Preventive control of Botryosphaeria canker affecting Quercus suber in southern Spain

Abstract

Botryosphaeria canker is likely the most injurious disease for cork production in the Mediterranean Basin. The exclusion ofBenomyl, the standardcommercial product used to prevent Botryosphaeriacanker, fromtheEUPesticide Database in 2003 necessitates the search for new alternatives to prevent cork oak cankering. In vitro experiments showed that every fungicide tested at 103 mg l-1 active ingredient was effective in reducing mycelial growth of Diplodia corticola. An initial field experiment showed that cork oak trunks sprayed with Thiophanate-methyl, Carbendazim, Difenoconazole, Pyraclostrobin or Copper-Calcium Sulphate under low-humidity environmental conditions exhibited significant decreases in the number and length of trunk lesions, 3 years post-treatment, compared with untreated trees.Asecond field experiment conducted underextremelywet conditions showed that only Thiophanate- methyl was effective, 2.5 years after treatments, when sprayed just after peeling. Finally, in a third field experiment, underwet conditions, the preventive effectiveness of Thiophanate-methyl, Copper-Calcium Sulphate and a mix of both fungicideswas confirmed, although no synergistic effect of the mixturewas measured. Copper- Calcium Sulphate or Thiophanate-methyl, when applied immediately after trunk peeling, is effective for preventive control of Botryosphaeria canker on cork oak and may be considered as an effective replacement for Benomyl.