|MURAMOTO, JOJI - UNIVERSITY OF CALIFORNIA|
|SHENNAN, CAROL - UNIVERSITY OF CALIFORNIA|
|ZAVATTA, MARGHERITA - UNIVERSITY OF CALIFORNIA|
|BAIRD, GRAEME - UNIVERSITY OF CALIFORNIA|
|TOYAMA, LUCINDA - UNIVERSITY OF CALIFORNIA|
Submitted to: International Journal of Fruit Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/29/2016
Publication Date: 8/3/2016
Citation: Muramoto, J., Shennan, C., Zavatta, M., Baird, G., Toyama, L., Mazzola, M. 2016. Effect of anaerobic soil disinfestation and mustard seed meal for control of charcoal rot in California strawberries. International Journal of Fruit Science. doi: 10.1080/15538362.2016.1199993.
Interpretive Summary: Soil-borne disease management without chemical fumigants remains a major challenge for strawberry production in California, and modifications to existing regulations are likely to intensify this challenge by further limiting availability of fumigants on a large percentage of strawberry acreage. Anaerobic soil disinfestation (ASD) and mustard seed meal amendments have demonstrated the ability to control certain soil-borne diseases in California strawberry production systems. Disease control is believed to result from the production certain volatiles that are generated directly through enzymatic reactions or by microorganisms that are active under anaerobic conditions. ASD with or without the application of mustard seed meal provided significant control of charcoal rot caused by the fungus Macrophomina phaseolina resulting in enhanced strawberry yields. Mustard seed meal alone provided incomplete control of charcoal rot and correspondingly lower yields relative to ASD, but yields were still higher than that attained in the grower standard control. ASD with rice bran 20 ton ha-1 as a carbon source shows promise for reducing charcoal rot of strawberry caused by M. phaseolina, but were not able to provide complete control. The trial is being repeated with refinements at the multiple locations to determine whether modification of the system may yield greater pathogen control can be achieved.
Technical Abstract: Anaerobic soil disinfestation (ASD) and mustard seed meal (MSM) appear to be promising non-fumigant alternatives for soilborne disease control. However studies of their effect on charcoal rot caused by Macrophomina phaseolina in California strawberry are limited. ASD with rice bran 20 t ha-1 (ASD-RB), MSM 4.5 t ha-1 (MSM), and ASD with rice bran 6.7 t ha-1 + MSM 4.5 t ha-1 (ASD-RB+MSM) were tested in a large-scale demonstration in a M. phaseolina-infested organic field in Oxnard, CA. A doubling of yields relative to the grower standard, and a reduction in mortality by M. phaseolina, was achieved by ASD-RB. MSM failed to control M. phaseolina and resulted in yields that were more than 20% below the ASD-RB yield. Yield in the ASD-RB+MSM plot was intermediate between ASD-RB and MSM. A combination of phytotoxicity following transplanting, and subsequent salinity damage due to high nitrate levels over the winter may have reduced yields in the MSM treatment. Treatment effects on soil pH, EC, inorganic N dynamics and soil microbial communities were also examined. Transformations in microbial community structure associated with these alternative measures likely contributed to the overall level of disease control achieved.