Field Control of Olive Anthracnose Caused by Colletotrichum spp. under Mediterranean Conditions

Anthracnose, which is caused by multiple Colletotrichum species, is the most damaging fruit disease of olives worldwide, especially in areas with humid autumns such as Andalusia in Spain, the leading olive oil-producing region globally. In this region, four field trials were conducted between 2006 and 2010 to evaluate the efficacy of copper-based fungicides, systemic fungicides, calcium salts, and natural products for disease control. The epidemic intensity varied greatly across years, with only one season (2006) showing severe disease development. Under the conditions evaluated, copper-based fungicides applied in early autumn were consistently the most reliable treatments, confirming their key role in anthracnose management. No significant differences in copper wash-off were observed among the formulations tested. Compared with single autumn applications, additional copper sprays in spring did not result in any efficacy improvement under the epidemiological conditions of this study. Among alternative fungicides, strobilurins (trifloxystrobin and pyraclostrobin) showed good efficacy and may reduce the copper dosage required in integrated management programs. Tebuconazole, a triazole fungicide, resulted in the best efficacy against the pathogen, but it can only be applied in olive groves before flowering. Calcium-based compounds and plant extracts showed poor efficacy against the disease in all these trials. Overall, our results support early-autumn copper sprays as a key component of anthracnose control in the Mediterranean in southern Spain, whereas the complementary use of strobilurins could help reduce copper dependence within sustainable disease management strategies.