Johnny Sanchez and Eric Gallandt
Graduate Research Assistant in Ecology and Environmental Sciences, University of Maine, Orono, ME, USA; Professor of Weed Ecology, University of Maine, Orono, ME, USA
Interim report: February 26th, 2021
Take-home points:
- There was no difference between surrogates and real weeds in field cultivation susceptibility in 2019, while in 2020 real weeds were significantly less susceptible to cultivation than surrogate weeds
- Differences in efficacy results for each species were true for all tools
- Rates of efficacy across tools for artificial weeds did not reflect those of wild radish, but were similar to surrogate weeds
- Tiny Treffler out-performed all other included hand- and tractor-drawn tine harrows in both years
Problem
Tools for physical weed control are highly heterogenous in design, adjustment, and effectiveness (Gallandt et al. 2018). Moreover, the effectiveness of mechanical weeding implements can be considerably affected by variations in soil conditions, weed growth stage, weed density, and weed population (Duerinckx et al. 2005; Mohler 2001; Rasmussen et al. 2008). A better understanding of how specific design characteristics interact in real-world contexts, is important for the development of improved cultivation tools (Kurstjens and Perdok 2000).
Surrogate weeds are often a key component of studies of physical weed control (Gallandt 2010; Kolb and Gallandt 2012; Melander and McCollough 2020). Surrogate weeds are crop species, closely related to common agricultural weeds, that can respond similarly to weed control tactics (McCollough et al. 2020). Bred as crops, surrogate weeds lack complications such as complex patterns of dormancy (Malik et al. 2010), variable stands (Myers et al. 2005), and intricate emergence patterns (Egley and Williams 1991) often found among real weeds. The objective of this study was to evaluate the ability of broad leaf, cruciferous surrogate weeds to accurately reflect the cultivation susceptibility of related real weeds across six different flex-tine harrows with varying designs and degrees of cultivation aggressiveness.
Approach
Four species of commonly used surrogate weeds, including condiment mustards (Guillenia flavescens L.), (Brassica juncea L.), and (Sinapis alba L.) and canola (Brassica napus L.), were broadcast at a rate of 1,500 seeds m-2 and raked into the soil to simulate a stand of broadleaf weeds (Brown and Gallandt 2018; McCollough et al. 2020; Olsen et al. 2005). To ensure a sufficient stand of weeds, wild radish (Raphanus raphanistrum L.) was also sown in each plot at a target density of at least 50 plants per m^-2 (Gerhards et al 2020; Vanhala 2004). In 2020, 35 mm long wooden golf tees (Golf Tees Etc.) were also included (Kshetri et al. 2019).
To include a wide breadth of designs, six flex-tine harrows were used in this study: Lely tines on a Williams tool bar (Lely, Pella, IA), Tiny Treffler (Man@Machine, Netherlands), Johnny’s Selected Seeds Tine Weeding Rake (Johnny’s Selected Seeds, Fairfield, ME), Two Bad Cats Tine Weeder (Two Bad Cats LLC., North Clarendon, VT), Terrateck Light Tines (Terrateck, France), Terrateck Double Wheelhoe with tines (Terrateck, France). Weed control efficacy and crop mortality were determined by the percentage of plants killed in the permanent subplots (Evans et al. 2012; Kolb et al. 2010).
Results
There was no difference between surrogates and real weeds in field cultivation susceptibility in 2019, while in 2020 real weeds were significantly less susceptible to cultivation than surrogate weeds (Figure 1). Differences in efficacy results for each species were true for all tools. Rates of efficacy across tools for golf tees did not reflect those of wild radish but were similar to surrogate weeds. The Tiny Treffler out-performed all hand- and tractor-drawn tine harrows in both years (Figure 2).
