Weed Control – Removal and Eradication
Control of invasive weeds in the garden can be a difficult task, an understanding of identification and weed control and removal techniques for the home garden can be of great assistance to the gardener. Weeds are the most common garden pest, one years seeding means seven years weeding.
Weed removal techniques for the home garden.
One essential factor in weed control is to prevent seeding. If seeds are allowed to set in any one year they can remain viable in the soil for many years, so consider the old saying “One years seeding means seven years weeding”.
At the very least never allow weeds to flower and set seeds.
Weed Control Methods
- Weed Killer
This is chemical control by using herbicides. These work in different ways, some defoliate the plant, others are systemic and will kill the roots.
Two main types are available.
Broad Spectrum which will kill a wide range of plants
Selective, which will kill a narrow range of plants, usually related to the species.
Weed killer is also available as Contact, Systemic and Residual. Each of these working different ways and may have different long term effects.
- Weed Mat or Smothering
By depriving weeds of light and air many weeds can be controlled using these methods. However some will survive for very long periods even beneath weed mat. The use of black plastic as a short term method works by solarising the weeds, basically the heat builds up beneath the plastic and ‘burns the weeds.
All weeds can eventually be removed by digging, however some are easier than others. The weeds that form small bulbils and small easily broken root fragments that remain viable are the worst, digging can actually spread the weeds unless you carefully sift the soil to remove all of the bulbils and root fragments.
- Over-planting Some weeds can be controlled by over planting. This
works by selecting a more ‘desirable’ plant that will out compete weeds usually by depriving them of light. It is a method that works with some weeds, however not all.
WEED IDENTIFICATION and ERADICATION
Weeds are identified as any plant that is growing where it is not wanted and has a tendency to spread by self seeding, bulblet production or underground rhizomes. Common weeds include:
- Oxalis or ‘Soursob’ Oxalis pes-capres, ‘Creeping Oxalis’Oxalis corniculata.
- Cape Ivy
- English Ivy (Hedera species)
- Onion WeedOnion Weed
- Sticky Weed
- ‘Flat weed’ Hypochoeris radicata
- ‘Sow Thistle’ Sonchus oleraceus
- Tradescantia flaminensis ‘Wandering Jew’
How weeds spread
Weeds spread by seed, seed is easily dispersed by the wind, or by birds. Burrs, bulblets and roots are other methods.
Weeds are either monocots or diocots. Monocots have one leaf on germination, usually parallel veins (most grasses are monocts) . Diocots are broad leaf weeds such as clover, these have a network of veins.
Weeds may be annuals, biennials or perennials
Annual weeds live for one year and then die, they are spread by seed. So prevent seeding.
Biennial weeds produce seed in their second year of life. So again prevent seeding.
Perennial weeds are root based, or bulb based, they can seed and also spread by runners or bulbs. Breaking and dropping roots when removing them can cuase further spread. You need to prevent seeding and destroy or remove the root system.
NON CHEMICAL CONTROL
- Hand weeding is encouraged as this can be done at any time and saves on chemical use.
- Mulching is a great way to prevent weeds from growing.
- Close planting, weeds love open ground so close planting can help suppress weed spread.
- Check introduced plants and (potted plants) for weeds.
- Prevent weeds from flowering, dig, cut mow or cut but do not let them flower.
- Use a hoe to dig weeds to the surface on a hot day, this can kill roots.
- See a weed, remove it as soon as possible, before the root system develops.
By far the most popular chemical controls are Selective weed killers and Systemic weed killers based on glyphosate.
- Selective weed killers target different weeds, such as bindi and clover, or broad leaf weeds.
- Systemic weed killers will kill just about anything they come into contact with.