Broom & Gorse

Prevention

Prevention is the most important defense against broom and gorse invasion. These plants should never be intentionally planted outside their native habitats (none of these weedy brooms or gorse are native to the United States). Care should be taken to avoid transporting seeds to non-infected areas.

Immediate removal of new populations

Any new stands of broom or gorse should be removed immediately, before they fully establish themselves and begin seed production.

Mowing/Grazing

Smaller plants can be mowed with machinery or grazed by goats (brooms and gorse are unpalatable and potentially toxic to other grazing livestock) before they become too large and woody. Mowing and grazing does not remove the roots of the plants, and they will resprout from the underground root system. This method needs to be repeated annually and can help keep small populations from going to seed. Mowing and grazing can also be a follow-up method to control resprouts that emerge following other control methods. These methods, however, are not selective and may result in damage to native plants that are also in the treated area.

Digging/Pulling

Larger plants can be dug or pulled out using a weed wrench. This is more effective than mowing, as it removes much of the root system and reduces (but does not eliminate) the likelihood of re-sprouting. Digging and pulling plant roots disturbs the soil, which can stimulate broom and gorse seeds to sprout, potentially increasing the local population of these plants. Digging and pulling may be most effective in late summer, when plants are experiencing water stress. This method is laborious and only practical for small areas, or if there is a large pool of volunteer or inexpensive labor available.

Cutting/Sawing

Larger plants that cannot be dug or pulled out can be cut or sawed. Cuts should be made at or below the soil surface to reduce the chance of resprouting. Plants should be cut before they produce seeds, and follow-up control (mowing, grazing, fire or herbicides) should be used on future re-sprouted vegetation. Shredding the stump with an axe may decrease the likelihood of the plant resprouting. Like digging, cutting may be more effective if done during dry months when the plants are already experiencing water stress.

Heavy Equipment

Heavy equipment, such as bulldozers, backhoes, excavators, and brush hogs, can be used to remove dense thickets of broom and gorse. This should not be used in sensitive areas where native species are of concern. Follow-up control (mowing, grazing, fire or herbicides) should be used on future re-sprouted vegetation. Care should be taken to ensure that seeds are not carried by the equipment to off-site locations.

Herbicides

Herbicides can be effective in controlling brooms and gorse. Great care should be taken to avoid non-target species. Direct, manual application of herbicide to invasive plants is the most effective means to accomplish this, but it is laborious. Treating large areas with herbicides may result in standing dead biomass that could increase local fire risk.

Mulching

Applying a 3–4” layer of certified weed-free mulch or straw may inhibit broom and gorse seeds from sprouting. This method can be expensive and time-consuming, and may not be practical in large areas.

Fire

Controlled burning may be used to suppress large infestations of brooms and gorse. Controlled burns must be conducted during the rainy season, which is well after the plants have gone to seed. Fire may also stimulate broom and gorse seeds in the seed bank to germinate, potentially increasing the local population of these plants after the fire. Burned plants may also re-sprout from the root system, and follow-up control methods should be used on re-sprouted vegetation and seedlings.

Biological

There are a number of insects that feed on brooms and gorse, and several have been used but with limited success. Biological control is highly variable, as control agents are often not plant specific and not confined to the target area.

Steam Treatment

High-temperature steam may be applied to soil to destroy seeds near the soil surface. This method can be used to reduce the seed bank in large areas. Steam treatments are not target-specific, and can be expensive.

Cultural

Establishing native plants can prevent the establishment of non-native, invasive species. Native plants should be reintroduced as soon as possible to burned areas and sites where invasive plants have been removed. This is a crucial follow-up control that is often overlooked.

Follow-Up

The control methods listed above are most effective when used in combination with one another. Following the initial removal of the invasive species, annual monitoring and follow-up treatment should occur annually for at least five years. Native plants should be reintroduced to the site immediately, and their success monitored carefully.