IN ITALY

(pubblicato su 1st European Bois noir Workshop 2008)

M. Bacchiavini (1), N. Reggiani (2), N. Mori (3), Francesco Pavan (4)

(1) Consorzio Fitosanitario Provinciale di Reggio Emilia, Via F. Gualerzi 32, 42100 Reggio Emilia, Italy
(2) Consorzio Fitosanitario Provinciale di Modena, Via Andreoli 13, 41100 Modena, Italy
(3) AGREA Centro Studi, via Garibaldi 5/16 - 37057 San Giovanni Lupatoto, Verona, Italy
(4) Dipartimento di Biologia e Protezione delle Piante, Università di Udine, via delle Scienze, 208 - 33100 Udine, Italy

Abstract
In the last years, in North-Eastern Italy regions, grapevine Bois Noir (BN) disease is increasing in spreading importance. The insecticides applications against grape berry moth and other pests do not influence neither the population density of the vector Hyalesthes obsoletus Signoret, nor increase incidence of the disease. The natural transmission of BN to grapevine encompasses a fundamental role of some weed (i.e. bindweed and nettle) that can harbour BN phytoplasmas and are host for the insect vector.

Considering the ineffectiveness of chemical spray and the important epidemiological role of some weed, the only possible control of H. obsoletus appears to be the selective elimination of weeds hosting phytoplasmas.

From 2003 season, experimental trials to control BN, were carried out, on 20 vineyards located in Modena e Reggio province, using herbicides on weed hosting H. obsoletus inside and in the borders of the vineyards. The effectiveness of the adopted strategy has been evaluated both by means of the sampling of the insect vector to verify the amount of populations, and by mapping the vineyards in order to detect plants exhibiting for the first time BN symptoms.

The collected data showed that weeding on nettle and bindweed decreases the population of H. obsoletus in significant way in comparison with not weeded vineyards. The high variability in the number of new symptomatic plants among the vineyards that adopted the weed control did not permit to establish the efficacy of this strategy against BN disease.