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Weed Control Guidelines
How can weeds be controlled?

Why Control Weeds?
For successful establishment of trees and shrubs, an effective schedule of weed control is essential.

This first diagram illustrates the effect on root and shoot development of weeding different diameter areas around the base of oak transplants. The measurements were taken after a period of several weeks, and the results demonstrate very clearly just how effective weed clearance around growing saplings can be. In effect, there is almost four times the growth on a tree that is effectively cleared of competing weeds.

These first two photographs illustrate even more vividly just how detremental competition from weeds can be upon the growth of young trees. Both specimens have been planted for three years. The one on the far left has struggled within an uncontrolled plot, while the one on the right has flourished under a regime of regular weed control.

Even semi-mature trees, left untended, can suffer. The two contrasting situations illustrated here show trees (on the left) which have been regularly tended, while those on the right have had no weed control - the suffocating growth around the base has only been removed for the purposes of this photograph.

This final series of photographs (all courtesy of the Forestry Commission) illustrates the comparative effectiveness of different forms of weed control on the growth of young Sycamore saplings:

No weed control	Herbicide
Mulch	Total Mulch

When do we control weeds?
Weeds damage and restrict tree growth mainly during the summer months, but dead weeds collapsing on top of trees in the winter can also cause smothering.
The implementation of the first weed control regime each year should be timed to coincide with the soft growth phase of the target weeds. This will occur during mid to late Spring.

Subsequent applications should be made as required up until the end of October.
There are several options to be considered:

Chemical Weeding
This is the most effective method of controlling weeds if the weather is suitable. There are now an ever-increasing number of effective herbicides available, which can be split into two distinct groups:

• Translocated. These herbicides work by exploiting the plant’s own system of transporting natural fluids from one part of the living plant to another. Applied directly onto the plant’s leaves, the chemicals are translocated throughout the plant, even deep into the root system. The effectiveness of these herbicides depends entirely on ensuring that every weed is sprayed sufficiently.
• Residual. These herbicides act within the soil, where they kill the young germinating weeds before they break the soil’s surface. Careful selection of the chemical is needed to ensure that the herbicide used does not damage or retard the growth of the trees.

Mowing
Whilst it may look effective, mowing can actually slow the growth of trees and shrubs by encouraging increased competition for moisture and nutrients. Mowing does however combine well with other weed control methods if a tidy and well-presented site is desired. Removing their cover may also reduce damage by voles.

Cultivation
Traditional methods of weeding such as hoeing and, on a larger scale, ploughing physically cuts off the undesirable weeds below ground level. The leaves and stems can then be left to rot or desiccate. A disadvantage, however, is that some weed species actually multiply faster after this treatment. This method is usually restricted to smaller schemes where regular weeding can be carried out.

Mulching
This is an efficient method of preventing the germination of new weed seeds, but will only be truly effective if existing weeds have been eradicated beforehand by the use of herbicides or very thorough cultivational weeding. Various forms of mulch are available, including plastic, bark, straw, gravel or peat. Occasionally voles can cause problems burrowing under the mulch layer.

How can we help?
At Nicholsons we have several teams of fully trained, qualified and above all experienced weed control specialists. We would be happy to quote on a fixed-price basis for any work which you may require, large or small, whether hand or chemical weeding. For a free advisory visit and a no-obligation quotation please call or e-mail.

Contacts
If you would like further advice on weed control, please check out our interactive diagram by following this link, or contact Nicholson Nurseries, either by telephone or by using the email links on the Contacts page. It is also possible to request a site visit. Nicholsons staff are able to provide this service throughout Oxfordshire and the surrounding counties, and regularly make calls in Buckinghamshire, Warwickshire, Northamptonshire, Gloucestershire, Berkshire, Wiltshire and Worcestershire.