Wood discoloration and decay in grapevines with esca proper and their relationship with foliar symptoms

From two Italian vineyards affected with esca proper, vineyard A (Borghi, FC, Emilia-Romagna) and vineyard B (Controguerra, TE, Abruzzo), located in different wine-growing areas and with different cultivars, 165 vines were collected that had shown the leaf symptoms of esca proper in the years before. Each vine was inspected and the cubic volume of the main symptoms in the trunk was measured: discoloration, including the various forms of dark necrosis, and decay. In each vine of both vineyards the extent of wood deterioration was compared with the severity of the leaf symptoms recorded in the years before the vines were cut down. The existence of a correlation between discoloration and decay in the wood colonisation process was explored. No correlation was found between the severity of the wood deterioration and the severity of the leaf symptoms. The typical leaf symptoms were found also on vines that had only wood discoloration without any decay. There was no correlation between wood discoloration and decay in vineyard A in which the vine wood was more degraded, with a greater incidence of decay. In vineyard B, however, in which the incidence of decay was less, a correlation between decay and discoloration was potentially found

Some observations on the relationship of manifest and hidden esca to rainfall

This paper reports observations on the relationship between the yearly incidence of manifest esca (i.e. diseased plants which show foliar symptoms), hidden esca (that which remains asymptomatic throughout a growing season) and rainfall. Data from three vineyards (two in Tuscany and one in Emilia-Romagna, Italy) showed that rainfall in May-July or only in July was inversely related with hidden esca. For two vineyards, TB in Emilia-Romagna and CAR-3 in Tuscany, the spatial pattern of diseased vines in the first year of appearance of the foliar esca symp-toms was also determined. The maps of the vines in these vineyards indicated that diseased plants mostly occurred alone. This suggests that the disease had its origin in infected rooted cuttings or was triggered by inoculum aerially dispersed from distant sources and/or occurring, at least in hypothesis, in the soil

Understanding the control strategies effective against the esca leaf stripe symptom: the edge hypothesis

A peculiar symptom that may develop in grapevines affected by wood pathogens involved in the esca complex of diseases is the leaf stripe symptom, which also gives the name to the Grapevine Leaf Stripe Disease. Multiple studies have revealed strong links between fungal presence, wood symptomatology and expression of the leaf stripe symptom. However, numerous other factors have been shown to play roles in symptom onset, incidence, severity and yearly fluctuation of this disease. While the factors triggering the leaf stripe symptom are still under investigation, three control strategies have been proven effective for substantially reducing its expression, namely trunk surgery, and applications of sodium arsenite or a fertilizer mixture. These control strategies are examined here, including their (putative or confirmed) modes of action, and how they may influence the leaf stripe symptom development. In this article, we also propose the ‘edge’ hypothesis to tentatively explain symptoms onset, keeping in consideration past knowledge and recent advances in the understanding of the esca leaf stripe symptom. Ultimately, it is our intention to offer food-for-thought and and stimulate and stimulate debate within the phytopathological community

Italian Zeolitites in the Control of Grey Mould and Sour Rot and Their Effect on Leaf Reflectance, Grape and Wine

Abstract: The activity of two zeolitites, differing in the presence of copper and their particle size, was assessed in a Trebbiano d’Abruzzo white berry cultivar, towards grapevine grey mould and sour rot, a serious problem in almost all grapevine-growing areas. In 2018 and 2019, zeolitites were applied before forecast of rainfalls, which likely induce infection. In 2019, further applications were carried out 10 or 2 days before harvest, regardless of the rainfall, in order to verify the effect of the zeolitite residue on leaf reflectance and composition of grapes and wines. Both zeolitites significantly reduced the infections. Only the vines treated 2 days before harvest, especially with copper zeolitite, showed a decrease in leaf reflectance. However, no differences in the yield composition related to the time of zeolitite application, as well as a decrease of yield quality, were ever recorded. Furthermore, analysis of samples collected from vines treated with zeolitites showed increases in grape soluble solids and in wine alcohol content. Our results suggest the use of zeolitites against grapevine rots as a possible effective alternative to the application of synthetic fungicides in the development of environmentally friendly control strategies

