Integrated Rotation Systems for Soilborne Disease, Weed and Fertility Management in Strawberry/Vegetable Production

Abstract

Organic strawberry/vegetable producers in coastal California face soilborne disease, nutrient, and weed management challenges. In conventional systems, stringent regulations and air quality concerns make the sustainability of fumigantdependent systems uncertain. To evaluate efficacy of anaerobic soil disinfestation (ASD), mustard cake (MC) application and broccoli residue incorporation, we initiated trials at an organic farm (Org) and a conventional farm (Conv) with crop rotation (broccoli (Brassica oleracea L. italica) -strawberries (Fragaria ananassa), cauliflower (Brassica oleracea L. botrytis) -strawberries, or fallow -strawberries) as main plot in June 2011. Sub plots (ASD, MC, ASD+MC, untreated control (UTC), and fumigant (Pic-Clor 60. Conv only)) were applied prior to strawberry in October 2011. Cover crop and lettuce (Lactuca sativa) were grown after strawberries at Org only. Marketable fruit yield, weed density, and disease level were monitored during the strawberry season and soil inorganic N dynamics for the entire period. ASD+MC and ASD produced similar fruit yields as fumigant at the Conv site. ASD+MC produced greater fruit yield than UTC and MC at both sites and ASD at the Org site. ASD and ASD+MC produced high inorganic N in the soil 2 to 3 months after application at both sites. This caused salt damage on strawberry during early growth especially at Conv which may have reduced fruit yields in both treatments. Verticillium dahliae population in soil at strawberry transplanting was less than 1 microsclerotia/g soil at both sites. However, V. dahliae infection on strawberry plants at the end of the harvest season in Org was reduced by ASD and ASD+MC suggesting that the mechanisms of yield increase by ASD involved disease suppression. Weed suppression by ASD and MC was limited. The effect of broccoli rotation in V. dahliae and weed suppression was also limited and no synergistic effect of broccoli rotation with ASD and MC was observed.

Anaerobic soil disinfestation (ASD): a strategy for control of soil borne diseases in strawberry production

“…This was likely due to a combination of enhanced fertility in the early season and disease suppression in the later season. Indeed disease severity was significantly reduced with the ASD treatments (Zavatta et al, 2014). What is particularly interesting, however, is that the numbers of V. dahliae microsclerotia present in the soil were still lower in the ASD treatments almost 2 years later ( Figure 1B).…”

“…There was no significant effect of previous crop on the growth and yield response of strawberries irrespective of the disease management strategy used (see Zavatta et al, 2014, for details). However, when averaged across all previous crop treatments (fallow, broccoli and cauliflower) yields were highest in the ASD treatment with RB+MSM as the carbon source and ASD with RB only ( Figure 1A).…”

“…After strawberries, a legume/cereal mix winter cover crop was planted and followed with summer lettuce in all treatment plots. For management details see Zavatta et al (2014). Briefly broccoli 'Gypsy' and cauliflower 'Snow crown' were grown from June to September 2011 as main plots which were split prior to planting strawberries.…”

Effects of Sudangrass Cover Crop and Soil Solarization on Weed and Pathogen Management in Organic Strawberry Production

“…One disadvantage of anaerobic soil disinfestation is its variable weed control, (Zavatta et al 2014). In multiple California field trials anaerobic soil disinfestation has shown significant but modest, only 29%, reduction, over untreated plots and other times has had no significant effect on weed populations (Fennimore et al 2013, Zavatta et al 2014.…”

“…One disadvantage of anaerobic soil disinfestation is its variable weed control, (Zavatta et al 2014). In multiple California field trials anaerobic soil disinfestation has shown significant but modest, only 29%, reduction, over untreated plots and other times has had no significant effect on weed populations (Fennimore et al 2013, Zavatta et al 2014. Applications of anaerobic soil disinfestation with molasses have provided good control of nutsedge and excellent control of grass and broadleaf weeds in sub-tropical Florida where soil temperatures are warmer during anaerobic soil disinfestation (Rosskopf et al 2010).…”