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

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

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

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 symptoms 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

Effects of grapevine applications of fosetyl-aluminium formulations for downy mildew control on “esca” and associated fungi.

Esca of grapevine is a fungal disease with a complex aetiology that is common in almost all regions of the world where grapes are cultivated. Despite much research, no effective control of the disease has been found. We investigated possible activity of fosetyl-aluminium (fosetyl-Al), an active ingredient in many fungicides against downy mildew, to inhibit development of esca in grapevine and the main pathogens linked to the disease, Phaeomoniella chlamydospora (Pch) and Phaeoacremonium aleophilum (Pal). In greenhouse experiments conducted on vines artificially inoculated with Pch or Pal, we found a reduction in necrosis in the woody tissue. In field experiments conducted over several years statistically significant reductions in the annual and cumulative incidence of the disease symptoms, and in cumulative vine mortality, were seen. The effect of fosetyl-Al treatments on leaf gas exchange, levels of resveratrol and ε-viniferin in the wood, and enzymatic activities were also studied. Hypotheses regarding the mechanism of action of fosetyl-Al against esca are outlined, and the possible use of products containing the chemical, applied on foliage to control downy mildew, is discussed as a strategy for control of esca