development of the disease. To date, no varieties are known to be resistant to esca disease, however, given the same soil and climatic conditions, some varieties show less susceptibility to the disease, resulting, in some cases, in the almost complete absence of symptoms for periods of up to decades. During the webinar, some of the most significant results will be presented, which are the result of the monitoring that VCR has been conducting since 2006 in vineyards located at the VCR Marze Center in Fossalon di Grado (GO), covering an area of 136 hectares, which is home to more than 800 varieties of wine grapes, table grapes and rootstocks. These vineyards were made with “basic” category rooted cuttings, which corresponds to the highest sanitary level attributed to vine propagation material, in accordance with strict Community and National protocols. The VCR Marze Center in Fossalon is located 3 km from the Adriatic Sea, on land previously used for arable farming, in an isolated position from the nearest vine plantings. The results of monitoring conducted for decades at these plants support the thesis that, in the same cropping environment, genotype plays a crucial role in the etiology of esca malaria, regardless of the type of graft and clone adopted: we give back to the host its proper weight, in the disease pyramid.
Research innovations for the characterization, prevention and treatment of bait syndrome
Luca Nerva, CREA Conegliano Veneto
Decoy disease: new perspectives and innovative tools from the world of research
In recent years, several studies have proposed innovative solutions to combat esca malaria, with a focus on both treatment and prevention of the syndrome. CREA-VE in Conegliano (TV), in collaboration with Rauscedo Cooperative Nurseries, is developing a number of lines of research on the subject. In this regard, a first experiment has been activated that concerns the treatment of grapevine through the application of a latest-generation technology defined as RNA interference, to induce a defense response in the plant. A second line of research, on the other hand, involved not only Rauscedo Cooperative Nurseries and CREA-VE, but also the University of Parma, with which some new molecules based on jasmonic acid were developed. These molecules were assayed for their ability to slow down the colonization of woody tissues by fungi involved in esca syndrome. Initial results have shown that both through RNA interference and by using one of the jasmonic acid-based molecules, it is possible to block the growth of fungi in the tissues of plants affected by bait disease. Insights to better understand the physiological and molecular responses, along with an analysis to define what impact these technologies have on endophytic microflora are currently underway.
