Growing strawberries is not easy, since it requires intensive labor inputs for various management practices. In the eastern US, most strawberries are grown annually in open fields. They are vulnerable to winter freeze damage and frost damage in early spring. To cope with harsh weather events, many growers use row covers (lightweight spun-bound or non-woven covers) to increase ambient temperatures within the strawberry canopy and root zone. Row covers are often taken on and off several times a season by growers, from late autumn to early spring. In addition to row cover management, strawberry production is challenged by disease infections, the risk for which is significantly influenced by weather conditions such as leaf wetness and temperature. However, the environmental variables at the canopy-level in relation to disease infection risk has been poorly understood. The use of row covers could affect canopy microclimate conditions, further complicating disease management.
To monitor conditions throughout the seasons, we placed temperature and leaf wetness sensors in strawberry fields: within the canopies and adjacent to the fields, on a standard weather station tripod (elevated sensor placement). This allowed us to compare temperature and leaf wetness for plants grown under row covers or uncovered in the field. We also utilized the leaf wetness and temperature data to predict the risk of fruit rotting diseases, and then evaluated the usefulness of these models for triggering preventative fungicide applications.
When the plants were covered, average canopy temperatures increased, which protected the plants from winter injury and may have increased phenological growth in the autumn. When the plants were not covered, during the ripening period of the season, the canopy sensors were significantly warmer and wetter than the elevated weather station sensors. These warmer and more humid conditions led to the disease models reporting more days with high fruit disease risk. This triggered more fungicide applications for sensors placed at the canopy level vs. the elevated position. Despite this, the use of the disease models reduced the number of fungicide applications compared to the weekly grower standard treatment.
Sensor placement in strawberries is important for predicting disease risk and placement within the fruiting zone may more accurately report whether conditions are conducive for disease. Furthermore, these fungicide trials showed the effectiveness of utilizing disease prediction models for disease control with reduced fungicide inputs.
Scott D. Cosseboom, Anita Schoeneberg, John D. Lea-Cox, Jayesh Samtani, Charles S. Johnson and Mengjun Hu published this study in Plant Pathology:
TITLE IMAGE: A strawberry infected by Gray Mould, Botrytis cinerea. All images used with permission of the author.