Effects of crop rotation, anaerobic soil disinfestation, and mustard seed meal on disease severity and organic strawberry production in California
We report on an experiment comparing two and four-year organic crop rotations, with either lettuce or broccoli as the main rotation crop, and use of anaerobic soil disinfestation (ASD) or mustard seed meal (MSM) for soil-borne disease suppression in strawberry production. Strawberries were planted every other year in rotation with lettuce (let 2 year) or broccoli (br 2 year), and every fourth year in rotation with broccoliNDASHlettuce/cauliflowerNDASHbroccoli (br 4 year) or lettuce-broccoli-lettuce (let 4 year). Each rotation included four fertility/disease management approaches: 1) bare winter fallow + fertigation for strawberry (bf); 2) winter legume/cereal cover crop before vegetables and ASD prior to strawberry planting and subsequent fertigation (cc); 3) same as for cc except with supplemental compost and organic fertilizer added annually (cc + c + f); and 4) a cereal rye cover crop and m added prior to vegetable and strawberry planting (msm). Strawberry yields and wilt severity were monitored for each crop, and in year 6 (2017) pathogen levels in strawberry crowns were assessed using real-time qPCR. In all three years when strawberries were grown, yields were negatively related to the severity of wilt symptoms, and in year 4 (all rotations) and year 6 (2-year rotation) yields were higher in the br than the let rotations. In year 4, a positive effect of ASD was found in 2-year but not 4-year treatments, and in year six, highest yields were in the ASD treatments and lowest yields in the bf and msm treatments and let rotations. The main pathogen present was Verticillium dahliae, which was significantly reduced by the br rotations and ASD. In year 6, crown infection with V. dahliae was lower in br than let 2-year rotations. Rotation with broccoli and ASD show promise for reducing V. dahliae in organic strawberry production.
Shennan, C., Muramoto, J., Baird, G., Zavatta, M., Nobua, B. and Mazzola, M. (2020). Effects of crop rotation, anaerobic soil disinfestation, and mustard seed meal on disease severity and organic strawberry production in California. Acta Hortic. 1270, 63-70
Verticillium dahliae, soilborne disease, broccoli, lettuce, cover crops