As the two years of this study had contrary outcomes, concerning the accuracy of the reflection of wild radish by cruciferous surrogate weeds, the results of this study are largely inconclusive. While adverse weather conditions and different soil compositions may have led to the overall lower rates of weed control in 2020, the flex-tine harrows performed in nearly the same rank orders, suggesting that these factors did not affect the mean efficacies of each species relative to each other. Despite the extensive use of surrogate weeds in physical weed control research, as McCollough et al. (2020) note, there is simply a dearth of research comparing the competitive ability and response to weed control in the literature. Furthermore, inconclusive results suggest a need for increased thoughtfulness when selecting surrogate weed species and may advocate for similar studies to be conducted using other commonly used surrogate weed species.
References
Brown B, Gallandt E (2018). Evidence of Synergy with ‘Stacked’ Intrarow Cultivation Tools. Weed Res 58: 1–8.
Duerinckx K, Mouazen AM, Ramon AH. (2005). Effects of spring-tine settings and operational conditions on the mechanical performance of a weed harrow tine. Biosystems Engineering. 91: 21-34.
Egley G, Williams R. (1991). Emergence periodicity of six summer annual weed species. Weed Science. 39: 595-600.
Gallandt E. (2010). Evaluation of scale-appropriate weed control tools for the small farm. ONE09-098. Northeast SARE.
Gallandt E, Brainard D, Brown B. (2018). Developments in physical weed control. Pages 1-23 in Integrated weed management for sustainable agriculture. Burleigh Dodds Science Publishing.
Gerhards R, Späth M, Sökefeld M, Peteinatos G, Nabout A, Ayala VR. (2020). Automatic adjustment of harrowing intensity in cereals using digital image analysis. Weed Research. 00: 1-10.
Kolb LN, Gallandt ER. (2012). Weed management in organic cereals: advances and opportunities. Org. Agr. 2: 23-42.
Kshetri S, Jiken J, Steward B, Tang L, Tekeste M. (2019). Investigating effects of interaction of single tine and rotating tine mechanism with soil on weeding performance using simulated weeds. Transactions of the ASABE. 62:1283-1291.
Kurstjens DAG, Perdok UD. (2000). The selective soil covering mechanism of weed harrows on sandy soil. Soil & Tillage Research. 55: 193-206.
Malik M, Norsworthy J, Riley M, Bridges W. (2010). Temperature and light requirements for wild radish (Raphanus raphanistrum) germination over a 12-month period following maturation. Weed Science. 58: 136-140.
McCollough M, Gallandt E, Darby H, Molloy T. (2020). Band Sowing with Hoeing in Organic Grains: I. Comparisons with Alternative Weed Management Practices in Spring Barley. Weed Sci. 68: 285-293.
Melander B, McCollough M. (2020). Influence of intra-row cruciferous surrogate weed growth on crop yield in organic spring cereals. Weed Research. 60: 464-474.
Mohler CL, Marschner CA, Caldwell BA, DiTommaso A. (2016). Weed mortality caused by row-crop cultivation in organic corn-soybean-spelt cropping systems. Weed Technol 30: 648-654.
Myers M, Curran W, Vangessel M, Majek B, Scott B, Mortensen D, Calvin D, Karsten H, Roth G. (2005). The effect of weed density and application timing on weed control and corn grain yield. Weed Technology. 19: 102-107.
Olsen J, Kristensen L, Weiner J, Kristensen L, Weiner J. (2005). Species Effects of density and spatial pattern of winter wheat on suppression of different weed species density and pattern when weeds were controlled by herbicide were also investigated. Weed Sci. 53: 690–694.
Rasmussen J, Bibby BM, Schou AP. (2008). Investigating the selectivity of weed harrowing with new methods. Weed Research. 48: 523-532.
Vanhala P, Kurstjens D, Ascard J, Bertram A, Cloutier DC, Mead A, Raffaelli M, Rasmussen J (2004). Guidelines for physical weed control research: flame weeding, weed harrowing and intra-row cultivation. In: 6th EWRS Workshop on Physical and Cultural Weed Control, Lillehammer, Norway, 8-10 March 2004.
Figures
Figure 1.
Figure 2.
