Francesco Calzarano

Pathogenicity of fungi associated with a decay of kiwifruit

A decay of kiwifruit was noted for the first time in 9 to 10-year-old Italian vineyards. Trunk and cordons of symptomatic vines showed decayed areas surrounded and preceded by wood discolouration. Fomitiporia mediterranea (syn. F punctata) was recovered from decayed tissue, whereas Phaeoacrernonium parasiticum, Cadophora malorum and strains of Phaeoacrernonium aleophilum were found in the discoloured wood. Two-year-old potted kiwifruit vines of the cultivar Hayward were inoculated with a strain of each species in order to assess their ability to cause wood discolouration and decay. Six months after inoculation, discolouration was clearly evident in all plants inoculated with Phaeoacrernonium species and C. malorum. Decayed areas caused by F mediterranea were observed only in some potted plants either 15 or 18 months after inoculation. Some of the vines inoculated with P. aleophilum, C. malorum and F mediterranea shrivelled up completely. Inoculated fungi were always recovered from the discoloured and decayed tissue. Both types of wood deterioration observed in the field on diseased plants were reproduced in the pathogenicity tests.

The Contro of Esca : Status and Perspectives.

The development of an effective control strategy for esca greatly depends on major progress in understanding the disease biology and epidemiology. Experimental trials were carried out in vineyards and single infected vines in order to evaluate the effectiveness of different fungicides, application methods and cultural practices in controlling esca: experiences with sodium arsenite, dinitro-orthocresol, fosetyl Al, triazoles and first attempts with Trichoderma are discussed. Ongoing trials show promising results with fosetyl Al activity against Phaeoacremonium spp. under laboratory and greenhouse conditions, with the prospect of a favourable effect on esca control. Research is now being focused on the potential of a control strategy to prevent or reduce the establishment and development of the disease. The management of esca should be based on the age of the plant, the stage of the infection as well as the degree of spread of the disease.

Some Observations on the Relationship of Manifest and Hidden Esca to Rainfall

Summary. 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.

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.

A new wood decay of kiwifruit in Italy

Abstract A previously undescribed form of wood decay of kiwifruit (Actinidia deliciosa (A. Chev.) C. F. Liang et A. R. Ferguson) plants was observed in 8–10‐year‐old Emilia Romagna orchards in north‐central Italy. Symptoms appear as unspecific interveinal chlorosis of the leaf, which later may become necrotic resulting in premature leaf drop. Fruits never grow as large as on healthy plants nor do they reach full maturity. This foliage chlorosis occurred on current seasons shoots developing from canes growing horizontally from the cordon. Cross‐sections of the wood show white rot areas surrounded by brown necrosis of hard consistency, preceding the white rot in the colonisation of the wood. Isolations from the zone of hard consistency onto Potato Dextrose Agar (PDA) medium yielded Phaeoacremonium aleophilum, P. inflatipes, P. chlamydosporum, P. rubrigenum, and to a lesser extent, Phialophora sp., whereas Phellinus conchatus was commonly isolated from white rot diseased tissue. Although pathogenicity studies on host plants are still being carried out, a strong similarity with esca disease of grapevine could clearly be noticed.

Trans‐Resveratrol Extraction from Grapevine: Application to Berries and Leaves from Vines Affected by Esca Proper

Abstract Trans‐resveratrol is a metabolite involved in resistance of plants during biotic and abiotic stress. Here we report the optimization of a rapid solvent extraction protocol and its application to different parts of grapevines. We also demonstrate the influence of sample pretreatment with liquid nitrogen on trans‐resveratrol stability, which results as the key step in avoiding oxygen degradation during solvent extraction. Up to 94% of trans‐resveratrol was recovered using this procedure. Berries and leaves from healthy and symptomatic, esca proper–affected vines collected at two different phenological growth stages were analyzed. Trans‐resveratrol was determined in berry and leaf samples; symptomatic vines always showed a significantly higher amount with respect to healthy vines. The mean concentration of trans‐resveratrol in berries was 0.93 µg/gdm and 1.92 µg/gdm at veraison and 1.49 µg/gdm and 2.72 µg/gdm at harvest from healthy and symptomatic vines, respectively.

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.

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.