Preliminary Evaluation of Variations in Composition Induced by Esca on cv. Trebbiano d'Abruzzo Grapes and Wines

The present study examined the effect on quality caused by esca in both grape clusters and wines. In the last year (2000) of an eight-year survey of esca foliar symptoms, the vines of two cv. Trebbiano d’Abruzzo vineyards fell at the moment of grape clusters sampling, into 3 groups: 1. vines with esca symptoms; 2. vines that happened to be asymptomatic but that were known to be diseased because they had show leaf symptoms in at least one other survey year and 3. healthy vines. In a third vineyard, in the same growing area, grape clusters were sampled from vines with trunk renewal that had been restored and from unrenewed vines that had never shown esca leaf symptoms and were consequently presumed to be healthy. Preliminary results on grape clusters in the first two vineyards showed differences in composition between symptomatic vines on the one hand, and asymptomatic/diseased vines and healthy vines on the other, with symptomatic vines having lower levels of reducing sugars and a higher nitrogen concentration. As a result the alcohol content of wines from symptomatic vines was about 1% v:v lower than that of wines from the other two groups of vines. Grape clusters and wines from diseased/asymptomatic vines and healthy vines did not differ in the compositional parameters used in the test except for total polyphenols which gave contrasting data among the first two vineyards. In grape clusters and wines from the third vineyard the preliminary results likewise revealed no difference between vines with trunk renewal and unrenewed healthy vines. This finding would seem to corroborate the practice of trunk renewal as a means of restoring both vines and the quality of grape clusters. Research is continuing to evaluate the reliability of these results

Wood Discoloration and Decay in Grapevines with Esca Proper and Their Relationship with Foliar Symptoms

From two Italian vineyards affected with esca proper, vineyard A (Borghi, FC, Emilia-Romagna) and vineyard B (Controguerra, TE, Abruzzo), located in different wine-growing areas and with different cultivars, 165 vines were collected that had shown the leaf symptoms of esca proper in the years before. Each vine was inspected and the cubic volume of the main symptoms in the trunk was measured: discoloration, including the various forms of dark necrosis, and decay. In each vine of both vineyards the extent of wood deterioration was compared with the severity of the leaf symptoms recorded in the years before the vines were cut down. The existence of a correlation between discoloration and decay in the wood colonisation process was explored. No correlation was found between the severity of the wood deterioration and the severity of the leaf symptoms. The typical leaf symptoms were found also on vines that had only wood discoloration without any decay. There was no correlation between wood discoloration and decay in vineyard A in which the vine wood was more degraded, with a greater incidence of decay. In vineyard B, however, in which the incidence of decay was less, a correlation between decay and discoloration was potentially found

Control of Grapevine Downy Mildew by an Italian Copper Chabasite-Rich Zeolitite

Abstract: The progressive reduction in the quantities of copper regulated by the European Union is focusing the research on new formulations with a reduced copper content but equally effective. In this regard, the activity of an Italian copper chabasite-rich zeolitite, which proved to be effective against grapevine grey mold and sour rot, was assessed against downy mildew. A two-year study was carried out in the Abruzzo region, Italy, in a cv. Montepulciano vineyard. The applications of the copper zeolitite showed the same good results obtained by a standard integrated/conventional strategy based on contact and systemic fungicides. At harvest, in both trial years, the plants with infected bunches in the untreated control ranged from 86.25% to 100%, compared to 15–30% of the treated plants. Furthermore, infected bunches and berries of the untreated control vines were 70–100% while treated ones never exceeded 2.32%. Furthermore, an increase in the polyphenol content and color intensity in wines made from vines treated with copper zeolitite was confirmed and appeared to be particularly evident in hot and dry seasons. The activity of copper zeolitite towards downy mildew, the potential use against grey mold and sour rot and the protection of grapes from high temperatures indicate that this product is a promising tool for a viticulture environmentally friendly control strategy

