Analysis of Trace Volatile Compounds Emitted from Flat Ground and Formed Bed Anaerobic Soil Disinfestation in Strawberry Field Trials on California’s Central Coast

Anaerobic soil disinfestation (ASD) is emerging globally as an alternative to fumigant pesticides. To investigate ASD mechanisms, we monitored microbially produced volatile organic compounds (VOCs) and other volatile gases in situ using Fourier Transform Infrared Spectroscopy. Study plots infested with Fusarium oxysporum, Macrophomina phaseolina, and/or Verticillium dahliae included: organic flat ground (fASD, 6.7 + 13.5 megagrams per hectare, Mg/ha, rice bran/broccoli) and uncovered soil treated with mustard seed meal (MSM, 3.4 Mg/ha) at one site performed in fall of 2018; formed bed (bASD, 20 Mg/harice bran), control (UTC) and fumigant (FUM) at a second field site in fall of 2019 and 2021. Here, we present VOC diversity and temporal distribution. fASD generated 39 VOCs and GHGS, including known pathogen suppressors: dimethyl sulfide, dimethyl disulfide, and n-butylamine. bASD produced 17 VOCs and greenhouses gases (GHGs), 12 of which were also detected in fASD but in greater concentrations. Plant mortality and wilt score (fASD: 3.75% ± 4.79%, 2.8 ± 0.8; MSM: 6.25% ± 12.50%, 2.7 ± 0.3; bASD: 61.27% ± 11.26%, 4.1 ± 0.5; FUM: 13.89% ± 7.17%, 2.3 ± 0.2; UTC: 76.63% ± 25.11%, 4.3 ± 1.0) were significantly lower for fASD and MSM versus bASD and UTC (p \u3c 0.05). Only FUM was not statistically different from fASD and MSM, and was significantly lower than UTC and bASD (bASD-FUM, p \u3c 0.05; UTC-FUM, p \u3c 0.05). The cumulative strawberry yield from bASD-treated plots was not different from FUM or UTC (bASD: 60.3 ± 13.6; FUM: 79.4 ± 9.19; UTC: 42.9 ± 12.4 Mg/ha). FUM yield was significantly greater than UTC (p = 0.005). These results, and to a far greater extent, additional challenges faced during both bASD trials, suggest that bASD is not as effective or as feasible at maintaining overall plant health as fASD or traditional fumigants. However, differences in management practices and environmental conditions at both sites across years cannot be fully excluded from consideration and many of our observations remain qualitative in nature

TIF film, substrates and nonfumigant soil disinfestation maintain fruit yields

A 5-year project to facilitate the adoption of strawberry production systems that do not use methyl bromide initially focused on fumigant alternatives and resulted in increased use of barrier films that reduce fumigant emissions. The focus shifted in year 3 to evaluating and demonstrating nonfumigant alternatives: soilless production, biofumigation, anaerobic soil disinfestation (ASD) and disinfestation with steam. In the 2010–2011 strawberry production season, fruit yields on substrates were comparable to fruit yields using conventional methods. Anaerobic soil disinfestation and steam disinfestation also resulted in fruit yields that were comparable to those produced using conventionally fumigated soils. Additional work is in progress to evaluate their efficacy in larger-scale production systems in different strawberry production districts in California

Local Ecosystem Service Use and Assessment Vary with Socio-ecological Conditions: A Case of Native Coffee-Forests in Southwestern Ethiopia

Ecosystem-based management requires the promotion and integration of locally relevant ecosystem services. This needs an understanding of which ecosystem services local people value and how local valuation varies with socio-cultural and market factors. We convened ten focus group discussions and performed 105 household surveys from major indigenous groups and recent settlers about local values of various forest-based ecosystem services in changing landscapes of southwest Ethiopia. We found that the extent of ecosystem service use and assessment depends on socio-cultural background and gender of the informants, as well as income and cultural contributions of these services. Ecosystem service values vary in space and time where local people reported that they increasingly value services as they become scarce or in response to increased demands due to emerging markets or changes in production systems. Local people mostly appreciated a few services of high market value while most ecosystem services are not traded in local markets and hence not highly valued. Some low-rated ecosystem services such as fodder and medicinal plants were nonetheless widely used demonstrating the need to also conserve low rated ecosystem services that are used universally. We suggest promoting socio-cultural and other non-marketable ecosystem services to reduce the over-exploitation or exclusion of specific biodiversity components in conservation activities

A Cropping Systems Approach to Improving Water Use Efficiency in Semi-Arid Irrigated Production Areas

This recently-completed 3-year field study evaluated the effectiveness of winter cover crop incorporation and surface gypsum applications relative to conventional fallows for maintaining/improving soil physical properties, stand establishment and crop productivity in a cropping system relying on saline drainage water for irrigation. Six amendment/soil cover treatments were imposed on a rotation of tomato-tomato-cotton as summer crops. Drainage water accounted for about 70% of the total water applied over the course of the experiment. Yields of toamtoes irrigated with saline water were maintained relative to non-saline irrigation in year 1, but were decreased by 33% in year 2. Estimated cotton lint yields of plants irrigated with saline drainage water in 1994, following two seasons of drainage water irrigation, were similar to yields of plants irrigated exclusively with non-saline water. Soil surface crust strength, measured by micro penetrometer was lower in gypsum and cover-crop amended plots relative to saline water irrigated fallow plots during the period of cotton seedling emergence in 1994 in the third year of the experiment. Water stable aggregation was increased following cover crop incorporation relative to saline fallows. Following two seasons of saline drainage water reuse, emergence of cotton seedlings was highest in gypsum-amended plots, but considerably lower in cover crop incorporated plots. Mechanisms accounting for poor establishment following cover crop incorporation may include higher incidences of seed and seedling pathogens in plots where cover crop residues had been incorporated into the soil, and stubble-reinforced surface crusts that resulted in interconnected slabs that impeded timely seedling emergence. These findings and increasing soil surface ECe and SAR values during the course of this study point to the need for special management practices for sustained crop production if drainage water is routinely used

Can Hedgerows Attract Beneficial Insects and Improve Pest Control? A Study of Hedgerows on Central Coast Farms

The objectives of this study, conducted from 2005 to 2007, were (1) to assess the habitat quality of different hedgerow plants for insect natural enemies and pests, (2) to track the movement of insects from hedgerows into adjacent crop fields and (3) to test the effect of hedgerows on parasitism rates of an economically important pest, the cabbage looper (Trichoplusia ni). This study took place at four farms with hedgerows on the Central Coast of California