Integrated Management of Anthracnose (*Colletotrichum* spp.) in Strawberry and Berry Crops

Identification of Colletotrichum spp. and Symptoms in Berries

Strawberry and berry production in regions like Argentina and Latin America faces significant phytosanitary challenges. Among these, anthracnose stands out as a devastating disease, capable of seriously compromising crop yield and quality. Understanding its mechanisms and applying effective management strategies is fundamental to ensuring the profitability and sustainability of these crops. This integrated approach encompasses early identification, the implementation of preventive and control methods, and the incorporation of the latest innovations in the agricultural sector.

The anthracnose disease is caused by various fungal species of the genus Colletotrichum. The most common in strawberry (Fragaria x ananassa) and other berry crops such as blueberries and raspberries are Colletotrichum acutatum, C. gloeosporioides, and C. fragariae. Accurate identification of the disease is crucial for timely management. Symptoms vary depending on the affected plant part and the Colletotrichum species involved. On leaves, small, circular to irregular spots are observed, which eventually become necrotic and can coalesce. In flowers, dark lesions manifest, causing flower drop or the development of deformed fruits. Green fruits may exhibit sunken, dark brown to black spots, while on ripe fruits, these lesions are circular, soft, and depressed, often with concentric rings and a salmon or orange spore mass under high humidity conditions. Crowns and roots can also be affected, leading to wilting and plant death. Early diagnosis, often supported by recent molecular analyses, allows for the differentiation of these species and the adaptation of interventions.

Agronomic Practices for Anthracnose Mitigation

The implementation of appropriate cultural practices constitutes the first line of defense against anthracnose. The selection of healthy propagation material is imperative; using certified, pathogen-free seedlings drastically reduces the risk of disease introduction. Crop rotation disrupts the pathogen’s life cycle by eliminating inoculum sources in the soil, making it advisable to avoid monoculture of strawberries or berries in the same plot for at least three years. Irrigation management is another fundamental pillar: systems like drip irrigation or sub-irrigation are preferable to avoid prolonged foliar wetness, which favors spore germination and infection. Planting density and pruning should be optimized to ensure good canopy aeration, reducing relative humidity and temperature within the plant’s microclimate. The removal and destruction of infected harvest residues prevent inoculum buildup for future seasons. Furthermore, current research focuses on the development and use of strawberry and berry varieties with genetic resistance to the main Colletotrichum species, a sustainable strategy that reduces reliance on chemical treatments.

The integrated management of anthracnose combines biological and chemical strategies for effective and sustainable control. In the biological realm, the use of biocontrol agents has gained relevance. Microorganisms such as Trichoderma spp. and Bacillus subtilis are applied as biofungicides, colonizing roots or the plant surface and competing with the pathogen for nutrients and space, or producing antifungal compounds. These biological products are particularly valuable in organic farming programs and for reducing chemical residues on fruits. Regarding chemical control, the application of specific fungicides is a necessary tool, especially under conditions of high disease pressure. Rotation of active ingredients is crucial to prevent the development of resistance in Colletotrichum populations. Fungicides based on strobilurins, triazoles, and dithiocarbamates are commonly used, always respecting dosages, re-entry intervals, and pre-harvest intervals. Recent innovations include more specific and environmentally friendly formulations, as well as the use of precision application systems that minimize waste and maximize efficacy.

Biological and Chemical Alternatives in Colletotrichum Control

Active surveillance and constant monitoring are essential for the early detection of anthracnose and the implementation of corrective measures. A regular monitoring program involves visual inspection of plants, identification of initial symptoms, and, if necessary, sending samples to diagnostic laboratories. Modern technology offers tools such as environmental sensors and predictive models that, by integrating meteorological data (temperature, humidity, leaf wetness duration), can alert about conditions favorable for disease development, allowing for preventive applications. Climate change presents new challenges, with more erratic and extreme weather patterns that can alter the incidence and severity of anthracnose. Adaptation to these new conditions includes selecting varieties more resilient to water or thermal stress, implementing protected cultivation systems (high tunnels, greenhouses) that allow for greater microclimate control, and adopting precision agriculture practices that optimize resource use and reduce crop vulnerability. Plant genomics research is identifying resistance genes that could be incorporated into future varieties to improve disease tolerance under changing climatic scenarios.

Effective management of anthracnose in strawberries and berries demands a holistic vision that integrates preventive agronomic practices, the strategic use of biological and chemical tools, and constant monitoring. The key to success lies in anticipation and adaptation, leveraging technological innovations and scientific research to develop more resilient and productive cropping systems, thereby ensuring the quality and quantity of these valuable fruits for regional and global markets.