Foliar treatment of esca-proper affected vines with nutrients and bioactivators

Foliar treatment with nutrients and bioactivators was carried out in two vineyards affected with esca proper in 2004 and 2005. Changes in the foliar symptoms and in the quality of berries without lesions from treated symptomatic vines were assessed. Treated vines unexpectedly had a higher incidence and a greater severity of symptomatic leaves than untreated plants, most likely because physiological processes were stimulated by the treatments, possibly also because treatments facilitated the movement of toxins produced by the wood fungi of esca. However it cannot be excluded that the increase in foliar symptoms was due to the forced nutrition causing an imbalance between the various elements, and altering the mechanisms that vines use for the remission of foliar symptoms. This supposition seemed corroborated by the observation that treated vines diseased with esca proper had a weaker defense response than untreated diseased vines, and that treated diseased vines had lower levels of nitrogen and microelements, which are respectively involved in osmoregulation and as cofactors of enzymes involved in the defense response of the plant. The main quality parameters of berries without lesions from treated and untreated symptomatic vines were very similar

Benefit of Fungicide Treatment after Trunk Renewal of Vines with Different Types of Esca Necrosis

Vines cv. Trebbiano d’Abruzzo grown in three vineyards located in Teramo Province, Abruzzi, Italy, severely affected by esca proper, were subjected to trunk renewal and thereafter treated with triazoles and fosetyl Al fungicides, applied either by trunk injection via syringe, or by ground injection via injector pole. Trunk renewal, by cutting the trunk, made it possible to determine the extent and type of wood deterioration on the residual trunk portion, where it was found that rotted and discoloured wood often still remained. Fungicide treatment was begun in 1995, when trunk renewal was performed, and was continued until 1998; after this the vines continued to be monitored for a further 4 years until 2002. In 2002, vines that had received trunk injections after trunk renewal were in better vegetative condition than vines without such injections, with full yield and lower mortality. Cyproconazole was particularly effective when trunk injected, but was not effective when injected into the ground. A possible explanation for this is given. Moreover the effect that the severity of the wood necrosis observed at the time of trunk renewal had on treatment effectiveness was evaluated. The current lack of similar trials and studies in other vineyards makes standardisation of control methods difficult; any positive effects may have been due to concurrent factors such as cultivar vigour, or peculiar environmental or cultural conditions

Effect of Esca on the Quality of Berries, Musts and Wines

Variations in the composition of berries, musts and wines in three groups of vines: 1. vines with foliar esca symptoms; 2. asymptomatic esca diseased vines; and 3. healthy vines, were studied in 2001 and 2002 in two “Trebbiano d’Abruzzo” vineyards in the Abruzzi region, Italy, to determine the effect of esca. Vines were grouped by foliar symptoms that had been recorded in annual inspections for 10 years: symptomatic vines by definition showed foliar symptoms in the sampling years (2001 and 2002); asymptomatic esca diseased vines showed no symptoms during the sampling years though they were known to be diseased because they had had foliar symptoms in at least one previous annual inspections; healthy vines were those with no symptoms at any time during the 10-year survey. The quality of berries, musts and wines obtained from vines with trunk renewal that had been restored, and of healthy unrenewed vines was compared in another vineyard of the same cultivar. Fairly similar results were obtained over the two sampling years, with a strong reduction in sugar levels of the must from symptomatic vines, leading to a lower ethanol content in the wine made from that must. These findings confirmed those of the preliminary investigation carried out in 2000. The yield pressed from symptomatic vines also had significantly higher levels of malic acid (causing higher total acidity), and of total nitrogen, potassium and total polyphenols. Berries from symptomatic vines had much higher levels of trans-resveratrol, possibly because of the spots on the leaves and berries. Small and non-significant differences between the yields of healthy vines and asymptomatic diseased vines were found, suggesting a slight loss in the quality of musts and wines from asymptomatic diseased vines. The yield of trunk-renewed vines was similar to that of healthy unrenewed vines, despite an increase of trans-resveratrol in the berries and of total nitrogen in the must of the trunk-renewed vines