 |
The Gardener's Almanac |  |
||||
| Index | FAQ's | Links | Photos | Guest book | ||
| Weeds |
|
|
As most gardeners are very much aware, there are a number of weeds that are quick to colonise, but difficult to eradicate.
Small clumps/patches of these weeds can generally be forked out before they become a nuisance, but when large clumps have been allowed to form, chemical control is often the most efficient way to remove them.
Weedkillers should be a last resort, and only used where control by cultural methods have failed.
There are basically three types of weedkiller: contact, which only kills the plant tissue it touches; systemic, which is taken in by the plant and spreads down into the roots and kill the plants off; and residual which are non-selective and often persist in the soil for up to six to eight weeks.
The most effective are based either on glyphosate, ammonium sulphamate or SBK (a brushwood killer).
Always check manufacturer's recommendations for individual herbicide properties and methods of application.
Do's & Dont's;
Always read the instructions on the packaging.
Adherence to these instructions is a legal requirement.
Do not buy more than you need as many weedkillers have short shelf lives.
Wear protective clothing, in particular, gloves, mask and goggles.
Where possible use a pump sprayer as opposed to a watering can, this is both more accurate and more ecconomical
Keep a dedicated sprayer/watering can for use with weedkillers to reduce the risk of contaminating cultivated plants
Apply weedkiller using a spray coarse enough not to drift but fine enough to cover foliage evenly.
Do not spray on windy days.
For small applications use ready-to-use packs.
Weed types;
Bindweed
A twining, fast-growing climber with white, trumpet-like flowers.
This is a difficult weed to eradicate by cultural methods as its roots can extend up to 5m or more.
Persistent digging and hoeing can eradicate bindweed in a couple of years.
Glyphosate based weedkillers are effective when the weed has reached the flowering stage. Earlier spring applications are generally less successful.
Chickweed;
Is an annual weed that continues to grow throughout the winter months.
In smaller areas hand removal is best as hoeing can cause it to transplant, otherwise use a Glyphosate based weedkiller.
Couch grass;
A vigorous, perennial grass that spreads rapidly by rhizomes (underground stems).
If any part of these rhizomes are left in after weeding these will also regenerate, so total clearance is the best course of action.
Refrain from using a rotovator if there is any of this weed about as all it will do is cut the rhizome into small pieces, and make matters worse.
In lawns or grassed areas are affected close mowing may eliminate it.
Glyphosate based weedkillers can be effective on young shoots so a spring application can often be quite successful.
With heavy infestions digging out may be the best course of action.
If the ground is not required for at least six months some of the residual type weedkillers may be effective.
Black plastic sheeting and landscape fabrics can help to suppress the weeds.
After removing the covers an application of a glyphosate weedkiller may be required.
Ground elder;
Another invasive weed that that spreads by rhizomes, and requires similar treatment to 'couch grass'
Glyphosate weedkillers are fairly effective but several applications may be necessary.
Japanese knotweed;
Japanese knotweed is a notifiable weed which can only be disposed of in licensed landfill sites or burned on site.
It was originally planted as an ornamental plant but now is one of the UK's most invasive weeds.
Digging out the roots will deal with small scale infestations.
Repeated applications of glyphosate weedkiller when the weed is 600-1200mm (2'-4') high can sometimes be effective.
Covering small, young clumps with landscape fabric may also provide control.
Field horsetail;
or Marestail as it is sometimes known.
This weed has been around since prehistoric times.
It is a deep-rooted, creeping weed that is difficult to get rid of.
Continued hoeing and pulling out can weaken it, as will repeated applications of glufosinate-ammonium or glyphosate-based weedkillers.
Lawn weedkillers and mowing can suppress it in lawns, and path weedkillers can be effective on paved areas.
Weeds such as brambles, stinging nettles and creeping thistles are perennial weeds that are best dug out completely to prevent spreading.
Always check manufacturer's recommendations for individual herbicide properties and methods of application.
About this Site © The Gardener's Almanac 2005 Top of page