Can "stacking" increase weed control efficacy in hand tools?

Rebecca Champagne1 and Eric Gallandt2

1PhD Candidate, Ecology and Environmental Sciences, and 2Professor, University of Maine

Interim report: February 19, 2021

Take-home points:

  • Two- and three-tool combinations have higher weed control efficacy compared to single tools.

  • Crop mortality did not differ between tools and tool combinations at one true leaf. In table beet, crop mortality at 1-2 true leaves was higher than bush bean mortality.

  • Some tool combinations resulted in antagonism rather than synergy, suggesting tool interference with another tool mode of action. While efficacy was greater than a single tool in these instances, it was not greater than the sum of the individual tools.


An important goal of weed management is improving cultivation tool efficacy. Brown and Gallandt (2018) examined cultivation tool “stacking” or using more than one cultivation tool at a time, with promising results. A cultivator equipped with one, two, or three types of intra-row tools and the resulting efficacy were examined, and increased efficacy was observed when tools were stacked relative to singular tool use. Organic farmers operating at a small scale may rely heavily on weeding labor with hand tools rather than tractor-mounted cultivation tools, especially during the early growth stages of the crop where it is important to manage weeds to give the crop a competitive advantage. However, the efficacy of different hand tools in various crops has not been well studied.


We evaluated the effects of single tools and tool stacking ( Table 1 ) on crop mortality and weed control efficacy with the Terrateck Double Wheel Hoe (Terrateck, Cesson-Sévigné, France) ( Fig. 1 ). Bush bean ( Phaseolus vulgaris ) and table beet ( Beta vulgaris L.) were chosen as the crops of interest to represent large and small seeded crops, respectively. Tool settings were based on recommendations from product technicians and initial tool stacking screening. Condiment mustard ( Brassica juncea ) was used as a surrogate weed and sown over the entire experimental area at crop planting with a Brillion drill.

Table 1. Terrateck tools and their respective abbreviations for this tool trial.

Tool Tool Abbreviation
Finger Weeders F
Biodiscs B
Precidiscs P
L-Sweeps L
Torsion Weeders T
Tine Harrows H

terrateck picture
Figure 1. Terrateck Double Wheel Hoe with torsions (T) followed by L-sweeps (L) on the second tool bar.


Crop mortality was not affected by tool number (1, 2, or 3 tools) in both bush bean and table beet ( p =0.297). However, table beet had higher crop mortality compared to bush bean at 1-2 true leaves (data not shown), and further research should be done in table beet at different growth stages to determine if larger beet plants will be less susceptible to mortality from cultivation with the Terrateck.

Intrarow surrogate weed efficacy was lower for single tools compared to two or three tool combinations in both crops ( Fig. 2 ). Interestingly, tool combinations starting with L-sweeps (L) or Torsions (T) had higher mean efficacy and lower variability than other tool combinations ( Fig. 3 ). The L-sweep +Torsion and Torsion +L-sweep combinations stood out in both crops for their additive effects. It is likely that these tools loosen the soil and partially sever or uproot weeds for the next tool. These tool combinations will be examined more closely going forward.

terrateck graph 1
Figure 2. Mean (± SE) weed control efficacy (%) by tool number, averaged across crops. Different letters indicate significant differences between means at a = 0.05.

Figure 3. Mean (±SE) in-row weed control efficacy (%) for select tool combinations in bush bean. Data is averaged across two experimental runs (n=18).

Next Steps

Additional data from 2020 will be analyzed, including hand weeding time 14 days after cultivation for each tool and tool combination, as well as crop fresh biomass at 40 days after planting to give a best estimate of yield.

Soil disturbance data is currently being analyzed to determine relationships between soil disturbance and efficacy for intra- and inter-row locations for each set of tools.

Tool “disturbance zones” will be determined to obtain better estimates of soil disturbance and efficacy. A soil bin study will be performed to analyze efficacy based on the disturbance zones.

Literature Cited

Brown B., and Gallandt, E.R. (2018). Evidence of synergy with ‘stacked’ intrarow cultivation tools. Weed Research 58: 1-8.