Grubbing: Grub Hoes

Non-Chemical Weed Control: Grub Hoes, Chris McDonald from Cal-IPC on Vimeo.

Special Tips

For better penetration in hard soils, use longer, skinnier hoe blades. A freshly sharpened blade will increase soil penetration and reduce user fatigue, so keep blades sharp by filing. Blades become dull more quickly when used in rocky or cobbly soils.

Under conditions where the soil is hard, a grub hoe can be used to sever weeds at ground level by scraping, although oscillating hoes are generally preferred for this (see Scuffle Hoeing BMP). In soils that are moist, loamy or soft, a grub hoe may be used to pull out weeds by pulling the hoe across the soil surface.

Consider which of the many grub hoe designs may be most useful for your situation. . Forked hoes are used more for dislodging weed roots in loose soils (see Cultivation BMP). Some hoes are designed for niche uses such as planting tree seedlings (i.e. a hoedad). A variety of hybrid tools are also available that combine a hoe blade with other tool heads. For instance, a mattock combines a pick and a hoe implement in its dual-purpose head.

Optimal Conditions for Use

The grub hoe is most effectively used for plants that crown sprout, are shallowly rooted, or are not too woody, in soils without rocks or cobbles, and in relatively flat terrain.

Caveats

In order for control with a hoe to be successful, all parts of the weed that can produce new plants must be severed from their roots. If the plant can resprout or form underground storage structures, such as nutlets, bulbs, or corms, hoeing plants may not be sufficient to control the population. If hoeing does not completely remove plants that can regrow from plant fragments, the technique may actually help to propagate rather than suppress a weed. Hoeing can disturb soils, creating areas where some weed species may thrive (including tumbleweed Salsola spp., mustards Brassicaspp., and stinkwort Dittrichia graveolens). Soil disturbance may also bury weed seeds promoting future germination through a seed bank.

Potential Hazards to Humans, Environment, and Cultural Resources

Human hazards. Low. The most direct hazard from using a hoe is being struck with the blade or shaft. Workers should be well separated so they do not injure one another when swinging a hoe or striking the blade on the ground. Worker training is advised. A good rule of thumb is 10’ spacing between workers (“watch your dime!”). Closed-toe shoes or boots may prevent or lessen injury if struck on the foot with a hoe. If used too aggressively users may get blisters on their hands or may get fatigued quickly. Workers should use a hoe that allows them to stand upright without too much bending to lessen the strain on the back. Finding the right type of hoe blade, shaft length, balance of the hoe, and regular sharpening may alleviate these problems and improve ergonomics. Repeated stooping can cause significant back injury especially with too short a handle or if the hoe is used improperly or not sized properly for the worker. The short-handled hoe has been banned from use in the professional contractor industry in California for worker-safety reasons.

Cultural resources. Moderate. A hoe can damage objects below ground so it should be used with caution in culturally sensitive areas.

Habitat. Moderate. Hoeing can disturb soil, creating conditions where some weeds thrive, especially in high light environments. This tool can also disturb biological soil crusts in a wildland setting.

Sensitive species. Low-moderate. Hoeing may damage small animal burrows.

Erosion. Low-moderate. Since a hoe is relatively small and is manually powered erosion would become a risk if a large group of people were intensively hoeing a single area, especially if the site was sloped, near a streambank that could erode, or on highly erodible soils.

Consider Combining with the Following Non-Chemical Methods

Other hand tools that can remove woody weeds, such as weed pullers, saws and cutting tools (see BMP’s for those techniques) are useful when working on sites that have a variety of weed types such as annuals and woody or mature perennial weeds. On sites where precision work needs to be conducted, hand pulling or small hand tools may be needed around sensitive plants.

Don’t Use This Technique When/For

If a weed is able to reproduce vegetatively, there is a significant chance the grub hoe will not be an effective tool and may even spread plant fragments around. This includes deeply rooted perennials like perennial pepperweed (Lepidium latifolium) and Japanese knotweed (Fallopia japonica). This also includes weeds that have underground storage structures, (rhizomes, nutlets, bulbs or tubers) such as nutsedges (Cyperus spp.) and Johnsongrass (Sorghum halepense). And it includes weeds that form stolons or resprout from nodes, such as Bermuda grass (Cynodon dactylon) or Cape ivy (Delairea odorata), since the chopping action of the hoe can sever runners and numerous plant fragments may re-root in the soil.

