Preventive control of Diplodia canker affecting Quercus suber in southern Spain

Abstract: After the no inclusion of Benomyl in the EU Pesticide Database, new alternatives to prevent Diplodia canker disease affecting cork oaks were needed in southern Spain. In summer 2006 a first field experiment was carried out in a cork oak rangeland at Seville province. Six chemical products effective in vitro, plus a biological product (Trichoderma) were sprayed to recently peeled cork oak trunks in a randomized blocks experimental design. Three years after treatments, cork oaks sprayed with Pyraclostrobin, Difenoconazole, Carbendazim, Copper-Calcium Sulphate and Thyophanate-methyl showed a significant decrease in number and length of trunk lesions in comparison with untreated trees. A second field trial was performed in summer 2007 at Cádiz province under a wetter environment, spraying systemic fungicides and Trichoderma immediatly after cork extraction or 24 h after. Two years and a half after treatments only Thyophanate-methyl was effective when sprayed just after peeling. Finally, a third set of sprayings were made in summer 2010 under the wet conditions of Cádiz. Thyophanate-methyl, Copper-Calcium Sulphate and a mix of both fungicides were applied to trunks immediatly after peeling, and 2.5 years after spraying, the preventive effectiveness of both fungicides was confirmed, although no synergistic effect of the mixture was achieved.