Suppression of weed and insect populations by living cover crop mulches in organic squash production

Abstract

Living mulch systems can provide multiple agronomic and ecosystem benefits, including reducing erosion and decreasing weed and pest pressure. However, inconsistent yields and lack of best practices for weed and pest management have contributed to their lack of adoption by farmers. In 2018 and 2019, living mulch practices for organic zucchini (Cucurbita pepo L.) production were assessed in Wisconsin on certified organic land. Living mulches of Dutch white clover (Trifolium repens), annual ryegrass (Lolium multiflorum), and a mix of Dutch white clover and annual ryegrass were compared with full tillage cultivated ground and straw mulch controls for effect on yield, fruit marketability, weed and pest counts, and weed management time. Mixed species living mulch, cultivated, and straw mulch treatments were consistently higher yielding than clover treatments, while ryegrass had variable results. No differences were observed in the number of squash bug (Anasa tristis) egg clusters per plant across mulch treatments, but clover treatments had fewer adult squash bugs, with ryegrass and mixed species living mulches also trending lower. Lower counts of striped cucumber beetles (Acalymma trivittatum) were also observed in living mulch treatments. Ryegrass and mixed species living mulches were generally more weed suppressive than clover and cultivated aisles, although living mulch treatments generally had more weeds than straw mulched aisles, apart from comparable suppression of grass weeds for ryegrass in 2019. Time required for weed management was greater for the living mulch treatments than straw, while cultivated treatments took longer to manage than all other treatments in 2019 and longer than ryegrass and straw in 2018. Despite higher weed counts in clover than in cultivated aisles in 2019, all living mulches required less time for weed management than cultivation, indicating that managing living mulches with mowing can be more efficient than hand cultivation, even with higher weed counts. Our results support previous evidence that certain living mulch species may reduce pest and weed pressure, but also reinforces that living mulch systems can negatively impact yield depending on species selection and environment.

Weed control, soil health, and yield tradeoffs of between-bed management strategies in organic plasticulture vegetable production

“…These results are aligned with previous work in plasticulture acorn squash (Cucurbita pepo cv. Table Ace) production (Nelson and Gleason, 2018), but contrast with results from Bruce et al (2022) where researchers found that clover/ryegrass and ryegrass living mulch between plastic mulched beds reduced zucchini (Cucurbita pepo cv. Dunja F1) yields compared to a cultivated and straw mulch control.…”

“…Previous research investigating the use of living mulches between plastic mulch beds have focused on comparisons against a narrow set of common grower practices. For example, comparing living mulch treatments to cultivation (Reiners and Wickerhauser, 1995;Rice et al, 2004;Butler, 2012;Reid and Klotzbach, 2013;Ivy et al, 2014;Warren et al, 2015) or straw/dead mulches (Law et al, 2006;Nelson and Gleason, 2018), but few have compared these practices against one another within the same experiment (Law et al, 2006;Bruce et al, 2022). Furthermore, mowing ambient weeds between plastic mulch beds is a common grower practice, but has gone relatively uninvestigated in the literature (Law et al, 2006).…”

Influence of flowering red clover on flower visitation in a sweet corn agroecosystem

“…Living mulches are often investigated for their ability to provide ecosystem services such as weed suppression and/or enhancing populations of arthropod natural enemies (Manandhar & Wright 2016;Kahl et al 2019;Bhaskar et al 2021;Bruce et al 2022;Yurchak et al 2023). Notwithstanding, flowering living mulches may also enhance floral visitor and potentially pollinator abundance through the provision of food.…”

Evaluating Pollination and Weed Control Strategies under Mesotunnel Systems for Organic Muskmelon Production in Iowa

“…However, living mulches may be a viable option for weed control in the furrows because the seed is relatively inexpensive. These mulches can also potentially enhance soil health by incorporating organic matter and limiting erosion (Bhaskar et al 2021;Brown 2017;Bruce et al 2022). Living mulches have been used in cucurbit production under rowcovers (Bruce et al 2022;Nair et al 2014).…”

“…These mulches can also potentially enhance soil health by incorporating organic matter and limiting erosion (Bhaskar et al 2021;Brown 2017;Bruce et al 2022). Living mulches have been used in cucurbit production under rowcovers (Bruce et al 2022;Nair et al 2014). In mesotunnels during an Iowa organic 'Athena' muskmelon trial, however, both seeding red clover (Trifolium pratense) alone and a mixture of annual ryegrass (Lolium multiflorum) plus red clover were ineffective because these mulches were outcompeted by weeds (Nelson 2019).…”