Supplementary Information

Small patches of weeds can be easily and effectively controlled with a grub hoe with few regards to the density of the weed population. It becomes more difficult to hoe large areas and often as weed cover increases it becomes somewhat more difficult to treat every single weed in the population. Often two or more hoeing treatments are needed to catch those weeds that survived the first treatment because they may have been accidentally buried or missed.

A grub hoe can be very effective on small- to medium-sized grasses, but large perennial bunch grasses may not be an appropriate target. As shrub size and woodiness of the stem and roots increase the tool becomes ineffective. Many weedy vines are able to re-sprout from a treatment, including from plant fragments in moist soils, in those cases a grub hoe would be ineffective. Seedlings of all plant growth forms including shrubs, trees and vines can be easily treated with a grub hoe.

As long as the plant being targeted with the hoe does not re-sprout, hoeing will be effective. Many perennials can resprout when cut, even a few inches below the soil surface and hoeing treatments will not be effective. Hoeing can be a successful technique on smaller woody perennials, but it is not applicable when the stem is too woody to cut and a cutting tool would be needed (such as an ax, saw, or loppers).

When used correctly and on susceptible weeds, the grub hoe is a highly effective tool regardless of propagule production. Because the blade is relatively small nearly every plant will need to be treated to stop reproduction, thus with plants that have a high propagule production if a few plants are missed numerous seedlings may germinate next season reducing the time it will take to eliminate the population. A grub hoe could exacerbate infestations of species that readily root from plant fragments (e.g., Cape ivy) and should not be used.

Hoeing will kill the above ground parts of a plant regardless of a species’ seed longevity. This tool also disturbs the soil which may cause some seeds to be buried, benefitting those weeds with moderate and long-lived seeds, perhaps germinating after treatments have ended years later. If treatments are repeated each year and plants do not produce new seed, then this method can be used to control weeds with moderate to long-lived seeds. If plants are difficult to detect, then this method will not work well on plants with long-lived seeds as treatments may not reduce the number of seeds being produced each year.

This technique is best suited to small scale infestations and is not suited for managing medium and large-scale infestations. As scale becomes larger, it is difficult to hoe that area unless labor is increased to levels appropriate to the infestation. Hoeing large areas is sometimes conducted by large groups of volunteers or workers as the tool is relatively easy to use, requires only moderate training and can be used for several hours by healthy volunteers.

When using a hoe on loose or difficult terrain it can become difficult to properly swing a grub hoe without losing balance or risking injury. On the other hand, a long-handled grub hoe can reach weeds that are up or down a short incline where other shorter tools could not reach.

A hoe is somewhat less effective in habitats where water is present due to the fact that severed weeds may be able to re-root and continue growing. This can be mitigated by moving the cut weeds out of wet areas to places where they can dry out and desiccate. While a grub hoe can easily penetrate muddy soils, often muddy habitats can have weed species that resprout from below ground, in that case this tool would be ineffective.

References

DiTomaso J.M. et al. 2013. Weed Control in Natural Areas in the Western United States. UC Weed Research and Information Center: Davis, CA. 544 pp.

Holloran, P., A. Mackenzie, S. Farrell and D. Johnson. 2004. The Weed Workers Handbook a Guide to Techniques for Removing Bay Area Weeds. The Watershed Project, California Invasive Plant Council: Richmond, CA. 120 pp.

Mazoyer, M. and L. Roudart. 2006. A History of World Agriculture from the Neolithic Age to the Current Crisis. Monthly Review Press: New York, NY. 528 pp.

Winter S.R. and Wiese, A.F. 1982. Economical Control of Weeds in Sugarbeets (Beta vulgaris). Weed Science 30:620-623

Authors and Credit

Lead Author: Christopher McDonald, University of California Extension Weed Specialist, UC ANR

Co-authors:None

Additional Contributors:

Phillip Cramer, Revegetation Specialist, Caltrans
Henry DiRocco, Integrated Vegetation Management Specialist, Laguna Canyon Foundation
Aaron Echols, Field Ecologist, Inland Empire Resource Conservation District

Efficacies