Anaerobic Soil Disinfestation, Not Wheat Precropping, Suppressed Charcoal Rot in Strawberries

Charcoal rot caused by Macrophomina phaseolina (Mp) has become a major threat to the California strawberry industry. We examined the effect of growing 'Summit 515' wheat as a precrop of strawberries with and without anaerobic soil disinfestation (ASD) on suppressing charcoal rot in strawberries. A series of pot experiments, replicated field trials on the Central Coast, and demonstration trials on commercial fields in the Southern Coast were conducted. Economic analysis using a partial budget was performed using data from the field trials. Growing wheat did not significantly reduce soil Mp populations, and growing and incorporating wheat failed to suppress charcoal rot in strawberries in a replicated field trial. In contrast, ASD applied within beds (bed-ASD) in a sandy loam demonstration trial and ASD applied on a flat ground (broadcast-ASD) in loamy sand replicated field trials suppressed charcoal rot in strawberries. However, the Mp populations in the soil were significantly reduced only in the demonstration trial. Potential mechanisms and cumulative Eh and cumulative soil temperature conditions required for those cases are discussed. In a clay loam demonstration trial, bed-ASD did not develop sufficient anaerobiosis and failed to suppress the disease because of large soil clods in the beds. A partial budget economic analysis indicated that broadcast-ASD may be cost-prohibitive, whereas the bed-ASD is more viable. Taken together, bed-ASD may be a viable option for suppressing charcoal rot in strawberries in sandy to loamy fields in the Southern Coast of California. Bed-ASD in fields with high-clay content soils remains challenging.[Formula: see text] Copyright © 2026 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.