Sustainable Weed Control: In-Row Weed Cultivation Strategies for Midwest Vegetable Growers

View the project final report

Commodities

Practices

• Pest Management: physical control
• Production Systems: organic agriculture

Seed bed preparation and soil management history are thought to have a large impact on the efficacy of mechanical cultivation, but limited information is available on of the mechanisms of these effects, and their implications for management. In a series of field trials on a loamy sand soil, we tested how pre-plant bed preparation (rolled vs not), historic compost use (12 previous years of annual applications vs none), and presence of soil crust (induced through application of molasses or not) influenced soil surface characteristics and the efficacy of flextine cultivation in bush beans (Phaseolus vulgaris) and sweet corn (Zea mays L.). Rolling beds prior to planting generally resulted in lower soil surface roughness, greater soil micro-penetrometer resistance, higher soil moisture content, and reduced efficacy of flextine cultivation compared to unrolled beds. Historic compost and molasses applications had few impacts on these soil characteristics and little or no effect on flextine efficacy. The results of this study challenge conventional cultivation wisdom that rolling seed beds improves cultivation efficacy by facilitating more uniform tine working depth. This potential benefit is offset by increasing soil hardness through compaction, which reduce the capacity of tines to disturb soil and uproot weeds. Our surprising results highlight the importance of characterization of soil conditions in cultivation research.

Table beets (Beta vulgaris) are among the most challenging crops to mechanically cultivate, but improved understanding and exploitation of cultivar differences in emergence, growth and morphological characteristics may improve cultivation success. In a series of field and greenhouse trials, four beet cultivars—Boro (B), Chioggia Guardsmark (CG), Moneta (M), and Touchstone Gold (TG)— were evaluated for their tolerance to deep planting and mechanical cultivation as well as their competitiveness with escaped weeds.  In one set of experiments, seeds of each cultivar were sown at 1, 2, 3 and 4 cm depth and monitored for emergence and early growth under both greenhouse and field conditions. In a separate field experiment, the effects of cultivar, cultivation tool (finger weeder vs hilling disk) and weed competition (none vs escaped weeds) on weed and beet survival, beet yield and final weed biomass were evaluated. We hypothesized that cultivars with greater root biomass and root anchorage force would be more tolerant to finger weeders, while those with greater shoot biomass and height would be more tolerant to hilling. In emergence studies, we found that under greenhouse conditions, B, CG and TG beet varieties could be planted at 3 or 4 cm depth to delay emergence by 1-2 days relative to shallower seeding depths, potentially allowing for a longer window to stale seedbed.  However, under field conditions, emergence from greater depths sometimes resulted in either no apparent difference in emergence timing or reduced total emergence and hence may be an impractical strategy, depending on soil conditions.  In field cultivation studies, we found that cultivars differed in their tolerance to cultivation, as well as competitiveness with weeds.  B had both the highest yield and was the most weed competitive. 

Learning Outcomes:

1. Vegetable farmers will have a greater awareness of in-row weed control technologies and practices.
2. Vegetable farmers, extension educators, and researchers will have a better understanding of how different in-row weed control technologies can be calibrated for various soil conditions.

Action Outcomes:

1. Vegetable farmers will be empowered to try alternative weed management strategies and evaluate them in the context of their specific production system.
2. Vegetable farmers will make in-row weed management decisions that will reduce pesticide use and improve soil health.
3. Researchers and extension educators will make well-rounded recommendations regarding in-row weed cultivation strategies.

Environment/Production Outcomes

1. Vegetable farmers will have the potential of greater profits as a result of reduced weeding costs and higher yields due to reduced weed interference.
2. Environmental sustainability will be improved through potential reductions in herbicide use and preservation of healthy soils.