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ARS Home » Pacific West Area » Salinas, California » Crop Improvement and Protection Research » Research » Publications at this Location » Publication #361774

Research Project: Management of Pathogens for Strawberry and Vegetable Production Systems

Location: Crop Improvement and Protection Research

Title: Evaluation of biopesticides for managing downy mildew of spinach in organic production systems in 2017 and 2018

item Kandel, Shyam
item SUBBARAO, KRISHNA - University Of California
item SHI, AINONG - University Of Arkansas
item Mou, Beiquan
item Klosterman, Steven

Submitted to: Plant Disease Management Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/19/2019
Publication Date: 8/29/2019
Citation: Kandel, S.L., Subbarao, K.V., Shi, A., Mou, B., Klosterman, S.J. 2019. Evaluation of biopesticides for managing downy mildew of spinach in organic production systems in 2017 and 2018. Plant Disease Management Reports. 13:V171.

Interpretive Summary: Downy mildew can cause major yield losses in organic spinach production and requires the frequent application of synthetic fungicides in conventional production. In organic production, biopesticides are acceptable and likely to provide a viable option to manage the downy mildew. Two field experiments were conducted in 2017 and 2018 by evaluating the performance of biopesticide treatments to reduce the incidence of downy mildew in spinach cultivar Viroflay. The biopesticides Procidic, MBI-110, Cueva, LifeGuard, Sil-Matrix, OSO 5%, Zonix, OxiDate 2.0, and TerraGrow were applied 20 (2017) or 30 (2018) days post seed sowing once a week for six consecutive weeks. The biopesticide Procidic significantly (a=10%) reduced the downy mildew incidence over the nontreated control in 2017 and therefore additional tests of Procidic are underway to determine if this biopesticide can repeatedly provide downy mildew disease control.

Technical Abstract: Experiments were conducted in 2017 and 2018 with spinach cultivar Viroflay, to investigate the effectiveness of biopesticides in minimizing spinach downy mildew (Peronospora effusa) incidence in field plots. ‘Viroflay’ has no known downy mildew resistance genes. The experiments were performed in two field tests at the USDA-ARS, Salinas, California. The conventional fungicide Aliette and untreated control were compared with nine biopesticides in a randomized complete block design, with four replications: Procidic (Greenspire Global, Inc.), MBI-110 (Marrone Bio Innovations, Inc.), Cueva, LifeGuard, Sil-Matrix, and OSO 5% (Certis USA LLC), Zonix (Brandt Consolidated, Inc.), and Oxidate 2.0 and TerraGrow (BioSafte Systems, LLC). A tenth biopesticide treatment was the combination of OSO 5% and Cueva. All pesticides were applied at their maximum label rates. Treatments were applied 20 (2017) or 30 (2018) days post-sowing (DPS). Disease incidence was less than 15% in both years. Procidic significantly reduced (P =0.05) disease incidence in both years at 23 and 33 DPS, respectively. Disease control was variable among the other treatments. Relatively smaller but statistically insignificant reduction in disease incidence was achieved with MBI-110, and the combination of OSO 5% and Cueva treatments. Procidic and potentially additional combination of treatments warrant further investigation for control of spinach downy mildew.