MACC

Cutting/Mowing
The time of year is an important factor when using cutting to control woody plants. Cutting plants in the spring just as the plant leafs out is the most effective. At leaf out, the plant’s roots are depleted of stored carbohydrates (or energy reserves) as they move from the roots to the branches in order to feed new growth. Removing the above-ground biomass just after the plants have fully leafed out prevents the plant from easily rebuilding its reserves through photosynthesis. Subsequent cutting of resprouting stems throughout the summer will further deplete the roots. By contrast, cutting during the winter does not remove as many stored carbohydrates, and the plant will resprout vigorously in the spring. Cutting or mowing a plant before its fruits mature can reduce its seed production. For example, cutting in mid-summer can be used to stop seed production in Asiatic bittersweet (Celastrus orbiculatus) vines. However, for cutting or mowing to effectively control the overall vigor and spread of an invasive plant population, it must be done several times during the growing season (June through September) and repeated for many years. Often, cutting is practical only when it can be integrated into an existing field mowing plan.

Pulling
Pulling plants out of the ground can be effective on species that have shallow roots and that do not reproduce through root suckering. For example, it is often possible to pull out most of the root system of glossy buckthorn (Frangula alnus) and garlic mustard (Alliaria petiolata). Some sprouting might occur, but reasonable control may be achieved. By contrast, species such as Asiatic bittersweet (Celastrus orbiculatus), Phragmites, and Japanese knotweed (Polygonum cuspidatum) have extensive root systems that are hard to remove. Plants will resprout vigorously from small sections of root left in the ground. While it is hard to control many species through pulling, if one comes across small, satellite populations it is worth taking the time to pull them out. One downside of pulling is that is disturbs the soil, which may provide a seed bed for other invasive plants to become established. Many aquatic plants reproduce by plant fragments, so thorough removal by hand is difficult except in very small populations. Water chestnut (Trapa natans) reproduces by seed and is an annual, so hand-pulling can be very effective. For a detailed discussion of control of aquatic plants through pulling, please see Section 4.3.1 of Massachusetts DCR’s Generic Environmental Impact Report (GEIR)
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Drawdowns
The temporary drawdown of dammed water bodies can be used to control certain aquatic plants. For example, drawdowns are effective on certain species such as Brazilian elodea (Egeria densa) and less effective on Hydrilla (Hydrilla verticillata). Drawdowns are only applicable in water bodies that can be easily drained. Drawdown can also be used to facilitate other control methods; they help with the placement of benthic barriers (fabrics used to smother invasive plant populations); and drawdowns prior to herbicide application reduce the volume of water that needs to be treated, in turn reducing the cost and amount of chemical used. For additional information on the use of drawdowns to control invasive plants, please see section 4.2 of Massachusetts DCR’s Generic Environmental Impact Report (GEIR). For a summary of drawdowns, please see page 79 of The Practical Guide to Lake Management in Massachusetts.