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POSTERS: Cultural Control I

P-151 - Effect of abiotic stresses on Macrophomina root rot development in California strawberry

Monday, August 4, 2025
3:45 PM - 4:30 PM HST
Location: Exhibit Hall 3
Abstract Text:

The causal agent of Macrophomina root rot, Macrophomina phaseolina, is a soilborne pathogen capable of causing devastating economic losses within the strawberry industry. Macrophomina root rot disease severity is highly dependent on environmental factors. Therefore, understanding which stressors contribute most to disease development is crucial for effective management. A field experiment evaluating the impact of drought and salt stress on disease severity of strawberry cultivars Fronteras and Sweet Ann was conducted at Cal Poly State University San Luis Obispo. Strawberry transplants were inoculated with M. phaseolina and subjected to one of five treatments consisting of a grower standard, a drought stress, two chloride stresses, and a high electrical conductivity (ECW) stress. The drought stress received irrigation once soil tension reached 60 kPa whereas the threshold for all other treatments was 10 kPa, as determined by soil tensiometers. For salt stress treatments, concentrated salt solutions were incorporated into the irrigation water using dosing pumps. The trial was visually assessed weekly for plant mortality. Both treatment and cultivar had a significant effect on plant mortality (P < 0.0001) and there was no significant interaction between the factors (P = 0.61). The treatments with significantly higher average plant mortalities, averaged across both cultivars, compared to the standard (36.7%) were drought (60.9%) and high ECW (47.4%). These results highlight the importance of utilizing soil tensiometers and improved water quality to minimize disease severity.